[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 171756
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE APR 17 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 7N10W 4N20W CROSSING THE EQUATOR AT
36W INTO NE BRAZIL NEAR 3N44W. CLUSTERS OF MODERATE/ISOLATED
STRONG CONVECTION ARE WITHIN 70-100 NM N OF THE AXIS BETWEEN 16W
AND 29W.

...DISCUSSION...

GULF OF MEXICO...
A MOSTLY DRY AND STABLE ATMOSPHERE DOMINATES THE GULF AND THE
STATE OF FLORIDA THANKS TO A WEAK 1019 MB HIGH PRES LOCATED OVER
THE SOUTHEASTERN US. THIS HIGH IS PRODUCING A NLY FLOW ACROSS
THE FAR E GULF AND FLORIDA PENINSULA INTO CUBA AND THE WESTERN
CARIBBEAN. BROKEN FAIR WEATHER STRATOCUMULUS CLOUDS ARE SEEN
OVER THE SE PORTION OF THE GULF. ALOFT...A RIDGE DOMINATES THE
ENTIRE GULF AND THE SE US ANCHORED ON A HIGH OVER THE NW
CARIBBEAN...WHILE A SHARP SHORTWAVE TROUGH IS OVER THE NEW
MEXICO AND CHIHUAHUA MEXICO. A PLUME OF UPPER LEVEL MOISTURE
ASSOCIATED WITH THE EPAC JETSTREAM EXTENDS NEWD ACROSS N-CENTRAL
MEXICO...SOUTH TEXAS AND THE NORTHERN GULF WATERS. THIS TROUGH
WILL SUPPORT THE NEXT COLD FRONT THAT IS FORECAST TO MOVE OFF
TEXAS COAST EARLY WED...REACHING THE STRAITS OF FLORIDA AND THE
YUCATAN CHANNEL BY LATE THU. SLY RETURN FLOW OF 15 TO 20 KT HAS
ALREADY ESTABLISHED OVER THE WESTERN GULF AHEAD OF THE NEXT COLD
FRONT. A 1008 MB LOW IS OVER NE MEXICO. THIS LOW IS FORECASTED
TO MOVE TOWARD THE BAY OF CAMPECHE DURING THE NEXT 24 HOURS.

CARIBBEAN SEA...
THE STRONG COLD FRONT THAT HAS AFFECTED THE FORECAST AREA IS
WEAKENING OVER THE CARIBBEAN SEA BUT IS GENERATING SOME
CLOUDINESS WITH EMBEDDED SHOWERS OVER HISPANIOLA AND PARTS OF
JAMAICA. PUERTO PLATA IN DOMINICAN REPUBLIC REPORTED AROUND 4
INCHES OF RAIN (106 MM) THIS MORNING WITH THE FRONTAL PASSAGE.
MOISTURE ASSOCIATED WITH THE REMNANTS OF THE FRONT WILL ALSO
AFFECT PUERTO RICO/VIRGIN ISLANDS LATE TODAY AND TOMORROW. NLY
WINDS OF NEAR 15 KT ARE BEHIND THE FRONT OVER THE NW CARIBBEAN
BUT WILL VEER TO THE E TONIGHT. VIS SAT IMAGERY ALSO SHOWS COLD
AIR STRATOCUMULUS CLOUDS OVER THE YUCATAN CHANNEL AND THE NW
CARIBBEAN. ALOFT...AN UPPER HIGH LOCATED OVER NE HONDURAS
EXTENDS A RIDGE EWD TO THE LESSER ANTILLES...GIVING THE AREA DRY
AIR AND MODERATE TO STRONG SUBSIDENCE. THE TRADES ARE LIGHT TO
MODERATE ACROSS MUCH OF THE AREA DUE TO THE WEAK PRES GRADIENT.

ATLANTIC OCEAN...
THE AFOREMENTIONED COLD FRONT IS WELL DEFINED OVER THE ATLC
ENTERING THE AREA NEAR 31N56W AND CONTINUING SW TO HISPANIOLA.
EARLIER QUIKSCAT PASS CLEARLY SHOWED THE WIND SHIFTS ASSOCIATED
WITH FRONT THAT IS STILL PRODUCING GALE FORCE WINDS AND
HAZARDOUS MARINE CONDITIONS...PARTICULARLY N OF 27N. A DEEP
LAYERED TROUGH OVER THE WEST ATLC IS SUPPORTING THIS FRONTAL
BOUNDARY. A 100 NM WIDE BAND OF LOW/MID CLOUDS WITH EMBEDDED
SHOWERS AND ISOLATED TSTMS IS RELATED TO THE FRONT OVER THE
ATLC. THE MID/UPPER LEVEL RIDGE OVER THE CARIBBEAN EXTENDS NE
INTO THE CENTRAL ATLC THROUGH THE LEEWARD ISLANDS. FARTHER
E...ANOTHER UPPER LEVEL TROUGH DOMINATES THE E ATLC WITH THE
AXIS EXTENDING SW TO THE DEEP TROPICS NEAR 7N48W. STRONG SWLY
WINDS AHEAD OF THE TROUGH ARE TRANSPORTING UPPER LEVEL
MOISTURE/HIGH CLOUDS FROM N SOUTH AMERICA NEWD TO W AFRICA JUST
N OF THE CAPE VERDE ISLANDS. AT THE SURFACE...A RIDGE DOMINATES
MOST OF THE E-CENTRAL ATLC WITH THE SFC HIGH LOCATED WELL NORTH
OF THE AREA.

$$
GR




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