000 AXNT20 KNHC 190557 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT MON SEP 19 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...SPECIAL FEATURES... A 1008 MB LOW IS EMBEDDED ALONG THE MONSOON TROUGH AXIS NEAR 12N37W. TOTAL PRECIPITABLE WATER IMAGERY INDICATES THAT LOW-LEVEL MOISTURE IS MAXIMIZED FROM 06N-14N BETWEEN 33W-40W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 07N-14N BETWEEN 35W-39W. ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE FOR THE DEVELOPMENT OF A TROPICAL DEPRESSION DURING THE NEXT COUPLE OF DAYS. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 13N17W TO A 1011 MB LOW NEAR 11N28W TO THE SPECIAL FEATURES 1008 MB LOW NEAR 12N37W TO 09N48W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 11N-13N BETWEEN 25W-30W. SCATTERED MODERATE CONVECTION IS FROM 04N-07N BETWEEN 22W-30W...AND FROM 05N-11N BETWEEN 30W-33W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER THE WESTERN GULF NEAR 23N93W AND CONTINUES TO SUPPORT A SURFACE RIDGE AXIS EXTENDING FROM THE SE CONUS OVER GEORGIA THROUGH 28N90W IN THE NORTH-CENTRAL GULF TO THE EAST-CENTRAL MEXICO COAST NEAR 22N98W. PRIMARILY E TO SE SURFACE WINDS IN THE RANGE OF 10-15 KT WERE NOTED ON EARLIER ASCAT PASSES AND THESE WINDS ARE EXPECTED TO PERSIST THROUGH THE OVERNIGHT HOURS. WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL SHORTWAVE TROUGH PROGRESSING ACROSS THE CENTRAL AND SOUTHERN U.S. PLAINS WHICH SUPPORTS A COLD FRONT EXTENDING FROM EASTERN OKLAHOMA INTO NORTH AND CENTRAL PORTIONS OF TEXAS. THIS FRONT IS FORECAST TO ENTER NW PORTIONS OF THE GULF EARLY TUESDAY AND BEGIN TO STALL...WHILE A REINFORCING FRONT WILL IMPACT THE NORTHERN GULF BY THURSDAY. OTHERWISE...A FEW AREAS OF ISOLATED SHOWERS AND TSTMS ARE ACROSS THE GULF...ONE NORTH OF THE LOWER FLORIDA KEYS NEAR 25N82W AND ANOTHER AREA WEST OF THE YUCATAN PENINSULA S OF 21N BETWEEN 90W-93W. CARIBBEAN SEA... AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER THE WESTERN CARIBBEAN NEAR 13N81W AND IS PROVIDING AN UPPER LEVEL DIFFLUENT ENVIRONMENT W OF 74W WITH SCATTERED SHOWERS AND TSTMS FOCUSED NEAR A SURFACE TROUGH ANALYZED FROM CENTRAL COSTA RICA NEAR 10N84W TO EASTERN HONDURAS NEAR 15N84W. LOW-LEVEL SPEED CONVERGENCE OF EASTERLY TRADES ARE GENERATING ISOLATED SHOWERS S OF 19N W OF 80W. E OF 74W...AN UPPER LEVEL TROUGH EXTENDS FROM THE SW NORTH ATLC SOUTHWARD TO A BASE OVER NE VENEZUELA. MIDDLE TO UPPER LEVEL MOISTURE CONTINUES TO BE ADVECTED ACROSS THE MUCH OF THE NE CARIBBEAN WITH ISOLATED SHOWERS AND TSTMS OCCURRING OVER THE EASTERN CARIBBEAN E OF 67W. THE UPPER LEVEL TROUGHING WILL BROADEN OUT THROUGH LATE TUESDAY OVER THE SW NORTH ATLC PROVIDING THE EASTERN AND CENTRAL CARIBBEAN WITH CONTINUED WEST- SOUTHWESTERLY FLOW AND HIGHER POSSIBILITY FOR WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS THROUGH WEDNESDAY. ATLANTIC OCEAN... AN UPPER LEVEL SHORTWAVE TROUGH IS PROGRESSING OVER THE WESTERN NORTH ATLC WITH AXIS ALONG 70W THAT SUPPORTS A COLD FRONT EXTENDING INTO THE DISCUSSION AREA NEAR 32N74W TO 31N77W WHERE THE FRONT BECOMES MORE DIFFUSE AS A DISSIPATING STATIONARY FRONT TO THE FLORIDA PENINSULA NEAR DAYTONA BEACH. SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING WITHIN 90 NM N AND 180 NM S OF THE FRONT. FARTHER TO THE SE...WATER VAPOR IMAGERY INDICATES AN UPPER LEVEL LOW IS CENTERED NEAR 23N66W. MIDDLE TO UPPER LEVEL MOISTURE CONTINUES TO STREAM NORTHWARD ON THE EASTERN PERIPHERY OF THE LOW WITH WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING OVER THE AREA FROM 19N-26N BETWEEN 62W-71W. ISOLATED SHOWERS ARE ALSO OCCURRING EAST OF THE LESSER ANTILLES FROM 13N-19N BETWEEN 59W-61W. THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE OF A BROAD UPPER LEVEL TROUGH DIPPING SOUTHWARD TO 15N BETWEEN 27W-45W. THIS TROUGH SUPPORTS A SURFACE TROUGH EXTENDING INTO THE DISCUSSION AREA NEAR 32N39W TO 27N45W WITH ISOLATED SHOWERS AND TSTMS OCCURRING N OF 27N BETWEEN 30W-41W. FARTHER SOUTH...A WEAK 1012 MB LOW IS CENTERED NEAR 17N46W THAT EXHIBITS A SMALL AREA OF SCATTERED MODERATE TO STRONG CONVECTION WITHIN 90 NM OF THE NORTHERN SEMICIRCLE. THIS LOW IS FORECAST TO CONTINUE DRIFTING WESTWARD OVER THE NEXT 24-36 HOURS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN