[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 090550
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT WED SEP 09 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...SPECIAL FEATURES...

HURRICANE FRED IS CENTERED NEAR 12.6N 30.6W AT 09/0300 UTC OR
ABOUT 385 NM WSW OF THE SOUTHERNMOST CAPE VERDE ISLANDS MOVING
WNW AT 10 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 987 MB.
MAXIMUM SUSTAINED WIND SPEED IS 65 KT WITH GUSTS TO 80 KT.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 10N-15N
BETWEEN 28W-34W. WIDELY SCATTERED MODERATE CONVECTION IS
ELSEWHERE FROM 7N-15N BETWEEN 26W-34W. SEE LATEST NHC FORECAST/
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE
DETAILS.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 64W S OF 18N MOVING W NEAR 18 KT. A
MAXIMUM IN DEEP LAYER MOISTURE IS NOTED IN THE TOTAL
PRECIPITABLE WATER IMAGERY N OF 14N ACROSS THE NE CARIBBEAN
WHICH IS LEADING TO AN INCREASED AREA OF WIDELY SCATTERED
SHOWERS N OF 15N BETWEEN 60W-67W...INCLUDING PORTIONS OF THE
LEEWARD ISLANDS...US/UK VIRGIN ISLANDS...AND PUERTO RICO.

TROPICAL WAVE IS ALONG 82W S OF 19N MOVING W NEAR 15 KT. THIS
WAVE REMAINS ILL-DEFINED ACROSS THE WRN CARIBBEAN AND MODERATELY
DRY AIR ON NLY FLOW ALOFT IS NOTED IN THE UPPER LEVELS. NO DEEP
CONVECTION ACCOMPANIES THIS WAVE.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 17N17W 15N27W 10N34W 7N45W
9N61W. BESIDES THE CONVECTION ASSOCIATED WITH HURRICANE FRED...
SCATTERED SHOWERS ARE ALONG THE W AFRICA COAST FROM 7N-18N
BETWEEN 12W-19W. POSSIBLE ISOLATED SHOWERS ARE ALSO FROM 3N-7N
BETWEEN 24W-49W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED ACROSS SRN
MEXICO NEAR 18N99W AND EXTENDS UPPER RIDGING ACROSS MUCH OF THE
GULF. HOWEVER...AN UPPER LEVEL TROUGH CLIPS THE FAR NE GULF AND
NRN FLORIDA PENINSULA N OF 27N. BETWEEN THESE TWO UPPER LEVEL
FEATURES...WNW FLOW ALOFT DOMINATES AND IS CARRYING MIDDLE TO
HIGH CLOUDINESS EWD N OF 25N W OF 88W WITH A FEW POSSIBLE
EMBEDDED ISOLATED SHOWERS. THE LACK OF ANY SIGNIFICANT SURFACE
FEATURES AND AN OVERALL WEAK PRESSURE GRADIENT IS PROVIDING THE
GULF WITH GENERALLY LIGHT WINDS CIRCULATING AROUND A SURFACE
RIDGE THAT EXTENDS FROM THE SE CONUS TO NEAR TUXPAN MEXICO.
UPPER LEVEL DIFFLUENCE IN ASSOCIATION WITH THE UPPER LEVEL RIDGE
IS GENERATING SCATTERED SHOWERS ACROSS THE WRN BAY OF CAMPECHE S
OF 22N W OF 95W...INCLUDING PORTIONS OF INTERIOR SRN MEXICO. THE
UPPER LEVEL TROUGHING ACROSS THE FLORIDA PENINSULA IS GENERATING
SCATTERED SHOWERS AND ISOLATED TSTMS S OF 26N E OF 83W...
INCLUDING PORTIONS OF THE FLORIDA KEYS AND STRAITS OF FLORIDA.

CARIBBEAN SEA...
AN UPPER LEVEL TROUGH DIPS SW FROM A SW NORTH ATLC UPPER LOW
CENTERED NEAR 23N69W ACROSS HISPANIOLA AND THE CENTRAL CARIBBEAN
TO THE SW CARIBBEAN AND OVER PANAMA. NLY UPPER LEVEL WINDS ARE
FOUND W OF 77W AND ARE PROVIDING AN OVERALL SUBSIDENT ATMOSPHERE
ACROSS THE NW CARIBBEAN AND PORTIONS OF CENTRAL AMERICA.
HOWEVER...SCATTERED SHOWERS AND TSTMS HAVE PERSISTED S OF CUBA
DUE TO THE PRESENCE OF A SURFACE TROUGH ANALYZED FROM 25N78W TO
20N81W AND ARE LOCATED FROM 17N-22N BETWEEN 77W-83W. MOSTLY DRY
AIR ON SWLY WINDS ALOFT ARE ACROSS THE REMAINDER OF THE
CARIBBEAN BASIN E OF 77W. A FEW ISOLATED SHOWERS AND TSTMS ARE S
OF 10N OVER THE SW CARIBBEAN DUE TO THE PROXIMITY OF THE ITCZ
AXIS ALONG 8N. MODERATE TO FRESH TRADE WINDS CONTINUE ACROSS THE
BASIN IN THE LOW LEVELS...WITH PASSING ISOLATED SHOWERS N OF 14N
E OF 72W. THE TROPICAL WAVE ALONG 64W WILL CONTINUE TO ENHANCE
THESE SHOWERS ACROSS THE NRN LEEWARD ISLANDS...US/UK VIRGIN
ISLANDS AND PUERTO RICO OVER THE NEXT 12-24 HOURS.

ATLANTIC OCEAN...
A SURFACE TROUGH ENTERS THE DISCUSSION AREA NEAR 32N74W AND
EXTENDS SSW OVER THE WRN TIP OF GRAND BAHAMA ISLAND TO NEAR
MIAMI FLORIDA. THIS TROUGH IS SUPPORTED ALOFT BY UPPER LEVEL
TROUGHING N OF 27N W OF 75W. ANOTHER SURFACE TROUGH IS ANALYZED
FROM ANDROS ISLAND IN THE BAHAMAS NEAR 25N78W ACROSS CENTRAL
CUBA AND INTO THE NW CARIBBEAN NEAR 20N81W. LOW-LEVEL
CONVERGENCE NEAR THE SURFACE TROUGH AND UPPER LEVEL DIFFLUENCE E
OF THE UPPER LEVEL TROUGHING ARE GENERATING SCATTERED SHOWERS
AND A FEW ISOLATED TSTMS OVER A LARGE PORTION OF THE W ATLC N OF
22N W OF 72W. FARTHER TO THE E...AN UPPER LEVEL LOW IS CENTERED
NEAR 23N69W AND IS GENERATING AN AREA OF SCATTERED SHOWERS FROM
19N-26N BETWEEN 62W-69W. EAST OF THIS AREA A 1013 MB SURFACE LOW
IS CENTERED NEAR 20N59W AND IS REMNANT ENERGY FROM THE TROPICAL
WAVE MOVING ACROSS THE ERN CARIBBEAN. SCATTERED SHOWERS ARE
WITHIN 90 NM OF THE CENTER OF THE LOW IN THE ERN SEMICIRCLE.
INTO THE CENTRAL ATLC...A DISSIPATING COLD FRONT DIPS INTO THE
DISCUSSION AREA NEAR 31N39W AND EXTENDS WSW TO 29N48W. POSSIBLE
ISOLATED SHOWERS ARE WITHIN 90 NM EITHER SIDE OF THE FRONT. S OF
THE FRONT...A SURFACE TROUGH IS ANALYZED ALONG 24N40W TO 16N42W.
SCATTERED SHOWERS AND ISOLATED TSTMS ARE FROM 21N-25N BETWEEN
36W-41W. ACROSS THE TROPICAL ERN ATLC...AN UPPER LEVEL RIDGE IS
E OF 40W AND IS ENHANCING THE CONVECTION ASSOCIATED WITH
HURRICANE FRED.

$$
HUFFMAN





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