000 AXNT20 KNHC 190005 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT AUG 18 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...SPECIAL FEATURES... TROPICAL DEPRESSION HELENE IS INLAND CENTERED NEAR 22.6N 98.8W AT 18/2100 UTC...OR ABOUT 65 MI WNW OF TAMPICO MEXICO... MOVING WNW AT 4 KT. MAXIMUM SUSTAINED WIND SPEED IS 25 KT WITH GUSTS TO 35 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1009 MB. THE BROAD CYCLONIC CIRCULATION ASSOCIATED WITH HELENE CONTINUES TO DOMINATE MUCH OF THE SW GULF S OF 25N AND W OF 94W...WITH WIDELY SCATTERED MODERATE CONVECTION. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT2/WTNT32 KNHC AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. THE CIRCULATION ASSOCIATED WITH HELENE IS EXPECTED TO DRIFT WNW OVER THE NEXT 24 HOURS AND WEAKEN...AND INTERACT WITH SIERRA MADRE ORIENTALES OF MEXICO TO PRODUCE SIGNIFICANT RAINFALL... WITH THE POTENTIAL FOR WIDESPREAD HEAVY RAINS...LEADING TO AREAS OF FLASH FLOODING AND MUDSLIDES. HURRICANE GORDON IS LOCATED NEAR 34.3N 35.2W AT 19/0000...OR ABOUT 525 NM WSW OF THE AZORES...MOVING E AT 18 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 965 MB. MAXIMUM SUSTAINED WIND SPEED IS 90 KT WITH GUSTS TO 110 KT. SATELLITE IMAGERY SHOWS A 20 NM WELL DEFINED EYE. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM 33N-36N BETWEEN 33W-37W. THE GOVERNMENT OF PORTUGAL HAS ISSUED A HURRICANE WARNING FOR THE CENTRAL AND EASTERN AZORES. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT3/WTNT33 AND THE FULL FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS. A VIGOROUS TROPICAL WAVE IS LOCATED IN THE ERN ATLC ALONG 30W...WITH A ASSOCIATED 1008 MB LOW NEAR 14N30W EMBEDDED WITHIN THE MONSOON TROUGH. THIS WAVE IS MOVING WESTWARD AROUND 20 KT. SCATTERED MODERATE TO STRONG CONVECTION IS FROM 14N-17N BETWEEN 30W-33W. CONDITIONS APPEAR CONDUCIVE FOR GRADUAL DEVELOPMENT DURING THE NEXT FEW DAYS...AND THIS SYSTEM HAS A HIGH CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. GLOBAL MODELS HAS A WWD TRAJECTORY TOWARDS THE CARIBBEAN. INTERESTS ACROSS THE E AND NE CARIBBEAN SHOULD MONITOR THE PROGRESS OF THIS SYSTEM AS IT TREKS ACROSS THE ATLC. ...TROPICAL WAVES... A TROPICAL WAVE IS LOCATED ACROSS THE CENTRAL TROPICAL ATLC ALONG 42W...WITH AN ASSOCIATED 1010 MB LOW NEAR 11N42W EMBEDDED WITHIN THE MONSOON TROUGH. THIS WAVE IS MOVING W AT 15-20 KT. SAHARAN AIR CONTINUES TO DOMINATE THIS WAVE AND LIMIT CONVECTION. SCATTERED SHOWERS ARE WITHIN 90 NM OF THE WAVE AXIS. A CARIBBEAN TROPICAL WAVE IS ALONG ABOUT 73W S OF 20N MOVING WWD NEAR 20 KT. THIS WAVE HAS BEEN ACCOMPANIED BY A LARGE AREA OF SAL. SCATTERED MODERATE TO STRONG CONVECTION IS PRESENTLY OVER HISPANIOLA FROM 18N-20N BETWEEN 70W-73W. SIMILAR CONVECTION IS OVER N VENEZUELA AND N COLOMBIA FROM 7N-12N BETWEEN 70W-74W. THE CARIBBEAN ALSO HAS SCATTERED SHOWERS WITHIN 120 NM OF THE WAVE AXIS FROM 12N-18N. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXITS THE W AFRICAN COAST NEAR 14N17W...AND CONTINUES WWD TO A LOW PRES 1008 MB NEAR 14N30W...THEN CONTINUES WSW TO A LOW PRES NEAR 11N42W...THEN CONTINUES ON TO 7N47W... WHERE IT TRANSITIONS TO AN ITCZ...CONTINUING ON TO 5N52W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM 9N-12N BETWEEN 18W-24W...FROM 10N-13N BETWEEN 30W-36W...AND FROM 7N-10N BETWEEN 38W-43W. ...DISCUSSION... GULF OF MEXICO... WEAK SURFACE RIDGING EXTENDS FROM THE W ATLC ACROSS SRN FLORIDA AND INTO THE CENTRAL GULF...THEN NW INTO THE NW GULF. HELENE IS DRIFTING FURTHER INLAND ACROSS MEXICO. A WEAK SURFACE TROUGH IS OVER N CENTRAL FLORIDA...YIELDING ISOLATED MODERATE CONVECTION. A WEAK COLD FRONT IS SINKING SWD ACROSS THE N GULF STATES WITH NUMEROUS MODERATE TO STRONG CONVECTION ERUPTING ACROSS S LOUISIANA AND THE NEARSHORE COASTAL WATERS...AND IS EXPECTED TO SHIFT SLOWLY ESE TONIGHT. BROAD UPPER TROUGHING ACROSS THE E TWO-THIRDS OF THE US.S WILL MAINTAIN MILD W TO NW FLOW ALOFT ACROSS THE N AND NE GULF AND YIELD UNSTABLE CONDITIONS...AND THUS ACTIVE CONVECTION IS EXPECTED THERE THROUGH TONIGHT. ACROSS THE SW AND S CENTRAL GULF...MOIST AND UNSTABLE SELY SURFACE FLOW CONTINUES TO SPREAD MOISTURE TOWARDS TEXAS AND THE MEXICAN OFFSHORE WATERS. SE WINDS 15-20 KT WITH SEAS 6-7 FT ARE LIKELY TO CONTINUE ACROSS THIS REGION. CARIBBEAN SEA... A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN. SEE ABOVE. ELSEWHERE...SCATTERED MODERATE TO STRONG CONVECTION IS ALONG THE COAST OF NICARAGUA FROM 10N-15N BETWEEN 81W-86W. SIMILAR CONVECTION IS OVER CUBA BETWEEN 75W-83W. 10-20 KT TRADEWINDS ARE OVER THE CARIBBEAN SEA WITH STRONGEST WINDS ALONG THE COAST OF N COLOMBIA. SCATTERED SHOWERS ARE OVER THE SW CARIBBEAN S OF 14N. EXPECT THE TROPICAL WAVE TO CONTINUE TO MOVE W AT 20 KT WITH SHOWERS OVER THE NEXT 24 HOURS. ALSO EXPECT MORE CONVECTION OVER THE SW CARIBBEAN. ATLANTIC OCEAN... A 1022 MB HIGH IS CENTERED OVER THE CENTRAL ATLANTIC NEAR 27N57W. A LARGE AREA OF AFRICAN DUST EXTENDS FROM 15N-30N E OF 60W. IN THE UPPER LEVELS...DIFFLUENCE FROM THE UPPER TROUGH OVER THE SE UNITED STATES IS PRODUCING WIDELY SCATTERED MODERATE CONVECTION OVER THE W ATLANTIC FROM 27N-32N BETWEEN 72W-80W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORMOSA