[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 131059
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...ITCZ...

ITCZ AXIS IS ANALYZED ALONG 05N09W 04N19W TO THE EQUATOR NEAR
28W...THEN INTO NE BRAZIL NEAR 04S38W. SCATTERED MODERATE AND
ISOLATED STRONG CONVECTION IS FROM 02N-06N E OF 07W TO THE PRIME
MERIDIAN. ISOLATED MODERATE CONVECTION IS FROM 05N-08N BETWEEN
11W-15W.

...DISCUSSION...

GULF OF MEXICO...
NW FLOW ALOFT IS ACROSS MUCH OF THE GULF THIS MORNING DUE TO AN
EXPANSIVE UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER
CENTRAL MEXICO NEAR 20N100W. WATER VAPOR IMAGERY INDICATES AN
UPPER LEVEL TROUGH CONTINUES TO ROTATE OVER THE MID-ATLC STATES
THAT SUPPORTS A COLD FRONT THAT AT 13/0900 UTC EXTENDS ACROSS
THE FLORIDA PENINSULA FROM STUART TO FORT MYERS BEACH AND INTO
THE SE GULF NEAR 26N84W. THE FRONT CONTINUES STATIONARY WESTWARD
TO 26N95W. WHILE MUCH OF THE UPPER LEVEL SUPPORT FOR THIS FRONT
IS LOCATED IN THE W ATLC...THE FRONT GENERALLY 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 LOWER MISSISSIPPI RIVER VALLEY NEAR 34N91W. THE FRONT
IS FORECAST TO GRADUALLY BECOME MORE DIFFUSE AND DISSIPATE
THROUGH THE DAY ON WEDNESDAY 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 AND MOVES NE TOWARDS THE
GREAT LAKES REGION.

CARIBBEAN SEA...
AN AMPLIFIED MIDDLE TO UPPER LEVEL TROUGH IS LOCATED OVER THE
WESTERN CARIBBEAN WITH AXIS EXTENDING FROM THE SW NORTH ATLC
NEAR 25N75W S-SW OVER EASTERN CUBA AND JAMAICA 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 HOWEVER...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 EASTERN PUERTO RICO
ALONG 15N70W TO LAKE MARACAIBO WITH WIDELY 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 MORNING THAT SUPPORTS A COLD FRONT ANALYZED
INTO THE DISCUSSION AREA NEAR 32N75W EXTENDING SW TO THE FLORIDA
PENINSULA NEAR STUART. A PRE-FRONTAL TROUGH ALSO EXTENDS FROM
THE COLD FRONT NEAR 29N77W TO 24N80W. SATELLITE IMAGERY AND
LIGHTNING DATA INDICATE SCATTERED SHOWERS AND TSTMS ARE
OCCURRING WITHIN 120 NM EAST OF THE FRONT N OF 26N. THE
REMAINDER OF THE W ATLC WEST OF 50W IS UNDER THE INFLUENCE OF A
SURFACE RIDGE ANCHORED BY A 1025 MB HIGH CENTERED NE OF BERMUDA
NEAR 34N59W. THE RIDGE AXIS EXTENDS FROM THE HIGH TO THE SE
BAHAMAS. AN UPPER LEVEL LOW IS CENTERED NEAR 30N45W IN THE
CENTRAL ATLC AND CONTINUES TO SUPPORT A WEAK 1015 MB LOW
CENTERED VERY NEAR THE UPPER LEVEL LOW. A STATIONARY FRONT IS
ANALYZED FROM 32N45W INTO THE LOW CENTER THEN A SURFACE TROUGH
EXTENDS SOUTH FROM THE LOW ALONG 28N44W TO 24N50W. THIS AREA OF
DEEP LAYER TROUGHING IS LARGELY EMBEDDED WITHIN THE SUBTROPICAL
RIDGE PRODUCING AN AREA OF WIDELY SCATTERED SHOWERS FROM 25N-33N
BETWEEN 38W-45W. THIS ACTIVITY IS LIKELY ENHANCED BY UPPER LEVEL
DIFFLUENCE LOCATED 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 OVER THE EASTERN ATLC
INFLUENCES THE OPEN WATERS E OF 35W UNDER MOSTLY FAIR AND STABLE
CONDITIONS.

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

$$
HUFFMAN


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