000 AXPZ20 KNHC 061557 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC MON APR 06 2009 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 1530 UTC. ...ITCZ... THE INTERTROPICAL CONVERGENCE ZONE LIES ALONG A LINE FROM 06N78W TO 00N108W TO 01N120W TO 06N140W. SCATTERED MODERATE WITHIN 90 NM OF THE AXIS BETWEEN 125W AND 127W...AND WITHIN 120 NM OF THE AXIS W OF 137W. ...DISCUSSION... GAP WINDS... BIG MARINE STORY IS AN EVOLVING LATE SEASON GULF OF TEHAUNTEPEC GAP WIND EVENT. A STRONG COLD FRONT DRAPED FROM THE NORTHEAST GULF OF MEXICO INTO THE BAY OF CAMPECHE AND ACROSS THE ISTHMUS OF TEHUANTEPEC WILL CONTINUE MOVING SOUTHEAST TODAY AND TONIGHT. THE STRONG SURFACE RIDGE IN THE WAKE OF THIS FRONT WILL PROVIDE A STRONG SURFACE PRESSURE GRADIENT ACROSS THE ISTHMUS OF TEHUANTEPEC...WHICH IS FORECAST TO RESULT IN WINDS REACHING GALE FORCE BY THIS EVENING...AND TO STORM FORCE OVERNIGHT TONIGHT INTO EARLY TUE. WINDS ARE FORECAST TO REACH 55 KT AT THIS TIME...THOUGH WOULD NOT BE SURPRISED TO LOCALLY HIGHER WINDS GIVEN THE EXPECTED STEEP LOW LEVEL LAPSE RATES IN THIS REGION. THESE WINDS ARE FORECAST TO SUBSIDE TO GALE FORCE BY LATE TUE BEFORE DIMINISHING EARLY WED. THE STRONGEST WINDS ARE EXPECTED BETWEEN 07/0600 UTC AND 07/1200 UTC. GIVEN THE STRONG WINDS WILL BUILD SEAS UP TO 17-18 FT BASED ON WAVEWATCH GUIDANCE...WITH SEAS UP TO 8 FT IN NORTHEASTERLY SWELL PROPAGATING AS FAR DOWNSTREAM AS 05N105W BY THU. THE SAME SURFACE RIDGE WILL CONTINUE RESULTING IN NW TO N WINDS UP TO 20 KT ACROSS THE GULF OF CALIFORNIA DURING THE NEXT DAY. HOWEVER...THE DISPLACEMENT OF THE PRIMARY SURFACE RIDGE AXIS EASTWARD FROM THE GREAT BASIN REGION AND NORTHERN ROCKIES PRECLUDES A STRONGER WIND EVENT IN THE GULF OF CALIFORNIA. ALSO...THE INCREASING TRADE WINDS OVER THE CARIBBEAN REGION ARE FORECAST TO EXTEND INTO THE GULF OF PAPAGAYO BY TUE NIGHT...WHEN SURFACE WINDS ARE EXPECTED TO REACH 20 TO 25 KT. OF NOTE...CLIMATOLOGICALLY GULF OF TEHUANTEPEC GAP WIND EVENTS OCCUR BETWEEN OCTOBER AND APRIL. ON AVERAGE...THE LAST WIND EVENT TAKES PLACE AROUND THE FIRST OF APRIL. THE LATEST TEHUANTEPEC STORM EVENT ON RECORD OCCURRED APRIL 14-16 OF 2008 WITH A TOTAL DURATION OF 60 HOURS. ELSEWHERE... A DISSIPATING STATIONARY FRONTAL TROUGH CURRENTLY EXTENDS FROM 30N128W TO 25N138W. THE EDGE OF A 1344 UTC HIGH RESOLUTION QSCAT PASS AT 1344 UTC INDICATED SW WINDS OF 20 TO 25 KT N OF 28N AND E OF THE FRONT. THIS FRONT IS CURRENTLY BEING SUPPORTED BY A CLOSED UPPER LOW CENTERED NEAR 34N135W. COMPUTER MODEL GUIDANCE SUGGESTS THAT THIS LOW WILL BE PUSHED EASTWARD DURING THE NEXT DAY AND WEAKEN AS AN UPPER LEVEL RIDGE TO ITS WEST MOVES EASTWARD AND AN UPPER LEVEL JET MAXIMUM PROPAGATES AROUND THE LOW. IN RESPONSE...THE FRONT WILL CONTINUE TO DISSIPATE...WITH THE CORRESPONDING STRONGER WIND FIELD CONTRACTING AND WEAKENING IN INTENSITY. HOWEVER...NORTHWESTERLY SWELL OF 8 TO 11 FT WILL OVERTAKE A LARGE PART OF THE DISCUSSION AREA THROUGH MIDWEEK. FARTHER TO THE S...THE AXIS OF THE SUBTROPICAL JET STREAM STRETCHES ALONG A LINE FROM 20N140W TO 25N120W TO CENTRAL BAJA CALIFORNIA. THIS JET IS ADVECTING MID TO UPPER LEVEL MOISTURE EASTWARD ACROSS THE DISCUSSION AREA...WITH UPPER LEVEL DIVERGENCE ASSOCIATED WITH THIS JET SUPPORTING SCATTERED MODERATE CONVECTION ALONG AND N OF THE ITCZ FROM 08N TO 10N W OF 137W. SE OF THIS JET...ATMOSPHERIC STABILITY AND DEEP LAYER DRY AIR IN THE VICINITY OF AN UPPER HIGH NEAR 13N100W IS SUPPORTING FAIR WEATHER ACROSS MUCH OF THE SE PORTION OF THE DISCUSSION AREA. $$ COBB