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AXNT20 KNHC 240556
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT THU APR 24 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC.


...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH EXITS W AFRICA AND PASSES THROUGH COASTAL SECTIONS OF SENEGAL NEAR 13N16.5W AND ON TO NEAR 08N20W...WHERE IT TRANSITIONS TO ITCZ. THE ITCZ THEN EXTENDS WESTWARD THROUGH 01N29W TO 00N40W TO COASTAL BRAZIL NEAR 01.5S46W. WIDELY SCATTERED MODERATE TO STRONG CONVECTION WAS NOTED FROM 03S TO 05N BETWEEN 13W AND 23W...WHILE SCATTERED STRONG CONVECTION WAS NOTED N OF 04N TO WELL INLAND BETWEEN 10W AND 14W...AND N OF THE EQUATOR BETWEEN 05E AND 04W. ISOLATED MODERATE CELLS WERE OCCURRING IN A NARROW LINE FROM 60 TO 150 NM N OF THE ITCZ BETWEEN 29W AND 45W.


...DISCUSSION...


...THE GULF OF MEXICO... MILDLY DIFFLUENT UPPER LEVEL FLOW PREVAILS ACROSS THE GULF THIS MORNING AS UPPER RIDGING IS SHIFTING SLOWLY E ACROSS THE CENTRAL U.S. AND BROAD TROFFING EXTENDS FROM THE N CENTRAL GULF S-SW THROUGH THE BAY OF CAMPECHE AND INTO THE TROPICAL EPAC ALONG 94W. A WEAK MIDDLE LEVEL CYCLONIC VORTEX CAN BE SEEN IN WATER VAPOR IMAGERY ACROSS THE N CENTRAL GULF NEAR 27N87.5W AND SHIFTING EASTWARD...AND IS BECOMING SEPARATED FROM MIDDLE TO UPPER LEVEL TROFFING ACROSS THE NW ATLC. THIS IS YIELDING DRY AND GENERALLY STABLE CONDITIONS ALOFT N OF 25N. THE UPPER RIDGE WILL SHIFT E TO ALONG 80W BY 00Z THIS EVENING...FOLLOWED BY A DEEP LAYERED TROUGH CURRENTLY CROSSING THE ROCKIES TO SHIFT E INTO THE MS VALLEY. THIS DEEP LAYERED TROUGH WILL SUPPORT A FRONTAL SYSTEM MOVING SE THROUGH TEXAS TODAY...THEN SLOW TONIGHT ACROSS SE TEXAS AND NW LOUISIANA. CURRENTLY...A 1015 MB HIGH IS CENTERED ACROSS THE NE GULF NEAR 27N86.5W...WITH MODERATE SE TO S RETURN FLOW PREVAILING ACROSS W AND NW PORTIONS. THE HIGH WILL SHIFT E TO THE FLORIDA PENINSULA TODAY AHEAD OF THE APPROACHING FRONT...AND COLLAPSE. RETURN FLOW ACROSS ALL BUT SE PORTIONS WILL PROVIDE SUFFICIENT MOISTURE FOR LATE AFTERNOON AND EVENING CONVECTION ACROSS N AND NW COASTAL PORTIONS AS UPPER CONDITIONS DESTABILIZE IN ADVANCE OF THE APPROACHING UPPER TROUGH. THE FRONT IS FORECAST TO STALL LATE TONIGHT-EARLY FRI MORNING ACROSS THE NORTHERN COASTS AND COASTAL WATERS ALONG ABOUT 30N...AND WEAKEN.


...THE CARIBBEAN SEA... A BROAD UPPER RIDGE DOMINATES ALL BUT FAR NW PORTIONS OF THE CARIBBEAN THIS MORNING...YIELDING MODEST UPPER CONFLUENCE AND MOSTLY STABLE CONDITIONS ALOFT. THE ATLANTIC RIDGE IS PRESENTLY CENTERED ACROSS THE NE ATLC AND EXTENDS SW AND WEAKLY TO PUERTO RICO AND THE NE CARIBBEAN...MAINTAINING GENERALLY LIGHT TO MODERATE TRADE WINDS ACROSS THE CARIBBEAN BASIN THIS MORNING. THE EXCEPTION IS ALONG THE COAST OF VENEZUELA...THE ABC ISLANDS AND NE COLOMBIA...WHERE WINDS TO 20 KT ARE NOTED. ACTIVE DEEP CONVECTION IS OCCURRING ACROSS MUCH OF N COLOMBIA ATTM AND SPREADS N INTO THE IMMEDIATE WATERS WITHIN 45 NM OF THE COAST. AN OLD FRONTAL ZONE PERSISTS FROM THE ATLANTIC W-SW ACROSS HISPANIOLA THEN W TO JUST W OF THE CAYMAN ISLANDS NEAR 19N83W. ISOLATED TO WIDELY SCATTERED SHOWERS ARE SEEN NEAR THE BOUNDARY...MOSTLY W OF THE CAYMANS. HIGH PRES WILL BUILD N OF THE AREA THIS WEEKEND...ALLOWING TRADE WINDS TO INCREASE OVER THE SOUTH CENTRAL CARIBBEAN AND GULF OF HONDURAS. ADDITIONALLY...A BROAD ZONE OF LOW LEVEL MOISTURE ACROSS THE TROPICAL N ATLC S OF 15N WILL MOVE W-NW ACROSS THE LESSER ANTILLES TODAY AND ACROSS THE E CARIBBEAN THROUGH TONIGHT TO YIELD WIDELY SCATTERED TO SCATTERED BRIEF PASSING SHOWERS.


...HISPANIOLA... AN OLD FRONTAL ZONE MENTIONED ABOVE...IN THE FORM OF A TROUGH...EXTENDS W-SW ACROSS THE N HALF OF HISPANIOLA. TPW ANIMATIONS SUGGEST THE BEST MOISTURE IS CONVERGING N OF THIS TROUGH AND ACROSS N COASTAL SECTIONS AND THE IMMEDIATE COASTAL WATERS TO 21N. THIS BOUNDARY WILL CONTINUE TO WEAKEN TODAY...BUT SUFFICIENT LLVL MOISTURE WILL COMBINE WITH PREVAILING LIGHT TO MODERATE E-SE LLVL FLOW TO FOCUS AFTERNOON AND EVENING CONVECTION ACROSS N CENTRAL AND NW PORTIONS OF THE ISLAND. DUE TO A NARROW MID LEVEL RIDGE ACROSS THE AREA...CONDITIONS ARE NOT EXPECTED TO BE VERY UNSTABLE...AND ONLY ISOLATED MODERATE TSTMS ARE EXPECTED. LOOKING AHEAD...THE TRAILING END OF A WEAK COLD FRONT PASSING EASTWARD TO THE NORTH OF HISPANIOLA WILL DRIFT TO THE NORTHERN COAST OF HISPANIOLA BY SUNDAY. THIS WILL COINCIDE WITH THE ARRIVAL OF WEAK TROUGH IN THE MID TO UPPER LEVELS...ALLOWING FOR INCREASED SHOWERS AND INLAND THUNDERSTORMS BY SUNDAY.


...THE ATLANTIC OCEAN... A BROAD MID TO UPPER LEVEL TROUGH CONTINUES TO MOVE EASTWARD OVER THE NW ATLANTIC...REACHING FROM OFFSHORE OF NEW ENGLAND SE TO A BASE NEAR 28N64W. MIDDLE TO UPPER LEVEL DYNAMICS AHEAD OF THIS TROUGH AREA INTERACTING WITH A STALLED AND WEAKENING FRONTAL ZONE...EXTENDING FROM 31N54W TO NW HAITI...TO PRODUCE AN AREA OF SCATTERED MODERATE CONVECTION WITHIN 180 NM SE OF THE FRONTAL TROUGH N OF 26N. THE BROAD DEEP LAYERED TROUGH ALSO SUPPORTS A FRONTAL BOUNDARY APPROACHING BERMUDA AND N PORTIONS OF THE AREA...FROM THE NW. A WEAK 1015 MB HIGH WAS NOTED BETWEEN THESE TWO BOUNDARIES...CENTERED OVER THE SE BAHAMAS. THE NEW FRONT WILL DRIFT SE ACROSS THE WATERS NORTH OF 25N THROUGH SATURDAY FOLLOWED BY MODERATE RIDGING. THIS WILL INCREASE TRADE WIND FLOW S OF 22N W OF 60W THIS WEEKEND.

FARTHER EAST...THE ATLC RIDGE EXTENDS FROM 1029 MB HIGH NEAR 34N30W TO PUERTO RICO AND THE WATERS JUST N OF THE MONA PASSAGE. RECENT ASCAT DATA INDICATED MODERATE TRADEWINDS 15-20 KT OCCURRING S OF THE RIDGE W OF 30W...AND GENERALLY S OF 18-20N... WITH SEAS 8 TO 9 FT AS NOTED BY ALTIMETER SATELLITE PASSES BETWEEN 40W AND 45W. MODERATE TO FRESH N TO NE FLOW IS NOTED OVER THE FAR EASTERN TROPICAL ATLC WATERS EAST OF 35W TO THE COAST OF AFRICA. MINIMAL TRADE WIND CONVERGENCE IS INHIBITING SIGNIFICANT CONVECTION ALONG THE ITCZ...ALTHOUGH UPPER RIDGING ACROSS EQUATORIAL E ATLC AND CENTRAL AFRICA ARE ENHANCING SHOWERS AND THUNDERSTORMS IN THE DEEP TROPICS SOUTH OF 10N EAST OF 20W.

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

$$ STRIPLING

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