[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 122345
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SAT MAR 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...ITCZ...

ITCZ AXIS IS ANALYZED ALONG 07N12W 02N19W CROSSING THE EQUATOR
NEAR 25W AND ALONG 01S41W THEN INTO NE BRAZIL NEAR 02S44W.
SCATTERED MODERATE CONVECTION IS S OF 04N W OF 22W. ALONG THE
WESTERN EXTENT OF THE ITCZ AXIS A SURFACE TROUGH IS ANALYZED
FROM 06N49W TO 03S46W. SCATTERED MODERATE AND ISOLATED STRONG
CONVECTION IS WITHIN 120 NM EITHER SIDE OF THE BOUNDARY...
INCLUDING INTERIOR PORTIONS OF NE BRAZIL N OF 05S E OF 51W.

...DISCUSSION...

GULF OF MEXICO...
RELATIVELY DRY AIR AND UPPER LEVEL SUBSIDENCE WITHIN WEST-
NORTHWESTERLY UPPER LEVEL FLOW IS EVIDENT ON WATER VAPOR IMAGERY
THIS EVENING ACROSS THE GULF BASIN. THIS WIDESPREAD SUBSIDENCE
CONTINUES TO SUPPORT A 1027 MB SURFACE HIGH CENTERED IN THE NE
GULF NEAR 29N84W. MOSTLY CLEAR SKIES ARE NOTED ON SATELLITE
IMAGERY AND THESE FAIR WEATHER CONDITIONS ARE EXPECTED TO LAST
THROUGH THE OVERNIGHT HOURS INTO SUNDAY MORNING. THE HIGH IS
FORECAST TO GRADUALLY SHIFT EASTWARD THROUGH MONDAY AND LOCATE
OVER THE SW NORTH ATLC. INCREASED SE WINDS ARE EXPECTED OVER THE
WESTERN GULF WITH THE NEXT WEAK FRONTAL BOUNDARY FORECAST TO
EMERGE OFF THE TEXAS AND LOUISIANA GULF COASTS BY LATE MONDAY
INTO EARLY TUESDAY.

CARIBBEAN SEA...
AN UPPER LEVEL RIDGE AXIS EXTENDS ACROSS THE TROPICAL ATLC ALONG
07N TO SOUTH AMERICA AND THEN W-NW TOWARDS THE NW CARIBBEAN SEA
NEAR 17N78W. MOSTLY DRY AIR AND A STABLE ATMOSPHERE ALOFT
ACCOMPANIES THIS UPPER LEVEL RIDGING ACROSS THE CARIBBEAN SEA
BASIN THIS EVENING. EARLIER MORNING ASCAT PASSES INDICATED E-NE
TRADES IN THE 10 TO 20 KT RANGE GENERALLY S OF 17N...WITH HIGHER
NE WINDS IN THE 15 TO 25 KT RANGE OCCURRING OVER PORTIONS OF THE
NW CARIBBEAN AND IN THE VICINITY OF THE WINDWARD PASSAGE. HIGH
PRESSURE CURRENTLY LOCATED OVER THE NE GULF OF MEXICO AND A
DIFFUSE COLD FRONT ANALYZED NE OF CUBA IS CREATING THE ENHANCED
NE FLOW FILTERING THROUGH THE WINDWARD PASSAGE AND THE WATERS
BETWEEN CUBA AND JAMAICA THIS EVENING. THE HIGH IS FORECAST TO
SLIDE EASTWARD INTO THE SW NORTH ATLC BY EARLY MONDAY AND
PRODUCE STRONGER EASTERLY FLOW AS THE PRESSURE GRADIENT
TIGHTENS. THESE TRADES WILL PERSIST THROUGHOUT MUCH OF THE WEEK
AS THE HIGH IS EXPECTED TO REMAIN NEARLY STATIONARY.

ATLANTIC OCEAN...
A DEEP LAYERED TROUGH CONTINUES TO SLOWLY MOVE ACROSS THE
WESTERN NORTH ATLC SUPPORTING A COLD FRONT THAT ENTERS THE SW
NORTH ATLC REGION NEAR 32N63W AND EXTENDS SW TO ALONG 25N68W
BECOMING MORE DIFFUSE ACROSS THE SE BAHAMAS AND EASTERN CUBA.
SCATTERED SHOWERS ARE OCCURRING WITHIN 120 NM EITHER SIDE OF THE
FRONT. A WEAK PRE-FRONTAL SURFACE TROUGH IS ANALYZED FROM 32N62W
TO 23N63W WITH ISOLATED SHOWERS WITHIN 120 NM EITHER SIDE OF THE
BOUNDARY. FARTHER EAST INTO THE CENTRAL ATLC...AN WEAK UPPER
LEVEL CUT-OFF LOW IS CENTERED NEAR 25N42W THAT SUPPORTS A
SURFACE TROUGH ANALYZED FROM 25N49W TO NEAR 20N35W. INDICATIONS
FROM EARLIER MORNING ASCAT PASSES SHOW A STRONG SHEAR AXIS
EXISTS ALONG THIS BOUNDARY WITH STRONGER E TO NE WINDS LOCATED
TO THE NE OF THE BOUNDARY. LOW-LEVEL SPEED CONVERGENCE ALONG
WITH THE UPPER LEVEL DIFFLUENT ENVIRONMENT PROVIDED BY THE UPPER
LEVEL LOW IS GENERATING SCATTERED SHOWERS COVERING THE AREA N OF
THE SURFACE TROUGH AXIS FROM 20N-28N BETWEEN 31W-50W. ELSEWHERE
OVER THE EASTERN ATLC...A DIFFUSE AND DISSIPATED COLD FRONT IS
ANALYZED INTO THE DISCUSSION AREA NEAR 32N22W AND EXTENDS
WESTWARD ALONG 30N TO NEAR 36W. ISOLATED SHOWERS ARE OCCURRING
WITHIN 90 NM EITHER SIDE OF THE FRONT. THIS FRONT IS SUPPORTED
ALOFT BY AN UPPER LEVEL TROUGH LOCATED N OF 28N BETWEEN 15W-30W.

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

$$
HUFFMAN




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