[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 112349
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST THU DEC 11 2008

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...THE ITCZ...
THE ITCZ IS CENTERED ALONG 8N13W 5N30W 7N45W 9N56W 8N61W. A
SURFACE TROUGH REMAINS EMBEDDED WITHIN THE ITCZ ALONG 57W SOUTH
OF 13N. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
5N-10N BETWEEN 50W-57W. SIMILAR CONVECTION IS ALSO NOTED WITHIN
100 NM N OF AXIS BETWEEN 44W-50W. ELSEWHERE...SCATTERED MODERATE
CONVECTION IS FROM 5N-8N BETWEEN 23W-28W.

...DISCUSSION...

GULF OF MEXICO...
AN EXTRATROPICAL CYCLONE CURRENTLY CENTERED OVER THE CAROLINAS
IS PRODUCING A WIDE VARIETY OF PRECIPITATION OVER THE SE CONUS.
A COLD FRONT EXTENDS FROM THIS LOW ACROSS THE SE COAST OF
FLORIDA AND WESTERN CUBA INTO THE CARIBBEAN SEA. A REINFORCING
COLD FRONT IS BEHIND STRETCHING FROM THE FLORIDA PANHANDLE
ACROSS THE CENTRAL GULF NEAR 25N90W TO 23N94W. A DEEP LAYERED
TROUGH PRESENTLY IMPACTING THE E CONUS AND THE GULF REGION
SUPPORTS THESE FRONTS. A BAND OF SHOWERS AND TSTMS IS WITHIN 120
NM E OF THE FRONT WHILE BROKEN TO OVERCAST STRATOCUMULUS CLOUDS
COVERS MUCH OF THE GULF DUE TO THE COLD AIR ADVECTION OVER
RELATIVELY WARM WATERS. THICK LOW LEVEL CLOUDS ARE BANKED UP
AGAINST THE MOUNTAINS IN SE MEXICO COVERING ALSO THE BAY OF
CAMPECHE. A SFC RIDGE CENTERED ON A 1026 MB HIGH LOCATED OVER N
MEXICO IS BUILDING IN. THE TIGHT PRESSURE GRADIENT BETWEEN THIS
SURFACE RIDGE AND THE SURFACE LOW OVER THE CAROLINAS IS
RESULTING IN GALE FORCE WINDS ACROSS THE MIDDLE AND E GULF WHERE
A GALE WARNING IS IN EFFECT. SURFACE OBSERVATIONS AND AN EARLIER
ASCAT PASS CONFIRMED THESE WIND SPEEDS. ADDITIONALLY...STRONG N
TO NE SURFACE WINDS ARE BLOWING THROUGH THE ISTHMUS OF
TEHUANTEPEC RESULTING IN STORM FORCE WINDS IN THE E PACIFIC
REGION.

CARIBBEAN SEA...
AS OF 2100 UTC...A COLD FRONT IS OVER WESTERN CUBA...THE NW
CARIBBEAN AND N HONDURAS NEAR 15N86W. HAVANA CUBA REPORTED
STRONG TSTMS AND GUSTY WINDS OF 18 KT WITH THE PASSAGE OF THE
FRONT DURING THE AFTERNOON. SIMILAR WEATHER CONDITIONS WERE
REPORTED IN N HONDURAS. LOW/MID CLOUDS LINGERING BEHIND THE
FRONT ARE NOTED OVER THE NW CARIBBEAN...PARTS OF THE YUCATAN
PENINSULA...BELIZE...GUATEMALA AND HONDURAS. THE FRONT WILL
CONTINUE TO MOVE EWD ACROSS CENTRAL CUBA AND THE CAYMAN ISLANDS
TONIGHT. MODERATE TO STRONG NLY WINDS OF 20 TO 25 KT ARE
EXPECTED IN THE WAKE OF THE FRONT OVER THE NW CARIBBEAN TONIGHT
AND FRI. THE REMAINDER OF THE CARIBBEAN SEA REMAINS UNDER THE
INFLUENCE OF A STRONG HIGH PRES SYSTEM...ANALYZED 1040 MB...NEAR
THE AZORES. PATCHES OF LOW LEVEL MOISTURE CARRIED BY THE TRADE
WINDS CONTINUES TO MOVE EWD AROUND THE PERIPHERY OF THIS SFC
HIGH WHICH IS ALSO PRODUCING A WIDE SWATH OF MODERATE TO STRONG
ELY WINDS ACROSS THE ATLANTIC OCEAN AND THE E-CENTRAL
CARIBBEAN...WITH THE STRONGEST WINDS NEAR THE COAST OF COLOMBIA.
SATELLITE IMAGERY REVEALS A BAND OF BROKEN SHALLOW MOISTURE WITH
EMBEDDED MAINLY LIGHT SHOWERS EXTENDING FROM THE LEEWARD ISLANDS
TO JAMAICA. ALOFT...A RIDGE WITH AXIS ALONG 76W DOMINATES MOST
OF THE BASIN. MID/UPPER-LEVEL MOISTURE CONTINUES STREAMING
ACROSS CENTRAL AMERICA AND THE W CARIBBEAN IN SOUTHWESTERLY FLOW
ALOFT. SCATTERED MODERATE CONVECTION IS OVER E PANAMA IN THE
VICINITY OF A 1008 MB SURFACE LOW LOCATED NEAR 9.5N77W. UPPER
DIFFLUENCE ASSOCIATED WITH THE AFOREMENTIONED RIDGE IS ENHANCING
THIS ACTIVITY.

ATLANTIC OCEAN...
A STRONG CUT-OFF LOW SPINNING OVER THE SE CONUS SUPPORTS A 999
MB SURFACE LOW SITUATED OVER THE CAROLINAS. THE ASSOCIATED COLD
FRONT ENTERS THE FORECAST AREA NEAR 32N79W THEN CONTINUES SW
ACROSS SE FLORIDA AND WESTERN CUBA INTO THE CARIBBEAN SEA. COLD
ADVECTION BEHIND THE FRONT WILL KEEP TEMPS IN THE MID TO UPPER
60S TO THE LOWER 70S IN SOUTH FLORIDA THIS FRIDAY. SCATTERED TO
NUMEROUS SHOWERS AND THUNDERSTORMS ARE ALONG AND AHEAD OF THE
COLD FRONT OVER THE W ATLC CURRENTLY AFFECTING THE NW BAHAMAS.
GALE FORCE WINDS ARE BLOWING AHEAD OF THE FRONT N OF THE NW
BAHAMAS AND WEST OF 77W DUE TO THE STRONG PRES GRADIENT BETWEEN
THE SURFACE LOW OVER THE CAROLINAS AND THE STRONG SFC HIGH OVER
THE ATLANTIC OCEAN. SUBSIDENCE AROUND THIS 1040 MB SURFACE HIGH
CENTERED NEAR THE AZORES IS GENERALLY SUPPORTING FAIR WEATHER
CONDITIONS ACROSS MUCH OF THE E-CENTRAL ATLC. HOWEVER... AN
UPPER LOW CENTERED NEAR 27N48W IS PRODUCING SCATTERED SHOWERS
FROM 21N-26N BETWEEN 41W-48W. THIS SFC HIGH IS ALSO GENERATING A
WIDE SWATH OF MODERATE TO STRONG ELY WINDS ACROSS THE OCEAN
PARTICULARLY FROM 20N-32N BETWEEN 30W-60W. ACROSS THE DEEP
TROPICS...A MAINLY WESTERLY FLOW ALOFT IS PRESENT. A JET-STREAM
BRANCH WITH CORE WINDS OF 70-90KT CROSSES JUST N OF THE CAPE
VERDE ISLANDS.

$$
GR



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