000 AXPZ20 KNHC 131013 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC SUN APR 13 2008 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 0915 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 6N78W 6N90W 6N110W 5N125W 4N140W. SCATTERED MODERATE TO STRONG CONVECTION EXISTS FROM 2N-6N BETWEEN 86W-90W...AND WITHIN 120 NM N OF THE AXIS BETWEEN 112W-114W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 60 NM N OF THE AXIS BETWEEN 92W-98W...AND ALSO WITHIN 120 NM N OF THE AXIS BETWEEN 103W-107W. SCATTERED STRONG CONVECTION IS INCREASING OVER THE GULF OF TEHUANTEPEC...AND EXTENDS S TO 13N BETWEEN 94W-96W. ...DISCUSSION... W OF 110W... A NEARLY MID/UPPER LEVEL CYCLONIC CIRCULATION NEAR 22N122W IS SLOWLY MOVING ENE WITH A TROUGH EXTENDING SW TO 21N124W WHERE IT BECOMES A SHEAR AXIS INTO A QUASI-STATIONARY MID/UPPER CYCLONIC CIRCULATION MOVING W 15 KT NEAR 20N131W. A MID/UPPER LEVEL TROUGH EXETNDS FROM THE SW UNITED STATES SW INTO THE CYCLONIC CIRCULATION NEAR 22N122W. THE UPPER LEVEL FLOW IS CYCLONIC FROM 14N-25N BETWEEN 118W-135W...BUT BECOMES ANTICYCLONIC N OF 25N AND W OF 135W. A JET STREAM STRETCHES FROM 15N125W ENE TO 19N115W TO ACROSS CENTRAL MEXICO. SATELLITE-DERIVED WINDS INDICATE A MAX OF 70 KT ASSOCIATED WITH THIS JET. AMPLE UPPER LEVEL MOISTURE IN THE FORM OF HIGH LEVEL CLOUDINESS IS BEING TAPPED FROM THE DEEP CENTRAL TROPICS BY THE JET AND CHANNELED NEWD TOWARDS NRN AND CENTRAL MEXICO WHERE IT MERGES WITH MID/UPPER LEVEL MOISTURE ALSO BEING ADVECTED NE AHEAD OF THE CIRCULATION CENTER NEAR 22N122W. THIS MOISTURE SPREADS AS FAR E AS THE NE GULF OF MEXICO. WATER VAPOR IMAGERY IS DEPICTING MODERATE TO STRONG SUBSIDENCE IN THE AREA OF UPPER CYCLONIC FLOW DUE TO THE CYCLONIC CIRCULATION NEAR 22N126W...AND ALSO WITHIN 120 NM EITHER SIDE OF THE SHEAR AXIS. ANTICYCLONIC FLOW W OF 135W IS DUE TO BROAD MID/UPPER RIDGING NOTED JUST W OF THE REGION WITH EXTENSIVE MID/UPPER CLOUDINESS RIDING OVER THE RIDGE AND TOWARDS THE REGION...BUT ERODES ALONG 140W AS IT ENCOUNTERS DRY AIR ASSOCIATED WITH THE MODERATE TO STRONG SUBSIDENCE. MID/UPPER LEVEL SW FLOW IS NOTED FROM 7N-14N W OF 120W. NWP MODELS CONTINUE TO SUGGEST THAT A COLD FRONT WILL PUSH INTO THE FAR NW SECTION EARLY THIS AFTERNOON AND WEAKEN AS STRONG HIGH PRES BEHIND IT BRIDGES OVER IT AND RESULTS IN A TIGHTENING OF THE PRES GRADIENT ACROSS THAT AREA. THE HIGH IS FORECAST TO BUILDS SEWD INTO THE AREA LATER TODAY THROUGH TUE AND WEAKEN SOME LATER IN THE UPCOMING WEEK. THE TIGHT PRES GRADIENT WILL BRING NE WINDS IN THE RANGE OF 20-25 KT WITH POSSIBLE BRIEF GUSTS TO 30 KT ACROSS THOSE WATERS BY TONIGHT AND THROUGH TUE...THEN DECREASE LATE TUE NIGHT AND THROUGH THE REMAINDER OF THE WEEK. SEAS THERE WILL BUILD TO 13 FT BY LATE TONIGHT (PER WAVEWATCH GUIDANCE)...THEN SUBSIDE TO 8 FT BY LATE IN THE WEEK. A TIGHT GRADIENT OVER THE FAR NE PART WILL ACCOUNT FOR NW FLOW OF 20-25 KT NEAR NRN BAJA CALIFORNIA AND SRN CALIFORNIA WITH SEAS 8-11 FT IN NW SWELL LATE TUE THROUGH WED...THEN DIMINISH LATE WED AND THU. AT THE SURFACE...A RIDGE AXIS EXTENDS THROUGH 32N135W TO 26N127W AND TO NEAR 20N119W. 0600 UTC PRES ANALYSIS REVEALS HIGH PRES DOMINATING MUCH OF THIS AREA N OF 15N AND W OF 118W WITH MOSTLY CLEAR SKIES WITH THE EXCEPTION OF THE FAR SW PORTION WHERE SCATTERED LOW CLOUDS MOVING W ARE SEEN. A WEAK SURFACE TROUGH DRIFTING W EXTENDS FROM 8N115W TO 2N117W...AND IS ENHANCING ITCZ CONVECTION BETWEEN 112W-115W. E OF 110W... BROAD MID/UPPER LEVEL ANTICYCLONIC FLOW GENERALLY COVERS THIS AREA WITH A MEAN RIDGE AXIS EXTENDING FROM NRN S AMERICA WNW THROUGH 7N82W 11N90W AND TO NEAR 17N105W. A VERY MOIST UPPER FLOW PATTERN PRESENT TO THE E OF 95W IS SUSTAINING NUMEROUS SHOWERS AND TSTMS THERE WITH ADDITIONAL ENHANCEMENT OF THIS ACTIVITY PROVIDED BY A 1010 MB LOW DRIFTING W NEAR 9N89W...WHICH ALSO HAPPENS TO BE UNDER SLIGHT UPPER LEVEL DIFFLUENCE. EXPECT THIS ACTIVITY TO CHANGE LITTLE OVER THE NEXT 2-3 DAYS PER LOW LEVEL MOISTURE GUIDANCE. GAP WINDS...LATEST NWP MODELS SUGGEST THAT WINDS IN THE GULF OF TEHUANTEPEC WILL INCREASE TO N AT 20 KT WITHIN A FEW HOURS... THEN INCREASE TO GALE FORCE BY LATE TONIGHT...POSSIBLY REACHING UP TO 40 KT...AS A RATHER STRONG COLD FRONT FOR THIS TIME OF YEAR PUSHES FAR S THROUGH MEXICO AND INTO THE NW CARIBBEAN LATE THIS AFTERNOON AND INTO MON. WITH VERY PRONOUNCED HIGH PRES ESTABLISHING ITSELF OVER SE MEXICO AND THE WRN GULF...EXPECT THESE GALE CONDITIONS TO CONTINUE INTO WED MORNING. THE COMBINATION OF THE LOW NEAR 9N89W AND HIGH PRES THAT WILL BUILD S INTO THE NW CARIBBEAN BEHIND THE COLD FRONT IS EXPECTED TO BRING SURGES OF NE 20-25 KT WINDS THROUGH THE GULF OF PAPAGAYO BEGINNING MON MORNING AND CONTINUE THROUGH THE END OF THE WEEK. $$ AGUIRRE