000 AXPZ20 KNHC 010948 CCA TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC SAT SEP 01 2007 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0845 UTC. ...SPECIAL FEATURES... TROPICAL STORM HENRIETTE CENTERED NEAR 17.4N 103.2W...OR ABOUT 130 NM SSE OF MANZANILLO MEXICO. HENRIETTE IS MOVING WNW AT 10 KT...AND ON THIS TRACK THE CENTER OF THE TROPICAL STORM IS EXPECTED TO MOVE NEAR OR PARALLEL TO THE SOUTHWEST COAST OF MEXICO. HOWEVER...ANY DEVIATION TO THE NORTH OF THE TRACK WOULD BRING STRONGER WINDS TO THE COAST. MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO 55 KT. ESTIMATED CENTRAL PRESSURE IS 997 MB. CURRENTLY...NUMEROUS MODERATE AND ISOLATED STRONG CONVECTION IS MAINLY ON THE W SIDE OF HENRIETTE ALONG THE MEXICAN COAST...N OF 16N BETWEEN 104W AND 107W. ADDITIONAL STRENGTHENING IS FORECAST DURING THE NEXT 24 HOURS. HENRIETTE IS EXPECTED TO PRODUCE TOTAL RAINFALL ACCUMULATIONS OF 3 TO 5 INCHES ALONG THE SOUTHWEST COAST OF MEXICO...WITH POSSIBLE ISOLATED MAXIMUM AMOUNTS OF 10 INCHES. LIFE-THREATENING FLASH FLOODS AND MUDSLIDES ARE POSSIBLE. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP1/WTPZ21 KNHC FOR MORE DETAILS. TROPICAL DEPRESSION GIL IS CENTERED NEAR 18.6N 120.0W...OR ABOUT 570 NM WSW OF THE SOUTHERN TIP OF BAJA CALIFORNIA...AT 01/0900Z UTC MOVING W AT 9 KT. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1001 MB. THE CENTER OF GIL REMAINS EXPOSED UNDER STRONG ELY SHEAR...AND A WEAKENING TREND WILL PERSIST AS IT MOVES W INTO A DRIER AND MORE STABLE ENVIRONMENT. MODERATE SHEAR AND SLIGHTLY COOLER WATER WILL ALSO WEAKEN GIL OVER THE NEXT 24 TO 36 HOURS. WHILE THERE IS CURRENTLY NO SIGNIFICANT CONVECTION ASSOCIATED WITH GIL...PULSES OF MODERATE OR EVEN STRONG CONVECTION MAY STILL OCCUR THROUGH TODAY. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP5/WTPZ25 KNHC FOR MORE DETAILS. ...ITCZ... AXIS CENTERED ALONG 9N84W 19N110W 9N130W 9N140W. SCATTERED MODERATE CONVECTION WITHIN 120 N OF AXIS BETWEEN 87W AND 92W. NUMEROUS MODERATE ISOLATED STRONG WITHIN 120 NM EITHER SIDE OF AXIS BETWEEN 104W AND 107W...ON WEST SIDE OF HENRIETTE. ...DISCUSSION... E OF 110W... BROAD UPPER RIDGING FROM CENTRAL MEXICO TO A PROMINENT UPPER ANTICYCLONE OFF THE BAJA COAST IS MAINTAINING MODERATE ELY SHEAR OVER MUCH OF THE AREA S OF 15N. THE EXPECTED TRACK OF HENRIETTE WILL SKIRT JUST ALONG THE NRN BOUNDARY OF THIS SHEAR HOWEVER AS IT PARALLELS THE MEXICAN COAST. THUS THE STORM IS IN A POSITION TO INTENSIFY FURTHER...WHILE ORGANIZED CONVECTION REMAINS SOMEWHAT LIMITED ELSEWHERE. THE MOST DEVELOPED CONVECTION REMAINS ALONG THE MEXICAN COAST FROM AROUND HENRIETTE NW TO JUST S OF MAZATLAN. THIS MAINLY DUE TO STRONG OFFSHORE FLOW ON THE W SIDE OF THE STORM CONVERGING WITH SWLY GRADIENT FLOW. HEAVY RAINFALL ALONG MOUNTAINOUS COASTAL AREAS WILL BE THE MAIN IMPACT OF THE STORM OVER COUPLE OF DAYS. W OF 110W... NLY BOUNDARY LAYER FLOW AND SUBSIDENCE IN THE MID AND UPPER LEVELS CONTINUE TO KEEP THE ATMOSPHERE DRY AND STABLE OVER MUCH OF THE AREA. THIS IS NOT ONLY ROBBING THE WEAKENING TROPICAL DEPRESSION GIL OF MOISTURE...BUT IS SUPPRESSING CONVECTIVE DEVELOPMENT OVER THE ENTIRE AREA...INCLUDING ALONG THE ITCZ. PATCHES OF STRATOCUMULUS ARE NOTED ON SATELLITE IMAGERY IN THE NLY FLOW W OF GIL AND N OF THE ITCZ. ALTHOUGH GIL IS WEAKENING...ITS WESTWARD MOVEMENT INTO HIGHER PRESSURE IS ALLOWING SURFACE WINDS TO INCREASE SLIGHTLY TO AROUND 20 KT IN THE AREA W OF GIL AND N OF 20N AS INDICATED BY QUIKSCAT AND SHIP OBSERVATIONS. HIGH PRES REMAINS FAIRLY WEAK TO THE NW OF THE AREA...SO WINDS MAY NOT INCREASE MUCH MORE THAN THEY ALREADY ARE...ESPECIALLY AS GIL WEAKENS TO A REMNANT LOW. THERE CONTINUES TO BE SOME INTERACTION BETWEEN GIL AND WITH THE CROSS EQUATORIAL FLOW...ALLOWING MODERATE TO FRESH SWLY WINDS ALONG THE ITCZ $$ CHRISTENSEN