[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 161744
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST MON FEB 16 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...THE ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 4N8W 2N20W 1N30W CROSSING THE
EQUATOR AT 37W...AND INTO NE BRAZIL NEAR 2S47W WHERE SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FIRED UP. ELSEWHERE...
ISOLATED MODERATE CONVECTION IS WITHIN 100 NM EITHER SIDE OF
AXIS BETWEEN 8W AND 15W. SIMILAR CONVECTION IS WITHIN 130 NM N
OF AXIS BETWEEN 20W AND 24W...AND BETWEEN 30W AND 40W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 1500 UTC...A COLD FRONT ENTERS THE GULF OF MEXICO THROUGH
THE STRAITS OF FLORIDA THEN CONTINUES MAINLY WEST TO NEAR 23N86W
WHERE IT BEGINS TO DISSIPATE. VIS SATELLITE IMAGERY SHOWS A ROPE
CLOUD AT THE LEADING EDGE OF THE FRONT...WHILE DOPPLER RADAR
REVEALS ISOLATED SHOWERS BETWEEN THE FLORIDA KEYS AND THE COAST
OF CUBA. HIGH PRESSURE CURRENTLY OVER THE CENTRAL CONUS IS
INVADING THE NORTHERN GULF WATERS PRODUCING N TO NE WINDS OF 15
TO 20 KT. THESE WINDS ARE USHERING IN A RELATIVELY COOLER AND
DRIER AIR MASS. COLD AIR STRATOCUMULUS CLOUDS ARE BEHIND THE
FRONT WHICH IS EXPECTED TO MOVE S OF THE AREA EARLY THIS
AFTERNOON. THE FRESH NE WINDS WILL VEER MORE SE TO S TONIGHT AS
THE HIGH PRES SHIFTS EAST OVER THE EASTERN U.S. SOUTHERLY RETURN
FLOW IS FORECAST TO DEVELOP OFF THE TEXAS COAST ON TUE. IN THE
UPPER LEVELS...A RIDGE...ANCHORED ON A HIGH OVER THE EPAC NEAR
11N97W...DOMINATES THE ENTIRE GULF PRODUCING STRONG NW FLOW AND
ALSO STRONG SUBSIDENCE S OF 26N INCLUDING SE MEXICO AND THE
YUCATAN PENINSULA. A 130-150 KT UPPER LEVEL JET IS INLAND OVER
THE NORTH GULF STATES. 90-110 KT UPPER LEVEL WINDS ARE OVER THE
N GULF N OF 26N.

CARIBBEAN SEA...
MAIN WEATHER FEATURE ACROSS THE BASIN EARLY THIS AFTERNOON IS
THE SURFACE TROUGH PRESENTLY AFFECTING THE WINDWARD ISLANDS AND
THE FAR SE CARIBBEAN. THE TROUGH AXIS EXTENDS FROM MARTINIQUE TO
NE VENEZUELA NEAR 8N63W. TRINIDAD REPORTED 1.39 INCHES OF RAIN
FOR THE PAST 24 HOURS ENDING THIS MORNING AT 7 AM. SFC DATA AND
A RECENT QSCAT PASS CLEARLY INDICATE THE WIND SHIFT ASSOCIATED
WITH THE TROUGH. IN ADDITION...THE CLOUD PATTERN IS EXHIBITING
SOME CYCLONIC TURNING. THE MOISTURE THAT ACCOMPANIES THIS TROUGH
WILL CONTINUE TO AFFECT THE SE CARIBBEAN SPREADING OVER THE ABC
ISLANDS LATER TODAY INTO TUE. ON THE OTHER HAND...THE COLD FRONT
CURRENTLY OVER THE STRAITS OF FLORIDA AND THE SOUTHERN GULF OF
MEXICO WILL MOVE ACROSS WESTERN CUBA THIS AFTERNOON FOLLOWED BY
MODERATE NLY WINDS...THEN THE FRONT WILL MOVE QUICKLY EWD
REACHING THE WINDWARD PASSAGE BY TUE MORNING AND AFFECTING
HISPANIOLA TUE AFTERNOON. THE FRONT IS FORECAST BY THE COMPUTER
MODELS TO MOVE ACROSS PUERTO RICO AND THE VIRGIN ISLANDS TUE
EVENING INTO WED. IN THE MEAN TIME...PATCHES OF LOW LEVEL
MOISTURE CARRIED BY THE TRADE WINDS ARE NOTED OVER THE CENTRAL
AND WESTERN CARIBBEAN...MORE CONCENTRATED IN A BAND EXTENDING
FROM E CUBA TO THE GULF OF HONDURAS. MODERATE TO FRESH TRADE
WINDS ARE BLOWING ACROSS THE REGION WITH THE STRONGEST WINDS OF
UP TO 25 KT NEAR THE COAST OF COLOMBIA. IN THE UPPER LEVELS...
A RIDGE/TROUGH/RIDGE PATTERN COVERS THE AREA WITH STRONG
SUBSIDENCE OVER THE WEST AND CENTRAL CARIBBEAN.

ATLANTIC OCEAN...
A GALE CENTER IS TAKING SHAPE OVER THE W ATLC NEAR 31.5N71W. THE
TRAILING COLD FRONT EXTENDS SW ACROSS THE NW BAHAMAS AND THE
STRAITS OF FLORIDA INTO THE GULF OF MEXICO. THE FRONT IS
FORECAST TO QUICKLY MOVE EWD AS THE EXTRATROPICAL LOW RAPIDLY
INTENSIFIES BECOMING A 1001 MB GALE CENTER NEAR BERMUDA THIS
EVENING. THIS LOW PRES CENTER WILL CONTINUE TO DEEPEN TO A 998
MB STORM CENTER IN ABOUT 24 HOURS...LIKELY REACHING NEAR
HURRICANE FORCE WINDS OVER THE CENTRAL ATLC TUE AFTERNOON. TIGHT
PRES GRADIENT BETWEEN THIS EXTRATROPICAL CYCLONE AND HIGH PRES
OVER THE EASTERN CONUS WILL PRODUCE A LARGE AREA OF FRESH TO
STRONG WINDS N OF 25N BETWEEN 47W-67W. THE REMAINDER OF THE
ATLANTIC DISCUSSION AREA IS UNDER THE INFLUENCE OF A RIDGE
ANCHORED BY A 1023 MB HIGH LOCATED NEAR 27N34W. THIS SYSTEM IS
GENERATING MOSTLY FAIR WEATHER...AND A WIDESPREAD SWATH OF 20 TO
25 KT OVER THE TROPICS...PARTICULARLY BETWEEN 35W AND 55W.
STRONG WLY FLOW ALOFT IS NOTED OVER THE N SECTION OF THE W AND
CENTRAL ATLC DUE TO THE PRESENCE OF A JET-STREAM WHICH ALSO
CROSSES THE N GULF STATES. AN UPPER-LEVEL TROUGH RUNS FROM THE
MADEIRA ISLANDS TO THE CAPE VERDE ISLANDS. A JET-STREAM BRANCH
WITH CORE WINDS OF 90-110 KT IS AROUND THE BASE OF THIS TROUGH
CROSSING OVER AND JUST SOUTH THE CAPE VERDE ISLANDS...AND
ENTERING W AFRICA THROUGH SENEGAL.

$$
GR






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