[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 120553
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT MAY 12 2012

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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL
ATLC NEAR 11N15W TO 7N17W WHERE THE ITCZ CONTINUES ALONG 5N21W
ALONG 4N34W TO INLAND OVER SOUTH AMERICA NEAR 1N51W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE N OF 3N TO THE COAST OF
LIBERIA BETWEEN 8W-11W AND FROM 6N-9N E OF 14W TO INLAND OVER
SIERRA LEONE. SMALL CLUSTERS OF SCATTERED MODERATE CONVECTION
ARE WITHIN 90/120 NM N OF THE ITCZ BETWEEN 24W-42W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER RIDGE IS THE DOMINATING THE GULF WITH THE AXIS
EXTENDING FROM AN UPPER HIGH OFF THE COAST OF GUATEMALA IN THE E
PACIFIC REGION OVER THE YUCATAN PENINSULA TO OVER APALACHICOLA
BAY FLORIDA. AN UPPER LOW IS OVER S OKLAHOMA WITH AN UPPER
TROUGH EXTENDING S TO OVER TEXAS EXTENDING E TO OVER THE LOWER
MISSISSIPPI VALLEY. UPPER DIFFLUENCE BETWEEN THESE UPPER LEVEL
FEATURES GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N
OF 25N TO INLAND OVER THE N GULF COAST BETWEEN 85W-94W. THE
UPPER FLOW IS DRAWING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
FROM OVER S MEXICO INTO THE BAY OF CAMPECHE TO 20N BETWEEN
93W-97W AND OVER NE MEXICO WITHIN 60 NM ALONG THE COAST BETWEEN
23N-25W WITH ISOLATED SHOWERS COVERING THE REMAINDER OF THE W
GULF. SHOWERS/THUNDERSTORMS WILL GRADUALLY SHIFT E THROUGH SAT
NIGHT. A SURFACE TROUGH WILL MOVE OFF THE MEXICAN AND TEXAS
COASTS EARLY SAT REACHING FROM S/CENTRAL LOUISIANA TO NE BAY OF
CAMPECHE BY SUN AFTERNOON AND FROM THE MISSISSIPPI DELTA TO NW
YUCATAN BY EARLY MON. THE TROUGH WILL THEN DRIFT E AND BECOME
DIFFUSE OVER THE NE GULF BY LATE TUE AS A WEAK PRESSURE GRADIENT
SETS UP ACROSS THE GULF IN ITS WAKE AND REMAIN IN PLACE THROUGH
WED.

CARIBBEAN SEA...
AN UPPER RIDGE OVER THE GULF OF MEXICO COVERS THE CARIBBEAN TO
70W AND IS ANCHORED BY AN UPPER HIGH OFF THE COAST OF GUATEMALA
IN THE E PACIFIC REGION. THE UPPER TROUGH OVER THE W ATLC
EXTENDS S OVER THE E CARIBBEAN E OF 70W. MODERATE TO EASTERLY
TRADE WINDS ARE USHERING IN LOW LEVEL MOISTURE WITH SCATTERED
SHOWERS W OF 70W WITH PATCHES OF HAZE BEING REPORTED OVER THE
WINDWARD ISLANDS. AFTERNOON THUNDERSTORMS THAT WERE DEVELOPED
OVER THE HISPANIOLA REMAIN ACROSS THE S PORTION OF THE ISLAND
AND WITHIN 45 NM ALONG THE S COAST. WATER VAPOR SATELLITE
IMAGERY SHOWS MODERATE SUBSIDENCE AND DRY STABLE AIR OVER THE
REMAINDER OF THE CARIBBEAN SUPPORTING FAIR WEATHER TONIGHT. THE
UPPER LEVEL TROUGH WILL SHIFT SLOWLY E THROUGH SUN NIGHT. W ATLC
SURFACE RIDGE WILL STRENGTHEN ALLOWING THE TRADE WINDS TO
INCREASE ACROSS MUCH OF THE CARIBBEAN THROUGH WED.

ATLANTIC OCEAN...
AN UPPER TROUGH IS OVER THE W ATLC BETWEEN 60W-75W EXTENDING S
OVER THE E CARIBBEAN AND SUPPORTING A COLD FRONT THAT ENTERS THE
W ATLC OVER BERMUDA TO 28N70W WHERE IT BECOMES STATIONARY AND
DISSIPATES TO THE BAHAMA ISLANDS NEAR 26N77W. ISOLATED SHOWERS/
THUNDERSTORMS ARE WITHIN 175/200 NM E OF THE FRONT N OF 24N. A
SURFACE RIDGE IS BUILDING W OF THE FRONT ANCHORED BY A 1022 MB
HIGH OVER THE OHIO VALLEY. AN UPPER RIDGE IS JUST TO THE E
EXTENDING FROM 20N60W TO BEYOND 32N56W PROVIDING DIFFLUENCE
ALOFT TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
WITHIN 90 NM OF LINE FROM 21N62W TO 28N63W. A BROAD SURFACE
RIDGE COVERS THE CENTRAL ATLC N OF 20N BETWEEN 35W-60W. AN UPPER
LOW IS OVER THE E ATLC CENTERED NEAR 34N31W SUPPORTING A 1016 MB
LOW NEAR 32N32W WITH AN OCCLUDED FRONT EXTENDING N AND A SURFACE
TROUGH ENTERING THE DISCUSSION AREA NEAR 32N24W EXTENDING TO
25N27W. A JET STREAM IS TO THE E OF THE SURFACE TROUGH WITH
WINDS OF 80 TO 110 WITHIN 150 NM OF LINE FROM 25N35W TO BEYOND
32N23W. THE LAST VISIBLE SATELLITE IMAGES SHOW SAHARAN DUST
COVERING THE TROPICAL ATLC MAINLY S OF 20N TO THE MONSOON
TROUGH/ITCZ E OF THE CARIBBEAN ISLANDS. THE WEAK COLD FRONT WILL
CONTINUE TO WEAKEN THROUGH EARLY SAT AND BECOME STATIONARY FROM
NEAR 32N62W TO 26N67W TO 20N74W BY LATE SAT AFTERNOON. THE FRONT
WILL WEAKEN TO TROUGH SAT NIGHT INTO SUN AS IT MOVES INTO THE
CENTRAL ATLC. A SURFACE RIDGE WILL BUILD W OVER CENTRAL AND W
ATLC SAT THROUGH WED. A WEAK COLD FRONT WILL MOVE ACROSS THE SE
U.S. MON AND APPROACH THE NE FLORIDA COAST LATE TUE AND WED.

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

$$
PAW





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