Tropical Weather Discussion
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746 AXNT20 KNHC 292342 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT FRI APR 29 2016 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 07N12W TO 05N15W TO 04N26W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 04N26W TO 03N40W TO 01N50W. ISOLATED MODERATE CONVECTION IS FROM 01N TO 06N BETWEEN 12W AND 20W...AND FROM 03N TO 07N BETWEEN 43W AND 55W. ...DISCUSSION... GULF OF MEXICO... WEST TO NORTHWESTERLY UPPER LEVEL FLOW PREVAILS OVER THE GULF BASIN THIS EVENING WITH AN UPPER LEVEL TROUGH NOTED ON WATER VAPOR IMAGERY TO THE NORTH-NORTHWEST OVER MUCH OF THE CENTRAL UNITED STATES. GIVEN THE UPPER LEVEL DYNAMICS OVER THE CENTRAL PLAINS...AN AREA OF LOW PRESSURE CONTINUES TO DEVELOP ACROSS NORTH TEXAS AND SOUTHERN OKLAHOMA GENERATING A STRENGTHENED PRESSURE GRADIENT AND FRESH TO STRONG SOUTHERLY WINDS ACROSS THE WESTERN GULF WATERS W OF 90W. EAST OF 90W...WINDS REMAIN E-SE AT GENTLE TO MODERATE BREEZE LEVELS UNDER MOSTLY FAIR SKIES. AS THE LOW PRESSURE AREA TRACKS NORTH-NORTHEASTWARD THROUGH SAT...SE WINDS ACROSS THE WESTERN GULF WILL PERSIST AT STRONG LEVELS THEN GRADUALLY DECREASE BY SAT NIGHT INTO EARLY SUN. SURFACE RIDGING ANCHORED TO THE EAST ACROSS THE SW NORTH ATLC WILL REMAIN IN PLACE ACROSS THE NORTHERN GULF THROUGH MON NIGHT...WHEN A COLD FRONT IS FORECAST TO EMERGE OFF THE TEXAS AND LOUISIANA COASTS AND MOVE EASTWARD EARLY TUE THROUGH WED AND THEN BEGIN TO WEAKEN ACROSS THE SE GULF WATERS WED NIGHT. CARIBBEAN SEA... GENERALLY NORTHWESTERLY FLOW ALOFT PREVAILS OVER MUCH OF THE CARIBBEAN SEA BASIN THIS EVENING THAT IS PROVIDING FOR RATHER TRANQUIL CONDITIONS AT THE SURFACE. TRADE WINDS REMAIN IN A RANGE OF GENTLE TO OCCASIONAL FRESH LEVELS AS WEAK RIDGING CONTINUES TO PROMOTE A WEAK PRESSURE GRADIENT ACROSS THE BASIN. WHILE SKIES THIS EVENING ARE MOSTLY CLEAR...MUCH OF THE ACTIVE WEATHER IS NOTED ACROSS HISPANIOLA AND PUERTO RICO AS PEAK DAYTIME HEATING AND INSTABILITY ARE GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS GENERALLY N OF 16N BETWEEN 62W AND 72W. THIS ACTIVITY IS LIKELY ENHANCED DUE TO BROAD SURFACE TROUGHING N OF 20N BETWEEN 55W AND 75W ACROSS PORTIONS OF THE SW NORTH ATLC REGION. THE BROAD TROUGHING IS EXPECTED BECOME DIFFUSE BY SUN NIGHT WITH SLIGHTLY STRONGER TRADE WINDS EXPECTED ACROSS THE EASTERN AND CENTRAL CARIBBEAN DUE TO A LOCALLY STRENGTHENING PRESSURE GRADIENT. HISPANIOLA... NORTHWESTERLY FLOW ALOFT PREVAILS OVER HISPANIOLA...HOWEVER A MIDDLE TO UPPER LEVEL TROUGH IS NOTED ON WATER VAPOR IMAGERY TO THE NORTH ACROSS THE SW NORTH ATLC REGION. GIVEN LOWER LEVEL INSTABILITY AND PEAK DAYTIME HEATING...SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING ACROSS THE ISLAND THIS EVENING. A SURFACE TROUGH ANALYZED ALONG 70W/71W TO THE NORTH IS ALSO PROVIDING LOW-LEVEL ENHANCEMENT TO THE ONGOING ACTIVITY. CONVECTION WILL LIKELY DISSIPATE THROUGH THE LATE EVENING AND EARLY OVERNIGHT HOURS...HOWEVER RE-DEVELOP SAT AND SUN AFTERNOONS UNTIL THE BROAD TROUGHING TO THE NORTH BECOMES DIFFUSE AND DISSIPATES ON SUN NIGHT INTO MON. ATLANTIC OCEAN... FAIRLY BROAD UPPER LEVEL TROUGHING IS NOTED ON WATER VAPOR IMAGERY OVER MUCH OF THE SW NORTH ATLC THIS EVENING. A MID-LEVEL TROUGH AXIS EXTENDS FROM NEAR 30N67W SW TO A BROAD BASE NEAR 22N76W THAT IS SUPPORTING A PAIR OF SURFACE TROUGHS...ONE ANALYZED FROM 20N71W TO 29N71W AND THE OTHER FROM 24N63W TO 31N59W. MOST CONVECTION ASSOCIATED WITH THESE BOUNDARIES REMAINS TO THE EAST OF THE BOUNDARY ALONG 71W AS MIDDLE TO UPPER LEVEL DYNAMICS ARE MORE FAVORABLE WITH WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS STRETCHING FROM ACROSS HISPANIOLA AND PUERTO RICO NE TO NEAR 30N50W. THE TROUGHING IS EXPECTED TO WEAKEN BY SUN EVENING WITH RIDGING BUILDING IN ACROSS THE WATERS TO THE NORTH OFF THE COAST OF THE CAROLINAS SUN NIGHT INTO MON. FARTHER EAST...A CUT-OFF MIDDLE TO UPPER LEVEL LOW IS CENTERED NEAR 28N33W THAT SUPPORTS A 1008 MB SURFACE LOW CENTERED NEAR 30N33W AND AN ASSOCIATED FRONTAL BOUNDARY EXTENDING FROM THE LOW TO 28N27W TO 22N28W TO 17N40W THEN DISSIPATING WEST TO 17N50W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE CONFINED TO WITHIN 90 NM OF THE LOW CENTER...AND WITHIN 90 NM E-NE OF THE FRONT N OF 27N. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN

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