[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 032344
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST WED DEC 03 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 ANALYZED ALONG 7N12W 4N25W 6N43W 4N54W. SCATTERED
MODERATE CONVECTION IS WITHIN 200 NM SOUTH OF AXIS BETWEEN 20W-30W.
A CLUSTER OF MODERATE TO STRONG CONVECTION IS OVER SE LIBERIA.
SIMILAR CONVECTION IS ALSO NOTED NEAR 4N12W...AND 3N13W.

...DISCUSSION...

GULF OF MEXICO...
SWLY UPPER LEVEL FLOW...AHEAD OF AN AMPLIFYING UPPER-LEVEL TROUGH
OVER WESTERN TEXAS AND NORTHERN MEXICO...DOMINATES THE ENTIRE GULF
REGION. THESE WINDS ARE TRANSPORTING MID/UPPER LEVEL MOISTURE FROM
THE EPAC ACROSS NORTH-CENTRAL MEXICO INTO TEXAS AND THE NW CORNER OF
THE GULF. MODERATE TO STRONG SUBSIDENCE WITH DRY STABLE AIR AT THE
MIDDLE TO UPPER LEVELS OF THE ATMOSPHERE COVERS THE REMAINDER OF THE
AREA. AT THE SURFACE...A RIDGE EXTENDS FROM THE FLORIDA BIG BEND TO
THE YUCATAN PENINSULA. STRONG SOUTHERLY RETURN FLOW HAS BEEN
ESTABLISHED OVER THE NW WATERS IN ADVANCE OF THE NEXT COLD FRONT
FORECAST TO MOVE OFFSHORE THE TEXAS COAST LATE TONIGHT. THE FRONT
WILL EXTEND FROM THE FL PANHANDLE TO WRN BAY OF CAMPECHE BY LATE
THU. SCATTERED TO BROKEN COLD AIR STRATOCUMULUS CLOUDS ARE MOVING
NWD AROUND THE RIDGE OVER THE EASTERN GULF.

CARIBBEAN SEA...
A STATIONARY FRONT EXTENDS ACROSS THE SE BAHAMAS AND EASTERN CUBA
INTO THE CARIBBEAN SEA TO NEAR 13N82W. AN EARLIER ASCAT PASS STILL
INDICATED AN AREA OF 20-25 KT NLY WINDS JUST BEHIND THE FRONT NEAR
EASTERN CUBA AND JAMAICA. SCATTERED MODERATE SHOWERS WITH ISOLATED
TSTMS ARE NEAR THE TAIL END OF THE FRONT PARTICULARLY S OF 13N AND W
OF 82W. THIS CONVECTIVE ACTIVITY IS AFFECTING THE NICARAGUA AND
COSTA RICA COASTLINES. BROKEN STRATOCUMULUS CLOUDS ARE W OF THE
FRONT OVER THE NW CARIBBEAN. A WEAK SURFACE TROUGH IS NEAR THE N
COAST OF COLOMBIA ALONG 73W/74W SOUTH OF 16N. SCATTERED SHOWERS ARE
WITHIN 250 NM AHEAD OF THE TROUGH. MOISTURE ASSOCIATED WITH THIS
FEATURE IS FORECAST BY THE COMPUTER MODELS TO REACH THE ATLANTIC
COAST OF NICARAGUA THU AFTERNOON KEEPING THE CHANCE OF SHOWERS DOWN
THERE. AN UPPER LEVEL RIDGE STRETCHES FROM AN ANTICYCLONIC
CIRCULATION NEAR THE MONA PASSAGE SW TO COSTA RICA. MODERATE TO
STRONG SUBSIDENCE AND IMPLIED DRY AIR MASS IS NOTED ACROSS THE
EASTERN CARIBBEAN E OF 70W...HOWEVER SOME LOW TOPPED SHOWERS ARE
MOVING THROUGH PUERTO RICO AND THE LEEWARD ISLANDS USHERED IN ON
E-NE 15-20 KT TRADE WINDS. THE SAN JUAN DOPPLER RADAR REVEALS
SCATTERED LIGHT SHOWERS PASSING ACROSS THE U.S. VIRGIN ISLANDS AND
PUERTO RICO. STRONG SWLY UPPER LEVEL WINDS ARE SEEN OVER NORTH
CENTRAL AMERICA...THE NW CARIBBEAN AND CUBA.

ATLANTIC OCEAN...
A DEEP-LAYERED TROUGH IS OVER THE EASTERN U.S. AND THE WESTERN
ATLANTIC SUPPORTING A COLD FRONT THAT ENTERS THE FORECAST AREA NEAR
32N64W THEN CONTINUES SW TO NEAR 25N70W. AT THIS POINT...THE FRONT
BECOMES STATIONARY CROSSING THE SE BAHAMAS AND EASTERN CUBA INTO DE
CARIBBEAN SEA. A BAND OF MAINLY LOW/MID CLOUDS WITHIN 80 NM EITHER
SIDE OF THE FRONT CONTAINS EMBEDDED SHOWERS AND POSSIBLE WEAK
ISOLATED TSTMS. A 1029 MB SURFACE HIGH CENTERED OVER THE CAROLINAS
IS BEHIND THE FRONT. THIS HIGH ENVELOPS THE W ATLC...THE NW AND
CENTRAL BAHAMAS...WEST-CENTRAL CUBA...THE YUCATAN PENINSULA AND THE
EASTERN GULF OF MEXICO PRODUCING MOSTLY FAIR WEATHER. THIS SYSTEM IS
FORECAST TO MOVE MAINLY EWD ACROSS THE WEST ATLANTIC OCEAN DURING
THE NEXT 24 HOURS WHILE THE STATIONARY FRONT IS FORECAST TO
GRADUALLY WEAKEN AS IT DRIFTS WWD THROUGH THU. AN UPPER LEVEL HIGH
CENTERED NEAR THE MONA PASSAGE EXTENDS A RIDGE OVER MUCH OF THE
CENTRAL ATLC TO BEYOND 32N56W. ASIDE FROM THE AREA NEAR THE FRONT
MODERATE TO STRONG SUBSIDENCE COVERS THE FORECAST REGION W OF 50W.
LARGE MID/UPPER LEVEL CYCLONIC CIRCULATION IS CENTERED NEAR 26N43W
WITH A TROUGH EXTENDING SW TO 10N60W. A 90-110 KT NLY JETSTREAM IS W
OF THE TROUGH FROM 30N44W TO 19N52W AND A 90-110 KT SLY JET IS E OF
THE TROUGH FROM 15N44W TO 30N34W. AT THE SURFACE...A PAIR OF 1011 MB
SFC LOWS ARE NEAR 26N45W AND 31N46W. SCATTERED SHOWERS ARE NEAR THE
SFC LOWS. TO THE EAST...A SFC TROUGH RUNS FROM 24N42W TO 10N44W. THE
REMAINDER OF THE ATLANTIC OCEAN IS UNDER THE INFLUENCE OF A BROAD
RIDGE ANCHORED ON HIGH SOUTH OF THE CAPE VERDE ISLANDS NEAR 10N24W.

$$
GR





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