000 AXNT20 KNHC 252348 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT WED MAY 25 2011 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 2315 UTC. ...ITCZ... ITCZ AXIS IS ALONG 10N14W 05N24W 03N41W 04N50W. SCATTERED MODERATE CONVECTION IS FROM 02N-07N BETWEEN 19W-36W. ISOLATED MODERATE CONVECTION IS FROM 03N-05N BETWEEN 39W-42W. A SURFACE TROUGH IS ANALYZED ON THE WESTERN EDGE OF THE AXIS FROM 05N-09N ALONG 52W WITH NO SIGNIFICANT CONVECTION NOTED IN ITS VICINITY. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY INDICATES MUCH OF THE GULF IS UNDER THE INFLUENCE OF MODERATELY DRY AND SUBSIDENT W-NW FLOW ALOFT WHICH IS RESULTING IN REMARKABLY CLOUDLESS SKIES THIS EVENING. A SURFACE RIDGE AXIS EXTENDS FROM THE W ATLC ACROSS THE CENTRAL FLORIDA PENINSULA TO THE TEXAS GULF COAST NEAR CORPUS CHRISTI WITH MOSTLY E TO SE WINDS PREVAILING IN THE RANGE OF 10 TO 15 KT. WHILE SKIES REMAIN CALM IN A CONVECTIVE SENSE...THE LAST FEW VISIBLE SATELLITE IMAGES OF THE DAY HOWEVER ARE STILL SHOWING A HAZY ATMOSPHERE W OF 93W DUE TO THE ADVECTION OF SMOKE FROM SOUTHERN MEXICO WILDFIRES. A SELECT FEW OFFSHORE OIL RIGS...AND LAND-BASED AIRPORT METARS ACROSS TEXAS AND LOUISIANA ARE REPORTING VISIBILITIES BELOW 10 STATUTE MILES...8.7 NM. THE SURFACE RIDGE IS FORECAST TO REMAIN NEARLY STATIONARY ALONG THE NORTHERN GULF WATERS THROUGH THE WEEKEND WITH SOUTHERLY RETURN FLOW INCREASING BY SATURDAY AS ANOTHER STRONG LOW PRESSURE SYSTEM DEVELOPS OVER THE U.S. CENTRAL PLAINS. CARIBBEAN SEA... AN UPPER LEVEL TROUGH AXIS EXTENDS FROM THE SW NORTH ATLC ACROSS WESTERN CUBA INTO THE WESTERN CARIBBEAN TO HONDURAS. VERY DRY AIR AND STRONG SUBSIDENCE IS ACROSS THE NW CARIBBEAN WHERE CLEAR SKIES PREVAIL THIS EVENING. A FEW ISOLATED SHOWERS AND TSTMS ARE OCCURRING OVER INTERIOR PORTIONS OF CUBA...HOWEVER THOSE ARE EXPECTED TO DIMINISH OVER THE NEXT FEW HOURS DUE TO THE LOSS OF PEAK DAYTIME HEATING. EAST OF THE UPPER LEVEL TROUGH AXIS... MIDDLE TO UPPER LEVEL MOISTURE IS ADVECTING FROM THE SW CARIBBEAN TO NORTHEAST OF HISPANIOLA. A SURFACE TROUGH IS ANALYZED FROM NORTHERN COLOMBIA NEAR 11N75W TO 13N81W. ISOLATED SHOWERS ARE OCCURRING IN THE VICINITY OF AND TO THE NORTHEAST OF THE SURFACE TROUGH FROM 10N-20N BETWEEN 68W-81W. MEANWHILE... LIGHT EASTERLY TRADEWIND FLOW PERSISTS ACROSS THE ENTIRE BASIN WITH FAIR CONDITIONS AND MOSTLY CLEAR SKIES NOTED ACROSS THE FAR EASTERN CARIBBEAN AND LESSER ANTILLES THIS EVENING. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH AXIS EXTENDS OVER THE SW NORTH ATLC ALONG 32N74W TO WESTERN CUBA NEAR 22N81W THEN INTO THE WESTERN CARIBBEAN SEA. EAST OF THE TROUGH...THE REMAINDER OF THE SW NORTH ATLC IS UNDER THE INFLUENCE OF AN UPPER LEVEL RIDGE WITH AXIS ALONG 63W. DIFFLUENCE ALOFT BETWEEN THESE TWO UPPER LEVEL FEATURES IS SUPPORTING THE ADVECTION OF MOISTURE FROM THE CENTRAL CARIBBEAN SEA INTO THE W ATLC WITH ISOLATED SHOWERS AND TSTMS OCCURRING FROM 19N-30N BETWEEN 62W-73W. OTHERWISE...A SURFACE RIDGE EXTENDS SW FROM A 1019 MB HIGH CENTERED NW OF BERMUDA NEAR 33N67W. FARTHER EAST...AN UPPER LEVEL LOW IS CENTERED NEAR 29N47W AND SUPPORTS A FILLING 1011 MB SURFACE LOW NEAR 27N56W. A SURFACE TROUGH WRAPS INTO THE LOW AND EXTENDS ALONG 25N54W 23N58W TO 25N63W. ISOLATED SHOWERS ARE POSSIBLE WITHIN 240 NM OF THE LOW CENTER. THE UPPER LEVEL LOW ALSO SUPPORTS A FRONTAL TROUGH BOUNDARY ALONG 31N51W 28N46W 23N47W TO 19N58W THEN BECOMES A SHEAR LINE TO HISPANIOLA NEAR 19N70W. LOW-LEVEL CONVERGENCE AND MIDDLE TO UPPER LEVEL DIFFLUENCE ARE COMBINING TO GENERATE WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS FROM 18N-32N BETWEEN 37W-48W...INCLUDING WITHIN 90 NM EITHER SIDE OF THE SHEAR LINE. THE REMAINDER OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE EXTENDING SOUTHWARD INTO THE DISCUSSION AREA ALONG 34W. FINALLY...AN UPPER LEVEL LOW IS CENTERED OVER THE MADEIRA ISLANDS NEAR 33N17W. THIS DEEP LAYER TROUGH REFLECTS AS A 1012 MB LOW CENTERED NEAR 33N17W WITH A COLD FRONT WELL EAST ALONG 32N11W TO 27N18W ACROSS THE CANARY ISLANDS. ISOLATED SHOWERS ARE OCCURRING WITHIN 240 NM EAST OF THE FRONT...INCLUDING MUCH OF MOROCCO AND WESTERN SAHARA. ALSO OF NOTE...THE CIMSS SAHARAN AIR LAYER TRACKING PRODUCT INDICATES A SURGE OF AFRICAN DUST PRIMARILY FROM 10N-20N E OF 30W. THIS DUST FILLED AND DRY AIR LAYER WAS EVIDENT ON THE EARLIER MORNING SOUNDING AT DAKAR SENEGAL FROM ROUGHLY 975 MB UPWARDS TO 600 MB. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN