[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 111756
TWDAT

TROPICAL WEATHER DISCUSSION...UPDATED
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON OCT 11 2010

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1745 UTC.

...SPECIAL FEATURES...

A 1007 MB LOW IS CENTERED OFF THE COAST OF HONDURAS NEAR 16N84W
WITH A SURFACE TROUGH EXTENDING NE OF THE LOW CENTER TO NEAR
21N81W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION COVERS
THE NW CARIBBEAN BASIN AND PORTIONS OF CENTRAL AMERICA FROM
14N-23N BETWEEN 80W-86W. SATELLITE IMAGERY AND SFC OBSERVATIONS
OVER THE PAST 3 TO 6 HOURS INDICATE THAT THE LOW PRESSURE SYSTEM
HAS BECOME BETTER DEFINED THIS MORNING. THEREFORE...THERE IS A
HIGH CHANCE OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING
THE NEXT 48 HOURS AS IT MOVES WEST-NORTHWESTWARD AT AROUND 9 KT.
IF A TROPICAL CYCLONE DEVELOPS...TROPICAL STORM WATCHES AND/OR
WARNINGS WOULD BE REQUIRED FOR PORTIONS OF THE COAST OF
HONDURAS...BELIZE...AND THE YUCATAN PENINSULA OF MEXICO.
REGARDLESS OF DEVELOPMENT...HEAVY RAINFALL IS POSSIBLE OVER
PORTIONS OF NICARAGUA...HONDURAS...THE CAYMAN ISLANDS...BELIZE
...AND THE YUCATAN PENINSULA DURING THE NEXT COUPLE OF DAYS.

...TROPICAL WAVES...

TROPICAL WAVE EXTENDS FROM 12N71W TO 21N63W MOVING WNW AT 15 KT.
A GREAT PART OF THE WAVE HAS BECOME EMBEDDED WITHIN LARGER
SYNOPTIC-SCALE TROUGHING THAT EXTENDS FROM THE CENTRAL ATLC TO
NORTH OF HISPANIOLA. WHILE NO SIGNIFICANT DEEP CONVECTION IS
OBSERVED ON SATELLITE IMAGERY THIS AFTERNOON...A FEW POSSIBLE
AREAS OF WEAK SCATTERED SHOWERS MAY DEVELOP OVER THE NE AND
CENTRAL BASIN...ESPECIALLY NEAR THE SOUTHERN COASTAL WATERS OF
PUERTO RICO AND HISPANIOLA DURING THE LATE AFTERNOON HOURS.

...ITCZ...

A SURFACE TROUGH NEARLY PARALLELS THE WEST COAST OF AFRICA WITH
AXIS ALONG 15W FROM 6N TO 15N. THE ITCZ AXIS IS ANALYZED JUST
WEST OF THE SURFACE TROUGH NEAR 9N17W WESTWARD ALONG 7N25W
9N37W 7N47W 5N58W. SCATTERED MODERATE TO ISOLATED STRONG
CONVECTION IS WITHIN 200 NM SOUTH OF THE AXIS E OF 29W. SIMILAR
CONVECTION IS 160 NM ON NORTH OF THE AXIS BETWEEN 29W AND 50W.

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR IMAGERY AND UPPER LEVEL SATELLITE DERIVED WINDS
DISPLAY A VERY DRY AND STABLE AIRMASS ALOFT EMBEDDED IN THE
QUASI-ZONAL FLOW THAT COVERS THE GULF. THESE UPPER LEVEL
FEATURES SUPPORT FAIR WEATHER ACROSS THE REGION ANCHORED BY A
NEARLY STATIONARY 1018 MB HIGH AROUND 27N88W. THIS FEATURE IS
BRINGING LIGHT ANTI-CYCLONIC FLOW ACROSS THE ENTIRE GULF WITH
ONLY A FEW PATCHES OF LOW LEVEL STRATOCUMULUS CLOUDS OVER THE
AREA. STRONG SUBSIDENCE WILL CONTINUE OVER THE REGION FOR THE
NEXT 24 HOURS WITH NO SIGNIFICANT CHANGES EXPECTED.

CARIBBEAN SEA...
TOTAL PRECIPITABLE WATER IMAGERY INDICATES ELEVATED VALUES OF
MOISTURE ACROSS THE WESTERN CARIBBEAN SEA BETWEEN 80W AND 85W.
WITHIN THIS REGION OF DEEP LAYER MOISTURE...CYCLONIC FLOW OF
15-20 KT ROTATES AROUND THE SPECIAL FEATURE LOW PRESSURE SYSTEM
DISCUSSED ABOVE...PRODUCING SCATTERED MODERATE TO ISOLATED
STRONG CONVECTION FROM 14N-23N BETWEEN 80W-86W. SIMILAR
CONVECTION IS OVER THE SW BASIN S OF 14N BETWEEN 74W AND 82W.
ASIDE THE SPECIAL FEATURE AND ASSOCIATED CONVECTION...FAIR
WEATHER IS ELSEWHERE ACROSS THE AREA UNDER THE INFLUENCE OF DRY
AIR ALOFT NOTED ON WATER VAPOR IMAGERY. ONLY A FEW POSSIBLE
AREAS OF WEAK SCATTERED SHOWERS MAY DEVELOP OVER THE NE AND
CENTRAL BASIN...ESPECIALLY NEAR THE SOUTHERN COASTAL WATERS OF
PUERTO RICO AND HISPANIOLA THIS AFTERNOON...DUE TO A FAINTED
TROPICAL WAVE WITH AXIS ALONG 18N66W TO 13N71W.

ATLANTIC OCEAN...
A SURFACE TROUGH EXTENDS ACROSS THE CENTRAL ATLC ALONG 27N55W
23N64W 20N72W. THIS TROUGH IS WELL DEPICTED IN TOTAL PRECIP
WATER IMAGERY...BUOY OBSERVATIONS...AND LOW LEVEL SATELLITE
DERIVED WINDS. SCATTERED WEAK TO ISOLATED MODERATE CONVECTION IS
FOUND WITHIN 130 NM WEST OF THE TROUGH AXIS AND 180 NM EAST OF
THE AXIS. THE RIGHT-REAR QUADRANT OF A FAIRLY SHARP SUB-TROPICAL
JETSTREAK WITH AXIS FROM 28N64W TO 35N41W FURTHER SUPPORTS THIS
SYSTEM PROVIDING AN UPPER LEVEL DIFFLUENCE ENVIRONMENT TO IT.
COMPUTER MODELS SUGGEST THIS SYSTEM WILL SLOWLY SHIFT EAST OVER
THE NEXT 24 HOURS...FOLLOWED BY WEAKENING/DISSIPATION OVER THE
NEXT 48 TO 72 HOURS. FAIR WEATHER CONDITIONS ARE ELSEWHERE
ACROSS THE BASIN...UNDER THE INFLUENCE OF A ZONAL WESTERLY FLOW
OVER THE W ATLC W OF 65W WITH STRONG SUBSIDENCE AND DRY STABLE
AIR...AND A STRONG UPPER LEVEL RIDGE DOMINATING THE E AND
CENTRAL ATLC N OF 18N E OF 50W...ANCHORED BY A 1023 MB HIGH NEAR
27N36W. HOWEVER...AN UPPER TROUGH IS IN THE N CENTRAL ATLC OUT
OF OUR AREA OF DISCUSSION SUPPORTING A SURFACE TROUGH THAT
EXTENDS FROM A COLD FRONT NEAR 32N30W TO 28N40W TO 24N50W.
SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN 15
NM EITHER SIDE OF THE SURFACE TROUGH.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$

GARCIA



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