[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 132347
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST TUE NOV 13 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE 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.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 80W S OF 17N MOVING W NEAR 20 KT. THE
MIMIC TPW ANIMATION SHOWS THE WEAK MOISTURE SURGE RELATED TO
THIS WAVE MOVING INTO THE AREA OF DISTURBED WEATHER IN THE SW
CARIBBEAN...POSSIBLY ENHANCING IT SOME. DUE TO THE WIDESPREAD
DEEP CLOUDINESS ITS DIFFICULT TO TELL EXACTLY WHERE THE WAVE IS
LOCATED. FOR DETAILS REFER TO THE CARIBBEAN SECTION BELOW.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 8N13W 6N24W 7N37W 7N45W 4N53W.
SCATTERED MODERATE CONVECTION IS FROM 8N-11N BETWEEN 41W-43W.

DISCUSSION...

GULF OF MEXICO...
WEAKENING HIGH PRES...ANALYZED 1020 MB...IS CENTERED ABOUT 100
NM S OF MOBILE ALABAMA NEAR 29N87W. THIS HAS ALLOWED WINDS TO
WEAKEN ACROSS THE NRN HALF OF THE GULF BUT REMAIN MODERATE
ACROSS THE SRN PART. SAT IMAGERY SHOWS BROKEN CLOUDINESS WITH
POSSIBLE ISOLATED SHALLOW SHOWERS HOVERING OVER THE BAY OF
CAMPECHE...ASSOCIATED WITH LOW-LEVEL TROUGHING IN THE W
CARIBBEAN. SIMILAR CLOUDINESS AND ISOLATED SHOWERS ARE OVER SE
FLORIDA STREAMING IN FROM A WEAK SFC TROUGH IN THE BAHAMAS.
ALOFT...A MID TO UPPER LEVEL RIDGE HAS BUILT NWD INTO THE SW
GULF WHILE A SERIES OF UPPER SHORTWAVES PROPAGATE THROUGH THE
EXTREME NE PORTION. CURRENTLY...A WELL DEFINED SHORTWAVE EXTENDS
FROM THE MID-ATLANTIC TO THE MISSISSIPPI VALLEY. ABUNDANT
SUBSIDENCE LIES OVER THE BULK OF THE REGION...MOST PRONOUNCED
FROM 22N-26N W OF 83W. LOOKING AHEAD...SFC HIGH PRES IS
ANTICIPATED TO WEAKEN FURTHER AND RETREAT EWD AS A COLD FRONT
MOVES INTO THE NW PORTION LATE WED/EARLY THU.

CARIBBEAN SEA...
CLUSTERS OF SCATTERED MODERATE CONVECTION HAVE BEEN PERSISTING
OVER THE LAST SEVERAL HOURS IN THE SW CARIB...ROUGHLY S OF 13N W
OF 78W. THE PRIMARY TRIGGER FOR THE ACTIVITY APPEARS TO BE
DIFFLUENCE ALONG A STRETCHED MID TO UPPER RIDGE AXIS. A WEAK LOW
LATITUDE TROPICAL WAVE HAS TRACKED INTO THIS REGION AND MAY ALSO
BE PROVIDING SOME SUPPORT. FARTHER NW...A WEAK LOW-LEVEL TROUGH
LIES ALONG 87W FROM 15N-20N PRODUCING SCATTERED SHOWERS AND
ISOLATED TSTMS WITHIN 180 NM OF THE AXIS. THE TAIL END OF A
CENTRAL ATLC SFC TROUGH RUNS ACROSS PUERTO RICO AND HISPANIOLA
PRODUCING SCATTERED SHOWERS AND ISOLATED TSTMS OVER THE ISLANDS
AND SURROUNDING WATERS. THE REMAINDER OF THE AREA IS RATHER
TRANQUIL UNDER MODERATE TO FRESH TRADE WIND FLOW AND STABLE MID
AND UPPER LEVEL AIR ADVECTED BY FAIRLY ZONAL UPPER FLOW.

ATLANTIC OCEAN...
MODERATE SFC SUBTROPICAL RIDGING DOMINATES THE SW ATLC PRODUCING
NE TO ELY LOW-LEVEL FLOW ACROSS THE AREA. THE FLOW IS STRONGEST
JUST E OF A WEAK LOW-LEVEL PERTURBATION IN THE NW BAHAMAS. THE
BRISK WINDS ARE GENERATING ENOUGH INSTABILITY TO STIR UP AND
STEER STREAMS OF LOW CLOUDS AND QUICK MOVING SHALLOW SHOWERS
WHICH ARE ENHANCED OVER THE BAHAMAS AND SE FLA NEAR THE
AFOREMENTIONED SFC TROUGH. ALOFT...A SERIES OF WEAK SHORTWAVES
ARE PROPAGATING THROUGH A LARGE TROUGH SHARPENING IT IN SPOTS.
THE OVERALL BROAD TROUGH REACHES A BASE NEAR THE NRN LEEWARD
ISLANDS. THIS UPPER SYSTEM IS SUPPORTING A LINGERING STRETCHED
OUT OLD FRONTAL TROUGH ANALYZED ALONG 32N43W 22N54W TO PUERTO
RICO. LOW-LEVEL CONVERGENCE NEAR THE TROUGH COUPLED WITH
EXTENSIVE MID AND UPPER LEVEL SWLY FLOW IS PRODUCING SCATTERED
SHOWERS AND TSTMS FROM 23N-27N BETWEEN 46W-50W. ISOLATED TO
SCATTERED ACTIVITY IS ELSEWHERE WITHIN 150 NM OF THE BOUNDARY.

THE REMAINDER OF THE CENTRAL AND E ATLC IS UNDER A WEAK SFC PRES
PATTERN CONSISTING OF A NEARLY STATIONARY 1020 MB HIGH NEAR
27N30W AND A 1012 MB LOW JUST N OF THE AZORES. THIS PATTERN IS
ALLOWING WINDS TO BE LIGHT TO MODERATE ACROSS THE REGION. IN THE
MID AND UPPER LEVELS...A BROAD RIDGE/TROUGH PATTERN IS IN PLACE.
A SWLY JET ORIGINATES JUST E OF THE TROUGH BASE NEAR 12N30W AND
EXTENDS NE TO AFRICA NEAR 17N16W. DIFFLUENCE TO THE SE OF THE
JET IS PRODUCING ABUNDANT CLOUDINESS BUT NOT MUCH CONVECTION
ALONG THE ITCZ...WHICH WAS THE CASE YESTERDAY.

$$
CANGIALOSI


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