[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 012334
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU SEP 01 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM
THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON
SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

TROPICAL DEPRESSION LEE CENTERED NEAR 32.4N 51.5W...OR 675 NM E
OF BERMUDA...AT 01/2100 UTC MOVING NNW 4 KT. MAXIMUM SUSTAINED
WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 1010 MB. SEE LATEST NHC FORECAST/ADVISORY
UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE
INFORMATION. LEE HAS A COMPLETELY EXPOSED LOW-LEVEL CIRCULATION
WITH AN UPPER LOW TO ITS W PUSHING ALL DEEP CONVECTION OVER THE
ERN SEMICIRCLE. INFRARED IMAGERY INDICATES THAT A LARGE AREA OF
DRY AIR IS W OF 50W...WHICH IS ONLY HELPING TO DECOUPLE THE
SURFACE CIRCULATION FROM THE TSTMS. SCATTERED MODERATE
CONVECTION FROM 30N-34N BETWEEN 46W-50W.

TROPICAL DEPRESSION FOURTEEN CENTERED NEAR 19.6N 46.6W...OR 945
NM E OF THE NORTHERN LEEWARD ISLANDS...AT 01/2100 UTC MOVING WNW
10 KT. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40
KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB. SEE LATEST
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT34
KNHC FOR MORE DETAILS. THE LOW-LEVEL CIRCULATION OF T.D. 14 IS
ALSO NOW JUST ABOUT COMPLETELY EXPOSED WITH AN UPPER LOW TO ITS
S PUSHING ALL DEEP CONVECTION OVER THE NRN SEMICIRCLE. SCATTERED
MODERATE CONVECTION IS FROM 19N-24N BETWEEN 43W-51W...ALTHOUGH A
STRONG TSTM HAS DEVELOPED NEAR 20N48W JUST W OF THE CENTER
INDICATING THAT THE DEPRESSION IS TRYING TO HOLD ON. THE UPPER
LEVEL ENVIRONMENT IS NOT EXPECTED TO BECOME THAT FAVORABLE FOR
MUCH STRENGTHENING ALTHOUGH IT COULD BECOME A MINIMAL TROPICAL
STORM IN THE NEXT 24-48 HRS.

A 1008 MB LOW IS EMBEDDED WITHIN THE ITCZ NEAR 8N33W MOVING W
RATHER RAPIDLY AT 20-25 KT...ALTHOUGH SOME OF THIS MOVEMENT
COULD BE DUE TO A REFORMATION OF THE CENTER RATHER THAN PURE
TRANSLATION. THE LOW APPEARS TO HAVE GOOD UPPER LEVEL OUTFLOW TO
ITS S AND W...AND SOME SEMBLANCE OF A CONVECTIVE BAND HAS TRIED
TO FORM OVER THE WRN SEMICIRCLE. SCATTERED MODERATE CONVECTION
FROM 6N-13N BETWEEN 30W-38W. CONDITIONS ARE FAVORABLE FOR
STRENGTHENING AND TROPICAL CYCLONE DEVELOPMENT IS POSSIBLE ANY
TIME WITHIN THE NEXT 36 HRS.

...TROPICAL WAVES...

THE DAKAR UPPER AIR SOUNDING DATA INDICATES THAT A TROPICAL WAVE
MOVED OFF THE COAST AROUND 00 UTC EARLIER TODAY...AND SATELLITE
IMAGERY CONFIRMS THE EXISTENCE OF A WEAK CIRCULATION NEAR 20W. A
WAVE WILL LIKELY BE ADDED TO THE NEXT SURFACE ANALYSIS AT 00 UTC.

TROPICAL WAVE IS ADDED OVER THE WINDWARD ISLANDS ALONG 62W S OF
13N MOVING W 10-15 KT. THIS WAVE IS LIKELY THE SOUTHERN
EXTENSION OF THE WAVE WHICH SPAWNED TROPICAL DEPRESSION FOURTEEN
OVER THE CENTRAL ATLC WATERS...AND WAS OBSERVED IN THE CAYENNE
UPPER AIR SOUNDING AROUND 1200 UTC AUG 31. VISIBLE IMAGERY SHOWS
A SOMEWHAT WELL-DEFINED CIRCULATION MOVING ACROSS TRINIDAD AT
THE MOMENT WITH A CLUSTER OF WIDELY SCATTERED MODERATE
CONVECTION FROM 11N-13N BETWEEN 64W-67W...HEADING TOWARDS THE
ABC ISLANDS.

TROPICAL WAVE MOVING OVER CENTRAL AMERICA ALONG 84W/85W S OF 19N
MOVING W 15 KT. A LARGE CLUSTER OF CONVECTION AND A FAIRLY
WELL-DEFINED MID-LEVEL CIRCULATION IS NOTED OVER THE E PACIFIC
NEAR COSTA RICA AND NICARAGUA AND THE WAVE IS EXTRAPOLATED NWD
FROM THIS OVER THE NW CARIBBEAN. SCATTERED MODERATE/ISOLATED
STRONG S OF 15N BETWEEN 79W-86W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 13N14W 10N19W 13N30W...THEN ALONG
7N36W 13N56W 8N66W 8N80W. ISOLATED MODERATE CONVECTION OVER
SENEGAL AND THE GAMBIA FROM 12N-15N BETWEEN 13W-19W. SCATTERED
MODERATE/ISOLATED STRONG OVER PARTS OF CENTRAL AND NW VENEZUELA.

...DISCUSSION...

GULF OF MEXICO...
A LARGE BUT ELONGATED UPPER LEVEL HIGH IS CENTERED ALONG THE
NORTH AND SOUTH CAROLINA COASTLINE AND AN ASSOCIATED RIDGE AXIS
EXTENDS SWWD OVER THE FLORIDA PANHANDLE TO JUST OFF THE TEXAS
COAST. THIS FEATURE IS PRODUCING A LARGE SWATH OF E/SE FLOW OVER
THE E/CENTRAL GULF OF MEXICO...WHICH ALSO HAPPENS TO BE PUMPING
LARGE AMOUNTS OF TROPICAL MOISTURE OVER THE AREA FROM THE ATLC.
WATER VAPOR IMAGERY SHOWS AN INVERTED UPPER TROUGH LOCATED ON
THE W SIDE OF THE RIDGE...EXTENDING FROM THE ISTHMUS OF
TEHUANTEPEC TO EXTREME NE MEXICO. THE UPPER TROUGH IS PRODUCING
AN AREA OF SCATTERED MODERATE CONVECTION ON ITS DIFFLUENT W SIDE
FROM 21N-28N BETWEEN 91W-100W SOME OF WHICH IS MOVING INLAND
FROM CORPUS CHRISTI TEXAS SWD TO TAMPICO MEXICO. DIURNAL
CONVECTION WHICH DEVELOPED OVER THE YUCATAN PENINSULA IS BEING
DRAWN UP THE E SIDE OF THE TROUGH AND IS NOW S OF 22N BETWEEN
87W-94W. SCATTERED TSTMS HAVE ALSO DEVELOPED OVER FLORIDA AND
CUBA DURING THE DAY AND SOME OF THIS IS DRIFTING WWD OVER OPEN
WATERS FROM 22N-27N BETWEEN 80W-86W. ALTHOUGH GENERAL HIGH PRES
IS CENTERED OVER THE AREA AT THE SURFACE...A WEAK SURFACE TROUGH
HAS DEVELOPED AND EXTENDS FROM A 1012 MB LOW NEAR JACKSONVILLE
FLORIDA...SWWD TO 28N85W 26N94W...AND THIS COULD BE A FOCUS FOR
TSTMS IN THE COMING DAYS. DEEP TROPICAL MOISTURE COVERS
VIRTUALLY THE ENTIRE AREA AT THE MOMENT...WHICH EXPLAINS THE
HIGH COVERAGE OF TSTM ACTIVITY...BUT STRONG NELY FLOW IS
EXPECTED TO DEVELOP IN THE COMING DAYS WHICH WILL PUSH THIS AIR
MASS OVER SRN PARTS OF THE AREA BY MON.

CARIBBEAN...
AN ELONGATED YET SOMEWHAT CLOSED UPPER LOW IS CENTERED BETWEEN
CUBA AND THE CAYMAN ISLANDS...WITH THE TROUGH EXTENDING FROM E
CUBA TO THE YUCATAN COAST OF MEXICO. A FAIRLY SOLID JET IS
RACING FROM NICARAGUA/HONDURAS TO HISPANIOLA AND IS PUMPING
MOISTURE NEWD TOWARD THE W ATLC ALTHOUGH CONVECTION SEEMS TO BE
FOCUSED OVER THE LAND AREAS OF CUBA AND THE YUCATAN WHERE
HEATING IS GREATEST. ELSEWHERE...A TRIO OF UPPER HIGHS ARE
CENTERED NEAR ST. CROIX (18N65W)...N OF COLOMBIA NEAR
14N73W...AND N OF PANAMA NEAR 11N81W. THIS IS KEEPING THE
STRONGEST SUBSIDENCE OVER THE E/CENTRAL CARIBBEAN AND HENCE VERY
LITTLE CONVECTION E OF 80W. A LARGE AREA OF DRY AIR IS EXPECTED
TO REMAIN OVER THE CARIBBEAN THROUGH AT LEAST MON WITH THE
GREATEST MOISTURE LIMITED TO THE FAR SW CARIBBEAN AND NEAR THE
YUCATAN CHANNEL.

WEST ATLANTIC...
IF THE NUMERICAL MODELS ARE CORRECT...AN INTERESTING PATTERN IS
SETTING UP OVER THE W ATLC IN THE NEXT SEVERAL DAYS. CURRENTLY A
WEAK COLD FRONT IS DROPPING DOWN OVER THE W ATLC WATERS N OF THE
AREA AND IS HOOKING UP WITH A 1012 MB LOW WHICH HAS DEVELOPED
NEAR JACKSONVILLE FLORIDA. THE FRONT IS NOT MUCH OF A FRONT AT
ALL WHEN CONSIDERING TEMP/DEWPOINT CONTRASTS BUT THERE IS SOME
SORT OF WIND SHIFT BOUNDARY. IN ADDITION...A 1012 MB LOW HAS
DEVELOPED ABOUT 85 NM SSE OF BERMUDA NEAR 31N64W WITH A TROUGH
EXTENDING SW TO 25N72W. THIS FEATURE LIES JUST W OF AN UPPER LOW
NEAR 31N55W...WITH AN EXTENSIVE TROUGH WHICH EXTENDS SW TO
24N65W TO E CUBA...WHICH THEN CONNECTS TO THE UPPER LOW OVER THE
NW CARIBBEAN. WIDELY SCATTERED MODERATE CONVECTION HAS DEVELOPED
NEAR THE SURFACE TROUGH FROM 24N-30N BETWEEN 60W-71W. THE GFS
DRIFTS THE SURFACE LOW TO THE SW AND DEVELOPS A COMPLEX
MULTICELLULAR LOW JUST NE OF THE BAHAMAS WITHIN 48 HRS. THIS
FEATURE THEN SPLITS WITH ONE LOW MOVING TOWARDS THE NRN BAHAMAS
AS STRONG HIGH PRES DEVELOPS OVER THE EASTERN U.S.

EAST/CENTRAL ATLANTIC...
A PAIR OF TROPICAL DEPRESSIONS...LEE AND FOURTEEN...ARE CENTERED
OVER THE CENTRAL ATLC WATERS AND BOTH ARE INTERMINGLED WITH
STRONG SHEAR-INDUCING UPPER LOWS NEAR 17N51W AND 31N56W. FARTHER
E OVER THE E ATLC...BROAD NWLY FLOW EXTENDS OVER THE SUBTROPICS
E OF 47W AND IS DIGGING AN UPPER TROUGH TOWARDS THE CANARY
ISLANDS THEN LIFTING NEWD TOWARDS MOROCCO AND PORTUGAL. A
SHORTWAVE IS DROPPING DOWN THE BACK SIDE OF THE TROUGH AND IS
EXPECTED TO DEVELOP A CUT-OFF LOW JUST SW OF THE AZORES IN THE
NEXT 48 HRS. A WEAK UPPER HIGH IS LOCATED S OF THE TROUGH NEAR
18N36W WITH FAIRLY CONSISTENT EASTERLY FLOW S OF 15N.

$$
BERG


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