000 AXPZ20 KNHC 091512 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC FRI APR 09 2010 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1500 UTC. ...ITCZ... AXIS IS CENTERED ALONG 04N77W TO 07N100W TO 07N112W...THEN CONTINUES FROM 03N126W TO 03N140W. SCATTERED MODERATE TO STRONG WITHIN 120-180 NM OF THE AXIS BETWEEN 112W AND 131W...AND WITHIN 60-90 NM OF THE AXIS BETWEEN 83W AND 89W. SCATTERED MODERATE ISOLATED STRONG FROM 08N TO 12N BETWEEN 100W AND 106W. ...DISCUSSION... A MID/UPPER LEVEL SHORTWAVE TROUGH EXTENDS FROM NW MEXICO SW TO 20N115W. A BROAD FLAT MID/UPPER LEVEL RIDGE IS PRESENT W OF THE TROUGH S OF 20N WITH THE ASSOCIATED ANTICYCLONE NEAR 09N126W MOVING E 10 KT. MODEST RIDGING IS ELSEWHERE W OF THE TROUGH. SUBTROPICAL JET STREAM BRANCH ENTERS THE AREA THROUGH 19N140W AND CONTINUES ALONG 21N125W THROUGH THE BASE OF THE TROUGH NOTED ABOVE BEFORE CURVING NE ACROSS SRN BAJA AND INTO NRN MEXICO. THIS JET IS TRANSPORTING UPPER LEVEL MOISTURE IN THE FORM OF SCATTERED TO BROKEN CIRRUS CLOUDS EWD TO NEAR 110W AND ACROSS NW MEXICO. AN AREA OF MODERATE SUBSIDENCE AND ASSOCIATED DRY AND STABLE CONDITIONS IS W OF THE TROUGH FROM 20N TO 29N BETWEEN 110W AND 130W. THE AREA OF MID/UPPER LEVEL RIDGING IS BEING FORCED EWD BY A LONG WAVE TROUGH WELL W OF THE REGION. ACROSS THE THE DEEP TROPICS...CONVECTION REMAINS ACTIVE ALONG THE ITCZ W OF 115W UNDER THE MID/UPPER LEVEL RIDGING. WITH UPPER LEVEL DIFFLUENCE IN PLACE...EXPECT CONVECTION NEAR THE ITCZ TO REMAIN FAIRLY ACTIVE W OF ABOUT 110W THROUGH THE NEXT 48 HRS. OVER THE EASTERN PORTION OF THE AREA...A WEAK MID/UPPER LEVEL TROUGH IS OVER EASTERN NICARAGUA WITH A VERY NARROW AXIS STRETCHING SW TO NEAR 8N93W. IT HAS HELPED FIRE UP A FEW SMALL CLUSTERS OF TSTMS FROM ALONG AND NEAR THE ITCZ BETWEEN 86W-93W. A WEAK MID/UPPER LEVEL CYCLONIC CIRCULATION DRIFTING W IS JUST S OF THE EQUATOR AT 95W. AT THE SURFACE...A RIDGE STRETCHES INTO THE AREA FROM A 1038 MB HIGH CENTERED N OF THE AREA 38N137W SE TO NEAR 18N115W. HIGH PRES COVERED THE AREA N OF 14N AND W OF 115W. THE PRES GRADIENT BETWEEN THE RIDGE AND LOWER PRES ASSOCIATED WITH THE ITCZ WAS MAINTAINING A LARGE AREA OF N-NE WINDS IN THE RANGE OF 20-25 KT W OF A LINE FROM 30N122W TO 22N126W. SIMILAR PRES GRADIENT BETWEEN THE AFOREMENTIONED RIDGE AND LOWER PRES OVER THE SW U.S. IS RESULTING IN A LARGE AREA OF NW 20-30 KT WINDS JUST N OF THE AREA E OF 125W. AS THE HIGH CENTER SLIDES SE AND WEAKENS THROUGH THE NEXT 24 HRS...THESE WINDS WILL DECREASE. THE HIGH WILL MOVE SE IN RESPONSE TO A RATHER VIGOROUS FRONTAL SYSTEM WHICH IS QUICKLY ADVANCING EWD. THIS SYSTEM WILL SWING A COLD FRONT INTO THE FAR NW WATERS SAT NIGHT AND THROUGH THE FAR NRN AND NE WATERS THROUGH THE REMAINDER OF THE WEEKEND INTO MON WHILE WEAKENING. WINDS AHEAD AND BEHIND THE FRONT WILL INCREASE TO ABOUT 30 KT WITH GALE CONDITIONS JUST N OF THE AREA. WINDS DIMINISH LATE SUN INTO MON AS HIGH PRES BUILDS IN ACROSS THE NRN AND CENTRAL WATERS BEHIND THE FRONT WITH A MUCH WEAKER GRADIENT. THE 12 UTC SEAS STATE ANALYSIS INDICATED MAXIMUM SEA HEIGHTS OF 12 FT JUST N OF 30N E OF 130W...WITH SEAS 9 TO 11 FT ACROSS MOST OF THE REMAINDER OF THE AREA W OF 110W TO THE EQUATOR IN MERGING NW AND SW SWELL. WAVE MODEL GUIDANCE SUGGESTS THAT THESE SEAS WILL SLOWLY SUBSIDE THROUGH SAT AFTERNOON...HOWEVER ANOTHER BATCH OF LONG PERIOD SWELLS ORIGINATING FROM THE NW WILL PROPAGATE INTO THE NRN WATERS LATER SAT AFTERNOON AND EVENING DUE TO THE FRONTAL SYSTEM. PRESENT INDICATIONS ARE THAT MAX SEAS WITH THIS SWELL TRAIN SHOULD REACH 14 TO 16 FT ALONG OR NEAR 30N LATE SUN INTO MON. GAP WINDS... FRESH TO STRONG TRADES OVER THE CARIBBEAN SEA CONTINUE TO FUNNEL W ACROSS THE GULF OF PAPAGAYO RESULTING IN PULSES OF NE 20 KT WINDS. THESE WINDS ARE FORECAST TO INCREASE TO 20-25 KT LATE TONIGHT...AND TO 30 KT BY LATE SAT NIGHT...BUT SHOULD BE A BRIEF OCCURRENCE. A RATHER STRONG COLD FRONT FOR EARLY IN APRIL IS CURRENTLY DRAPED ACROSS THE ISTHMUS OF TEHUANTEPEC. AS A RESULT OF THE TIGHT PRES GRADIENT BEHIND IT OVER SE MEXICO...N WINDS IN THE RANGE OF 20-30 KT HAVE ALREADY BEGUN TO FILTER SWD THROUGH THE GULF OF TEHUANTEPEC WITHIN 45 NM EITHER SIDE OF A LINE FROM 16N94.5W TO 13N96W. A HIGH RESOLUTION ASCAT PASS LATER THIS MORNING MAY DETERMINE THE INTENSITY OF THIS LATEST WIND EVENT. NWP MODEL GUIDANCE INDICATES THAT THESE WINDS SHOULD VARY LITTLE THROUGH THE NEXT 12 HRS...THEN DIMINISH TO 20-25 KT BY 24 HRS. SEAS ARE FORECAST TO REMAIN UP TO 10 FT THROUGH 24 HRS...THEN SUBSIDE TO 8 FT BY 48 HRS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ COBB