000 AXNT20 KNHC 220002 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN AUG 21 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 2300 UTC. ...SPECIAL FEATURES... TROPICAL STORM IRENE NEAR 17.7N 64.4W AT 2100 UTC AUG 21 OR ABOUT 25 MI...40 KM E OF ST CROIX OR ABOUT 120 MI...195 KM E-SE OF SAN JUAN PUERTO RICO. IRENE IS MOVING MOVING W-NW OR 285 DEG AT 15 KT. MINIMUM CENTRAL PRESSURE IS 999 MB. MAXIMUM SUSTAINED WIND SPEED IS 45 KT GUSTS 55 KT. PLEASE SEE THE LATEST INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADER MIATCPAT4/ WTNT34 KNHC AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. SCATTERED MODERATE TO STRONG CONVECTION IS MOSTLY N OF THE CENTER FROM 16N-23N BETWEEN 57W-67W. SAN JUAN PUERTO RICO RADAR CONTINUES TO CAPTURE THE CENTER OF IRENE AND THE INNER RAIN BANDS. TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 150 MILES...240 KM...MAINLY TO THE NORTH OF THE CENTER. A HURRICANE WARNING IS IN EFFECT FOR PUERTO RICO...VIEQUES...AND CULEBRA AS WELL AS FOR THE ENTIRE COASTLINE OF THE DOMINICAN REPUBLIC. TROPICAL DEPRESSION HARVEY NEAR 18.6N 93.8W AT 2100 UTC AUG 21 OR ABOUT 50 MI...75 KM NE OF COATZACOALCOS MEXICO OR ABOUT 285 MI...460 KM SE OF TUXPAN MEXICO. HARVEY IS MOVING W-NW OR 290 DEG AT 12 KT. MINIMUM CENTRAL PRESSURE IS 1007 MB. MAXIMUM SUSTAINED WIND SPEED IS 25 KT GUSTS 35 KT. PLEASE SEE THE LATEST INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADER MIATCPAT3/WTNT33 KNHC AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT3/ WTNT23 KNHC FOR MORE DETAILS. SCATTERED MODERATE TO STRONG CONVECTION IS OVER SOUTHERN MEXICO AND THE BAY OF CAMPECHE FROM 16N-20N BETWEEN 92W-97W. HARVEY IS EXPECTED TO PRODUCE ADDITIONAL RAINFALL ACCUMULATIONS OF 2 TO 4 INCHES OVER PORTIONS OF SOUTHEASTERN MEXICO...WITH POSSIBLE ISOLATED MAXIMUM AMOUNTS OF 10 INCHES. THESE RAINS COULD PRODUCE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES. HARVEY IS FORECAST TO BRIEFLY BECOME A TROPICAL STORM BEFORE MOVING INLAND MON MORNING. ...THE ITCZ/THE MONSOON TROUGH... A LOW PRES SYSTEM NEAR 18N29W IS FORECAST TO MOVE NW AND SEPARATE FROM THE MONSOON TROUGH. THE FLOW AROUND THE EAST SIDE OF THE LOW HAS BECOME THE DOMINANT FEATURE IN THE AREA. THIS HAS CAUSED THE THE MONSOON TROUGH TO SPLIT BETWEEN THE LOW AND THE AFRICAN COAST. SIMILARLY...THE BROAD CYCLONIC WIND FIELD ASSOCIATED TO T.S. IRENE HAS BECOME MORE UNIFORM TO ITS EAST CAUSING ANOTHER BREAK IN THE CLIMATOLOGICAL LOW-LEVEL TROPICAL CONVERGENCE IN THE AREA E OF IRENE TO AROUND 45W. THE MONSOON TROUGH EXTENDS FROM NEAR 18N23W TO 1008 MB LOW PRES NEAR 18N29W TO 08N40W TO 08N45W AND THEN CONTINUES FROM 11N75W TO THE BORDER OF COSTA RICA AND PANAMA. WIDELY SCATTERED MODERATE CONVECTION IS FROM 12N-22N BETWEEN 25W-31W. SIMILAR CONVECTION IS FROM 5N-11N BETWEEN 36W-51W. SCATTERED MODERATE CONVECTION LIES FROM 11N-15N BETWEEN 77W-81W AND S OF 11N TO PANAMA BETWEEN 80W-82W. ...DISCUSSION... GULF OF MEXICO... LOW LEVEL WINDS IN THE SOUTHWEST GULF ARE DOMINATED BY THE FLOW AROUND TROPICAL DEPRESSION HARVEY DESCRIBED IN THE SPECIAL FEATURES SECTION ABOVE. HARVEY IS FORECAST TO BRIEFLY BECOME A MINIMAL TROPICAL STORM BEFORE MAKING LANDFALL MON MORNING AND THEN DIMINISH TO A REMNANT LOW OVER CENTRAL MEXICO BY EARLY TUE. CONVECTIVE OUTFLOW ASSOCIATED WITH HARVEY IS BEING SHEARED WESTWARD BY THE UPPER LEVEL EASTERLIES ON THE SOUTH SIDE OF THE UPPER RIDGE AXIS THAT EXTENDS FROM AN ANTICYCLONE OVER TEXAS NEAR 32N98W INTO THE NE GULF TO NEAR CEDAR KEY FLORIDA. ELSEWHERE....SURFACE RIDGING OVER THE NORTHERN GULF OF MEXICO HAS BEEN SEVERED BY A WEAK TROUGH FROM S OF APALACHICOLA FLORIDA SOUTHWESTWARD TO 27N91W. ISOLATED MODERATE CONVECTION LIES E OF THE TROUGH N OF 28N. THIS TROUGH WILL GRADUALLY DIMINISH THROUGH MONDAY. CARIBBEAN SEA... THE PRIMARY CONCERN CONTINUES TO BE T.S. IRENE MOVING ACROSS THE VIRGIN ISLANDS. THERE IS A WELL-DEFINED UPPER-LEVEL ANTICYCLONE SITUATED OVER IRENE. THE VERTICAL LIFT INDUCED BY THIS ANTICYCLONE SHOULD ALLOW THE SYSTEM TO INTENSIFY AS IT TRACKS TOWARD THE EASTERN DOMINICAN REPUBLIC MON. TROPICAL STORM CONDITIONS ARE EXPECTED TO DIMINISH IN THE CARIBBEAN LATE MON OR EARLY TUE AS IRENE TRACKS THROUGH THE NORTHERN PORTION OF HISPANIOLA AND INTO THE SW NORTH ATLANTIC. SEE THE SPECIAL FEATURES SECTION ABOVE FOR FURTHER INFORMATION. ELSEWHERE...DIMINISHING LATE-DAY SHOWERS AND THUNDERSTORMS LIE ALONG THE SOUTH COAST OF CUBA AND THE NW COAST OF JAMAICA THIS EVENING. CONVECTION ASSOCIATED WITH THE MONSOON TROUGH ALSO LIES OVER THE SW CARIBBEAN. THIS CONVECTION IS DESCRIBED IN THE ITCZ/MONSOON TROUGH SECTION ABOVE. ATLANTIC OCEAN... AGAIN...THE PRIMARY CONCERN IS T.S. IRENE. THE MOST RECENT FORECAST CARRIES IRENE AS A MINIMAL HURRICANE INTO THE EASTERN DOMINICAN REPUBLIC BEFORE PASSING OVER THE NORTH PORTION OF HISPANIOLA MONDAY AND BETWEEN EASTERN CUBA AND GREAT INAGUA ISLAND BY TUE EVENING. THIS TRACK KEEPS IRENE OVER HISPANIOLA FOR 6-12 HOURS WHICH SHOULD WEAKEN THE SYSTEM BACK TO A TROPICAL STORM BEFORE EXITING INTO THE WARM ATLANTIC WATERS. SYMMETRIC CONVECTIVE OUTFLOW MANIFESTED AS CIRRUS CLOUDS EXTENDS AS FAR AS 660 NM NE QUADRANT AND 450 NM NW QUADRANT OF THE CENTER. THIS SYMMETRIC OUTFLOW IS ATTRIBUTABLE TO THE ANTICYCLONE OVER THE SYSTEM DISCUSSED IN THE CARIBBEAN SECTION ABOVE. ELSEWHERE...A 1027 MB HIGH IS OVER THE CENTRAL ATLANTIC NEAR 36N35W AND EXTENDS A RIDGE W-SW INTO NORTH FLORIDA AND E-SE TOWARD THE CANARY ISLANDS. SOUTH OF THE RIDGE LIES A LOW PRES CENTER NEAR 18N29W ASSOCIATED WITH THE MONSOON TROUGH. THIS LOW IS EMBEDDED IN DRY AIR AND AFRICAN DUST THAT IS INHIBITING DEEP CONVECTION. THIS LOW IS FORECAST TO MOVE NW OVER COOLER WATERS TO THE CENTRAL ATLANTIC OVER THE NEXT SEVERAL DAYS. ANOTHER LOW ALONG THE MONSOON TROUGH IS INLAND OVER WEST AFRICA NEAR 16N12W. THIS LOW HAS SCATTERED MODERATE TO STRONG CONVECTION WITHIN 45 NM N SEMICIRCLE AND 150 NM S SEMICIRCLE OF CENTER. THIS SYSTEM WILL BE CLOSELY MONITORED FOR FUTURE DEVELOPMENT AS IT MOVES OFFSHORE OVERNIGHT MON NIGHT. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ SCHAUER