[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 261135
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST MON NOV 26 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE IS ALONG 65W SOUTH OF 14N MOVING WEST 10 KT.
THIS LATE SEASON LOW AMPLITUDE WAVE IS GENERATING ISOLATED
SHOWERS OVER THE SOUTHERN PORTION OF THE EASTERN CARIBBEAN. THE
WAVE HAS A WEAK LOW CLOUD CURVATURE SIGNATURE.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 9N13W 5N25W 4N35W 2N51W.
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS WITHIN 200
NM N OF AXIS BETWEEN 22W-32W.

DISCUSSION...

THE GULF OF MEXICO...
A COLD FRONT EXTENDS FROM SE LOUISIANA TO 23N93W THEN CONTINUES
SW AS STATIONARY FRONT CROSSING JUST SOUTH OF VERACRUZ AND
CONTINUING NW TO THE FOOTHILLS OF THE SIERRA MADRE MOUNTAINS
ALONG 20N99W 22N100W. A WARM FRONT EXTENDS NEAR THE FLORIDA/
GEORGIA BORDER. MOSAIC DOPPLER RADAR FROM THE SE U.S. SHOWS A
BAND OF SHOWERS WITH EMBEDDED TSTMS AHEAD OF THE COLD FRONT
AFFECTING THE NORTH-CENTRAL GULF WATERS FROM 26N TO BEYOND 32N
BETWEEN 86W-90W AS WELL AS SE ALABAMA...THE FLORIDA PANHANDLE
AND NW GEORGIA. THE RISK OF A FEW SEVERE TSTMS EXISTS OVER THE
SE U.S. TODAY AS THE FRONT CONTINUES TO MOVES EWD. A SECOND BAND
OF MAINLY SHOWERS HAS DEVELOPED BEHIND THE FRONT AND IS MOVING
ACROSS SE LOUISIANA AND THE NW PORTION OF THE GULF. ALL THIS
CONVECTIVE ACTIVITY IS BEEN ENHANCED BY A DIFFLUENT PATTERN
ALOFT BETWEEN A CUT-OFF LOW SPINNING OVER OKLAHOMA/TEXAS AND A
RIDGE OVER THE CARIBBEAN SEA. LIGHTNING DATA SUPPORTS SCATTERED
TSTMS IN THIS AREA. BROKEN TO OVERCAST LOW CLOUDS WITH LIGHT
RAIN/DRIZZLE ARE NOTED OVER THE COLD SECTOR W OF THE COLD FRONT.
THE COOL AIR IS BANKING UP AGAINST THE E SLOPES OF THE SIERRA
MADRE MOUNTAINS. AN ASCAT PASS FROM AROUND 0400 UTC AND SFC
OBSERVATIONS INDICATED NW TO N WINDS OF 15 TO 20 KT BEHIND THE
COLD FRONT. THE REMAINDER OF THE REGION HAS MOSTLY FAIR WEATHER
WITH 10-15 KT SE TO SOUTH SURFACE FLOW. THE COLD FRONT IS
FORECAST TO EXTEND FROM THE FLORIDA BIG BEND TO THE BAY OF
CAMPECHE TONIGHT.

THE CARIBBEAN SEA...
BROAD UPPER RIDGE ANCHORED ON A HIGH LOCATED SOUTH OF HISPANIOLA
COVERS THE ENTIRE BASIN. UPPER DIFFLUENCE ASSOCIATED WITH THIS
FEATURE IS HELPING TO INDUCE CLUSTERS OF MODERATE TO STRONG
CONVECTION OVER THE W CARIBBEAN FROM 11N-18N BETWEEN 80W-86W.
THIS ACTIVITY IS AFFECTING THE CARIBBEAN PLAINS OF NICARAGUA AND
NE HONDURAS...AND IS FORECAST TO SPREAD WWD OVER CENTRAL AMERICA
AND THE GULF OF HONDURAS DURING THE NEXT 12-24 HOURS. A TROPICAL
WAVE IS GENERATING SOME SHOWER ACTIVITY OVER THE SE PORTION OF
THE SEA. POCKETS OF LOW LEVEL MOISTURE WITH MAINLY LIGHT SHOWERS
ARE MOVING ACROSS THE LEEWARD ISLANDS...THE UK/US VIRGIN
ISLANDS...PUERTO RICO AND DOMINICAN REPUBLIC UNDER AN ENE LOW
LEVEL FLOW AROUND A 1030 MB HIGH LOCATED NEAR 36N62W. INCREASED
PRES GRADIENT OVER THE CARIBBEAN HAS RAISED WINDS OVER MOST OF
THE AREA REACHING 20 TO 30 KT...MAINLY JUST OFFSHORE THE
COLOMBIAN COAST. THE TRADEWINDS ARE EXPECTED TO REMAIN IN THIS
RANGE THROUGH TONIGHT. WINDS AND SEAS WILL GRADUALLY DIMINISH
TUE THROUGH THU AS HIGH PRES N OF AREA WEAKENS AND SHIFTS E.

THE ATLANTIC OCEAN...
A 1030 MB HIGH CENTERED NEAR 36N62W DOMINATES THE W ATLC. THIS
FEATURE IS PRODUCING MODERATE TO STRONG TRADE WINDS E OF THE
LESSER ANTILLES...OVER MOST OF THE CARIBBEAN SEA AND SE BAHAMAS.
THE LEADING EDGE OF THIS HIGH IS A WEAKENING COLD FRONT THAT
ENTERS THE AREA NEAR 32N40W THEN CONTINUES SW TO NEAR 26N55W.
PATCHES OF LOW/MID CLOUDS ARE ALONG THE FRONTAL BOUNDARY. AHEAD
OF THE FRONT THERE IS A TROUGH...SURFACE REFLEXION OF AN UPPER
LOW SITUATED NEAR 26N40W. THIS TROUGH IS ALONG 38W FROM 20N-29N.
A SURFACE RIDGE ENVELOPS THE E ATLANTIC ANCHORED ON A 1036 MB
HIGH LOCATED WELL N OF AREA.

IN THE UPPER LEVELS...A RIDGE/TROUGH/RIDGE PATTERN COVERS THE
DISCUSSION AREA. THE RIDGE OVER THE CARIBBEAN EXTENDS NWD
THROUGH HISPANIOLA INTO THE W ATLC. SLY WINDS ON THE WESTERN
SIDE OF THIS RIDGE ARE ADVECTING DEBRIS MOISTURE FROM THE
CONVECTION OVER THE W CARIBBEAN ACROSS CUBA AND THE BAHAMAS
INTO THE W ATLC. A DEEP LAYERED TROUGH REMAINS OVER THE
E-CENTRAL ATLC EXTENDING SOUTH INTO THE TROPICS TO NEAR
10N50W. AN UPPER LOW IS ALONG THE TROUGH AXIS NEAR 26N40W. THIS
FEATURE IS GENERATING SCATTERED SHOWERS FROM 21N-30N BETWEEN
33W-41W. AN UPPER RIDGE EXTENDS FROM THE TROPICAL ATLC ALL THE
WAY N TO BEYOND 32N27W. THIS RIDGE IS ENHANCING CONVECTION ALONG
THE ITCZ AXIS. UPPER NWLY FLOW AND DRY AIR IS NOTED OVER THE
MADEIRA/CANARY ISLANDS ASSOCIATED WITH AN UPPER LOW OVER NW
AFRICA.

$$
GR






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