[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 110555
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT MON APR 11 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 05N08W 03N19W CROSSING THE EQUATOR
NEAR 27W THEN INTO NE BRAZIL NEAR 04S38W. ISOLATED MODERATE TO
STRONG CONVECTION IS FROM THE EQUATOR TO 04N BETWEEN 20W-26W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL RIDGE COVERS THE GULF OF MEXICO EXTENDING FROM
ANTICYCLONIC CIRCULATION OVER SOUTHERN MEXICO NEAR 16N96W. THE
UPPER LEVEL RIDGE AXIS EXTENDS N-NE OVER THE SE CONUS. THIS
FEATURE CONTINUES TO SUPPORT A WELL-ESTABLISHED SURFACE RIDGE
ANCHORED BY TWO HIGHS...1020 MB AND 1019 MB...CENTERED IN THE
VICINITY OF THE FLORIDA PENINSULA...ONE LOCATED IN THE NE GULF
WATERS AND THE OTHER NEAR ANDROS ISLAND BAHAMAS. S-SE WINDS TO
20 KT ARE OCCURRING OVER MUCH OF THE WESTERN TWO-THIRDS OF THE
GULF WHICH IS FORECAST TO PERSIST AND INCREASE SLIGHTLY W OF 90W
THROUGH MID-DAY MONDAY AS THE NEXT COLD FRONT APPROACHES FROM
CENTRAL TEXAS THROUGH THE OVERNIGHT HOURS. THE FRONT WILL EMERGE
OFF THE TEXAS GULF COAST SHORTLY AFTER NOONTIME MONDAY SHIFTING
WINDS N-NE OVER THE NW GULF WATERS. THE FRONT WILL QUICKLY MOVE
EAST OF THE GULF BY EARLY WEDNESDAY WITH LIGHT EASTERLY FLOW
EXPECTED ON THE SOUTHERN PERIPHERY OF A SURFACE RIDGE OVER THE
MISSISSIPPI RIVER VALLEY AND SE CONUS.

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 THROUGH THE WINDWARD PASSAGE TO THE SE
COAST OF NICARAGUA NEAR 11N84W. THIS VERY DRY AIR ALOFT IS
SUPPORTIVE OF VERY CLEAR SKIES W OF 68W AND IS EXPECTED TO
REMAIN IN PLACE THROUGH EARLY THURSDAY AS THE UPPER LEVEL TROUGH
AMPLIFIES SLIGHTLY AND MORE CONVECTIVE WEATHER POTENTIAL REMAINS
EAST OF THE TROUGH AXIS ALONG 70W. E OF 70W...E-NE TRADES
CONTINUE WITH BROAD SURFACE TROUGHING NOTED OVER THE LESSER
ANTILLES THIS EVENING. ISOLATED SHOWERS ARE OCCURRING S OF 17N E
OF 67W AND THIS AREA IS FORECAST TO BEGIN MOVING WESTWARD BY
EARLY WEDNESDAY AS THE 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 SHOWER
ACTIVITY E OF 70W OVER THE NEXT COUPLE OF DAYS.

ATLANTIC OCEAN...
A BROAD MIDDLE TO UPPER LEVEL TROUGH IS OVER THE SW NORTH ATLC
WATERS THAT SUPPORTS A COLD FRONT ENTERING THE DISCUSSION AREA
NEAR 32N50W THAT EXTENDS SW TO 27N62W THEN CONTINUES AS A
DISSIPATING STATIONARY FRONT ALONG 26N70W TO 29N76W. THE
STRONGEST UPPER LEVEL DYNAMICS APPEARS TO REMAIN N OF 28N WITH
SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING WITHIN 150 NM
EITHER SIDE OF THE COLD FRONT. A WEAK SURFACE TROUGH IS ALSO
LOCATED SOUTH OF THE FRONT ANALYZED FROM 20N59W TO 24N58W.
ISOLATED SHOWERS ARE NOTED ON INFRARED SATELLITE IMAGERY WITHIN
120 NM EITHER SIDE OF THE SURFACE TROUGH AXIS AND COVERING AN
AREA TO THE EAST FROM 21N-26N BETWEEN 51W-55W. THE REMAINDER OF
THE ATLC E OF 45W IS UNDER THE INFLUENCE OF A SURFACE RIDGE
EXTENDING FROM THE AZORES NEAR 36N25W TO 20N50W.

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

$$
HUFFMAN



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