Tropical Depression Thirteen Forecast 1
1:15PM EDT SUN SEPT 19 2004

Although these forecasts have been shown reliable, first consult and consider official products released by the National Hurricane Center.

...Yet another tropical depression forms in the eastern Atlantic...

...Based on 1630 UTC observations...

T-numbers are 1.5 for the disturbance in the eastern Atlantic, but most convincingly, QuikSCAT passes of the system show a distinct closed circulation, and show some rain-contaminated barbs of tropical storm force. However, organization within the storm is only par this morning. On the other hand, outflow has begun to become evident, and convection has quickly formed with the low-level circulation; therefore, I allow this to be upgraded to a tropical depression with winds of 25kts.

As of right now, Thirteen and Karl are moving at roughly the same speed around the weak ridge in the eastern Atlantic. Karl is probably moving the slowest it will for the next several days--at the least for enough time to have any effect on the next depression. A northwestward movement will probably be observed in the next couple days, as the storm basically follows the path of Karl; however, as the trough that will carry Karl moves to the northeast, the ridge will be able to build back to the west a little, and so the track forecast shifts back to the left after 96 hours, but maintains a distinct northward component in the forecast, while also decreasing the forward speed. Really, some uncertainty exists in the track forecast beyond 72 hours, as I would not be surprised to see a stall-out and a turn back to the west, and roughly the track forecast calls for this.

The intensity forecast is somewhat modest. Currently, the depression is experiencing light shear beneath the ridge; however, as the storm moves northwestward it may experience some heavier southwesterly shear associated with the trough with low-center past north of 30 latitude and west of 50 longitude. Additionally, the storm may intermittently experience some additional shear from Karl, and some minor surface upwelling from the immediate passing of that hurricane. I will allow the storm to develop into a hurricane through 72 hours, but as the depression intensifies, the reaction between Karl and the new system coudl become a bit more complex, possibly causing an extra northward component to the latter, and certainly a hinderance in intensification through 72 hours before Karl accelerates to sea. The track forecast also attempts to take into account this possibility, but the two systems are separated by about 10 degrees longitude, so the forecast nearly ignores any change to the track. As shear values increase after 72 hours, I call for some weakening, bringing the system back down to 55kts at 96 hours, but shear values are expected to lower again after 96 hours, and I allow the system to re-intensify the storm slightly after 96 hours, bringing the forecast to 60kts in 120 hours. INIT 13.4N 32.1W 25KTS
12HR 13.9N 33.7W 30KTS
24HR 14.3N 35.4W 40KTS
36HR 15.3N 37.3W 50KTS
48HR 16.8N 38.9W 60KTS
72HR 20.0N 41.5W 65KTS
96HR 22.9N 40.9W 55KTS
120HR 24.5N 42.9W 60KTS

Powell

379
WTNT43 KNHC 192046
TCDAT3
TROPICAL DEPRESSION THIRTEEN DISCUSSION NUMBER 1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT SUN SEP 19 2004

THE AREA OF DISTURBED WEATHER BETWEEN THE CAPE VERDE ISLANDS AND
HURRICANE KARL IS WELL ENOUGH ORGANIZED TO BE UPGRADED TO A
TROPICAL DEPRESSION. THE SHIPS AND GFDL MODELS INCREASE THE WIND
SPEED BY 20 AND 45 KT RESPECTIVELY OVER THE NEXT FEW DAYS. THE
OFFICIAL FORECAST IS LESS AGRESSIVE...ONLY INCREASING THE WIND TO 45
KT. THIS IS BASED ON THE SUGGESTION ON SATELLITE IMAGERY THAT THE
OUTFLOW FROM KARL IS IMPINGING ON THE NORTHERN PORTION OF THE
DEPRESSIONS CONVECTION AND MAY HAVE AN INHIBITING EFFECT.

THE INITIAL MOTION ESTIMATE IS 270/06. THE DEPRESSION IS NOT
REPRESENTED WELL IN THE GFS AND IN SEVERAL OTHER MODELS. THE TRACK
FORECAST PHILOSOPHY IS FOR A GENERAL WEST-NORTHWEST TO
NORTHWESTWARD MOTION FOR THE NEXT 120 HOURS TOWARD A WEAKNESS IN
THE SUBTROPICAL RIDGE LEFT BY HURRICANE KARL. THE OFFICIAL TRACK
FORECAST IS SIMILAR TO THE GFDL MODEL.

FORECASTER LAWRENCE

FORECAST POSITIONS AND MAX WINDS

INITIAL 19/2100Z 13.3N 33.2W 30 KT
12HR VT 20/0600Z 13.6N 34.8W 35 KT
24HR VT 20/1800Z 14.6N 37.2W 40 KT
36HR VT 21/0600Z 15.8N 39.3W 45 KT
48HR VT 21/1800Z 17.1N 41.5W 45 KT
72HR VT 22/1800Z 19.0N 44.0W 45 KT
96HR VT 23/1800Z 21.5N 46.0W 40 KT
120HR VT 24/1800Z 25.0N 48.0W 40 KT

601
WTNT23 KNHC 200235
TCMAT3
TROPICAL DEPRESSION THIRTEEN FORECAST/ADVISORY NUMBER 2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL132004
0300Z MON SEP 20 2004

TROPICAL DEPRESSION CENTER LOCATED NEAR 13.2N 34.1W AT 20/0300Z
POSITION ACCURATE WITHIN 45 NM

PRESENT MOVEMENT TOWARD THE WEST OR 280 DEGREES AT 10 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 1004 MB
MAX SUSTAINED WINDS 30 KT WITH GUSTS TO 40 KT.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 13.2N 34.1W AT 20/0300Z
AT 20/0000Z CENTER WAS LOCATED NEAR 13.1N 33.6W

FORECAST VALID 20/1200Z 13.5N 35.6W
MAX WIND 35 KT...GUSTS 45 KT.
34 KT... 60NE 60SE 60SW 60NW.

FORECAST VALID 21/0000Z 13.7N 37.0W
MAX WIND 40 KT...GUSTS 50 KT.
34 KT... 60NE 60SE 60SW 60NW.

FORECAST VALID 21/1200Z 13.9N 38.4W
MAX WIND 45 KT...GUSTS 55 KT.
34 KT... 60NE 60SE 60SW 60NW.

FORECAST VALID 22/0000Z 14.1N 39.9W
MAX WIND 50 KT...GUSTS 60 KT.
50 KT... 20NE 20SE 20SW 20NW.
34 KT... 60NE 60SE 60SW 60NW.

FORECAST VALID 23/0000Z 14.8N 42.9W
MAX WIND 55 KT...GUSTS 65 KT.
50 KT... 20NE 20SE 20SW 20NW.
34 KT... 60NE 60SE 60SW 60NW.

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 250 NM
ON DAY 4 AND 325 NM ON DAY 5...AND FOR INTENSITY NEAR 20 KT EACH DAY

OUTLOOK VALID 24/0000Z 15.3N 45.6W
MAX WIND 55 KT...GUSTS 65 KT.

OUTLOOK VALID 25/0000Z 15.9N 48.6W
MAX WIND 55 KT...GUSTS 65 KT.

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 13.2N 34.1W

NEXT ADVISORY AT 20/0900Z

FORECASTER JARVINEN/AGUIRRE

986
WTNT43 KNHC 200254
TCDAT3
TROPICAL DEPRESSION THIRTEEN DISCUSSION NUMBER 2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT SUN SEP 19 2004

THE INITIAL MOTION ESTIMATE IS 270/10. THIS MOTION IS
EXPECTED TO CONTINUE THROUGH THE NEXT 24 HOURS AROUND THE SOUTHERN
PERIPHERY OF THE DEEP-LAYERED RIDGE TO ITS NORTH...THE SAME RIDGE
THAT IS MOVING KARL. THE CONSENSUS OF THE FORECAST TRACK MODELS
SUGGEST THAT THE SYSTEM WILL MOVE IN A WEST TO WEST-NORTHWEST
DIRECTION. BASED UPON THIS GUIDANCE...THE OFFICIAL FORECAST TRACK
HAS BEEN ADJUSTED SIGNIFICANTLY TO THE LEFT OF THE PREVIOUS
FORECAST TRACK. THIS A MAJOR CHANGE TO THE PREVIOUS FORECAST
PACKAGE.

TD THIRTEEN IS EXHIBITING VERY COLD TOP CONVECTION NEAR THE CENTER
AND INTERMITTENTLY IN A BAND WITHIN 160 NM TO ITS NW. THE SYSTEM
HAS NOT SHOWN ANY SIGNIFICANT ORGANIZATION OVER THE PAST THE
PREVIOUS 6 HOURS AS IT HAS BEEN ENCOUNTERING SOME EASTERLY SHEAR.
DVORAK SATELLITE INTENSITY ESTIMATES FROM BOTH SAB AND TAFB ARE
2.0...JUST BELOW TROPICAL STORM STRENGTH. SINCE THE DEPRESSION IS
NOW FOLLOWING A MORE WESTERLY TRACK THAN PREVIOUSLY FORECASTED...
THE LATEST SHIPS MODEL GUIDANCE INDICATES THAT THE SHEAR OVER THE
SYSTEM WILL DECREASE OVER THE NEXT 36 HOURS... ALLOWING FOR
STRENGTHENING TO A TROPICAL STORM. AFTER THIS TIME THE SHEAR
INCREASES...ALTHOUGH...CONTINUED STRENGTHENING IS FORECAST. THE
OFFICIAL FORECAST FOLLOWS THE SHIPS GUIDANCE.

FORECASTER AGUIRRE/JARVINEN

FORECAST POSITIONS AND MAX WINDS

INITIAL 20/0300Z 13.2N 34.1W 30 KT
12HR VT 20/1200Z 13.5N 35.6W 35 KT
24HR VT 21/0000Z 13.7N 37.0W 40 KT
36HR VT 21/1200Z 13.9N 38.4W 45 KT
48HR VT 22/0000Z 14.1N 39.9W 50 KT
72HR VT 23/0000Z 14.8N 42.9W 55 KT
96HR VT 24/0000Z 15.3N 45.6W 55 KT
120HR VT 25/0000Z 15.9N 48.6W 55 KT

814
WTNT43 KNHC 200831
TCDAT3
TROPICAL DEPRESSION THIRTEEN DISCUSSION NUMBER 3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT MON SEP 20 2004

DVORAK INTENSITY ESTIMATES REMAIN AT 30 KT FROM ALL AGENCIES AND THE
INITIAL INTENSITY IS HELD AT 30 KT. THE DEPRESSION IS MAINTAINING
A SMALL BALL OF CONVECTION NEAR THE PRESUMED CENTER BUT HAS NO
DISCERNABLE OUTFLOW PATTERN AT THIS TIME. INDEED...THE DEPRESSION
IS CAUGHT BETWEEN HURRICANE KARL ABOUT 650 NM TO ITS WEST-NORTHWEST
AND A LARGE BUT DISORGANIZED AREA OF DISTURBED WEATHER TO ITS
SOUTHEAST. THE GFS...NOGAPS...AND UKMET ALL MAKE THE DEPRESSION
THE WEAKEST OF THESE THREE SYSTEMS WITHIN A COUPLE OF DAYS. WHILE
BOTH THE SHIPS AND GFDL GUIDANCE BRING THE DEPRESSION TO HURRICANE
STRENGTH...I AM RELUCTANT TO DO SO GIVEN THE COMPETING SYSTEMS IN
ITS NEAR ENVIRONMENT...AND IT IS QUITE FOSSIBLE THIS DEPRESSION
WILL BE SHORT-LIVED.

THE INITIAL MOTION ESTIMATE IS 275/10. FOR THE NEXT DAY OR SO THE
DEPRESSION SHOULD MOVE GENERALLY WESTWARD UNDERNEATH A MID-LEVEL
RIDGE TO THE NORTHWEST OF KARL. AFTER THAT THERE IS CONSIDERABLE
UNCERTAINTY WITH THE TRACK AS THE GUIDANCE MODELS ARE GIVING A WIDE
VARIETY OF POSSIBLE SOLUTIONS. THE GFS LOSES THE DEPRESSION IN THE
DISTURBANCE TO THE SOUTHEAST...WHILE THE UKMET ENTRAINS IT INTO
KARL. ON THE OTHER HAND...THE GFDL KEEPS THE DEPRESSION AND TAKES
IT WEST AND THEN WEST-SOUTHWEST AS HEIGHTS BUILD IN AFTER KARL
LIFTS OUT...WHILE THE BAM MODELS HAVE VARYING DEGREES OF A BEND TO
THE RIGHT. CURRENTLY THE DEPRESSION IS MOVING FASTER THAN
KARL...INCREASING THE CHANCE OF IT MOVING TO THE WEST-NORTHWEST OR
NORTHWEST ON KARL'S EASTERN PERIPHERY. THE OFFICIAL FORECAST HAS
BEEN ADJUSTED NORTH OF THE PREVIOUS FORECAST TO REFLECT THE
POSSIBILITY OF SOME INTERACTION...BUT THEN BENDS THE TRACK BACK TO
THE WEST NEAR THE END OF THE FORECAST PERIOD UNDER THE ASSUMPTION
THAT KARL WILL LEAVE THE DEPRESSION BEHIND. GIVEN THE VERY
COMPLICATED ENVIRONMENT...THIS IS A RATHER LOW CONFIDENCE FORECAST.

FORECASTER FRANKLIN

FORECAST POSITIONS AND MAX WINDS

INITIAL 20/0900Z 13.5N 34.9W 30 KT
12HR VT 20/1800Z 13.6N 36.4W 35 KT
24HR VT 21/0600Z 14.1N 38.2W 40 KT
36HR VT 21/1800Z 14.5N 39.7W 45 KT
48HR VT 22/0600Z 15.0N 41.5W 50 KT
72HR VT 23/0600Z 17.0N 45.0W 55 KT
96HR VT 24/0600Z 18.0N 48.0W 55 KT
120HR VT 25/0600Z 18.5N 51.0W 55 KT

000
WTNT43 KNHC 201200
TCDAT3
TROPICAL STORM LISA SPECIAL DISCUSSION NUMBER 4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 AM EDT MON SEP 20 2004

VARIOUS SATELLITE SOURCES AND INTENSITY ESTIMATES INDICATE THAT
TROPICAL DEPRESSION THIRTEEN HAS BECOME BETTER ORGANIZED AND HAS
STRENGTHENED. THE FIRST FEW VISIBLE SATELITE IMAGES INDICATE A
BANDING EYE FEATURE IS TRYING TO DEVELOP...AND A 20/0955Z SSMI
OVERPASS REVEALED A SMALL MID-LEVEL EYE WAS PRESENT. SUCH FEATURES
ARE TYPICALLY CHARACTERISTIC OF 45-55 KT TROPICAL CYCLONES. THE
INITIAL INTENSITY ESTIMATE OF 45 KT IS ALSO SUPPORTED BY A 20/0902Z
UW-CIMSS AMSU PRESSURE ESTIMATE OF 999.1 MB. THEREFORE...THE
DEPRESSION IS BEING UPGRADED TO TROPICAL STORM LISA.

THE INITIAL MOTION ESTIMATE IS 275/10. THERE IS NO CHANGE TO THE
PREVIOUS TRACK FORECAST OR REASONING. THIS SPECIAL ADVISORY IS ONLY
TO INDICATE THE INCREASE TO TROPICAL STRENGTH...AND AN INCREASE IN
THE INTENSITY FORECAST.

LISA IS A SMALL AND RATHER COMPACT TROPICAL CYCLONE. AS SUCH...IT IS
SUSCEPTIBLE TO SHARP CHANGES IN INTENSITY...BOTH STRENGTHENING AND
WEAKENING. THE VERTICAL SHEAR IS FORECAST TO REMAIN AROUND 10 KT OR
LESS FOR THE NEXT 24 HOURS...SO STRENGTHENING TO HURRICANE
INTENSITY IS FORECAST. AFTER THAT...LOW TO MODERATE VERTICAL SHEAR
IS EXPECTED TO POSSIBLY PUT A CAP ON THE INTENSIFICATION TREND...SO
ONLY SLOW STRENGTHENING IS FORECAST IN THE 24-48 HOUR PERIOD...WITH
A LEVELING OFF OF THE INTENSITY AFTER THAT. HOWEVER...IF LISA TAKES
A MORE SOUTHERLY TRACK TO THE LEFT OF THE OFFICIAL FORECAST TRACK
...THEN THE SHEAR WILL BE LESS AND MORE STRENGTHENING WOULD BE
POSSIBLE THAN WHAT THE OFFICIAL INTENSITY FORECAST IS INDICATING.

FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS

INITIAL 20/1200Z 13.5N 35.4W 45 KT
12HR VT 20/1800Z 13.6N 36.4W 55 KT
24HR VT 21/0600Z 14.1N 38.2W 65 KT
36HR VT 21/1800Z 14.5N 39.7W 70 KT
48HR VT 22/0600Z 15.0N 41.5W 75 KT
72HR VT 23/0600Z 17.0N 45.0W 75 KT
96HR VT 24/0600Z 18.0N 48.0W 75 KT
120HR VT 25/0600Z 18.5N 51.0W 75 KT

144
WTNT23 KNHC 201440
TCMAT3
TROPICAL STORM LISA FORECAST/ADVISORY NUMBER 5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL132004
1500Z MON SEP 20 2004

TROPICAL STORM CENTER LOCATED NEAR 13.6N 35.9W AT 20/1500Z
POSITION ACCURATE WITHIN 30 NM

PRESENT MOVEMENT TOWARD THE WEST OR 275 DEGREES AT 10 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 998 MB
MAX SUSTAINED WINDS 50 KT WITH GUSTS TO 60 KT.
34 KT....... 40NE 40SE 40SW 40NW.
12 FT SEAS.. 50NE 50SE 50SW 50NW.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 13.6N 35.9W AT 20/1500Z
AT 20/1200Z CENTER WAS LOCATED NEAR 13.5N 35.4W

FORECAST VALID 21/0000Z 13.8N 37.3W
MAX WIND 55 KT...GUSTS 65 KT.
50 KT... 20NE 20SE 20SW 20NW.
34 KT... 50NE 50SE 50SW 50NW.

FORECAST VALID 21/1200Z 14.3N 39.1W
MAX WIND 65 KT...GUSTS 80 KT.
64 KT... 15NE 15SE 15SW 15NW.
50 KT... 30NE 30SE 30SW 30NW.
34 KT... 60NE 60SE 60SW 60NW.

FORECAST VALID 22/0000Z 14.8N 40.6W
MAX WIND 70 KT...GUSTS 85 KT.
64 KT... 15NE 15SE 15SW 15NW.
50 KT... 30NE 30SE 30SW 30NW.
34 KT... 70NE 70SE 70SW 70NW.

FORECAST VALID 22/1200Z 15.5N 42.4W
MAX WIND 75 KT...GUSTS 90 KT.
50 KT... 35NE 35SE 35SW 35NW.
34 KT... 70NE 70SE 70SW 70NW.

FORECAST VALID 23/1200Z 16.8N 45.5W
MAX WIND 75 KT...GUSTS 90 KT.
50 KT... 35NE 35SE 35SW 35NW.
34 KT... 70NE 70SE 70SW 70NW.

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 250 NM
ON DAY 4 AND 325 NM ON DAY 5...AND FOR INTENSITY NEAR 20 KT EACH DAY

OUTLOOK VALID 24/1200Z 17.0N 48.5W
MAX WIND 75 KT...GUSTS 90 KT.

OUTLOOK VALID 25/1200Z 17.0N 51.5W
MAX WIND 75 KT...GUSTS 90 KT.

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 13.6N 35.9W

NEXT ADVISORY AT 20/2100Z

FORECASTER STEWART

451
WTNT43 KNHC 201500
TCDAT3
TROPICAL STORM LISA DISCUSSION NUMBER 5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT MON SEP 20 2004

LISA REMAINS A SMALLER THAN AVERAGE TROPICAL CYCLONE. BANDING
FEATURES HAVE CONTINUED TO IMPROVE THIS MORNING...INCLUDING AND
OCCASIONAL HINT OF A BANDING EYE FEATURE IN VISIBLE IMAGERY.
MICROWAVE IMAGERY FROM 20/0903Z AMSU AND 20/0955Z SSMI OVERPASSES
REVEALED A SMALL MID-LEVEL EYE WAS PRESENT. SUCH FEATURES ARE
TYPICALLY ASSOCIATED WITH 45-55 KT TROPICAL CYCLONES. THE INITIAL
INTENSITY ESTIMATE WAS INCREASED TO 50 KT BASED ON RECENT UW-CIMSS
AND CIRA AMSU PRESSURE ESTIMATES OF 999.1 AND 998 MB...
RESPECTIVELY. THEREFORE...THE INITIAL INTENSITY HAS BEEN MADE
HIGHER THAN THE DVORAK SATELLITE INTENSITY ESTIMATES OF 35 KT FROM
BOTH TAFB AND SAB...AND 30 KT FROM AFWA.

THE INITIAL MOTION ESTIMATE REMAINS 275/10. THERE REMAINS NO
SIGNIFICANT CHANGE TO THE PREVIOUS TRACK FORECAST OR REASONING.
LISA IS EXPECTED TO MOVE IN A WEST TO WEST-NORTHWESTWARD MOTION
THROUGHOUT THE FORECAST PERIOD AS THE SMALL CYCLONE MOVES AROUND
THE PERIPHERY OF A NARROW SUBTROPICAL TO THE NORTH. THE RIDGE
CURRENTLY BETWEEN LISA AND KARL TO THE NORTHWEST IS FORECAST BY
MOST OF THE MODELS TO REMAIN INTACT TO SOME DEGREE. THE NOGAPS
MODEL IS THE ONLY MODEL THAT WEAKENS THE RIDGE AND PULLS LISA
NORTHWARD AFTER 72 HOURS. HOWEVER...NOGAPS IS THE ONLY MODEL THAT
EVEN IDENTIFIES LISA BEYOND 24-36 HOURS...AND IT APPEARS TO BE
SUFFERING FROM ITS USUAL OVERDEVELOPMENT OF THE CYCLONE...WHICH
ALLOWS LISA TO ERODE THE NARROW RIDGE AND MOVE THROUGH IT. THIS
SOLUTION HAS BEEN DISCOUNTED GIVEN THE CURRENT VERY SMALL DIAMETER
OF LISA...AND THE STRONG HIGH PRESSURE SYSTEM TO THE NORTH EXPECTED
TO KEEP THE DIAMETER OF THE CYCLONE SMALLER THAN AVERAGE THROUGHOUT
THE FORECAST PERIOD. THE OFFICIAL FORECAST TRACK IS JUST AN UPDATE
OF THE PREVIOUS TRACK AND IS CLOSE TO THE GFDL AND DEEP BAM MODELS.

SMALL COMPACT TROPICAL CYCLONES LIKE LISA ARE SUSCEPTIBLE TO SHARP
CHANGES IN INTENSITY...BOTH STRENGTHENING AND WEAKENING. THE
VERTICAL SHEAR IS FORECAST TO REMAIN AROUND 10 KT OR LESS FOR THE
NEXT 24 HOURS...SO STRENGTHENING INTO A HURRICANE SEEMS
LIKELY...PERHAPS EVEN BY LATER TODAY. BY 36 HOURS...LOW TO MODERATE
NORTHEASTERLY VERTICAL SHEAR IS EXPECTED TO INHIBIT INTENSIFICATION
...SO ONLY SLOW STRENGTHENING IS FORECAST IN THE LONGER TIME
PERIODS. IF LISA REMAINS SOUTH OF 15N LATITUDE WHERE THE SHEAR IS
EXPECTED TO BE THE STRONGEST...THEN THE INTENSITY WILL LILELY BE
LESS THAN WHAT IS CURRENTLY FORECAST AND INDICATED BY THE SHIPS
INTENSITY MODEL.

FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS

INITIAL 20/1500Z 13.6N 35.9W 50 KT
12HR VT 21/0000Z 13.8N 37.3W 55 KT
24HR VT 21/1200Z 14.3N 39.1W 65 KT
36HR VT 22/0000Z 14.8N 40.6W 70 KT
48HR VT 22/1200Z 15.5N 42.4W 75 KT
72HR VT 23/1200Z 16.8N 45.5W 75 KT
96HR VT 24/1200Z 17.0N 48.5W 75 KT
120HR VT 25/1200Z 17.0N 51.5W 75 KT

752
WTNT43 KNHC 202100
TCDAT3
TROPICAL STORM LISA DISCUSSION NUMBER 6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT MON SEP 20 2004

ALTHOUGH BANDING FEATURES HAVE CONTINUED TO IMPROVE...LISA STILL
REMAINS A SMALL TROPICAL CYCLONE. THE BANDING EYE FEATURE OBSERVED
EARLIER TODAY HAS DISSAPEARED UNDER A STRONG BURST OF DEEP
CONVECTION OVER THE CENTER. THE INCREASED CONVECTIVE STRUCTURE...
THE INCREASE IN THE CENTRAL DEEP CONVECTION...AND A 20/1547Z AQUA1
OVERPASS SHOWING A MID- AND LOW-LEVEL EYE FEATURE ARE MY REASONS
FOR REMAINING HIGHER THAN THE DVORAK SATELLITE INTENSITY ESTIMATES
OF 45 KT FROM BOTH TAFB AND SAB...AND 35 KT FROM AFWA.

THE INITIAL MOTION ESTIMATE IS 280/10. THERE REMAINS NO
SIGNIFICANT CHANGE TO THE PREVIOUS TRACK FORECAST OR REASONING.
LISA IS EXPECTED TO CONTINUE MOVING IN A WEST TO WEST-NORTHWESTWARD
DIRECTION THROUGHOUT THE FORECAST PERIOD AS THE SMALL CYCLONE MOVES
AROUND THE PERIPHERY OF A NARROW SUBTROPICAL RIDGE LOCATED BETWEEN
LISA AND KARL. THE RIDGE IS FORECAST BY MOST OF THE MODELS TO
REMAIN INTACT...DESPITE THE POOR INITIALIZATION OF THE CYCLONE BY
ALL OF THE MODELS EXCEPT FOR NOGAPS. HOWEVER...THE NOGAPS MODEL
APPEARS TO OVERDEVELOPMENT OF THE CYCLONE...WHICH ALLOWS IT TO
ERODE THE NARROW RIDGE AND MOVE NORTHWESTWARD THROUGH IT. ON THE
OTHER HAND...THE GFDL...GFDN...AND DEEP BAM MODELS MOVE LISA
WESTWARD FOR ABOUT 72 HOURS AND THEN SOUTHWESTWARD AS A RIDGE
DEVELOPS TO THE NORTHWEST. UNTIL THE MODELS COME INTO MORE
REASONABLE AGREEMENT...THE OFFICIAL FORECAST REMAINS CLOSE TO THE
PREVIOUS FORECAST TRACKS AND FOLLOWS THE SYNOPTIC PATTERN OF ENOUGH
RIDGING KEEPING THE VERY SMALL TROPICAL CYCLONE MOVING WESTWARD...
WITH A GRADUAL DECREASE IN FORWARD SPEED AS THE RIDGE WEAKENS SOME.

COMPACT TROPICAL CYCLONES LIKE CAN STRENGTHEN FAIRLY QUICKLY...BUT
CAN ALSO WEAKEN JUST AS FAST. THE VERTICAL SHEAR IS FORECAST TO
REMAIN AROUND 10 KT OR LESS FOR THE NEXT 12 TO 18 HOURS...WHICH MAY
ALLOW LISA TO STRENGTHEN INTO A HURRICANE LATER TONIGHT OR TUESDAY.
AFTERWARDS 36 HOURS...LOW TO MODERATE NORTHEAST TO EASTERLY
VERTICAL SHEAR IS EXPECTED TO INHIBIT THE INTENSIFICATION
INTENSIFICATION PROCESS...BUT NOT AS MUCH AS IF IT WAS WESTERLY
SHEAR. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS
INTENSITY FORECAST...WHICH IS CONSISTENT WITH THE SHIPS MODEL...BUT
MUCH HIGHER THAN THE GFDL MODEL.

FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS

INITIAL 20/2100Z 13.8N 36.8W 55 KT
12HR VT 21/0600Z 14.1N 38.2W 65 KT
24HR VT 21/1800Z 14.6N 39.9W 70 KT
36HR VT 22/0600Z 15.2N 41.6W 75 KT
48HR VT 22/1800Z 15.9N 43.2W 75 KT
72HR VT 23/1800Z 16.7N 46.0W 80 KT
96HR VT 24/1800Z 17.0N 49.0W 75 KT
120HR VT 25/1800Z 17.0N 52.0W 75 KT

000
WTNT43 KNHC 210322
TCDAT3
TROPICAL STORM LISA DISCUSSION NUMBER 7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT MON SEP 20 2004

T-NUMBERS FROM TAFB AND SAB BOTH GIVE 45 KTS. THE PREVIOUS
INTENSITY OF 55 KTS IS REDUCED TO 50 KTS FOR THIS ADVISORY.
KARLS OUTFLOW IS BEGINNING TO SHEAR THE SYSTEM AND THIS SHOULD MAKE
ANY STRENGTHENING RATHER DIFFICULT. THE SHIPS MODEL ALSO SUGGESTS
THIS AND THE SYSTEM IS FORECAST TO UNDER GO LITTLE CHANGE DURING
THE NEXT TWO DAYS. AFTER THAT TIME THE SHEAR BEGINS TO WEAKEN AND
THE SYSTEM IS FORECAST TO REACH HURRICANE STRENGTH.

THE INITIAL MOTION ESTIMATE IS 275/10...THE SAME AS IT WAS 24 HOURS
AGO. JEANNE IS MOVING WESTWARD WITHOUT ANY INFLUENCE FROM KARLS
CIRCULATION. THERE REMAINS NO SIGNIFICANT CHANGE TO THE PREVIOUS
TRACK FORECAST OR REASONING. LISA IS EXPECTED TO CONTINUE MOVING IN
A WEST TO WEST-NORTHWESTWARD DIRECTION THROUGHOUT THE FORECAST
PERIOD AS THE SMALL CYCLONE MOVES AROUND THE PERIPHERY OF A NARROW
SUBTROPICAL RIDGE LOCATED BETWEEN LISA AND KARL. THE ONLY MODEL
THAT HAS A HINT OF WHAT IS GOING ON IS THE GFDL...WHICH MOVES THE
SYSTEM WESTWARD AND EVEN SLIGHTLY SOUTH-WESTWARD BEGINNING AT THE 4
DAY FORECAST PERIOD. THE OFFICIAL FORECAST IS ADJUSTED SLIGHTLY TO
THE LEFT TO COME MORE IN LINE WITH THE GFDL.

FORECASTER JARVINEN

FORECAST POSITIONS AND MAX WINDS

INITIAL 21/0300Z 13.8N 37.9W 50 KT
12HR VT 21/1200Z 13.9N 39.4W 50 KT
24HR VT 22/0000Z 14.5N 41.5W 50 KT
36HR VT 22/1200Z 15.1N 43.0W 55 KT
48HR VT 23/0000Z 15.4N 44.3W 55 KT
72HR VT 24/0000Z 15.6N 46.2W 60 KT
96HR VT 25/0000Z 15.7N 48.1W 70 KT
120HR VT 26/0000Z 16.1N 50.0W 70 KT

415
WTNT43 KNHC 210853
TCDAT3
TROPICAL STORM LISA DISCUSSION NUMBER 8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT TUE SEP 21 2004

LISA CONTINUES UNDER NORTHERLY SHEAR CAUSED BY THE OUTFLOW FROM
KARL..WITH THE CENTER IN THE NORTHERN SIDE OF THE VERY COLD
CONVECTIVE MASS. SATELLITE INTENSITY ESTIMATES ARE 55 KT FROM
SAB...AND 45 KT FROM TAFB AND AFWA. THE INITIAL INTENSITY REMAINS
50 KT FOR THIS ADVISORY...AND THIS MIGHT BE A LITTLE CONSERVATIVE.

THE INITIAL MOTION IS 280/10. LISA IS EMBEDDED IN A TROUGH
EXTENDING FROM HURRICANE KARL THROUGH LISA TO A DISTURBANCE
CENTERED NEAR 9.5N31W. EASTERLY LOW-LEVEL FLOW IS SEEN NORTHEAST
OF THE TROUGH AXIS AND WEST TO NORTHWEST FLOW SOUTHWEST OF IT.
THERE SEEM TO BE THREE POTENTIAL TRACK OPTIONS FOR LISA. FIRST...A
CONTINUATION OF THE CURRENT WESTWARD MOTION AS KARL MOVES AWAY AND
RIDGING DEVELOPS NORTH OF LISA. THIS IS FAVORED BY THE NHC98.
SECOND...A TURN TO THE NORTHWEST AND NORTH IN THE WAKE OF KARL.
THIS IS SUPPORTED BY THE NOGAPS AND THE UKMET. FINALLY...A TURN TO
THE SOUTHWEST AS THE DISTURBANCE TO THE SOUTHEAST DEVELOPS. THIS
IS SUPPORTED BY THE GFDL. THE TRACK FORECAST WILL FOLLOW THE
PREVIOUS WESTWARD MOTION AS THERE IS CURRENTLY NO OBVIOUS SIGN THAT
EITHER OF THE OTHER SCENARIOS ARE BEGINNING. ONE SMALL CHANGE IS
TO INTRODUCE A NORTHWESTERLY MOTION AFTER 96 HR...AS LISA WOULD BE
APPROACHING A WEAKNESS IN THE RIDGE TO THE NORTH BY THAT TIME.
THIS IS ANOTHER LOW CONFIDENCE FORECAST.

THE INTENSITY FORECAST IS EVEN LOWER CONFIDENCE. LISA IS A SMALL
SYSTEM BETWEEN TWO LARGER ONES...AND THERE IS A CHANCE THAT IT
COULD GET SWALLOWED...PARTICULARLY BY THE DISTURBANCE TO THE
SOUTHEAST. IF THAT DOES NOT HAPPEN... LARGE-SCALE MODELS ALL
FORECAST SIGNIFICANT NORTHEASTERLY SHEAR ALONG THE FORECAST TRACK
IN 48-72 HR...WHICH COULD CONSIDERABLY DAMAGE LISA. THE SHIPS AND
GFDL BOTH SLOWLY STRENGTHEN LISA IN SPITE OF THE SHEAR...AND THE
OFFICIAL FORECAST FOLLOWS THE SHIPS GUIDANCE. HOWEVER...THERE IS A
CHANCE LISA MIGHT NOT SURVIVE FOR 120 HR.

FORECASTER BEVEN

FORECAST POSITIONS AND MAX WINDS

INITIAL 21/0900Z 14.0N 38.9W 50 KT
12HR VT 21/1800Z 14.3N 40.3W 50 KT
24HR VT 22/0600Z 14.9N 42.0W 50 KT
36HR VT 22/1800Z 15.4N 43.6W 50 KT
48HR VT 23/0600Z 15.8N 45.2W 55 KT
72HR VT 24/0600Z 16.0N 47.5W 60 KT
96HR VT 25/0600Z 16.1N 50.0W 65 KT
120HR VT 26/0600Z 17.5N 51.5W 65 KT

824
WTNT43 KNHC 211500
TCDAT3
TROPICAL STORM LISA DISCUSSION NUMBER 9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT TUE SEP 21 2004

NORTHERLY SHEAR THAT HAD PREVIOUSLY BEEN AFFECTING LISA APPEARS TO
HAVE ABATED...AT LEAST FOR THE TIME BEING. THIS HAS ALLOWED OUTFLOW
TO REDEVELOP IN THE NORTHERN SEMICIRCLE. THE OVERNIGHT BURST OF
DEEP CONVECTION...INDICATED BY CLOUD TOPS COLDER THAN -80C...HAS
PERSISTED FOR MORE THAN 9 HOURS NOW. AN UW-CIMSS AMSU PRESSURE
ESTIMATE OF 987.4 MB...ALONG WITH A CIMSS 3-HR AVERAGE AODT OF
T4.1...OR 66 KT...SUGGEST THAT LISA COULD BE A HURRICANE. HOWEVER
...SUBJECTIVE DVORAK ESTIMATES ARE ONLY 45-55 KT FROM THE THREE
SATELLITE AGENCIES. THEREFORE...THE INITIAL INTENSITY IS BASED ON A
BLEND OF THESE VARIOUS INTENSITY ESTIMATES FOR THE TIME BEING.

THE INITIAL MOTION ESTIMATE IS 285/09. THERE REMAINS NO SIGNIFICANT
CHANGE TO THE PREVIOUS FORECAST TRACK OR REASONING. MOST OF THE NHC
MODEL GUIDANCE HAS BEEN OF LITTLE HELP...EXCEPT FOR THE GFDL...GFDN
AND CANADIAN MODELS. THE GFS...UKMET...AND NOGAPS HAVE ALREADY
MISSED THE SHARP NORTHWARD TURN OF HURRICANE KARL LOCATED TO THE
NORTHWEST OF LISA. THE 12 LOCATION OF KARL WAS ALREADY 18 HOURS
AHEAD OF AND AT LEAST 2 DEGREES OF LONGITUDE EAST OF THOSE MODELS.
THIS SUGGESTS THAT RIDGE LOCATED BETWEEN LISA AND KARL IS STRONGER
THAN THOSE MODELS HAVE BEEN FORECASTING...SO THE OFFICIAL ELANS
MORE HEAVILY TOWARD THE GFDL-GFDN-CANADIAN SOLUTIONS. THE RIDGE TO
THE NORTH OF TINY LISA IS EXPECTED TO REMAIN INTACT AND STRONG
ENOUGH TO STEER THE CYCLONE WEST-NORTHWEST OR WESTWARD UNTIL THE
END OF THE FORECAST PERIOD WHEN A TROUGH IS FORECAST TO DIG
SOUTHWARD BETWEEN 50-55W LONGITUDE AND WEAKEN THE RIDGE SLIGHTLY.
THIS MAY ALLOW LISA TO BRIEFLY GAIN SOME LATITUDE BEFORE THE TROUGH
LIFTS OUT AND THE RIDGE BUILDS BACK IN TO THE NORTH.

MODERATE TO WEAK NORTH TO NORTHEASTERLY SHEAR IS EXPECTED TO AFFECT
LISA FOR THE NEXT 36 HOURS OR SO. AS SUCH...THE INTENSITY IS HELD
CONSTANT DUE TO THE SMALL SIZE OF THE CYCLONE. AFTER THAT...THE
SHEAR IS EXPECTED TO WEAKEN TO 10-15 KT FROM THE EAST AND SOUTHEAST
...WHICH MAY ALLOW FOR SOME MODEST STRENGTHENING TO OCCUR...ASSUMING
LISA SURVIVES THE AFOREMENTIONED SHEAR PATTERN. NOTE-- SINCE LISA
IS A VERY SMALL CYCLONE...IT WILL BE SUBJECT TO RAPID FLUCTUATIONS
IN STRENGTH.

FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS

INITIAL 21/1500Z 14.2N 39.7W 60 KT
12HR VT 22/0000Z 14.6N 41.1W 60 KT
24HR VT 22/1200Z 15.2N 42.7W 60 KT
36HR VT 23/0000Z 15.7N 44.3W 60 KT
48HR VT 23/1200Z 15.9N 45.6W 65 KT
72HR VT 24/1200Z 16.0N 48.0W 65 KT
96HR VT 25/1200Z 16.5N 50.0W 70 KT
120HR VT 26/1200Z 17.5N 52.0W 70 KT

000
WTNT43 KNHC 212101
TCDAT3
TROPICAL STORM LISA DISCUSSION NUMBER 10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT TUE SEP 21 2004

LISA REMAINS A VERY COMPACT TROPICAL CYCLONE AND...AS SUCH...IS
SUBJECT TO RAPID FLUCTUATIONS IN INTENSITY. THIS MAY HAVE BEEN THE
CASE EARLIER TODAY AS AN SSMI OVERPASS INDCIATED THE MID-LEVEL
CIRCULATION/EYE FEATURE BECAME DISPLACED A LITTLE TO THE SOUTHWEST
OF THE LOW-LEVEL CENTER. THIS HAS RESULTED IN SIGNIFICANT
DIFFERENCES IN THE SATELLITE POSITION ESTIMATES. THE INITIAL
POSITION IS BETWEEN THE TWO CIRCULATION CENTERS. HOWEVER...DURING
THE PAST FEW HOURS A BURST OF DEEP CONVECTION...TOPS COLDER THAN
-80C...HAS DEVELOPED INTO A CDO-LIKE FEATURE OVER THE OLDER
LOW-LEVEL CENTER LOCATED FARTHER TO THE EAST. THE INTENSITY REMAINS
UNCHANGED AT 60 KT...WHICH IS ONLY SLIGHTLY HIGHER THAN THE DVORAK
INTENSITY ESTIMATE OF T3.5...OR 55 KT...FROM TAFB.

THE INITIAL MOTION ESTIMATE IS NOW 285/07. ONCE AGAIN...THERE
REMAINS NO SIGNIFICANT CHANGE TO THE PREVIOUS FORECAST TRACK OR
REASONING. MOST OF THE GLOBAL MODELS EITHER LOSE LISA WITHIN 24
HOURS...OR QUICKLY TURN THE CYCLONE NORTHWEST AND THEN NORTHWARD
LIKE THE NOGAPS AND UKMET MODELS ARE INDICATING. HOWEVER...THOSE
TWO MODELS HAVE HAD A PERSISTENT RIGHT-OF-TRACK BIAS THE PAST 24
HOURS SINCE THEY HAVE NOT HANDLED THE RIDGE BETWEEN KARL AND LISA
VERY WELL. WHILE THE AFOREMENTIONED RIDGE IS NARROW...IT IS STRONG
TO KEEP VERY SMALL LISA MOVING WEST TO WEST-NORTHWESTWARD. IN
ADDITION...A LARGE TROPICAL DISTURBANCE LOCATED A FEW HUNDRED MILES
SOUTHEAST OF LISA IS EXPECTED TO INDUCE SOME SOUTHWARD COMPONENT OF
MOTION AS THAT DISTURBANCE CONTINUES TO LIKELY GROW AND INTENSITY.
THE GFDL HAS BEEN THE ONLY MODEL TO CONSISTENTLY PICK UP ON THIS
INTERACTION AND IT FORCES LISA SHARPLY SOUTHWARD IN 48 HOURS. WHILE
THE SPECIFICS OF THE GFDL TRACK ARE LIKELY OVERDONE...ITS
CONSISTENT TREND IN MOVING LISA SOUTHWARD CAN NOT BE IGNORED. A
SLIGHT SOUTHWARD BEND IN THE TRACK IS INDICATED BY THE OFFICIAL
FORECAST. THIS IS ALSO CONSISTENT WITH ALL THE GLOBAL MODELS
FORECASTING A RIDGE TO BUILD OVER AND TO THE EAST OF THE LEEWARD
ISLANDS BY 96-120 HOURS.

DUE TO THE VERY SMALL SIZE OF LISA...NO SIGNIFICANT INTENSITY
INCREASES ARE FORECAST...EVEN THOUGH RAPID FLUCTUATIONS ARE
CERTAINLY POSSIBLE.

FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS

INITIAL 21/2100Z 14.4N 40.3W 60 KT
12HR VT 22/0600Z 14.8N 41.5W 60 KT
24HR VT 22/1800Z 15.2N 43.0W 60 KT
36HR VT 23/0600Z 15.2N 44.5W 65 KT
48HR VT 23/1800Z 15.0N 45.7W 65 KT
72HR VT 24/1800Z 15.0N 47.0W 70 KT
96HR VT 25/1800Z 15.5N 48.5W 75 KT
120HR VT 26/1800Z 17.5N 50.5W 75 KT

000
WTNT43 KNHC 220229
TCDAT3
TROPICAL STORM LISA DISCUSSION NUMBER 11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT TUE SEP 21 2004

ON IR SATELLITE IMAGES...LISA CONTINUES TO APPEAR AS A RATHER SMALL
BLOB OF CONVECTION...WITH LITTLE EVIDENCE OF BANDING FEATURES.
DVORAK INTENSITY ESTIMATES INDICATE NO CHANGE IN STRENGTH SO THE
WIND SPEED IS HELD AT 60 KT. THE CENTER IS ESTIMATED TO BE NEAR
THE EASTERN SIDE OF THE DENSE OVERCAST...WHICH IS CONSISTENT WITH
SOME EAST-NORTHEASTERLY SHEAR OVER THE SYSTEM. THERE IS A LARGE
TROPICAL DISTURBANCE ENCROACHING FROM THE EAST...WHICH COULD CUT
OFF SOME OF THE INFLOW INTO LISA. ALSO...MODERATE VERTICAL SHEAR
IS EXPECTED TO PERSIST OVER THE AREA. ONLY SLOW STRENGTHENING IS
FORECAST...IN ACCORDANCE WITH THE LATEST SHIPS GUIDANCE.

INITIAL MOTION HAS SLOWED A LITTLE...NOW 285/06. THE TRACK FORECAST
IS PROBLEMATIC. ALTHOUGH THE GFDL MODEL CONTINUES TO INDICATE THAT
LISA IS GOING TO TAKE A SOUTHWARD PLUNGE... POSSIBLY DUE TO THE
INFLUENCE OF THE EASTERN DISTURBANCE OR TO THE BUILDING OF A RIDGE
TO THE WEST...GLOBAL MODELS DO NOT SHOW MUCH OF A MID-LEVEL RIDGE
TO THE NORTH OF LISA OVER THE NEXT FEW DAYS. THE TRACK FORECAST FOR
THIS ADVISORY IS A LITTLE SLOWER AND SLIGHTLY TO THE NORTH OF THAT
FROM THE PREVIOUS ADVISORY. THIS IS WEST AND SOUTH OF THE
DYNAMICAL MODEL CONSENSUS...AND FASTER THAN THE LATEST FSU
SUPERENSEMBLE PREDICTION.

THE WIND RADII HAVE BEEN ADJUSTED SLIGHTLY BASED ON A 21Z QUIKSCAT
PASS.

FORECASTER PASCH

FORECAST POSITIONS AND MAX WINDS

INITIAL 22/0300Z 14.4N 40.5W 60 KT
12HR VT 22/1200Z 14.9N 41.6W 60 KT
24HR VT 23/0000Z 15.4N 43.0W 60 KT
36HR VT 23/1200Z 16.0N 44.2W 65 KT
48HR VT 24/0000Z 16.3N 45.2W 65 KT
72HR VT 25/0000Z 16.7N 47.0W 70 KT
96HR VT 26/0000Z 18.0N 48.5W 75 KT
120HR VT 27/0000Z 19.5N 50.0W 75 KT

624
WTNT43 KNHC 220832
TCDAT3
TROPICAL STORM LISA DISCUSSION NUMBER 12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT WED SEP 22 2004

THE SYSTEM CONTINUES AS A RATHER SMALL...AMORPHOUS...BLOB OF DEEP
CONVECTION ON SATELLITE IMAGES. ALTHOUGH THE CLOUD TOPS ARE VERY
COLD...THERE IS LITTLE ORGANIZATION OTHER THAN A CONCENTRATION NEAR
THE CENTER. BASED ON DVORAK CLASSIFICATIONS... THE INTENSITY IS
ADJUSTED DOWNWARD SLIGHTLY. THERE IS SOME CONCERN ABOUT HOW THE
EVOLUTION OF THE STORM WILL BE AFFECTED BY THE DISTURBANCE TO ITS
EAST-SOUTHEAST. THE LATTER SYSTEM COULD ALSO BECOME A TROPICAL
CYCLONE...AND WOULD PROBABLY BE A LARGER ONE THAN LISA. THUS IT IS
POSSIBLE THAT THE LARGER SYSTEM COULD ABSORB LISA. OTHERWISE THE
ENVIRONMENT IS MARGINALLY FAVORABLE FOR STRENGTHENING. THE
OFFICIAL FORECAST SHOWS SOME STRENGTHENING BUT IS BELOW THE SHIPS
GUIDANCE BEYOND 2 DAYS BECAUSE OF THE POTENTIALLY UNFAVORABLE
INFLUENCE OF THE SYSTEM TO THE EAST.

IT IS NOT EASY TO LOCATE THE CENTER...BUT...BECAUSE OF THE MODERATE
EAST-NORTHEASTERLY SHEARING ENVIRONMENT...IT IS ESTIMATED TO BE
NEAR THE EASTERN EDGE OF THE DENSE OVERCAST. THE INITIAL MOTION IS
ESTIMATED TO BE 285/6. TRACK GUIDANCE IS FAR FROM
STRAIGHTFORWARD...WITH CONSIDERABLE SCATTER AMONG THOSE DYNAMICAL
MODELS THAT ARE ABLE TO TRACK A CENTER IN THEIR FORECAST FIELDS.
THE GFDL MODEL SHOWS A SHARP SOUTHWARD TURN FOLLOWED BY A SHARP
NORTHWARD TURN. THE NOGAPS SHOWS ERRATIC MOTION...AND THE GFS
LOSES THE VORTEX IN ITS OUTPUT. ONLY THE U.K. MET OFFICE MODEL
TRACK IS SOMEWHAT CLIMATOLOGICAL...SINCE IT DEPICTS A GRADUAL TURN
TO THE NORTHWEST. THAT DOES NOT SEEM TO BE AN UNREASONABLE
SCENARIO...SINCE I DO NOT EXPECT LISA TO HAVE MUCH OF A MID-LEVEL
RIDGE TO ITS NORTH OVER THE NEXT SEVERAL DAYS. GIVEN THE
UNCERTAINTIES AND DIVERGENCE IN THE MODEL OUTPUT...THE OFFICIAL
FORECAST IS EVEN SLOWER THAN THE PREVIOUS ONE.

FORECASTER PASCH

FORECAST POSITIONS AND MAX WINDS

INITIAL 22/0900Z 14.5N 41.2W 55 KT
12HR VT 22/1800Z 14.8N 42.0W 55 KT
24HR VT 23/0600Z 15.2N 43.2W 55 KT
36HR VT 23/1800Z 15.6N 44.3W 60 KT
48HR VT 24/0600Z 15.8N 45.0W 65 KT
72HR VT 25/0600Z 16.5N 46.5W 70 KT
96HR VT 26/0600Z 17.5N 48.0W 70 KT
120HR VT 27/0600Z 18.5N 49.0W 70 KT

000
WTNT43 KNHC 230304
TCDAT3
TROPICAL STORM LISA DISCUSSION NUMBER 15
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT WED SEP 22 2004

METEOSAT-8 IMAGERY DURING THE PAST FEW HOURS INDICATES THAT THE LOW
LEVEL CENTER OF LISA COMPLETELY SEPARATED FROM THE DEEP CONVECTION.
DURING THE PAST FEW HOURS...THE WELL-DEFINED LOW LEVEL CIRCULATION
HAS BEEN DRIFTING...AND IS NOW NEARLY STATIONARY. FURTHER...THIS
LOW LEVEL CENTER TUCKED UNDER CONVECTION ASSOCIATED WITH THE BROAD
CIRCULATION OF THE TROPICAL DISTURBANCE APPROACHING FROM THE EAST.
IN FACT...NEW CONVECTION IS NOW FORMING NEAR THIS LOW LEVEL
CENTER...AND THE CONVECTIVE BANDS ARRIVING FROM THE EAST ALSO SEEM
BE WRAPPING AROUND THE CENTER OF LISA. THEREFORE...THE MERGER OF
THE TWO SYSTEMS APPEARS TO BE IN PROGRESS. WHILE IT IS STILL
POSSIBLE THAT THE MERGED SYSTEM COULD BECOME FOCUSED ELSEWHERE
WITHIN THE BROAD EAST-WEST ORIENTED CIRCULATION...WE WILL FOR NOW
ASSUME THAT THIS WILL NOT OCCUR AND WILL MAINTAIN THE EXISTING LISA
CIRCULATION AS THE DOMINANT ENTITY.

NOW THAT THE DISTURBANCE MOVING IN FROM THE EAST HAS JUST ABOUT COME
INTO PHASE WITH THE CENTER OF LISA...WITH SOME UNCERTAINTY WE
EXPECT A GENERAL WESTWARD MOTION TO BEGIN WITHIN THE NEXT FEW HOURS
AND THEN CONTINUE THROUGH ABOUT 36 HOURS. NOT SURPRISINGLY...THE
MODELS ARE HANDLING THIS MERGER/INTERACTION IN A VARIETY OF
WAYS AND IT IS DIFFICULT TO FOLLOW A MODEL CONSENSUS...ESPECIALLY
DURING THE FIRST TWO DAYS OF THE FORECAST. THE MODELS DO GENERALLY
AGREE...HOWEVER...ON AN EVENTUAL TURN TO THE NORTHWEST INTO A
WEAKNESS IN THE NARROW SUBTROPICAL RIDGE TO THE NORTH...FOLLOWED BY
A STRONG UPPER-LEVEL TROUGH OVER THE CENTRAL ATLANTIC THAT SHOULD
INDUCE A NORTH-NORTHWESTWARD MOTION BY DAYS 4
AND 5. THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY
BEYOND ABOUT 48 HOURS.

LACKING ANY REASON TO CHANGE THE CURRENT INTENSITY...IT WILL BE HELD
AT 45 KNOTS. NORTHERLY SHEAR IS CURRENTLY IMPACTING LISA...BUT
SHIPS INDICATES THIS SHEAR SHOULD ABATE IN ABOUT 36 HOURS...WHICH
MAY ALLOW FOR SOME GRADUAL STRENGTHENING. THE OFFICIAL FORECAST
CLOSELY FOLLOWS SHIPS AND BRINGS LISA TO HURRICANE INTENSITY BY 72
HOURS.

FORECASTER KNABB/AVILA

FORECAST POSITIONS AND MAX WINDS

INITIAL 23/0300Z 13.2N 41.2W 45 KT
12HR VT 23/1200Z 13.2N 41.8W 45 KT
24HR VT 24/0000Z 13.3N 42.4W 45 KT
36HR VT 24/1200Z 13.5N 43.2W 50 KT
48HR VT 25/0000Z 14.0N 44.2W 55 KT
72HR VT 26/0000Z 16.0N 45.5W 65 KT
96HR VT 27/0000Z 18.5N 47.0W 70 KT
120HR VT 28/0000Z 21.0N 48.0W 70 KT

975
WTNT43 KNHC 230832
TCDAT3
TROPICAL STORM LISA DISCUSSION NUMBER 16
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT THU SEP 23 2004

LISA IS CONTINUING TO MERGE WITH A NEARBY TROPICAL DISTURBANCE. A
LOW- TO MID-LEVEL TROUGH EXTENDING EASTWARD A FEW HUNDRED MILES
FROM THE ESTIMATED CENTER OF THE STORM IS PROBABLY A REFLECTION OF
THIS DISTURBANCE. SATELLITE IMAGERY SUGGESTS THAT MOST OF THE DEEP
CONVECTION IN THIS COMBINED SYSTEM IS NOW BEING PRODUCED BY THE
CIRCULATION OF LISA... AND NOT THE DISTURBANCE. BASED ON DVORAK
CLASSIFICATIONS...THE INTENSITY IS HELD AT 45 KT. LISA'S
UPPER-LEVEL OUTFLOW IS BEING RESTRICTED BY NORTHERLY UPPER-LEVEL
FLOW FROM THE OUTFLOW OF LARGE AND POWERFUL HURRICANE KARL. AS
KARL MOVES FARTHER NORTHWARD...ITS INFLUENCE ON LISA WILL DIMINISH.
NOT MUCH CHANGE IN STRENGTH IS LIKELY UNTIL THE SYSTEM BECOMES
BETTER ORGANIZED AND MORE CONSOLIDATED...WHICH IS LIKELY TO HAPPEN
WITHIN A DAY OR SO.

THE ESTIMATED INITIAL MOTION IS A WESTWARD DRIFT. THERE IS NO
CHANGE TO THE TRACK FORECAST REASONING FROM THE PREVIOUS PACKAGE.
A WEAK RIDGE TO THE NORTH SHOULD STEER LISA SLOWLY WESTWARD TO
WEST-NORTHWESTWARD FOR THE NEXT COUPLE OF DAYS. THEREAFTER A
MID-TROPOSPHERIC TROUGH IN THE VICINITY OF 50W IS LIKELY TO INDUCE A
TURN TOWARD THE NORTHWEST AND NORTH-NORTHWEST. THE OFFICIAL
FORECAST IS VERY SIMILAR TO THE PREVIOUS ONE...AND NEAR THE LEFT
SIDE OF THE DYNAMICAL MODEL SUITE.

FORECASTER PASCH

FORECAST POSITIONS AND MAX WINDS

INITIAL 23/0900Z 13.2N 41.4W 45 KT
12HR VT 23/1800Z 13.3N 41.9W 45 KT
24HR VT 24/0600Z 13.4N 42.6W 45 KT
36HR VT 24/1800Z 13.6N 43.2W 50 KT
48HR VT 25/0600Z 14.2N 44.0W 55 KT
72HR VT 26/0600Z 16.5N 45.5W 65 KT
96HR VT 27/0600Z 19.0N 47.0W 70 KT
120HR VT 28/0600Z 21.5N 48.0W 70 KT

180
WTNT43 KNHC 232046
TCDAT3
TROPICAL DEPRESSION LISA DISCUSSION NUMBER 18
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT THU SEP 23 2004

VISIBLE SATELLITE IMAGERY SHOWS THAT NORTHERLY SHEAR HAS BLOWN AWAY
THE DEEP CONVECTION AND EXPOSED A LOW LEVEL CLOUD CENTER TO THE
NORTHEAST OF WHERE A CENTER LOCATION WAS ESTIMATED ON THE PREVIOUS
ADVISORY. THIS REQUIRES A RELOCATION OF THE CENTER AND IMPLIES
THAT THE CENTER HAS MOVED IN A CYCLONIC OOP OVER THE PAST 24 HOURS
AND IS NOW MOVING ABOUT 300/05. THE GLOBAL TRACK MODELS ARE IN
GOOD AGREEMENT ABOUT A SLOW MOSTLY NORTH-NORTHWESTWARD MOTION
TOWARD A WEAKNESS IN THE SUBTROPICAL RIDGE TO THE NORTH OF LISA.
THE OFFICIAL TRACK FORECAST FOLLOWS A CONSENSUS OF THE GUIDANCE AND
IS ADJUSTED TO THE RIGHT OF THE PREVIOUS ADVISORY DUE TO THE
RELOCATION.

THE ABSENCE OF ANY DEEP CONVECTION NEAR THE CENTER IS GROUNDS FOR
DOWNGRADING LISA TO A TROPICAL DEPRESSION. THE SHIPS MODEL
INDICATES THAT THE VERTICAL SHEAR WILL WEAKEN SOME OVER THE NEXT 72
HOURS AND THE OFFICIAL FORECAST IS FOR MODEST INTENSIFICATION
THROUGH 72 HOURS...A LITTLE MORE THAN SHIPS BUT NOT NEARLY AS
AGGRESSIVE AS THE GFDL MODEL.

FORECASTER LAWRENCE

FORECAST POSITIONS AND MAX WINDS

INITIAL 23/2100Z 14.3N 40.7W 30 KT
12HR VT 24/0600Z 14.4N 41.0W 30 KT
24HR VT 24/1800Z 14.9N 41.9W 30 KT
36HR VT 25/0600Z 16.0N 43.1W 35 KT
48HR VT 25/1800Z 17.3N 44.1W 45 KT
72HR VT 26/1800Z 20.2N 45.2W 55 KT
96HR VT 27/1800Z 23.0N 46.0W 55 KT
120HR VT 28/1800Z 27.0N 47.0W 55 KT

000
WTNT43 KNHC 240237
TCDAT3
TROPICAL DEPRESSION LISA DISCUSSION NUMBER 19
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT THU SEP 23 2004

SHORTWAVE INFRARED IMAGERY DEPICTS A POORLY DEFINED EXPOSED
LOW-LEVEL CIRCULATION CENTER DISPLACED ABOUT 80 NM TO THE NORTHEAST
OF THE REMAINING DEEP CONVECTION. 20 KT OF NORTHEASTERLY SHEAR
CONTINUES TO IMPACT LISA. THE SHIPS MODEL SUGGESTS SLIGHT
WEAKENING OF THE NORTHERLY SHEAR OVER THE NEXT 48 HOURS.
AFTERWARD...THE INTENSITY MODEL INDICATES THAT LISA WILL ENCOUNTER
INCREASING SOUTHWESTERLY SHEAR AHEAD OF AN APPROACHING MID/UPPER
TROUGH FROM THE NORTHWEST. THE GFS INDICATES STRONGER SOUTHWESTERLY
SHEAR BY DAY 4 AND OPENS LISA INTO A WAVE. THE OFFICIAL FORECAST
CALLS FOR GRADUAL STRENGTHENING THROUGH THE ENTIRE FORECAST BUT NOT
QUITE AS GENEROUS AS THE PREVIOUS PACKAGE.

INITIAL MOTION IS 290/6 KT. FORECAST TRACK PHILOSOPHY REMAINS
UNCHANGED FROM THE PREVIOUS ADVISORY. A GRADUAL TURN TO THE
NORTH-NORTHWEST WITHIN A WEAKNESS IN THE SUBTROPICAL RIDGE IS
EXPECTED DURING THE NEXT 48 HOURS. THE OFFICIAL TRACK IS ADJUSTED
TO THE LEFT OF THE PREVIOUS FORECAST TO CONFORM WITH THE CONU
CONSENSUS.

FORECASTER ROBERTS/AVILA

FORECAST POSITIONS AND MAX WINDS

INITIAL 24/0300Z 14.7N 42.0W 30 KT
12HR VT 24/1200Z 15.1N 42.8W 30 KT
24HR VT 25/0000Z 15.9N 44.1W 30 KT
36HR VT 25/1200Z 16.9N 45.1W 30 KT
48HR VT 26/0000Z 18.5N 46.0W 35 KT
72HR VT 27/0000Z 21.0N 47.0W 40 KT
96HR VT 28/0000Z 24.0N 48.0W 45 KT
120HR VT 29/0000Z 28.5N 48.5W 50 KT

000
WTNT43 KNHC 240858
TCDAT3
TROPICAL DEPRESSION LISA DISCUSSION NUMBER 20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT FRI SEP 24 2004

SHORTWAVE AND ENHANCED BD INFRARED IMAGERY SUGGEST THAT THE
PREVIOUSLY EXPOSED LOW-LEVEL CIRCULATION CENTER HAS BEGUN TO MOVE
BENEATH THE NORTHEASTERN EDGE OF THE DEVELOPING DEEP CONVECTION.
THIS LEADS US TO BELIEVE THAT THE NORTHERLY SHEAR MAY BE DECREASING
SOMEWHAT. DVORAK CURRENT SATELLITE INTENSITY ESTIMATES ARE 35 KT
FROM TAFB AND 30 KT FROM SAB. THE INITIAL INTENSITY WILL REMAIN AT
30 KT BASED PRIMARILY ON A 24/0511Z TRMM OVERPASS WHICH INDICATED A
POORLY DEFINED LOW CENTER. SHIPS SUGGESTS WEAKENING OF THE
NORTHERLY SHEAR DURING THE NEXT 48 HOURS. AFTER THE 48 HOUR
PERIOD...THE INTENSITY MODEL INDICATES THAT LISA WILL ENCOUNTER
INCREASING SOUTHWESTERLY SHEAR AHEAD OF AN APPROACHING MID/UPPER
TROUGH FROM THE NORTHWEST...BUT NOT SIGNFICANT ENOUGH TO PREVENT
FURTHER INTENSIFICATION. THE GFS ON THE OTHER HAND INDICATES
STRONGER SOUTHWESTERLY SHEAR AT THE SAME TIMEFRAME AND OPENS THE
TROPICAL CYCLONE INTO A WAVE. THE OFFICIAL FORECAST CALLS FOR
GRADUAL STRENGTHENING THROUGH THE ENTIRE FORECAST AND IS BASED
PRIMARILY ON THE SHIPS MODEL.

INITIAL MOTION IS 280/9 KT. THERE IS NO CHANGE TO THE TRACK FORECAST
REASONING FROM THE PREVIOUS PACKAGE. A WEAKENING RIDGE TO THE NORTH
SHOULD INFLUENCE A WEST-NORTHWEST MOTION DURING THE NEXT 24 HOURS.
THEREAFTER AN APPROACHING MID LEVEL TROUGH SHOULD INDUCE A TURN
TOWARD THE NORTHWEST AND NORTH-NORTHWEST. THE OFFICIAL FORECAST IS
SLIGHTLY TO THE LEFT OF THE PREVIOUS FORECAST AND IS BASED ON THE
CONU CONSENSUS.

FORECASTER ROBERTS/BEVEN

FORECAST POSITIONS AND MAX WINDS

INITIAL 24/0900Z 14.6N 43.5W 30 KT
12HR VT 24/1800Z 15.2N 44.6W 35 KT
24HR VT 25/0600Z 16.5N 45.7W 40 KT
36HR VT 25/1800Z 18.0N 46.5W 45 KT
48HR VT 26/0600Z 19.5N 47.2W 55 KT
72HR VT 27/0600Z 23.5N 47.5W 55 KT
96HR VT 28/0600Z 28.0N 46.0W 60 KT
120HR VT 29/0600Z 33.0N 43.5W 60 KT

000
WTNT43 KNHC 241445
TCDAT3
TROPICAL DEPRESSION LISA DISCUSSION NUMBER 21
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT FRI SEP 24 2004

EARLY MORNING VISIBLE SATELLITE IMAGERY SHOWED THAT THE CENTER OF
THE TROPICAL CYCLONE WAS NEAR THE NORTH EDGE OF THE DEEP
CONVECTION...AND AN 0852 UTC QUIKSCAT DATA SUGGESTED THAT LISA WAS
LIKELY A TROPICAL STORM OVERNIGHT. 12Z DVORAK INTENSITY ESTIMATES
WERE 35 KT FROM ALL AGENCIES. HOWEVER...SINCE THEN THE LOW LEVEL
CENTER HAS ONCE AGAIN BECOME EXPOSED AND IS NOW LOCATED ABOUT 70 NM
NORTH OF THE CONVECTION. THEREFORE LISA WILL REMAIN A 30 KT
TROPICAL DEPRESSION FOR THIS ADVISORY.

THE CENTER HAS BEEN RELOCATED SOUTHWARD BASED ON VISIBLE SATELLITE
IMAGERY. THE INITIAL MOTION IS HARD TO DETERMINE...BUT 24 HOUR
SATELLITE LOOPS SUGGEST THAT LISA COMPLETED ITS ORIGINAL CYCLONIC
LOOP LATE YESTERDAY AND THEN MOVED WEST-SOUTHWESTWARD FOR A TIME
OVERNIGHT. IT IS ASSUMED THAT A WEST-NORTHWEST MOTION WILL RESUME
SHORTLY AND THE INITIAL MOTION IS ESTIMATED TO BE 285/7 KT.

THE FORECAST TRACK REMAINS SIMILAR TO THE PREVIOUS ONE THROUGH 72
HOURS. THE RIDGE NORTH OF LISA WILL CONTINUE TO WEAKEN AS A LARGE
MID/UPPER LEVEL TROUGH MOVES SOUTHEAST INTO THE CENTRAL ATLANTIC.
THIS SHOULD TURN LISA NORTHWESTWARD AND NORTHWARD DURING THE NEXT 48
TO 72 HOURS. IN THE LONGER RANGE...THE GFS AND GFDL INDICATE THAT
THE TROUGH MAY NOT COMPLETELY PICK UP THE CYCLONE WHILE THE NOGAPS
AND UKMET ARE MUCH FASTER AND FURTHER NORTHEAST. THE OFFICIAL
TRACK INDICATES A SOMEWHAT SLOWER MOTION AT 96 AND 120 HOURS THAN
THE PREVIOUS ADVISORY AND LEANS A LITTLE CLOSER TO THE GFS/GFDL
SOLUTION.

GLOBAL MODELS SUGGESTS THAT THE NORTHERLY SHEAR SHOULD WEAKEN A
LITTLE DURING THE NEXT 24-36 HOURS. THE OFFICIAL FORECAST CALLS FOR
SLOW STRENGTHENING THROUGH 72 HOURS THEN LEVELS OFF THE INTENSITY
AS LISA IS EXPECTED TO ENCOUNTER SOUTHWESTERLY SHEAR AHEAD OF THE
MID/UPPER LEVEL TROUGH. THE INTENSITY FORECAST IS NOT NEARLY AS
AGGRESSIVE AS THE SHIPS MODEL...WHICH BRINGS LISA TO A HURRICANE IN
60 HOURS. THE 12Z RUN OF THIS MODEL WAS ALSO INITIALIZED WHEN LISA
APPEARED TO BE STRONGER THAN IT DOES NOW.

FORECASTER BROWN/FRANKLIN

FORECAST POSITIONS AND MAX WINDS

INITIAL 24/1500Z 14.1N 43.3W 30 KT
12HR VT 25/0000Z 14.8N 44.3W 30 KT
24HR VT 25/1200Z 16.3N 45.5W 35 KT
36HR VT 26/0000Z 17.8N 46.2W 40 KT
48HR VT 26/1200Z 19.8N 46.7W 50 KT
72HR VT 27/1200Z 24.0N 46.4W 55 KT
96HR VT 28/1200Z 28.0N 45.0W 55 KT
120HR VT 29/1200Z 31.5N 43.5W 55 KT

000
WTNT43 KNHC 242029
TCDAT3
TROPICAL DEPRESSION LISA DISCUSSION NUMBER 22
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT FRI SEP 24 2004

VISIBLE SATELLITE IMAGERY CONTINUES TO SHOW THAT THE CENTER
OF LISA REMAINS WELL TO THE NORTH OF THE DEEP CONVECTION.
18Z DVORAK DATA T NUMBERS FROM ALL AGENCIES SUPPORT 30 KT
AND LISA WILL REMAIN A TROPICAL DEPRESSION FOR THIS ADVISORY.

BECAUSE THE LOW LEVEL CLOUD SWIRL HAS BEEN EASY TO TRACK TODAY...
THERE IS A LITTLE MORE CONFIDENCE IN DETERMINING THE INITIAL MOTION
FOR THIS ADVISORY. THE CENTER HAS BEEN WOBBLING AROUND A TRACK OF
285/9 KT. THE MODELS REMAIN CONSISTANT IN FORECASTING A TURN TOWARD
THE NORTHWEST AND NORTH DURING THE NEXT 24 TO 48 HOURS AHEAD OF A
MID/UPPER LEVEL TROUGH MOVING SOUTHEASTWARD INTO THE CENTRAL
ATLANTIC. THE OFFICIAL FORECAST FOLLOWS THIS SCENARIO CLOSELY. IN
THE LONGER RANGE THE GLOBAL MODELS INDICATE THAT LISA WILL NOT GET
PICKED UP AHEAD OF THE TROUGH AND ARE NOW FORECASTING A SLOW
NORTHWARD MOTION AT DAYS 4 AND 5. THE OFFICIAL TRACK WAS ADJUSTED
WESTWARD BUT REMAINS A LITTLE NORTHEAST OF GLOBAL MODEL CONSENSUS
AT 96 AND 120 HOURS AND LEANS A LITTLE CLOSER TO THE GFS SOLUTION.

NORTHERLY SHEAR IS STILL FORECAST TO WEAKEN DURING THE NEXT
24-36 HOURS. THE OFFICIAL FORECAST CALLS FOR SLOW STRENGTHENING
THROUGH 72 HOURS THEN LEVELS OFF THE INTENSITY AS LISA IS
EXPECTED TO ENCOUNTER SOUTHWESTERLY SHEAR. THE INTENSITY FORECAST
FOLLOWS THE SHIPS MODEL CLOSELY...BUT IS NOT NEARLY AS AGGRESSIVE AS
THE GFDL MODEL...WHICH MAKES LISA A HURRICANE IN ABOUT 36-48 HOURS.

FORECASTER BROWN/FRANKLIN

FORECAST POSITIONS AND MAX WINDS

INITIAL 24/2100Z 14.4N 44.4W 30 KT
12HR VT 25/0600Z 14.9N 45.5W 35 KT
24HR VT 25/1800Z 16.2N 46.6W 40 KT
36HR VT 26/0600Z 17.8N 47.2W 45 KT
48HR VT 26/1800Z 19.7N 47.6W 50 KT
72HR VT 27/1800Z 23.8N 47.8W 60 KT
96HR VT 28/1800Z 27.5N 47.8W 60 KT
120HR VT 29/1800Z 31.0N 47.8W 60 KT

000
WTNT43 KNHC 252035
TCDAT3
TROPICAL STORM LISA DISCUSSION NUMBER 26
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT SAT SEP 25 2004

LISA AS BEEN WOBBLING AROUND AN ESTIMATED TRACK OF 335/9 KT. THE
EXACT MOTION HAS BEEN SOMEWHAT DIFFICULT TO DETERMINE AS SEVERAL
SMALL CLOUD SWIRLS HAVE BEEN ROTATING AROUND A MEAN CENTER. THE
CONVECTIVE BAND ON THE EAST SIDE HAS WRAPPED CLOSER TO THE CENTER
DURING THE DAY. HOWEVER...CURRENT DVORAK INTENSITY ESTIMATES
REMAIN 35 KT FROM ALL AGENCIES AND LISA WILL REMAIN A 35 KT
TROPICAL STORM ON THIS ADVISORY.

DYNAMICAL MODELS ARE IN FAIRLY GOOD AGREEMENT WITH LISA TRACKING
NORTH-NORTHWEST TOWARD A BREAK IN THE SUBTROPICAL RIDGE OVER THE
CENTRAL ATLANTIC. LATE IN THE FORECAST PERIOD...THERE ARE
DIFFERENCES IN THE MODELS AS A MID-LEVEL RIDGE IS FORECAST TO BUILD
EASTWARD ACROSS THE CENTRAL ATLANTIC. THE NOGAPS AND UKMET WHICH
START OUT WITH A SLOWER NORTHWEST MOTION TURN LISA WEST-NORTHWEST
NEAR THE END OF THE FORECAST PERIOD AS THE RIDGE BUILDS.
HOWEVER...THE GFS AND GFDL WHICH HAVE A FASTER MOTION DO NOT SHOW
AS SHARP A TURN. THE OFFICIAL FORECAST IS ADJUSTED A LITTLE TO THE
RIGHT AND DOES NOT LEAN TOWARD ONE SOLUTION OR THE OTHER...BUT
REMAINS VERY CLOSE TO THE CONSENSUS OF THE GLOBAL MODELS.

THE INTENSITY FORECAST CALLS FOR SLOW STRENGTHENING THROUGH
72 HOURS...THEN LEVELS LISA OFF JUST BELOW HURRICANE STRENGTH.
THIS FOLLOWS THE SHIPS MODEL CLOSELY THROUGH 72 HOURS...THEN
IS A LITTLE MORE CONSERVATIVE AT THE END OF THE FORECAST PERIOD.

FORECASTER BROWN/AVILA

FORECAST POSITIONS AND MAX WINDS

INITIAL 25/2100Z 17.2N 45.8W 35 KT
12HR VT 26/0600Z 18.3N 46.4W 40 KT
24HR VT 26/1800Z 19.8N 47.1W 45 KT
36HR VT 27/0600Z 21.4N 47.9W 50 KT
48HR VT 27/1800Z 23.2N 48.7W 55 KT
72HR VT 28/1800Z 25.5N 50.0W 60 KT
96HR VT 29/1800Z 28.0N 51.0W 60 KT
120HR VT 30/1800Z 30.0N 52.0W 60 KT