000 AXPZ20 KNHC 230923 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC SUN AUG 23 2009 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 0900 UTC. ...SPECIAL FEATURE... TROPICAL STORM HILDA WAS LOCATED NEAR 13.7 139.3W OR ABOUT 1000 NM EAST-SOUTHEAST OF HILO HAWAII AT 23/0900 UTC. HILDA WAS MOVING W OR 275 DEG AT 8 KT. THE MAXIMUM SUSTAINED WINDS HAVE INCREASED TO 40 KT WITH GUSTS TO 50 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE WAS 1003 MB. SCATTERED STRONG CONVECTION WAS CONFINED TO WITHIN 180 NM W AND 30 NM E SEMICIRCLES. THIS ASYMMETRIC CONVECTIVE PATTERN IS DUE TO MODERATE EASTERLY SHEAR. THIS SHEAR IS EXPECTED TO CONTINUE OVER THE COUPLE OF DAYS ONLY ALLOWING FOR SLOW INTENSIFICATION. THIS SYSTEM IS EXPECTED TO CROSS INTO THE CENTRAL PACIFIC HURRICANE CENTER OF RESPONSIBILITY BY MIDDAY. ADDITIONAL INFORMATION ON TROPICAL STORM HILDA CAN BE FOUND UNDER AWIPS/WMO HEADERS MIATCPEP1/WTPZ31 KNHC. AN AREA OF LOW PRESSURE ASSOCIATED WITH A TROPICAL WAVE IS LOCATED NEAR 14N109W. THE ESTIMATED MINIMUM PRESSURE IS 1009 MB. SATELLITE IMAGES SHOW A LARGE AREA OF CLOUDINESS WITH EMBEDDED DISORGANIZED SHOWERS AND TSTMS FROM 10N-17N BETWEEN 109W-117W. THE STRONGEST CONVECTION IS LOCATED S AND W OF THE ILL-DEFINED CENTER WITHIN THE ITCZ. A 0500 UTC ALTIMETER PASS REVEALED 8-10 FT COMBINED SEAS S OF THE LOW CENTER ENHANCED BY S TO SW SWELL. CONDITIONS APPEAR FAVORABLE FOR FURTHER DEVELOPMENT AND INDEED MANY OF THE NWP MODELS SHOW SOME DEVELOPMENT. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 123W FROM 09N TO 15N MOVING W 10 KT OVER THE PAST 24 HOURS. SHORTWAVE IR IMAGES SHOW A CIRCULATION CENTER NEAR 13N. WHILE THIS WAVE DOES HAVE FAIR STRUCTURE IN ITS CLOUD FIELD...CONVECTION IS VERY LIMITED. ...ITCZ... THE INTERTROPICAL CONVERGENCE ZONE IS ALONG 07N78W 10N96W 13N107W 13N130W 12N140W. SCATTERED MODERATE CONVECTION IS FROM 01N TO 06N E OF 81W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS FROM 10N TO 18N BETWEEN 110W AND 118W. ...DISCUSSION... N OF 20N... A FAIRLY COMPLEX MID-UPPER PATTERN REMAINS IN PLACE ACROSS THE SUBTROPICS. A LARGE UPPER HIGH IS SITUATED JUST S OF SRN BAJA NEAR 22N111W...AN ELONGATED UPPER LOW OFF THE NRN BAJA COAST NEAR 31N121W...ANOTHER UPPER HIGH NEAR 21N137W...AND ANOTHER UPPER LOW WEST OF THE AREA NEAR 18N151W. WHILE THE PATTERN IS AMPLIFIED...THE ONLY SENSIBLE WEATHER IS NEAR MEXICO WHERE UPPER DIFFLUENCE AND OROGRAPHIC LIFT ALONG THE SIERRA MADRE OCCIDENTAL IS PRODUCING SCATTERED SHOWERS AND TSTMS ALONG AND W OF THE MOUNTAIN RANGE. A WEAK LOW LEVEL TROUGH ASSOCIATED WITH THE UPPER LOW OFF THE NRN BAJA COAST...HAS WEAKENED THE SUBTROPICAL RIDGE AND HENCE THE TRADES. THIS TROUGH WILL PERSIST FOR ANOTHER DAY OR SO ALLOWING WINDS TO BE MAINLY LESS THAN 20 KT...EXCEPT FOR OVER THE FAR NW CORNER. A MIX OF N AND S SWELL WILL ELEVATE SEAS TO 6 TO 8 FT ACROSS MUCH OF THE AREA THROUGH TUE. S OF 20N... A DEEP MOIST ENVIRONMENT IS PRESENT ACROSS MUCH OF THE TROPICS...ENHANCED BY DIFFLUENT MID-UPPER FLOW. THE DIFFLUENT FLOW IS MOST PRONOUNCED IN THE VICINITY OF THE TROPICAL WAVE AND AREA OF LOW PRES...SPECIAL FEATURE...NEAR 110W. SEE ABOVE FOR MORE DETAILS. LONG PERIOD...14-17 SECOND...S TO SW SWELL IS PROPAGATING ACROSS MUCH OF THE AREA AND WILL CONTINUE FOR ANOTHER DAY OR TWO BEFORE SUBSIDING. $$ CANGIALOSI