[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 081756
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU OCT 08 2009

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
1715 UTC.

...SPECIAL FEATURES...

TROPICAL DEPRESSION HENRI IS CENTERED NEAR 19.8N 62.0W AT
08/1500 UTC...OR ABOUT 110 NM N-NE OF THE NRN LEEWARD ISLANDS
MOVING W AT 11 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1010
MB. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT.
SCATTERED STRONG CONVECTION IS FROM 17N-23N BETWEEN 56W-61W. SEE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/
WTNT25 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 22W S OF 15N MOVING W NEAR 15 KT.
LOW-LEVEL SATELLITE DERIVED WINDS SHOW CYCLONIC CURVATURE S OF
13N IN THE VICINITY OF THE WAVE AXIS. ISOLATED SHOWERS COVER A
VERY LIMITED AREA SURROUNDING THE WAVE FROM 8N-13N BETWEEN
19W-23W AS SAHARAN DUST IS LOCATED N OF 10N E OF 30W TO THE W
AFRICA COAST.

TROPICAL WAVE IS ALONG 56W S OF 15N MOVING W NEAR 22 KT. VISIBLE
SATELLITE IMAGERY INDICATES AN INVERTED-V CLOUD SIGNATURE NEAR
THE WAVE AXIS. A MAXIMUM IN DEEP LAYER MOISTURE IS ALSO OBSERVED
IN TOTAL PRECIPITABLE WATER IMAGERY BETWEEN 50W-60W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 8N-14N BETWEEN
54W-60W.

TROPICAL WAVE IS ALONG 75W S OF 16N MOVING W NEAR 18 KT. THE
WAVE LIES IN A VERY BROAD AREA OF DEEP LAYER MOISTURE ACROSS THE
SRN HALF OF THE CARIBBEAN BASIN S OF 15N AS OBSERVED IN THE
TOTAL PRECIPITABLE WATER IMAGERY. LOCATED BENEATH AN UPPER LEVEL
RIDGE...DRY AIR AND SUBSIDENCE ALOFT ARE CONFINING ANY DEEP
CONVECTION NEAR THE WAVE. ISOLATED SHOWERS ARE OCCURRING FROM
12N-16N BETWEEN 75W-79W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 12N16W 12N20W 10N23W 6N38W
7N54W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN
150 NM EITHER SIDE OF THE AXIS BETWEEN 26W-40W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED NEAR
30N85W COVERS THE ENTIRE GULF AND STATE OF FLORIDA. STRONG
SUBSIDENCE AND PLENTY OF DRY AIR IS NOTED ON WATER VAPOR IMAGERY
ASSOCIATED WITH THE UPPER LEVEL HIGH. AT THE SURFACE...A 1021 MB
HIGH IS CENTERED IN THE NE GULF NEAR 28N86W. WIND FLOW
CIRCULATING AROUND THE SURFACE HIGH CONTINUES TO PROVIDE MOST OF
THE GULF WITH SELY WINDS OF 10-15 KT OVER THE CENTRAL GULF
WATERS AND UP TO 25 KT ACROSS THE WRN GULF. A WEAKNESS IN THE
SURFACE RIDGE ACROSS NRN FLORIDA SUPPORTS A STATIONARY FRONT
FROM FLAGLER BEACH TO THE BIG BEND REGION AND OVER THE FLORIDA
PANHANDLE. BECAUSE OF THE STRONG SUBSIDENCE ALOFT...THE FRONT
REMAINS DRY AND IS FORECAST TO BECOME MORE DIFFUSE THROUGH THE
REST OF THE AFTERNOON AND EVENING. THE WINDS ARE FORECAST TO
REMAIN STRONG THROUGH FRIDAY ACROSS THE WRN GULF EAST OF A
DEVELOPING AREA OF LOW PRESSURE ACROSS THE SRN U.S. PLAINS WITH
A COLD FRONT POISED TO ENTER THE NW GULF FRIDAY EVENING.

CARIBBEAN SEA...
THE WRN CARIBBEAN W OF 72W IS UNDER E-NE UPPER LEVEL FLOW ON THE
SRN PERIPHERY OF A BROAD UPPER LEVEL RIDGE CENTERED IN THE NE
GULF OF MEXICO. DRY SUBSIDENT AIR IS SUPPORTING GENERALLY FAIR
WEATHER N OF A LINE FROM THE MONA PASSAGE WWD TO THE CENTRAL
NICARAGUA COAST NEAR 13N84W. LOW-LEVEL MOISTURE IS LOCATED
GENERALLY S OF 15N AS NOTED BY TOTAL PRECIPITABLE WATER IMAGERY
AND COUPLED WITH ATMOSPHERIC INSTABILITY IS GENERATING WIDELY
SCATTERED SHOWERS AND TSTMS OVER THE SW CARIBBEAN BETWEEN
77W-84W. AN UPPER LEVEL TROUGH IS ACROSS THE CENTRAL CARIBBEAN
WITH THE AXIS STRETCHING FROM NRN COLOMBIA THROUGH THE MONA
PASSAGE TO 21N66W. E OF THE TROUGH AXIS...MOIST SLY UPPER LEVEL
FLOW DOMINATES OVER THE ERN CARIBBEAN AND IS GENERATING ISOLATED
SHOWERS S OF 16N BETWEEN 67W-72W. FRESH TO STRONG TRADE WINDS
ARE ACROSS MUCH OF THE BASIN WITH THE STRONG WINDS LOCATED ALONG
THE COAST OF COLOMBIA.

ATLANTIC OCEAN...
TROPICAL DEPRESSION HENRI CONTINUES TO IMPACT THE TROPICAL NORTH
ATLC WATERS NE OF THE NRN LEEWARD ISLANDS...SEE SPECIAL FEATURES
ABOVE. FARTHER TO THE NW OVER THE W ATLC...AN UPPER LEVEL
ANTICYCLONIC CIRCULATION IS CENTERED OVER THE NE GULF AND
EXTENDS UPPER LEVEL RIDGING TO 60W. MOSTLY DRY AIR AND STRONG
SUBSIDENCE IS NOTED ON WATER VAPOR IMAGERY...HOWEVER THE TAIL
END OF A WRN ATLC COLD FRONT ENTERS THE DISCUSSION AREA NEAR
BERMUDA AND EXTENDS WSW TO 30N77W...THEN CONTINUES WWD TO
FLAGLER BEACH FLORIDA AS A WEAKENING STATIONARY BOUNDARY. WITH
DRY CONDITIONS ALOFT AND A VERY STABLE ATMOSPHERE IN PLACE OVER
THE W ATLC...SIGNIFICANT SHOWERS AND CONVECTION REMAIN N OF 32N
IN ASSOCIATION WITH THE FRONTAL BOUNDARY. THE REMAINDER OF THE
CENTRAL AND ERN ATLC IS UNDER THE INFLUENCE OF A RATHER LARGE
SURFACE RIDGE OF HIGH PRESSURE. CENTERED ON A 1024 MB HIGH NEAR
26N45W...THE RIDGE EXTENDS NE TO A 1023 MB HIGH CENTERED NEAR
31N30W AND BEYOND 32N27W. A WEAKNESS WITHIN THE RIDGE IS
ANALYZED AS A SURFACE TROUGH FROM 29N37W TO 32N37W. THIS TROUGH
IS SUPPORTED ALOFT BY A SHARP UPPER LEVEL SHORTWAVE TROUGH WITH
AXIS FROM 24N46W TO BEYOND 32N36W. ISOLATED SHOWERS ARE FROM
25N-32N BETWEEN 35W-40W.

$$
HUFFMAN


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