[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 071747
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SAT FEB 07 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...

ITCZ IS CENTERED ALONG 6N11W 2N20W 1N35W CROSSING THE EQUATOR AT
43W INTO NE BRAZIL NEAR 2S47W. ISOLATED MODERATE CONVECTION IS
WITHIN 70 NM S OF AXIS BETWEEN 11W-14W. ELSEWHERE...SCATTERED
SHOWERS ARE ALONG THE ITCZ AXIS.

...DISCUSSION...

GULF OF MEXICO...
A STRONG 1035 MB SURFACE HIGH PRESSURE CENTERED ALONG THE
FLORIDA/GEORGIA BORDER NEAR 31N/83W DOMINATES THE PATTERN
ACROSS THE ENTIRE GULF PRODUCING MOSTLY FAIR WEATHER AND SE-S
RETURN FLOW. SCATTERED COLD AIR STRATOCUMULUS CLOUDS ARE STILL
NOTED OVER THE GULF MOVING N UNDER THE PREDOMINANT WIND FLOW.
ALOFT...A MID/UPPER LEVEL RIDGE DOMINATES THE WEST-CENTRAL GULF
WHILE A SHORT-WAVE TROUGH IS OVER THE EASTERN GULF AND WESTERN
CUBA. THE SURFACE HIGH IS EXPECTED TO DRIFT E OVER THE NEXT
COUPLE OF DAYS AS THE NEXT LOW PRESSURE SYSTEM DEVELOPS OVER THE
SRN PLAIN STATES...GRADUALLY INCREASING ELY WINDS OVER THE
STRAITS OF FLORIDA AND SLY WINDS ACROSS THE WRN GULF THIS
AFTERNOON INTO EARLY NEXT WEEK. THE NEXT COLD FRONT IS EXPECTED
TO MOVE OFF THE TEXAS COAST EARLY WED.

CARIBBEAN SEA...
A SFC TROUGH...REMNANTS OF AN OLD FRONTAL BOUNDARY...EXTENDS
FROM PUERTO RICO TO THE SW CARIBBEAN NEAR 12N80W. SCATTEROMETER
AND SFC DATA INDICATE NELY WINDS OF 20 TO 30 KT EITHER SIDE OF
THE TROUGH AXIS. THESE MODERATE TO FRESH WINDS ARE TRANSPORTING
SCATTERED TO NUMEROUS SHOWERS ACROSS THE UK/US VIRGIN ISLANDS...
PUERTO RICO...AND THE MONA PASSAGE AS SEEN ON THE SAN JUAN
DOPPLER RADAR. SIMILAR WEATHER PATTERN IS ALSO OBSERVED OVER THE
N PORTION OF HISPANIOLA. A SECOND SFC TROUGH...EMBEDDED WITHIN
FRESH TRADES...LIES ALONG 69W S OF 15N. VIS SATELLITE IMAGERY
REVEALS A SWIRL OF LOW CLOUDS ASSOCIATED WITH THIS TROUGH WHICH
IS GENERATING SCATTERED SHOWERS OVER THE ABC ISLANDS. ADDITIONAL
CONCENTRATED BANDS OF SHOWERS ARE ALSO AFFECTING EASTERN
NICARAGUA AND COSTA RICA LIKELY RELATED TO THE LOW-LEVEL
WIND/SPEED CONVERGENCE. THE SPEED CONVERGENCE OVER THIS REGION
IS A RESULT OF STRONG TRADES OVER THE CENTRAL CARIBBEAN. SIMILAR
CLOUDINESS ARE FOUND OVER PARTS OF HONDURAS...BELIZE AND
GUATEMALA. MOST OF THIS MOISTURE IS SHALLOW IN NATURE AND CAPPED
BY MODERATE TO STRONG SUBSIDENCE ALOFT DUE TO THE PRESENCE OF A
MID/UPPER-LEVEL RIDGE ANCHORED ON A HIGH OVER CENTRAL VENEZUELA.
STRONG SWLY WINDS ARE OVER THE NW CARIBBEAN AND CUBA AHEAD OF
THE PREVIOUSLY MENTIONED SHORT-WAVE TROUGH. THE COMBINATION OF
STRONG RIDGING N OF THE AREA AND LOW PRES OVER S AMERICA WILL
MAINTAIN FRESH TO STRONG TRADES OVER THE CENTRAL AND W CARIBBEAN
INTO EARLY MON.

ATLANTIC OCEAN...
AN DEEP LAYERED TROUGH EXTENDING ACROSS THE NW ATLC OFF THE
COAST OF NEWFOUNDLAND/NOVA SCOTIA SUPPORTS A COLD FRONT THAT
ENTERS THE DISCUSSION AREA NEAR 31N48W THEN CONTINUES SW TO JUST
N OF PUERTO RICO NEAR 19N66W. AT THIS POINT...IT BECOMES A SFC
TROUGH...REMNANTS OF THIS FRONT OVER THE CARIBBEAN SEA.  LOW-
LEVEL CONVERGENCE IS SUPPORTING SCATTERED SHOWERS WITHIN 90 NM
EITHER SIDE OF THE FRONTAL BOUNDARY PARTICULARLY N OF 25N. A
STRONG HIGH PRES SYSTEM IS IN THE WAKE OF THE FRONT WITH THE
MAIN CENTER OF 1035 MB OVER THE FLORIDA/GEORGIA BORDER. NE WINDS
OF 20 TO 25 KT AROUND THE SOUTHERN PERIPHERY OF THIS HIGH ARE
ADVECTING COLD AIR STRATOCUMULUS CLOUDS ACROSS THE BAHAMAS AND
THE GREATER ANTILLES. E OF THE FRONT...DEEP LAYERED UPPER
RIDGING IS ACROSS MUCH OF THE CENTRAL AND EASTERN ATLC WITH THE
ASSOCIATED 1031 MB SURFACE HIGH SITUATED NEAR 32N32W. A HIGHLY
AMPLIFIED ELONGATED TROUGH LIES SE OF THE RIDGE CROSSING BETWEEN
THE CANARY AND CAPE VERDE ISLANDS TO NEAR 20N32W THEN CONTINUING
SW INTO THE DEEP TROPICS TO NEAR THE NE COAST OF BRAZIL. STRONG
SWLY FLOW AHEAD OF THIS TROUGH IS PRODUCING A PLUME OF
TRANSVERSE HIGH CLOUDS ACROSS THE TROPICS E OF 36W.

$$
GR





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