000 AXNT20 KNHC 262349 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT THU MAY 26 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ANALYZED FROM 01N46W TO 08N43W MOVING W AT 10 KT. EMBEDDED WITHIN THE ITCZ AXIS...THIS WEAK PERTURBATION IS INDICATED IN TOTAL PRECIPITABLE WATER IMAGERY WITHIN A REGION OF ELEVATED LOW-LEVEL MOISTURE SURROUNDING THE WAVE AXIS BETWEEN 43W-49W. AN EARLIER MORNING ASCAT PASS AROUND 26/1246 UTC ALSO CAPTURED CYCLONIC WINDS ABOUT THE WAVE AXIS N OF 04N BETWEEN 42W-45W. SCATTERED MODERATE CONVECTION IS FROM 01N-07N BETWEEN 42W-49W IN ASSOCIATION WITH THE WAVE. TROPICAL WAVE IS ANALYZED FROM 05N-12N ALONG 55W MOVING W AT 10 KT. THE WAVE IS INDICATED VERY WELL IN TOTAL PRECIPITABLE WATER IMAGERY WITH THE NORTHWARD EXTENT OF THE LOW-LEVEL MOISTURE EXTENDING TO NEAR 12N54W. THE ASCAT INSTRUMENT ALSO PASSED OVER PORTIONS OF THE WAVE EARLIER AROUND 26/1244 UTC INDICATING CYCLONIC WINDS ABOUT THE WAVE AXIS AND STRONGER EASTERLIES NEAR 11N53W. SIGNIFICANT CONVECTION REMAINS LIMITED THIS EVENING WITH ISOLATED MODERATE CONVECTION FROM 07N-09N BETWEEN 54W-57W. ...ITCZ... ITCZ AXIS IS ALONG 09N14W 01N35W 03N45W 03N51W. ISOLATED MODERATE CONVECTION IS FROM 02N-06N BETWEEN 17W-26W. WIDELY SCATTERED MODERATE CONVECTION IS FROM THE EQUATOR TO 06N BETWEEN 29W-37W...AND FROM THE EQUATOR TO 06N BETWEEN 39W-52W. ...DISCUSSION... GULF OF MEXICO... A MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH IS PROGRESSING ACROSS EASTERN LOUISIANA THIS EVENING AND SUPPORTS A STATIONARY FRONT DRAPED ALONG THE WESTERN LOUISIANA AND ENTIRE TEXAS GULF COAST THIS EVENING. IMPACTS ACROSS THE NW GULF WATERS REMAIN LIMITED WITH THIS FRONT AS MOST WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS REMAIN N OF 30N AND E OF 91W OVER INTERIOR PORTIONS OF THE GULF COASTAL PLAIN. A FEW ISOLATED SHOWERS AND TSTMS HOWEVER ARE EAST OF THE FRONT N OF 29N BETWEEN 86W AND THE MISSISSIPPI DELTA REGION IN THE VICINITY OF 90W. THE REMAINDER OF THE GULF IS UNDER THE INFLUENCE OF A WEAK PRESSURE GRADIENT IN ASSOCIATION WITH A SURFACE RIDGE AXIS EXTENDING FROM THE SW NORTH ATLC ACROSS THE CENTRAL FLORIDA PENINSULA TO NEAR 27N95W. THIS WEAK GRADIENT IS GENERATING LIGHT ANTICYCLONIC WIND FLOW ACROSS MUCH OF THE GULF. WHILE CONVECTION REMAINS CONFINED TO PORTIONS OF THE NE GULF...THE LAST FEW VISIBLE SATELLITE IMAGES OF THE DAY ARE STILL SHOWING A HAZY ATMOSPHERE W OF 92W DUE TO THE ADVECTION OF SMOKE FROM SOUTHERN MEXICO WILDFIRES. A SELECT FEW OFFSHORE OIL RIGS...AND LAND-BASED COASTAL AIRPORT METARS ACROSS TEXAS AND LOUISIANA ARE REPORTING VISIBILITIES BELOW 10 STATUTE MILES...OR 8.7 NM. AS THE FRONTAL BOUNDARY STALLS AND LIFTS NORTHWARD OVER THE NEXT 12 TO 24 HOURS...THE SURFACE RIDGE WILL GRADUALLY STRENGTHEN INDUCING STRONGER E TO SE WINDS ACROSS THE WESTERN GULF BY EARLY SATURDAY AS ANOTHER SURFACE LOW PRESSURE SYSTEM INTENSIFIES OVER THE CENTRAL AND SOUTHERN U.S. PLAINS THROUGH THE REMAINDER OF THE WEEKEND INTO MONDAY. CARIBBEAN SEA... AN UPPER LEVEL TROUGH AXIS EXTENDS FROM THE SW NORTH ATLC NEAR THE SE BAHAMAS ACROSS EASTERN CUBA TO A BASE OVER NORTHERN NICARAGUA NEAR 14N84W. VERY DRY AIR AND STRONG SUBSIDENCE IS NOTED ON WATER VAPOR IMAGERY 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 AND PORTIONS OF NORTHWESTERN SOUTH AMERICA TO NORTHEAST OF HISPANIOLA. DYNAMIC FORCING REMAINS SPARSE WITH THE MIDDLE TO UPPER LEVEL TROUGHING AND CONVECTION THIS EVENING IS LIMITED TO ISOLATED SHOWERS AND TSTMS IN THE VICINITY OF THE WINDWARD PASSAGE N OF 18N BETWEEN 72W-77W. THIS ACTIVITY SPREADS EASTWARD ACROSS INTERIOR PORTIONS OF HISPANIOLA REMAINING MOSTLY N OF THE CARIBBEAN SEA WATERS. ELSEWHERE...A SURFACE TROUGH IS ANALYZED OVER THE SE CARIBBEAN FROM 12N65W SOUTHWARD ACROSS CENTRAL VENEZUELA TO 06N65W. ISOLATED SHOWERS AND TSTMS ARE OCCURRING OVER INTERIOR PORTIONS OF VENEZUELA THIS EVENING WITH DEBRIS CLOUDINESS SPREADING NORTHWARD. MEANWHILE...GENTLE TO MODERATE TRADEWIND FLOW IS FORECAST TO PERSIST ACROSS THE BASIN WITH FAIR CONDITIONS AND MOSTLY CLEAR SKIES NOTED ACROSS THE FAR EASTERN CARIBBEAN AND LESSER ANTILLES THIS EVENING. ATLANTIC OCEAN... MOSTLY WEST-SOUTHWESTERLY UPPER LEVEL FLOW IS ACROSS THE SW NORTH ATLC BETWEEN AN UPPER LEVEL TROUGH OVER THE EASTERN CONUS AND AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED NEAR 11N62W. A LARGE AREA OF UPPER LEVEL DIFFLUENCE ASSOCIATED WITH THIS FLOW IN TANDEM WITH A SHEAR LINE ANALYZED ALONG 20N BETWEEN 58W AND 72W IS PROVIDING FOCUS FOR SCATTERED SHOWERS AND ISOLATED TSTMS OVER A BROAD AREA OF THE W ATLC FROM 18N-28N BETWEEN 60W-72W. THE REMAINDER OF THE SW NORTH ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE EXTENDING SW FROM A 1021 MB HIGH CENTERED NEAR 31N72W. FARTHER EAST...AN UPPER LEVEL LOW IS CENTERED NEAR 32N48W AND SUPPORTS A COMPLEX AND BROAD AREA OF LOW PRESSURE ANALYZED AS A 1015 MB LOW NEAR 27N51W AND A 1014 MB LOW CENTERED NEAR 26N56W. A SURFACE TROUGH EXTENDS FROM THE 1015 MB LOW TO 23N58W WITH POSSIBLE ISOLATED SHOWERS FROM 23N-28N BETWEEN 48W-60W. THE UPPER LEVEL LOW ALSO SUPPORTS A SHEAR LINE BOUNDARY BOUNDARY ALONG 32N51W 31N46W 27N45W TO 24N47W. LOW-LEVEL CONVERGENCE AND MIDDLE TO UPPER LEVEL DIFFLUENCE ARE COMBINING TO GENERATE WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS FROM 21N-34N BETWEEN 39W-48W. THE PRESSURE GRADIENT WITH THIS FEATURE REMAINS STRONGEST TO THE NORTHEAST IN THE VICINITY OF 32N45W WITH GALE FORCE E-SE WINDS OCCURRING FROM 31N-36N BETWEEN 40W-52W. THE REMAINDER OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE EXTENDING SOUTHWARD INTO THE DISCUSSION AREA ALONG 35W. 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 33N16W WITH A SURFACE TROUGH EXTENDING FROM THE LOW TO 27N21W. ALSO OF NOTE...THE CIMSS SAHARAN AIR LAYER TRACKING PRODUCT INDICATES AN AREA OF AFRICAN DUST FANNING WESTWARD OFF THE AFRICAN COAST PRIMARILY FROM 10N-20N E OF 40W. THIS DUST FILLED AND DRY AIR LAYER WAS EVIDENT ON THE EARLIER MORNING 26/1200 UTC SOUNDING AT DAKAR SENEGAL FROM ROUGHLY 975 MB UPWARDS TO 550 MB. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN