[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 182332
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST FRI FEB 18 2011

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
2345 UTC.

...ITCZ...

THE ITCZ IS ANALYZED FROM THE COAST OF LIBERIA NEAR 7N11W TO
3N20W TO 1N30W THEN S OF THE EQUATOR NEAR 40W INTO SOUTH
AMERICA NEAR 1S45W. CLUSTERS OF SCATTERED MODERATE ISOLATED
STRONG CONVECTION ARE LOCATED FROM 1N TO 4N BETWEEN THE PRIME
MERIDIAN AND 11W. SCATTERED STRONG CONVECTION IS LOCATED ALONG
THE SOUTH AMERICA COAST FROM THE EQUATOR TO 3N AND EXTENDS
OFFSHORE UP TO 240 NM.

...DISCUSSION...

GULF OF MEXICO...
BROAD RIDGING ALOFT COVERS MOST OF THE GULF WITH WATER VAPOR
IMAGERY INDICATING STRONG SUBSIDENCE ACROSS THE ENTIRE AREA.
WINDS ALOFT ARE STRONGEST OVER THE NW GULF AND MEASURE IN THE 40
TO 50 KNOT RANGE. THIS PATTERN WILL CHANGE LITTLE OVER THE NEXT
48 HOURS. AT THE SURFACE...A 1026 MB HIGH IS ANCHORED OVER THE
FLORIDA PANHANDLE NEAR APALACHICOLA PROVIDING CLEAR SKIES OVER
MOST OF THE GULF WITH THE EXCEPTION OF A FEW PATCHES OF LOW
CLOUDS AND FOG ABOUT 60 NM OFF THE COAST OF MEXICO FROM VERACRUZ
TO MATAMOROS AND ALONG THE UPPER TEXAS COAST. GALVESTON TEXAS
RECENTLY REPORTED VISIBILITIES OF 1 NM IN FOG. LIGHT EAST TO
SOUTHEAST RETURN FLOW IN THE 10 TO 15 KNOT RANGE IS NOTED OVER
MOST OF THE GULF. EXPECT LITTLE CHANGE IN THE OVERALL PATTERN
THROUGH THE WEEKEND.

CARIBBEAN SEA...
WESTERLIES ALOFT COVER THE ENTIRE CARIBBEAN BASIN WITHIN A
RIDGE-TROUGH PATTERN WITH THE RIDGE AXIS ALONG 85W AND
DOWNSTREAM TROUGH ALONG 70W WHICH WAS THE SOUTHERN EXTENSION OF
A MIDDLE/UPPER LEVEL TROUGH OVER THE W-CENTRAL ATLANTIC PUSHING
SOUTH ACROSS HISPANIOLA. THE STRONGEST WINDS ARE OCCURRING
OVER THE NE PORTION OF THE BASIN WHERE 60-70 KNOT WINDS ARE
OCCURRING IN THE ENTRANCE REGION OF THE SUBTROPICAL JETSTREAM
OVER THE W-CENTRAL ATLANTIC. STRONG SUBSIDENCE ALOFT COVERS THE
CARIBBEAN. AT THE SURFACE...TRADE WINDS OF 10 TO 15 KNOTS
EXCEPT LOCALLY 20 KT IN THE WINDWARD PASSAGE AND S OF HISPANIOLA
ARE EXPECTED TO INCREASE LATE SUNDAY AND MONDAY REACHING 20 TO
25 KT OVER MOST AREAS E OF 75W.

ATLANTIC OCEAN...
A MIDDLE/UPPER LEVEL TROUGH DOMINATES THE FLOW W OF ABOUT 50W
WITH THE AXIS LOCATED THROUGH 32N54W 22N64W TO HISPANIOLA.
STRONG SUBSIDENCE ALOFT IS LOCATED S OF 25N W OF 60W. AXIS OF
SUBTROPICAL JET ORIGINATES NEAR THE BASE OF THE TROUGH NEAR
18N65W AND CONTINUES NE THROUGH 24N60W TO 30N50W AND THEN TURNS
MORE ENE BEYOND 32N45W. SATELLITE DERIVED WINDS INDICATE WINDS
OF 100 TO 115 KNOTS BETWEEN 45W AND 55W. A BROAD RIDGE ALOFT IS
LOCATED OVER THE TROPICS S OF ABOUT 18N BETWEEN 30W AND 55W.
WESTERLIES ALOFT COVER MOST OF THE EASTERN HALF OF THE ATLANTIC
N OF ABOUT 10N. A MIDDLE/UPPER LEVEL SHORTWAVE TROUGH APPEARS TO
BE UNDERCUTTING THE RIDGE WITH AXIS FROM THE COAST OF MAURITANIA
THROUGH THE CAPE VERDE ISLANDS TO AN UPPER LOW NEAR 12N26W.
AT THE SURFACE...A NARROW RIDGE OF HIGH PRESSURE EXTENDS FROM A
1028 MB CENTER NEAR APALACHICOLA FLORIDA EASTWARD ALONG 30N TO
58W. A DISSIPATING COLD FRONT EXTENDS THROUGH 32N23W TO 25N39W
AND THEN CONTINUES AS A SHEAR AXIS THROUGH 23N50W TO JUST N OF
PUERTO RICO. UPWARD MOTION TO THE S OF THE SUBTROPICAL JET WAS
RESULTING IN A 5 TO 7 DEGREE WIDE BAND OF BROKEN/OVERCAST MID
AND HIGH LEVEL CLOUDINESS FROM THE SHEAR AXIS NORTHWARD OVER THE
OPEN ATLANTIC.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
COBB






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