615
AXNT20 KNHC 281118
TWDAT
TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST SAT NOV 28 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1000 UTC.
..ITCZ
THE ITCZ AXIS IS CENTERED ALONG 9N12W 7N22W 4N34W 5N53W.
ISOLATED MODERATE/STRONG CONVECTION IS FROM 4N-7N BETWEEN
9W-18W. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 90 NM OF
THE AXIS BETWEEN 26W-39W.
..DISCUSSION
GULF OF MEXICO...
SURFACE HIGH PRESSURE CONTINUES TO DOMINATE THE GULF OF MEXICO
THIS MORNING ANCHORED BY A 1022 MB HIGH OFF THE COAST OF
LOUISIANA NEAR 28N92W. THIS AREA OF HIGH PRESSURE BRINGS
GENERALLY FAIR WEATHER ACROSS MUCH OF THE BASIN. HOWEVER...MOIST
SWLY AND DIFFLUENT FLOW ALOFT BETWEEN A SHORTWAVE UPPER TROUGH
OVER TEXAS AND AN UPPER LEVEL RIDGE COVERING THE GULF ARE
SUPPORTING SCATTERED SHOWERS ACROSS THE NW GULF FROM 24N-31N
BETWEEN 91W-95W...AS NOTED ON RADAR IMAGERY. LIGHT TO GENTLE
SURFACE WINDS ARE ACROSS THE AREA. EXPECT THE SURFACE RIDGE TO
SHIFT EWD AS SLY RETURN FLOW INCREASES OVER THE WRN GULF AHEAD
OF THE NEXT COLD FRONT FORECAST TO MOVE OFF THE TEXAS COAST
EARLY MON.
CARIBBEAN SEA...
AS OF 0900 UTC...A STATIONARY FRONT EXTENDS ACROSS THE NW
CARIBBEAN FROM E CUBA NEAR 20N75W TO NW OF JAMAICA NEAR 19N79W
CONTINUING ALONG 18N82W TO CENTRAL HONDURAS NEAR 14N87W.
ISOLATED SHOWERS ARE ALONG THE FRONT AXIS...WITH SCATTERED
SHOWERS NW OF THE FRONT FROM 17N-19N BETWEEN 80W-85W. SCATTERED
SHOWERS/THUNDERSTORMS ARE ACROSS THE SW CARIBBEAN S OF 10N
BETWEEN 74W-80W DUE TO SURFACE CONVERGENCE NEAR THE E PACIFIC
ITCZ...AND A 1007 MB LOW OVER COLOMBIA NEAR 8N76W. THE ACTIVITY
IS ALSO ENHANCED BY DIFFLUENT FLOW ALOFT BETWEEN AN UPPER LEVEL
TROUGH IN THE E PACIFIC AND AN UPPER LEVEL RIDGE COVERING THE
CARIBBEAN. THE REMAINDER OF THE CARIBBEAN IS EXPERIENCING
GENERALLY FAIR WEATHER UNDER THE INFLUENCE OF DRY AND SUBSIDENT
AIR ALOFT ASSOCIATED WITH THE AFOREMENTIONED UPPER LEVEL RIDGE
COVERING THE ENTIRE BASIN WITH AXIS ALONG 75W. NE SURFACE WINDS
OF 15-20 KT ARE NW OF THE FRONT...WITH FRESH TO STRONG ELY
TRADEWINDS COVERING THE REMAINDER OF THE BASIN. EXPECT THE FRONT
TO REMAIN STATIONARY AND BECOME DIFFUSE BY LATER TONIGHT WITH
SHOWER ACTIVITY CONTINUING ALONG THE FRONT AXIS.
ATLANTIC OCEAN...
A COLD FRONT EXTENDS ACROSS THE W ATLC ENTERING THE DISCUSSION
AREA E OF BERMUDA NEAR 32N61W CONTINUING ALONG 25N66W TO THE FAR
SE BAHAMAS NEAR 21N71W TO E CUBA NEAR 20N75W BECOMING STATIONARY
ACROSS THE CARIBBEAN. A PRE-FRONTAL SURFACE TROUGH IS AHEAD OF
THE FRONT FROM 27N62W TO 20N69W. ISOLATED SHOWERS ARE ALONG THE
FRONT AXIS...AND WITHIN 100 NM AHEAD OF THE TROUGH AXIS.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE E OF THE AXIS N OF
27N BETWEEN 55W-60W. THE FRONT IS SUPPORTED BY AN UPPER LEVEL
TROUGH OVER THE WRN ATLC WITH AXIS EXTENDING FROM AN UPPER LEVEL
LOW S OF MAINE TO E OF THE SE BAHAMAS. DIFFLUENT FLOW ALOFT
BETWEEN THIS UPPER LEVEL TROUGH AND AN UPPER LEVEL RIDGE
EXTENDING FROM THE CARIBBEAN ACROSS PUERTO RICO TO NEAR 33N52W
IS SUPPORTING THE SHOWER ACTIVITY E OF THE FRONT. ACROSS THE
CENTRAL ATLC...A NARROW UPPER LEVEL TROUGH WITH AXIS ALONG 49W
IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS FROM 18N-31N
BETWEEN 44W-49W...AND FROM 16N-18N BETWEEN 49W-52W. THE UPPER
TROUGH ALSO SUPPORTS A PAIR OF SURFACE TROUGHS MADE EVIDENT BY
SE-NE WIND SHIFTS IN ASCAT SCATTEROMETER DATA. THE FIRST IS E OF
THE LESSER ANTILLES EXTENDING FROM 17N54W TO 12N55W. THE SECOND
IS TO THE N EXTENDING FROM 25N51W TO 20N53W. THE AFOREMENTIONED
SHOWER ACTIVITY LIES TO THE E OF THESE TROUGHS MORE ASSOCIATED
WITH THE UPPER DIFFLUENT ZONE. THE REMAINDER OF THE E ATLC IS
DOMINATED BY A BROAD SURFACE RIDGE ANCHORED BY A 1027 MB AZORES
HIGH N OF THE DISCUSSION AREA NEAR 38N31W.
WALTON
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