[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 120556
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT TUE APR 12 2011

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTION 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...ITCZ...

ITCZ AXIS IS ANALYZED ALONG 05N09W 02N22W CROSSING THE EQUATOR
NEAR 27W THEN INTO NE BRAZIL NEAR 05S36W. SCATTERED MODERATE AND
ISOLATED STRONG CONVECTION IS FROM 02N-07N BETWEEN 16W-27W.

...DISCUSSION...

GULF OF MEXICO...
A MIDDLE TO UPPER LEVEL TROUGH CONTINUES TO PROGRESS ACROSS THE
LOWER MISSISSIPPI RIVER VALLEY THIS EVENING SUPPORTING A COLD
FRONT THAT AT 12/0300 UTC ENTERS THE GULF OF MEXICO NEAR CAMERON
LOUISIANA THEN S-SW ALONG 27N95W TO 23N97W THEN INLAND ACROSS
EAST-CENTRAL MEXICO NEAR 21N97W. WATER VAPOR IMAGERY INDICATES
FAIRLY DRY CONDITIONS AND OVERALL STRONG SUBSIDENCE ALOFT OVER
MUCH OF THE GULF SO CONVECTION WITH THE FRONT IS LIMITED TO A
PRE-FRONTAL SQUALL LINE EXTENDING FROM MOBILE BAY NEAR 31N88W TO
30N90W IMPACTING THE COASTAL WATERS BETWEEN 87W-91W. MOST OF THE
STRONGER AND MORE INTENSE CONVECTION IS LOCATED OVER INTERIOR
PORTIONS OF SE ALABAMA AND WEST-CENTRAL GEORGIA. GLOBAL MODEL
GUIDANCE INDICATES STRONGER NE WINDS TO 20 KT ARE EXPECTED BY
SUNRISE TUESDAY NW OF THE FRONT DUE TO AN INCREASED PRESSURE
GRADIENT ACROSS THE NW GULF...HOWEVER SEVERAL MODELS INCLUDING
THE GFS...ECMWF...AND NAM ALL SHOW THOSE THIS WIND FIELD TO
REMAIN BRIEF LASTING ONLY UNTIL AROUND 12/1500 UTC. A 1021 MB
HIGH CENTERED OVER WEST TEXAS NEAR ABILENE IS FORECAST TO CREATE
THIS INCREASE GRADIENT AND SHIFT EASTWARD THROUGH EARLY
WEDNESDAY PROVIDING THE GULF WITH LIGHT ANTICYCLONIC WINDS.

CARIBBEAN SEA...
DRY AIR AND STRONG SUBSIDENCE IS NOTED ON WATER VAPOR IMAGERY
ACROSS MUCH OF THE WESTERN CARIBBEAN IN ASSOCIATION WITH BROAD
TROUGHING EXTENDING FROM THE SW NORTH ATLC REGION. THE UPPER
LEVEL TROUGH AXIS EXTENDS FROM AN UPPER LEVEL LOW CENTERED NORTH
OF HISPANIOLA NEAR 21N71W TO NORTHERN PANAMA NEAR 08N80W. THIS
VERY DRY AIR ALOFT IS SUPPORTIVE OF CLEAR SKIES W OF 70W AND IS
EXPECTED TO REMAIN IN PLACE THROUGH THURSDAY AS THE UPPER LEVEL
TROUGH AMPLIFIES SLIGHTLY. HIGHER POTENTIAL CONVECTIVE WEATHER
REMAINS EAST OF THE TROUGH AXIS ALONG 70W. E OF 70W...E-NE
TRADES CONTINUE WITH A SURFACE TROUGH ANALYZED FROM 11N66W TO
MONTSERRAT NEAR 17N62W. WIDELY SCATTERED SHOWERS AND ISOLATED
TSTMS ARE OCCURRING E OF A LINE FROM THE US/UK VIRGIN ISLANDS
NEAR 18N65W TO ARUBA NEAR 12N70W. THIS AREA IS FORECAST TO
REMAIN NEARLY STATIONARY THROUGH EARLY WEDNESDAY AS A FRONTAL
BOUNDARY TO THE NORTH OVER THE W ATLC SHIFTS NE OF THE AREA OVER
THE NEXT 24 TO 36 HOURS. TOTAL PRECIPITABLE WATER VALUES REMAIN
HIGH OVER THE SE CARIBBEAN AND THIS ADDED LOW-LEVEL MOISTURE
WILL CONTINUE TO SUPPORT SCATTERED SHOWER ACTIVITY E OF 70W OVER
THE NEXT COUPLE OF DAYS.

ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL TROUGH IS OVER THE CENTRAL ATLC THAT
SUPPORTS A COLD FRONT ENTERING THE DISCUSSION AREA NEAR 32N44W
EXTENDING SW TO 30N49W THEN CONTINUES W-SW AS A STATIONARY FRONT
ALONG 28N60W TO 22N69W. THE STRONGEST UPPER LEVEL DYNAMICS ARE
EVIDENT ON WATER VAPOR IMAGERY N OF 27N WITH SCATTERED SHOWERS
AND ISOLATED TSTMS OCCURRING FROM 28N-33N BETWEEN 43W-49W. SOUTH
OF THE FRONT ACROSS THE SW NORTH ATLC...A WEAK 1016 MB LOW AND
SURFACE TROUGH IS NEAR 22N61W WITH VERY LITTLE ASSOCIATED SHOWER
ACTIVITY. THE REMAINDER OF THE ATLC E OF 45W IS UNDER THE
INFLUENCE OF A SURFACE RIDGE EXTENDING FROM THE AZORES NEAR
38N27W TO 22N45W.

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

$$
HUFFMAN




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