[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 272347
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON SEP 27 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

AN AREA OF BROAD LOW PRESSURE IS LOCATED OVER THE NW CARIBBEAN
SEA FOCUSED AROUND A 1004 MB LOW CENTERED OVER NORTHERN BELIZE
NEAR 18N88W. A SURFACE TROUGH EXTENDS E-SE FROM THE LOW TO
17N82W. SCATTERED MODERATE TO STRONG CONVECTION IS FROM 17N-22N
BETWEEN 85W-91W...WHICH INCLUDES A LARGE PORTION OF THE YUCATAN
PENINSULA. THIS AREA OF LOWER PRESSURE OVER THE NW CARIBBEAN IS
WEDGED IN BETWEEN TWO UPPER LEVEL ANTICYCLONES...ONE CENTERED
OVER SOUTHERN MEXICO NEAR 20N98W AND THE OTHER CENTERED OVER THE
WESTERN CARIBBEAN SEA NEAR 17N79W. THESE UPPER LEVEL FEATURES
ARE PROVIDING AN UPPER DIFFLUENT ENVIRONMENT OVER THE NW
CARIBBEAN KEEPING CONDITIONS FAVORABLE FOR GRADUAL DEVELOPMENT
OF THIS SYSTEM OVER THE NEXT COUPLE OF DAYS AS IT TRACKS N-NE.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 13N16W 09N24W 08N36W THEN RESUMES
NEAR 10N40W 10N50W 08N59W. A SURFACE TROUGH IS ANALYZED WITHIN
THE ITCZ FROM 09N38W TO 15N35W WITH ISOLATED MODERATE CONVECTION
WITHIN 90 NM WEST OF THE SURFACE TROUGH FROM 12N-15N.
ELSEWHERE...SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS
FROM 03N-09N BETWEEN 25W-37W. SCATTERED MODERATE CONVECTION IS
ALSO FROM 06N-13N BETWEEN 42W-48W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL TROUGH IS OVER THE TENNESSEE RIVER AND LOWER
MISSISSIPPI RIVER VALLEYS WITH AXIS THAT EXTENDS INTO THE
NORTH-CENTRAL GULF WATERS ALONG 16N86W TO 30N86W TO 25N91W. THIS
UPPER LEVEL TROUGH SUPPORTS A COLD FRONT THAT ENTERS THE GULF
NEAR APALACHEE BAY TO 28N85W THEN SW ALONG 24N94W TO THE MEXICO
COAST NEAR TUXPAN. A PRE-FRONTAL TROUGH IS LOCATED SE OF THE
COLD FRONT ANALYZED FROM 27N86W TO THE EASTERN BAY OF CAMPECHE
NEAR 20N92W. WITH THE MIDDLE TO UPPER LEVEL SUPPORT STRONGEST N
OF 26N...SCATTERED SHOWERS AND TSTMS ARE MAINLY CONCENTRATED
OVER THE NE GULF AND FLORIDA PENINSULA THIS EVENING N OF 27N
EAST OF THE COLD FRONT TO 78W IN THE W ATLC. A FEW SCATTERED
SHOWERS AND TSTMS ARE ALSO S OF 27N OVER INTERIOR PORTIONS OF
THE FLORIDA PENINSULA. ELSEWHERE S OF THE COLD FRONT OVER THE SW
GULF...CONVERGENT LOW-LEVEL WINDS AND A DIFFLUENT UPPER LEVEL
ENVIRONMENT ARE GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS
S OF 23N W OF 93W. IN THE WAKE OF THE COLD FRONT OVER THE NW
GULF...STRONG NW TO N SURFACE WINDS PREVAIL SUPPORTED ALOFT BY
VERY DRY AND SUBSIDENT NW FLOW.

CARIBBEAN SEA...
AN UPPER LEVEL ANTICYCLONE IS CENTERED OVER SOUTHERN MEXICO NEAR
20N98W THAT EXTENDS AN UPPER LEVEL RIDGE AXIS SOUTHEASTWARD TO
ANOTHER UPPER LEVEL ANTICYCLONE CENTERED NEAR 17N79W. AN UPPER
LEVEL RIDGE AXIS THEN EXTENDS EASTWARD TO 14N61W OVER THE
REMAINDER OF THE CARIBBEAN BASIN. THIS UPPER LEVEL PATTERN IS
PROVIDING A DIFFLUENT ENVIRONMENT ALOFT AND IN TURN SUPPORTS THE
WIDESPREAD SHOWERS AND SCATTERED TSTMS NOTED ON SATELLITE
IMAGERY MOSTLY LOCATED W OF 64W. THE MOST CONCENTRATED AREA OF
CONVECTIVE ACTIVITY HOWEVER IS ASSOCIATED WITH A BROAD AREA OF
LOW PRESSURE CENTERED OVER NORTHERN BELIZE NEAR 18N88W AS A 1004
MB LOW CENTER. SCATTERED MODERATE TO STRONG CONVECTION IS MOSTLY
LOCATED WITHIN 180 NM OF THE CENTER...AND OVER INTERIOR PORTIONS
OF THE YUCATAN PENINSULA THIS EVENING. GLOBAL MODEL GUIDANCE IS
COMING INTO BETTER AGREEMENT ON FURTHER ORGANIZATION OF THIS
BROAD AREA OF LOW PRESSURE OVER THE WESTERN CARIBBEAN. WITH THE
APPROACHING UPPER LEVEL TROUGH CURRENTLY IMPACTING THE EASTERN
GULF OF MEXICO...CYCLOGENESIS IS FORECAST TO OCCUR OVER THE NW
CARIBBEAN AND ANY SURFACE LOW...TROPICAL OR SUBTROPICAL...WILL
QUICKLY MOVE N-NE OVER THE FLORIDA STRAITS AND FAR W ATLC WATERS
THROUGH THURSDAY MORNING.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH IS OVER THE EASTERN GULF OF MEXICO
PROVIDING THE W ATLC W OF 75W WITH MOIST SW UPPER LEVEL FLOW.
THIS ALONG WITH AN APPROACHING COLD FRONT IS GENERATING
SCATTERED SHOWERS AND TSTMS OVER THE FLORIDA PENINSULA AND W
ATLC WATERS N OF 26N W OF 77W. FARTHER SE...AN UPPER LEVEL RIDGE
EXTENDS TO 27N76W FROM AN ANTICYCLONIC CIRCULATION IN THE
WESTERN CARIBBEAN SEA CENTERED NEAR 17N79W. THE RIDGE IS
PROVIDING AN UPPER LEVEL DIFFLUENT ENVIRONMENT OVER CUBA AND THE
FLORIDA STRAITS THAT IS GENERATING SCATTERED SHOWERS AND
ISOLATED TSTMS S OF 25N BETWEEN 79W-82W AND WITHIN 60 NM OF THE
NORTHERN CUBA AND HISPANIOLA COASTLINES. SCATTERED SHOWERS
EXTENDS FARTHER SE OVER THE MONA PASSAGE AND PUERTO RICO
REMAINING S OF 21N BETWEEN 63W-70W. A 1015 MB LOW IS ANALYZED IN
THE CENTRAL ATLC NEAR 29N60W CONTINUING TO GENERATE SCATTERED
SHOWERS WITHIN 120 NM OF THE CENTER. OVER THE EASTERN ATLC...THE
REMNANTS OF LISA ARE ANALYZED AS A 1015 MB LOW CENTERED NEAR
28N31W AND A SURFACE TROUGH EXTENDING NE TO 31N29W AND SW TO
25N35W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE LOCATED NORTH
OF THE LOW CENTER FROM 29N-32N BETWEEN 28W-32W. OTHERWISE THE
REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE
OF HIGH PRESSURE N OF 18N WITH THE EXCEPTION OF BOTH WEAK LOW
PRESSURE AREAS MENTIONED ABOVE.

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

$$
HUFFMAN


WWWW
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