000 AXPZ20 KNHC 281543 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC SUN SEP 28 2014 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1500 UTC. ...SPECIAL FEATURES... HURRICANE RACHEL IS BEGINNING TO WEAKEN WHILE CONTINUING TO MOVE SLOWLY NORTH-NORTHWESTWARD. AT 28/1500 UTC...RACHEL IS CENTERED NEAR 21.5N 117.2W OR ABOUT 410 NM...765 KM W OF THE SOUTHERN TIP OF BAJA CALIFORNIA MOVING N-NW OR 340 DEG AT 5 KT. MAXIMUM SUSTAINED WINDS HAVE DECREASED TO 70 KT WITH GUSTS TO 85 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 984 MB. NUMEROUS MODERATE TO STRONG CONVECTION IS NOTED WITHIN 90 NM OF THE CENTER. RACHEL MAY TEMPORARILY BECOME STATIONARY IN 24 TO 36 HOURS BEFORE DRIFTING SOUTHWESTWARD LATE MONDAY OR TUESDAY. STEADY WEAKENING IS EXPECTED DURING THE NEXT 48 HOURS...AND RACHEL SHOULD BECOME A TROPICAL STORM BY MONDAY. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP3/ WTPZ23 FOR MORE DETAILS. ...TROPICAL WAVES... A TROPICAL WAVE MOVING WESTWARD ACROSS SOUTHERN MEXICO NEAR THE GULF OF TEHUANTEPEC EXTENDS INTO THE EPAC TO NEAR 12N95W. THIS WAVE IS GENERATING AN AREA OF SCATTERED MODERATE ISOLATED STRONG CONVECTION FROM 12N TO 15N BETWEEN 95W AND 100W. THE WAVE IS EXPECTED TO SHIFT SLOWLY WESTWARD DURING THE NEXT FEW DAYS AND FORM A BROAD AREA OF LOW PRES S OF SOUTHERN MEXICO. ACTIVE CONVECTION AND GUSTY WINDS IN THUNDERSTORMS WILL ACCOMPANY THIS EVOLVING FEATURE THE NEXT FEW DAYS. COMPUTER MODEL GUIDANCE SUGGESTS THAT THIS AREA OF WEATHER COULD BE THE NEXT TROPICAL SYSTEM TO DEVELOP IN THE EASTERN PACIFIC...AND A TROPICAL DEPRESSION COULD FORM BY THE MIDDLE OF THIS WEEK. THIS BROAD AREA OF WEATHER HAS NOW A HIGH CHANCE OF DEVELOPING INTO A TROPICAL CYCLONE WITHIN THE NEXT 5 DAYS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM 08N78W TO 12N95W TO 10N104W TO 09N110W THEN CONTINUES SW OF HURRICANE RACHEL FROM 14N120W TO 12N130W. THE ITCZ EXTENDS FROM 12N130W TO 11N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS WITHIN 180 NM S OF TROUGH BETWEEN 92W AND 95W...AND WITHIN 150 NM N OF TROUGH BETWEEN 95W AND 100W. SCATTERED MODERATE CONVECTION IS NOTED FROM 08N TO 11N BETWEEN 106W AND 109W...AND WITHIN 30 NM OF 07N135W. ...DISCUSSION... RESIDUAL SWELL ASSOCIATED WITH A DISSIPATED FRONTAL BOUNDARY CONTINUES TO AFFECT MAINLY THE N WATERS N OF 17N W OF 112W. PART OF THIS SWELL EVENT IS INTERACTING WITH SWELL GENERATING BY HURRICANE RACHEL...PARTICULARLY ACROSS THE AREA FROM 17N TO 27N BETWEEN 113W AND 125W. RESIDUAL SWELL WILL CONTINUE TO SUBSIDE THROUGH EARLY TUE. HIGH PRES BUILDING BEHIND THE OLD FRONT HAS ENHANCED NW WINDS ALONG THE COAST OF BAJA CALIFORNIA N OF 30N. AT THE SAME TIME...A LOW NEAR YUMA ARIZONA IS TIGHTENING THE PRESSURE GRADIENT IN THE NORTHERN GULF OF CALIFORNIA N OF 28N. AN EARLIER ASCAT PASS SHOWED SW WINDS IN EXCESS OF 25 KT N OF 29N. WINDS WILL DIMINISH IN THE REGION BY LATE TODAY AS THE LOW MOVES FARTHER NORTH. AN AREA OF MODERATE TO FRESH NE WINDS IS ALSO NOTED FROM 18N TO 22N W OF 133W PER THE MOST RECENT ASCAT PASS. A NEW ROUND OF LONG PERIOD SW SWELL IS PUSHING NORTHWARD ACROSS THE EQUATOR FROM THE SOUTHERN HEMISPHERE...AND WILL COVER MUCH OF THE AREA S OF 04N W OF 110W BY MON MORNING...AND S OF A LINE FROM 03.4S100W TO 05N120W TO 06N140W BY TUE MORNING...WITH BUILDING SEAS TO 9 FT. $$ GR