000 AXNT20 KNHC 221022 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EST TUE APR 22 2014 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1115 UTC. ...THE ITCZ/MONSOON TROUGH... THE MONSOON TROUGH PASSES THROUGH COASTAL SECTIONS OF SENEGAL NEAR 12N16W TO 04N24W. THE ITCZ CONTINUES FROM THERE CROSSING THE EQUATOR ALONG 38W TO 02S45W NEAR THE COAST OF BRAZIL. A SURFACE TROUGH...A CONVERGENCE LINE...EXISTS FROM THE COAST OF LIBERIA NEAR 06N10W TO 04N24W. NUMEROUS MODERATE SCATTERED STRONG CONVECTION WAS NOTED SOUTH OF THE SURFACE TROUGH EAST OF 25W. ...DISCUSSION... ...THE GULF OF MEXICO... A BROAD 1017 MB SURFACE HIGH IS CENTERED SOUTH OF COASTAL MISSISSIPPI AT 28N89W. A SECOND BROAD HIGH OF 1018 MB IS LOCATED NEAR SOUTHERNMOST TEXAS AT 26N97W. DUE TO A FLAT PRESSURE GRADIENT...SURFACE WINDS ACROSS THE GULF ARE GENTLE BREEZE OR WEAKER. ISOLATED DEEP CONVECTION FIRED UP OVER THE HIGH TERRAIN OF MEXICO DURING THE LATE AFTERNOON DIURNAL MAXIMUM YESTERDAY. FORCING FOR THIS DEEP CONVECTION NORTH OF 25N MAY BE DUE IN PART TO A MID TO UPPER LEVEL TROUGH MOVING ACROSS TEXAS. A COUPLE OF ISOLATED THUNDERSTORMS ARE STILL OCCURRING ALONG THE EASTERN FLANK OF THE SIERRA MADRE MOUNTAINS...THOUGH THESE SHOULD DIMINISH SHORTLY. ELSEWHERE ACROSS THE GULF...NO SIGNIFICANT DEEP CONVECTION OR SHOWERS ARE OCCURRING. OVER THE NEXT TWO DAYS...THE WEAK HIGH SHOULD REMAIN RELATIVELY STATIONARY OVER THE GULF. A WEAK COOL FRONT WILL APPROACH THE U.S. GULF COAST LATE TODAY AND MAY BARELY REACH THE NORTHERN GULF. DEEP CONVECTION MAY OCCUR IN ASSOCIATION WITH THIS WEAK FRONT...BUT WITH LITTLE TO NO MOIST SOUTHERLY RETURN FLOW IN ADVANCE...EXPECT THE EXTENT OF THUNDERSTORMS TO BE RATHER LIMITED. ...THE CARIBBEAN SEA... A SURFACE TROUGH EXTENDS FROM HAITI TO THE NORTHWESTERN CARIBBEAN SEA. THIS...ALONG WITH SOME SUBSTANTIAL LOW-LEVEL MOISTURE DEPICTED IN THE TOTAL PRECIPITABLE WATER IMAGERY... PROMOTED DEVELOPMENT OF ISOLATED DEEP CONVECTION IN ASSOCIATION WITH AFTERNOON HEATING OVER EASTERN CUBA...JAMAICA...THE EASTERN BAHAMAS...AND HISPANIOLA LATE ON MONDAY. WITH THE NORTH-SOUTH PRESSURE GRADIENT RATHER FLAT...EASTERLY TRADES ACROSS THE CARIBBEAN ARE MODERATE TO GENTLE BREEZES...WITH THE EXCEPTION OF FRESH BREEZE NORTHEASTERLIES JUST NORTH OF COLOMBIA. IF ANYTHING...THE PRESSURE GRADIENT AND ASSOCIATED TRADEWINDS MAY WEAKEN EVEN MORE DURING THE NEXT TWO DAYS. AS THE TROUGH IS EXPECTED TO DISSIPATE IN THE NEXT DAY OR SO...THIS MAY REDUCE CHANCES OF DEEP CONVECTION OVER THE NEXT TWO DAYS OVER THE CARIBBEAN...WHICH IS OVERLAID BY SUBSIDENT UPPER LEVEL WESTERLIES TYPICAL FOR THIS TIME OF YEAR. ...HISPANIOLA... A SURFACE TROUGH EXTENDS FROM HAITI TO THE NORTHWESTERN CARIBBEAN SEA. THIS...ALONG WITH SOME SUBSTANTIAL LOW-LEVEL MOISTURE DEPICTED IN THE TOTAL PRECIPITABLE WATER IMAGERY... PROMOTED DEVELOPMENT OF ISOLATED DEEP CONVECTION IN ASSOCIATION WITH AFTERNOON HEATING OVER HISPANIOLA LATE ON MONDAY. AS THE SURFACE TROUGH IS EXPECTED TO DISSIPATE IN THE NEXT DAY OR SO...THIS MAY REDUCE CHANCES OF DEEP CONVECTION OVER THE NEXT TWO DAYS OVER HISPANIOLA...WHICH IS OVERLAID BY SUBSIDENT UPPER LEVEL WESTERLIES TYPICAL FOR THIS TIME OF YEAR. ...THE ATLANTIC OCEAN... A 1002 MB SURFACE LOW WAS LOCATED A FEW HUNDRED MILES EAST OF NORTH CAROLINA NEAR 34N67W. A COLD FRONT FROM THE LOW EXTENDS SOUTHWESTWARD IN OUR AREA FROM 32N64W TO HISPANIOLA. ISOLATED DEEP CONVECTION EXISTS WITHIN 60 NM OF THE FRONT NORTH OF 28N. SURFACE SOUTHWESTERLY WINDS AHEAD OF FRONT ARE FRESH TO STRONG BREEZE CONDITIONS...BUT ARE WEAKER BEHIND THE FRONT. A SURFACE TROUGH ALSO IS PRESENT FROM THE LOW SOUTHWESTWARD TO THE EASTERN BAHAMAS...THOUGH THIS FEATURE HAS NO SIGNIFICANT CONVECTION OR WINDS WITH IT. THE LOW IS VERTICALLY STACKED WITH AN UPPER LOW OBSERVED IN THE WATER VAPOR IMAGERY AT THE SAME LOCATION. THE UPPER LOW IS STARTING TO OPEN UP INTO A TROUGH AND BE ADVECTED QUICKLY TOWARD THE EAST. THE COLD FRONT ASSOCIATED WITH THE LOW HAS LIMITED BAROCLINICITY...BUT IT WILL CONTINUE TO INITIATE ISOLATED TO SCATTERED DEEP CONVECTION ALONG AND JUST EAST OF THE FRONT. IN A COUPLE OF DAYS...THE LOW AND THE FRONT WILL BE ABSORBED WITHIN A NEWLY DEVELOPING EXTRATROPICAL LOW AND MORE VIGOROUS COLD FRONT...THE LATTER WILL REACH OUR NORTHERN BORDER LATE WEDNESDAY. FARTHER EAST...A FRONTAL BOUNDARY STRADDLES THE NORTHERN BORDER FROM 32N48W TO 30N37W TO 32N29W WITH THE WESTERNMOST PORTION BEING A WARM FRONT AND THE REMAINDER A COLD FRONT. THIS FRONTAL BOUNDARY IS WELL-DEFINED...THOUGH SURFACE WINDS IN ASSOCIATION WITH IT ONLY REACH FRESH BREEZE CONDITIONS. THE FRONT WILL PROGRESS EASTWARD...BUT NOT MUCH FARTHER EQUATORWARD...AND HAVE LIMITED TO NO ASSOCIATED DEEP CONVECTION. ELSEWHERE...A 1022 MB SURFACE HIGH IS LOCATED AT 29N45W WITH ASSOCIATED RIDGING EXTENDING ZONALLY ACROSS MOST OF THE ATLANTIC AROUND 28N. THE MODEST PRESSURE GRADIENT EQUATORWARD OF THE RIDGE IS PRODUCING TRADEWINDS OF AT MOST FRESH BREEZE CONDITIONS. LITTLE CHANGE IS EXPECTED FOR THE NEXT COUPLE OF DAYS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LANDSEA