000 AXPZ20 KNHC 060957 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC MON APR 06 2009 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 0900 UTC. ...ITCZ... THE INTERTROPICAL CONVERGENCE ZONE LIES ALONG A LINE FROM 08N84W TO 04N95W TO 01N105W AND FROM 02N120W TO 05N130W TO 05N140W. SCATTERED MODERATE CONVECTION IS FROM 04N TO 06N BETWEEN 89W AND 96W. ...DISCUSSION... GAP WINDS... A STRONG COLD FRONT DRAPED FROM NORTHEAST GULF OF MEXICO INTO THE BAY OF CAMPECHE AND THEN NORTHWESTWARD OVER CENTRAL MEXICO IS FORECAST TO CONTINUE PROGRESSING SOUTHEASTWARD DURING THE NEXT DAY. 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 A LATE SEASON GULF OF TEHAUNTEPEC STORM FORCE WIND EVENT...WITH STRONG NORTHERLY WINDS DEVELOPING LATE TODAY AND CONTINUE THROUGH TUESDAY NIGHT IN THE GULF OF TEHUANTEPEC. AT PRESENT...IT APPEARS WINDS WILL REACH GALE FORCE BY 07/0000 UTC BEFORE REACHING STORM FORCE BY 07/0600 UTC. THESE WINDS ARE FORECAST TO SUBSIDE TO GALE FORCE BY 08/0000 UTC BEFORE DIMINISHING DURING THE DAY WEDNESDAY. THE STRONGEST WINDS ARE EXPECTED BETWEEN 07/0600 UTC AND 07/1200 UTC...WHEN BOTH SURFACE PRESSURE GRADIENT IS MAXIMIZED...AND NOCTURNAL DRAINAGE FLOW IN THE PRESENCE OF DEEP LAYER DRY AIR EMBEDDED WITHIN A BROAD UPPER LEVEL RIDGE OVER THE SE PORTION OF THE DISCUSSION AREA WILL BE MAXIMIZED. DURING THIS TIME...COMPUTER MODEL GUIDANCE SUGGESTS THAT AVERAGE FLOW BETWEEN THE SURFACE AND 925 MB WILL REACH UP TO 55 KT...AND THUS THE FORECAST FOR THE GULF OF TEHUANTEPEC REFLECTS A SLIGHTLY MORE INTENSE WIND EVENT WITH A SOMEWHAT BROADER WIND FIELD. THESE WINDS WILL LIKELY BE MIXED TO THE SURFACE...GIVEN THE STEEPER LOW LEVEL LAPSE RATES IN THIS REGION. THE STRONG WINDS WILL BUILD SEAS UP TO 16 FT BASED ON WAVEWATCH GUIDANCE...WITH SEAS UP TO 8 FT IN NORTHEASTERLY SWELL PROPAGATING AS FAR DOWNSTREAM AS 04N107W BY THURSDAY. THE SAME SURFACE RIDGE WILL CONTINUE RESULT IN NW TO N WINDS UP TO 20 KT ACROSS THE GULF OF CALIFORNIA DURING THE NEXT DAY. HOWEVER... WITH THE DISPLACEMENT OF THE PRIMARY SURFACE RIDGE AXIS 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 TUESDAY NIGHT...WHEN SURFACE WINDS ARE EXPECTED TO REACH 20 KT. ELSEWHERE... A DISSIPATING STATIONARY FRONT CURRENTLY EXTENDS FROM 30N130W TO 24N140W. THE QUIKSCAT PASS AROUND 06/0600 UTC INDICATES NW WINDS OF 20 TO 25 KT W OF THE FRONT N OF 26N...WHERE NW SWELL CONTAINING SEAS UP TO 15 FT IS PRESENT. THIS FRONT IS CURRENTLY BEING SUPPORTED BY A CLOSED UPPER LOW CENTERED NEAR 36N133W. 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 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 17N140W TO 24N119W 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 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. OF NOTE...CLIMATOLOGICALLY THE TEHUANTEPEC WIND EVENTS OCCUR BETWEEN OCTOBER AND APRIL. ON AVERAGE...THE LAST 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. $$ COHEN/GR