000 AXNT20 KNHC 060544 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 105 AM EST TUE MAR 06 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 W AFRICA TO A 1008 MB LOW NEAR 13N15W CONTINUING SW TO 4N22W. THE ITCZ CONTINUES FROM 4N22W CROSSING THE EQUATOR AT 32W TO THE COAST OF BRAZIL NEAR 4S42W. SCATTERED MODERATE CONVECTION IS FROM 3S-4N BETWEEN 23W-26W...AND FROM 1S-5N BETWEEN 30W-32W. ...DISCUSSION... GULF OF MEXICO... A DRY AND STABLE AIRMASS SITS OVER THE GULF OF MEXICO TONIGHT PROVIDING MOSTLY FAIR WEATHER BASIN-WIDE. SURFACE RIDGING DOMINATES ANCHORED BY A 1029 MB HIGH S OF LOUISIANA NEAR 29N90W. LIGHT ANTI-CYCLONIC FLOW IS AROUND THE HIGH WITH WIND SPEEDS INCREASING RADIALLY FROM THE CENTER REACHING 20 KTS IN THE SE GULF. THE SURFACE RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE OVER MEXICO AND THE CENTRAL CONUS. WATER VAPOR IMAGERY INDICATES DRY AIR ALOFT AND STRONG SUBSIDENCE OVER THE BASIN...WHICH ARE HELPING SUPPORT CLEAR SKIES ACROSS THE MAJORITY OF THE AREA BESIDES A FEW PATCHES OF STRATOCUMULUS CLOUDS IN THE SW GULF. BROAD UPPER TROUGHING COVERS THE ERN HALF OF THE BASIN SUPPORTING A SECONDARY COLD FRONT THAT PUSHED INTO THE W ATLC AND ACROSS NRN FLORIDA. THE MAIN FRONT CONTINUES TO MOVE THROUGH THE CENTRAL ATLC. EXPECT THE SURFACE HIGH TO MERGE WITH A HIGH TO THE N AND STRENGTHEN...WHICH WILL INCREASE SURFACE RETURN FLOW ACROSS THE GULF. CARIBBEAN SEA... A SHEAR AXIS...REMNANTS OF A FRONTAL BOUNDARY...CONTINUE TO IMPACT THE NW CARIBBEAN. THE AXIS EXTENDS FROM ERN CUBA NEAR 21N76W TO NRN HONDURAS AT 16N86W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 100 NM N OF THE AXIS NEAR HONDURAS BETWEEN 82W-87W. POSSIBLE ISOLATED SHOWERS ALSO EXTEND NW OF THE AXIS TO THE YUCATAN CHANNEL WHERE LOW-LEVEL CLOUD COVER IS PRESENT. A FEW ISOLATED SHOWERS ARE ALSO WITHIN 100 NM S OF THE AXIS ACROSS JAMAICA BETWEEN 75W-80W. BESIDES MOISTURE IN THE NW CARIBBEAN...THE REMAINDER OF THE BASIN IS UNDER DRY AIR ALOFT AROUND A BROAD UPPER LEVEL RIDGE OVER THE CENTRAL AND ERN CARIBBEAN...WHICH IS HELPING MAINTAIN CLEAR SKIES AND FAIR CONDITIONS BESIDES SOME LOW-LEVEL CLOUD COVER ACROSS THE SW CARIBBEAN. TRADEWIND FLOW OF 20-25 KTS IS ACROSS THE ERN AND CENTRAL CARIBBEAN REACHING 30 KTS NEAR THE COAST OF COLOMBIA. GALE FORCE WINDS ARE EXPECTED TO BEGIN NEAR THE COAST BY 0600 UTC. EXPECT THE SHEAR AXIS TO REMAIN STATIONARY BEFORE DISSIPATING LATER TODAY. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH IS OVER THE W ATLC ALONG 72W SUPPORTING A PAIR OF COLD FRONTS. THE PRIMARY FRONT ENTERS THE DISCUSSION AREA NEAR 32N60W EXTENDING TO 27N67W WHERE IT TRANSITIONS INTO A SHEAR AXIS TO ERN CUBA AT 21N76W. ISOLATED SHOWERS ARE WITHIN 160 NM BEHIND THE FRONT AND SHEAR AXIS. THE SECONDARY FRONT ENTERS THE AREA NEAR 32N75W TO NRN FLORIDA NEAR 30N80W. POSSIBLE ISOLATED SHOWERS ARE ALONG THE AXIS. THE CENTRAL ATLC IS DOMINATED BY SURFACE RIDGING AROUND A 1031 MB HIGH NEAR 35N42W. THE RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE EXTENDING FROM THE NE CARIBBEAN TO THE NE NEAR 44N34W. AN UPPER LEVEL LOW IS TO THE E CENTERED NEAR 32N29W WITH AXIS EXTENDING TOWARDS THE WINDWARD ISLANDS. THE UPPER LOW SUPPORTS A 1021 MB LOW NEAR 33N29W. A SURFACE TROUGH EXTENDS FROM THE LOW CENTER TO 29N32W. POSSIBLE ISOLATED SHOWERS ARE E OF THE AXIS N OF 29N BETWEEN 26W-31W. UPPER LEVEL RIDGING COVERS THE TROPICAL ATLC CENTERED OVER W AFRICA NEAR 8N4W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON