000 AXPZ20 KNHC 112152 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC TUE OCT 11 2011 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2145 UTC. ...SPECIAL FEATURES... HURRICANE JOVA CENTERED WAS NEAR 18.3N 105.4W OR ABOUT 85 NM SW OF MANZANILLO MEXICO OR ALSO 145 NM S OF CABO CORRIENTES AT 11/2100 UTC MOVING N-NE OR 030 DEG AT 5 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 973 MB. MAXIMUM SUSTAINED WIND SPEED HAS DECREASED TO 85 KT WITH GUSTS TO 105 KT OVER THE PAST FEW HOURS. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP5/WTPZ25 KNHC FOR MORE DETAILS. VISIBLE SATELLITE IMAGERY FROM THROUGHOUT THE DAY HAS NICELY REVEALED VERY TIGHT BANDING COILED AROUND THE CENTER OF JOVA. FEATURES ASSOCIATED WITH THE CYCLONE...HOWEVER THE EYE FEATURE NOTED OVER THE PAST COUPLE OF DAYS IS NO LONGER VISIBLE AS THE CYCLONE HAS NOW BEGUN A WEAKENING TREND...AND INSTEAD A CDO (CENTRAL DENSE OVERCAST) FEATURE HAS BECOME MORE APPARENT DURING THE AFTERNOON. ITS ASSOCIATED CONVECTION CONSISTS OF THE NUMEROUS STRONG TYPE WITHIN 60 NM S AND SW OF THE CENTER. SCATTERED STRONG CONVECTION IS ELSEWHERE WITHIN 60 NM IN THE NE QUADRANT...150 NM IN THE SW QUADRANT AND 60 NM IN THE NW QUADRANT. THE LATEST NHC ADVISORY FORECASTS JOVA TO CONTINUE TO WEAKEN TONIGHT PRIOR TO MAKING LANDFALL INLAND MEXICO TONIGHT...THEN MOVE OVER THE WESTERN PORTION OF MEXICO WED AND WED NIGHT. JOVA WILL THEN WEAKEN RAPIDLY TO A DEPRESSION LATE WED NIGHT...AND TO A REMNANT LOW BY THU AFTERNOON. VERY HAZARDOUS CONDITIONS IN THE FORM OF VERY HEAVY RAINFALL IN AMOUNTS OF 6-12 INCHES WITH ISOLATED AMOUNTS TO 20 INCHES WILL RESULT IN FLASH FLOODING AND LIFE-THREATENING MUDSLIDES. LARGE AND DANGEROUS SWELLS WILL CONTINUE TO PROPAGATE TO THE W CENTRAL MEXICO COASTLINE RESULTING IN LIFE-THREATENING RIP CURRENTS. ALSO...DANGEROUS STORM SURGE IS EXPECTED TO PRODUCE SIGNIFICANT COASTAL FLOODING NEAR AND TO THE E OF WHERE THE CENTER MAKES LANDFALL. TROPICAL STORM IRWIN WAS CENTERED NEAR 14.9N 114.2W AT 11/2100 UTC MOVING E OR 095 DEG AT 7 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1003 MB. MAXIMUM SUSTAINED WIND SPEED HAS INCREASED SLIGHTLY TO 40 KT WITH GUSTS TO 50 KT DURING THE PAST FEW HOURS. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP1/WTPZ21 KNHC FOR MORE DETAILS. LATEST SATELLITE IMAGERY SHOWS ASSOCIATED CONVECTION MAKING A COMEBACK. SCATTERED STRONG CONVECTION IS WITHIN 90 NM OF THE CENTER IN THE NE QUADRANT AND WITHIN 180 NM IN THE SW QUADRANT. SIMILAR CONVECTION IS ELSEWHERE WITHIN 60 NM OF THE CENTER. LATEST NHC FORECAST INTENSIFIES IRWIN SLIGHTLY THROUGH WED EVENING...THEN BEGINS TO WEAK IT THEREAFTER AS IT DRAWS IN A STABLE AIR MASS FROM THE W AND CONTINUES TO BE HAMPERED BY ELY UPPER SHEAR. A 1006 MB LOW LOCATED NEAR 13N94W IS DRIFTING N. THE LOW REMAINS UNDER AN UPPER LEVEL NE SHEAR ENVIRONMENT INHIBITING IT FROM BECOMING ORGANIZED INTO A MORE SIGNIFICANT LOW PRES SYSTEM. LATEST SATELLITE IMAGERY SHOWS WHAT APPEARED TO BE EARLIER CONVECTION THAT WAS MORE CLOSELY TIED TO IT NOW DISLODGED TO ITS W IN THE FORM OF SCATTERED STRONG CONVECTION FROM 12N-14N BETWEEN 96W-98W. SIMILAR CONVECTION IS WITHIN 120 NM OF THE CENTER IN THE E QUADRANT...AND ELSEWHERE WITHIN 120 NM OF THE CENTER IN THE S SEMICIRCLE. LATEST FORECAST INDICATES THAT UPPER LEVEL WINDS ARE NOT FORECAST TO BECOME FAVORABLE TO ALLOW THE LOW TO DEVELOP FURTHER BEFORE IT MOVES ONSHORE THE MEXICAN COAST NEAR THE SW PORTION OF THE GULF OF TEHUANTEPEC ON THU. TILL THEN WINDS OF 20-30 KT WILL EXIST WITHIN 60 NM OF THE LOW THROUGH THE NEXT 24 HRS...THEN DECREASE TO 20-25 KT IN 48 HRS. THE LOW WILL HAVE A LOW CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HRS. THE MAIN ISSUE WITH REGARDS TO HAZARDS WILL BE THE VERY GOOD POTENTIAL OF HEAVY RAINS THAT ARE EXPECTED OVER PORTIONS OF SOUTHEASTERN MEXICO AND GUATEMALA DURING THE NEXT SEVERAL DAYS WHICH MAY CAUSE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES. INTERESTS ALONG THOSE COASTS SHOULD CONTINUE TO MONITOR THE PROGRESS OF THIS SYSTEM. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM 13N87W TO LOW PRES NEAR 13N94W...THEN RESUMES W OF IRWIN FROM 12N118W TO 9N130W TO 10N135W. ALL SIGNIFICANT AREAS OF DEEP CONVECTION IS DESCRIBED ABOVE IN ASSOCIATED WITH THE TROPICAL CYCLONES AND LOW AT 13N94W. CLUSTERS OF SCATTERED MODERATE TO STRONG CONVECTION ARE ALONG AND WITHIN 60-75 NM OF THE CENTRAL AMERICAN COAST BETWEEN 85W-92W WHERE IT IS SIGNIFICANTLY BEING FURTHER ENHANCED BY CONVERGENCE AT THE SURFACE ALONG THE TROUGH AXIS COUPLED WITH UPPER LEVEL DIFFLUENCE ALOFT OVER THE CONVECTION. ...DISCUSSION... ...E OF 130W... A DEEP LAYER TROUGH PROGRESSING SOUTHEASTWARD EXTENDS FROM THE SOUTHWESTERN U.S. SW TO NEAR 17N123W. A BROAD UPPER RIDGE IS BUILDING SOUTHEASTWARD TOWARDS THE WESTERN U.S. IN THE WAKE OF THE TROUGH. SATELLITE WATER VAPOR IMAGERY SHOWS MODERATE SUBSIDENCE AND ASSOCIATED DRY AIR PRESSING SWD BETWEEN A LINE FROM 23N109W TO 11N130W AND 30N. AT THE SURFACE...THE EASTERN PERIPHERY OF HIGH PRES RIDGING THAT STRETCHES SOUTHEASTWARD FROM A HIGH CENTER LOCATED JUST NW OF THE AREA EXTENDS FROM 30N130W TO NEAR 23N121W. A VERY STABLE AIR MASS IN PLACE UNDER THE SUBSIDENCE AREA IS ALLOWING FOR SCATTERED TO BROKEN STRATOCUMULUS CLOUDS TO PREVAIL N OF 24N AND BETWEEN 119W-130W ...WHILE MOSTLY CLEAR SKIES ARE SEEN E OF 119W. TO THE SE OF THE AFOREMENTIONED LINE...BROAD LOW PRES EXTENDS WESTWARD FROM MEXICO AND CENTRAL AMERICA HELPING TO KEEP ABUNDANT TROPICAL MOISTURE IN PLACE IN ADDITION TO THAT MOISTURE ALREADY PROVIDED BY TROPICAL CYCLONES IRWIN...JOVA AND WITH THE LOW AT 13N94W. THE UPPER LEVELS OF THIS PART OF THE AREA IS CHARACTERIZED BY RIDGING THAT EXTENDS FROM AN ANTICYCLONE NEAR 16N95W HELPING TO SUSTAIN THE CONVECTION TIED TO THE TROPICAL CYCLONES AND WITH AND NEAR THE LOW AT 13N94W AS DESCRIBED ABOVE UNDER ITCZ/MONSOON TROUGH. TRADES HAVE DIMINISHED AS A RESULT OF THE WEAKENED RIDGE. HOWEVER...THE PRES GRADIENT BETWEEN THIS RIDGE AND LOWER PRES OVER NW MEXICO IS GENERATING A SMALL AREA OF FRESH N WINDS OVER N CENTRAL FORECAST WATERS N OF 23N BETWEEN 118W-128W WHERE N-NE 20 KT AND SEAS OF 8-10 FT IN MIXED NW-N SWELL ARE EVIDENT. AS THE GRADIENT SLACKENS OVER THE NEXT 48 HRS...THIS AREA OF NLY WINDS WILL DIMINISH TO N OF 28N BETWEEN 123W-130W IN 48 HRS...HOWEVER SEAS WILL REMAIN ON THE HIGH SIDE...UP TO 12 FT...IN A MIXED NW-N SWELL. AS HURRICANE JOVA APPROACHES THE COAST TONIGHT INTO EARLY WED...EXPECT THE PRES GRADIENT TO ALSO TIGHTEN OVER THE GULF OF CALIFORNIA WHERE JUST RECENTLY NW 20 KT HAVE BEGUN. THESE WINDS ARE FORECAST TO INCREASE TO 20-25 KT BY WED EVENING...BEFORE DROPPING OFF TO LESS THAN 20 KT BY THU MORNING. FRESH SOUTHWESTERLY MONSOON FLOW DOMINATES THE AREA S OF THE THREE SPECIAL FEATURES NOTED ABOVE. THE PRES GRADIENT IS STRONGEST BETWEEN HIGH PRES OVER THE EASTERN SOUTH PACIFIC AND THE AFOREMENTIONED LOW PRES SYSTEM NEAR 12.5N94W. A FEW SHIP OBSERVATIONS FROM TODAY OVER THE FAR EASTERN WATERS INDICATED SW WINDS OF 20-30 KT WITH SEAS OF 8-12 FT. THESE SW WINDS ARE FORECAST TO MERGE WITH THE LOW PRES DISCUSSED IN THE SPECIAL FEATURES SECTION AS PRESSURES FALL ALONG THE MONSOON TROUGH AND AROUND THIS LOW. THE 8-12 FT SEAS WILL THAN BUILD UP TO 14 FT IN 24 HRS...AND CONTINUE INTO 48 HRS AS A NEW BATCH OF SW SWELL MOVES INTO SOUTHERN PORTION S OF THE MONSOON TROUGH. SEAS CONTINUE TO REMAIN CHAOTIC OVER CENTRAL WATERS WHERE NW SWELL FROM THE FRONTAL SYSTEMS TO THE N...CROSS-EQUATORIAL SW SWELL...AND NE SWELL LINGERING FROM THE DIMINISHED TRADE WINDS ARE MERGING IN THE VICINITY OF HURRICANE JOVA AND TROPICAL STORM IRWIN. A NEW PULSE OF NW SWELL IS CURRENTLY PROPAGATING THROUGH THE AREA N OF 20N AND WILL HELP KEEP SEAS TO 9 FT OVER N CENTRAL WATERS WHERE THE AFOREMENTIONED FRESH N WINDS ARE IN PLACE. ...W OF 130W... MID/UPPER RIDGING MOSTLY PERSISTS OVER THIS PART OF THE AREA. AN UPPER LEVEL CYCLONIC CIRCULATION IS W OF THE AREA AT 21N145W WITH ITS EASTERN PERIPHERY CYCLONIC FLOW ALREADY IMPINGING INTO THIS PORTION OF THE AREA. SATELLITE WATER VAPOR IMAGERY SHOWS MODERATE SUBSIDENCE HERE...EXCEPT W OF 137W WHERE UPPER LEVEL MOISTURE IN THE FORM OF BROKEN CIRRUS CLOUDS STREAMING NORTHEASTWARD IS NOTED. AT THE SURFACE...A 1022 MB HIGH IS CENTERED NEAR 30N138W WITH A RIDGE E TO 130W. THE PRES GRADIENT BETWEEN THE RIDGE AND LOWER PRES TO THE S IS RESULTING IN NE-E WINDS OF 15-20 KT FROM ABOUT 19N-24N. THE GRADIENT IS EXPECTED TO DIMINISH IN ABOUT 12-18 HRS AS THE HIGH SHIFTS W AND WEAKENS. $$ AGUIRRE