000 AXNT20 KNHC 301755 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SAT JUN 30 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1745 UTC. ...TROPICAL WAVES... TROPICAL WAVE HEADS TOWARDS THE LESSER ANTILLES WITH AXIS EXTENDING FROM 18N55W TO 11N54W MOVING W AT ABOUT 15 KT. THIS SYSTEM IS EMBEDDED IN A SURGE OF ENHANCED DEEP MOISTURE NOTED ON TPW PRODUCT. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM 11N-16N BETWEEN 54W-58W. HOVMOLLER DIAGRAMS AND COMPUTER MODEL DATA INDICATED A WAVE MOVING ACROSS THE TROPICAL ATLC WATERS...NOT PREVIOUSLY NOTED DUE TO BEING A SHALLOW/WEAK SIGNATURE WAVE. THIS WAVE WAS FIRST ADDED ON THE 30/1200 UTC SURFACE ANALYSIS WITH AXIS EXTENDING FROM 11N35W TO 7N36W. THE CONVECTION RELATED TO THIS WAVE IS EMBEDDED WITHIN THE MONSOON TROUGH AXIS DISCUSSED BELOW. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE WEST AFRICAN COAST OF THE GAMBIA NEAR 13N17W ALONG 8N25W 8N34W TO 6N43W...WHERE THE ITCZ CONTINUES TO NEAR THE COAST OF SURINAME AROUND 6N55W. WIDELY SCATTERED MODERATE CONVECTION IS WITHIN 100 NM ON EITHER SIDE OF THE ITCZ/MONSOON TROUGH BETWEEN 30W-45W...AS WELL AS FROM 6N-12N E OF 30W. ...DISCUSSION... GULF OF MEXICO... CLUSTERS OF SCATTERED HEAVY SHOWERS AND THUNDERSTORMS CONTINUE TO AFFECT A GREAT PORTION OF THE WNW BASIN N OF 231 W OF 91W. THESE SHOWERS ARE MOVING INLAND ACROSS SE TEXAS...CREATING A COASTAL TROUGH ANALYZED FROM BEAUMONT TO CORPUS CHRISTI. THE ACTIVITY IS SUPPORTED ALOFT BY UPPER LEVEL DIFFLUENCE BETWEEN A NARROW UPPER RIDGE CENTERED NEAR 24N92W AND AN UPPER LEVEL LOW SPINNING OVER THE FAR NE MEXICO TERRITORY NEAR 27N100W. TO CENTRAL TEXAS DURING THE NEXT 24 HOURS. THE REMAINDER OF THE GULF E OF 91W IS DOMINATED BY SURFACE RIDGE AXIS EXTENDING WNW TO THE N-CENTRAL GULF FROM A WEAK 1018 MB HIGH CENTERED OVER THE WRN COAST OF THE SOUTHERN FLORIDA PENINSULA NEAR 26N82W. FAIR WEATHER CONDITIONS ARE EXPECTED TO CONTINUE OVER THIS REGION WITHIN THE NEXT SEVERAL DAYS. CARIBBEAN SEA... AN UPPER LEVEL TROUGH EXTENDS E TO W ACROSS MOST OF THE CARIBBEAN BASIN. HOWEVER...THIS FEATURE IS EMBEDDED IN DRY SUBSIDENT AIR ALOFT NOTED ON WATER VAPOR IMAGERY. HENCE MOST OF THE BASIN IS DOMINATED BY THIS AIRMASS KEEPING WEATHER CONDITIONS FAIR THIS AFTERNOON. THE ONLY AREA OF SCATTERED SHOWERS AND THUNDERSTORMS ARE OBSERVED OVER THE SW BASIN S OF 12N W OF 75W DUE TO CLOSE PROXIMITY TO THE MONSOON TROUGH ANALYZED FROM NRN COLOMBIA ALONG CENTRAL PANAMA INTO THE ERN PACIFIC ACROSS NRN COSTA RICA. COMPUTER MODELS SUGGEST THIS AREA OF CONVECTION WILL TRACK NW TO ERN NICARAGUA OVER THE NEXT 24 HOURS. OTHERWISE...15-20 KT TRADE WIND FLOW IS OBSERVED ACROSS THE DISCUSSION AREA...WITH THE STRONGEST WINDS GUSTING TO 25 KT WITHIN 130 NM OFF THE NRN COAST OF COLOMBIA. SOME SCATTERED WEAK CONVECTION WILL ENTER THE FAR ERN BASIN LATER TONIGHT... ASSOCIATED TO A TROPICAL WAVE. OTHERWISE...THE OVERALL FAIR WEATHER PATTERN ALONG WITH DRY CONDITIONS WILL LINGER ELSEWHERE OVER THE NEXT SEVERAL DAYS. ATLANTIC OCEAN... A WEAKENING UPPER LEVEL TROUGH MOVES ACROSS THE WRN N ATLC... SUPPORTING A STATIONARY FRONT EXTENDING SW INTO OUR DISCUSSION AREA ALONG 32N61W TO 27N70W. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE WITHIN 60-90 NM AHEAD OF THE FRONT AXIS. TO THE SE OF THIS FRONTAL BOUNDARY...AN UPPER LEVEL LOW IS NOTED ON WATER VAPOR IMAGERY CENTERED NEAR 28N57W SUPPORTING A WEAK SURFACE TROUGH ANALYZED FROM 25N62W TO 20N68W. SCATTERED WEAK SHOWERS ARE WITHIN 60 NM ON EITHER SIDE OF THE SRN HALF OF THE TROUGH AXIS. OTHERWISE...A BROAD SURFACE RIDGE DOMINATES THE REMAINDER OF THE ATLC. THE SURFACE RIDGE IS ANCHORED BY A 1031 MB HIGH W OF THE AZORES NEAR 39N34W. HOWEVER...AN UPPER LEVEL LOW MOVES WESTWARD ACROSS THE CENTRAL ATLC CENTERED NEAR 30N36W SUPPORTING A WEAK SURFACE TROUGH THAT CUTS THROUGH THE SURFACE RIDGE...ANALYZED FROM 31N33W TO 27N38W GENERATING SCATTERED WEAK SHOWERS WITHIN 130 NM ON EITHER SIDE OF ITS AXIS. OTHERWISE... FAIR WEATHER CONDITIONS ELSEWHERE ACROSS THE CENTRAL AND ERN ATLC. THE BENIGN WEATHER OVER THESE REGIONS IS FURTHER ENHANCED BY SAHARAN DUST ALOFT EVIDENT ON THE METEOSAT-9 SAL TRACKING PRODUCT. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GARCIA