[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 130553
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT WED APR 13 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 07N13W TO THE EQUATOR NEAR 25W...
THEN INTO NE BRAZIL NEAR 05S36W. ISOLATED MODERATE CONVECTION IS
FROM THE EQUATOR TO 05N BETWEEN 17W-26W.

...DISCUSSION...

GULF OF MEXICO...
NW FLOW ALOFT IS ACROSS MUCH OF THE GULF THIS EVENING DUE TO AN
EXPANSIVE UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER
CENTRAL MEXICO NEAR 20N100W. WATER VAPOR IMAGERY INDICATES AN
UPPER LEVEL TROUGH CONTINUE TO ROTATE OVER THE MID-ATLC STATES
THAT SUPPORTS A COLD FRONT THAT AT 13/0300 UTC EXTENDS ACROSS
THE FLORIDA PENINSULA FROM CAPE CANAVERAL TO BRADENTON AND INTO
THE EASTERN GULF TO 26N87W. THE FRONT CONTINUES STATIONARY W-SW
ALONG 26N90W TO 25N94W THEN INLAND OVER SOUTHERN MEXICO NEAR
VERACRUZ. WHILE MUCH OF THE UPPER LEVEL SUPPORT FOR THIS FRONT
CONTINUES TO LOCATE IN THE W ATLC...GENERALLY THE FRONT REMAINS
FAIRLY BENIGN WITH A NOTICEABLE CONTRAST IN DEWPOINTS ACROSS THE
BOUNDARY. RECENT SHIP AND BUOY OBSERVATIONS INDICATE A MUCH
DRIER AIRMASS IN PLACE N OF 26N AS A 1019 MB HIGH SETTLES IN
ACROSS THE NORTHERN GULF NEAR 29N90W. THE FRONT IS FORECAST TO
GRADUALLY BECOME MORE DIFFUSE AND DISSIPATE THROUGH THE
OVERNIGHT HOURS AS THE HIGH SHIFTS SLOWLY EASTWARD PROVIDING
LIGHT ANTICYCLONIC FLOW THROUGH LATE WEDNESDAY. S-SE RETURN FLOW
IS EXPECTED TO RE-ESTABLISH ACROSS THE WESTERN GULF BY EARLY
THURSDAY AS THE NEXT SURFACE LOW PRESSURE AREA ORGANIZES OVER
THE U.S. CENTRAL PLAINS.

CARIBBEAN SEA...
AN AMPLIFIED MIDDLE TO UPPER LEVEL TROUGH IS LOCATED OVER THE
WESTERN CARIBBEAN WITH AXIS EXTENDING FROM THE SW NORTH ATLC
NEAR 24N68W SW TO NORTHERN COSTA RICA NEAR 10N85W. STRONG
SUBSIDENCE AND DRY AIR ACCOMPANY THIS UPPER LEVEL FEATURE AND
THESE FACTORS CONTINUE TO PROVIDE OVERALL CLEAR SKIES AND FAIR
CONDITIONS FOR THE WESTERN CARIBBEAN W OF 72W. EAST OF THE
TROUGH AXIS...MOIST SOUTHWESTERLY FLOW IS ADVECTING A
CONSIDERABLE AMOUNT OF MIDDLE TO UPPER LEVEL MOISTURE ACROSS THE
EASTERN CARIBBEAN AND LESSER ANTILLES. A SURFACE TROUGH IS
ANALYZED FROM THE MONA PASSAGE TO CURACAO WITH SCATTERED SHOWERS
AND ISOLATED TSTMS E OF 70W. THE SURFACE TROUGH IS FORECAST TO
DRIFT WESTWARD AND GRADUALLY WEAKEN THROUGH EARLY FRIDAY WITH
EASTERLY TRADES REMAINING LIGHT DUE TO A RELAXED PRESSURE
GRADIENT ACROSS THE ENTIRE BASIN.

ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL TROUGH CONTINUES TO ROTATE OVER THE
MID-ATLC STATES THIS EVENING THAT SUPPORTS A COLD FRONT ANALYZED
INTO THE DISCUSSION AREA NEAR 32N77W EXTENDING SW TO THE FLORIDA
PENINSULA NEAR CAPE CANAVERAL. A PRE-FRONTAL TROUGH ALSO EXTENDS
FROM THE COLD FRONT NEAR 30N78W TO 25N80W. SATELLITE IMAGERY AND
LIGHTNING DATA INDICATE SCATTERED SHOWERS AND TSTMS ARE
OCCURRING WITHIN 60 NM EAST OF THE FRONT N OF 28N. THE REMAINDER
OF THE W ATLC WEST OF 50W IS UNDER THE INFLUENCE OF A WEAK
SURFACE RIDGE ANCHORED BY A 1026 MB HIGH CENTERED NE OF BERMUDA
NEAR 34N56W. THE RIDGE AXIS EXTENDS FROM THE HIGH TO THE CENTRAL
BAHAMAS. AN UPPER LEVEL LOW IS CENTERED NEAR 31N46W IN THE
CENTRAL ATLC AND CONTINUES TO SUPPORT A FRONTAL BOUNDARY
ANALYZED FROM 32N45W TO 23N48W. THIS AREA OF FRONTAL TROUGHING
LARGELY EMBEDDED WITHIN THE SUBTROPICAL RIDGE IS PRODUCING AN
AREA OF SCATTERED SHOWERS AND ISOLATED TSTMS FROM 24N-32N
BETWEEN 38W-45W. THIS ACTIVITY IS LIKELY ENHANCED BY UPPER LEVEL
DIFFLUENCE E OF THE UPPER LEVEL LOW. STRONG HIGH PRESSURE IS
EXPECTED TO BUILD IN OVER THE CENTRAL ATLC BY EARLY THURSDAY AND
DISSIPATE ANY REMNANTS OF THE FRONT. NE WINDS ON THE SOUTHERN
PERIPHERY OF A SURFACE RIDGE INFLUENCE THE EASTERN ATLC E OF 35W
UNDER MOSTLY FAIR CONDITIONS.

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

$$
HUFFMAN




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