000 AXPZ20 KNHC 150400 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC WED MAY 15 2013 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0300 UTC. ...SPECIAL FEATURES... A BROAD AREA OF 1007 MB LOW PRES IS NEAR 07.5N101.5W...OR ABOUT 600 MILES S-SW OF ACAPULCO MEXICO. EARLIER HIGH RESOLUTION ASCAT SCATTEROMETER PASSES INDICATED 20 TO 30 KT WINDS WITHIN 120 NM OF THE LOW IN THE E SEMICIRCLE...WITH 20 TO 25 KT WINDS WITHIN 150 NM IN THE SW QUADRANT OF THE LOW. SEAS OF 8 TO 11 FT ACCOMPANY THESE WINDS. ASSOCIATED CONVECTION WITH THE LOW IS AS IS DESCRIBED IN THE NEXT SECTION. GRADUAL DEVELOPMENT OF THIS SYSTEM IS POSSIBLE DURING THE NEXT COUPLE OF DAYS AS IT MOVES WEST TO NORTHWEST AT AROUND 10 KT...AND IT HAS A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM 07N78W TO 1007 MB LOW PRES NEAR 07.5N101.5W TO 09N121W. THE ITCZ AXIS EXTENDS FROM 09N121W TO 09N140W. SCATTERED MODERATE CONVECTION IS E OF A LINE FROM 07N81W TO 01N79W...WITHIN 90-120 NM S OF THE MONSOON TROUGH BETWEEN 85W AND 94W...AND ALSO WITHIN 240 NM IN THE N SEMICIRCLE AND 150 NM IN THE SE AND S QUADRANTS OF THE LOW CENTER. ISOLATED TO SCATTERED MODERATE CONVECTION IS FROM 09N TO 15N BETWEEN 105W AND 110W. ...DISCUSSION... AN UPPER LEVEL TROUGH IS ACROSS THE FAR NW PORTION OF THE DISCUSSION AREA FROM 32N127W TO 22N140W...WITH A DOWNSTREAM UPPER LEVEL RIDGE EXTENDING FROM 31N122W TO 21N118W. MODERATE TO STRONG SUBSIDENCE WITH DRY STABLE AIR AT THE MIDDLE AND UPPER LEVELS IS GENERALLY N OF A LINE FROM 23N107W TO 15N140W. AN UPPER LEVEL TROUGH EXTENDS FROM A CYCLONIC CIRCULATION CENTERED OVER NW MEXICO NEAR 31N107W TO 26N111W. A 70 TO 90 KT JET STREAM ACCOMPANIES THIS TROUGH FROM SW OF THE SOUTHERN TIP OF THE BAJA PENINSULA TO ACROSS NORTHERN MEXICO INTO TEXAS. AT THE SURFACE...HIGH PRES RIDGING DOMINATES THE WATERS N OF THE ITCZ AND MONSOON TROUGH W OF 110W. MAINLY MODERATE ANTICYCLONIC WINDS AND SEAS OF 5 TO 7 FT COVER THIS AREA WITH LITTLE CHANGE FORECAST THROUGH THE NEXT 48 HOURS. EARLIER FRESH TO NEAR GALE FORCE NORTHERLY WINDS IN THE GULF OF TEHUANTEPEC HAVE DIMINISHED TO FRESH TO STRONG DURING THE PAST SEVERAL HOURS ACCOMPANIED BY 8 TO 9 FT SEAS. RESIDUAL 8 TO 10 FT SWELL COVERS THE WATERS TO THE IMMEDIATE S FROM 11N TO 14N BETWEEN 94W AND 100W. THESE WINDS ARE INDUCED BY A TIGHT PRES GRADIENT OVER THE REGION WITH HIGH PRES RIDGING ALONG EASTERN/ COASTAL MEXICO...TROUGHING N OF THE ISTHMUS OF TEHUANTEPEC IN THE BAY OF CAMPECHE...AND LOW PRES TO THE S TO SW OF THE GULF... ASSOCIATED WITH THE MONSOON TROUGH. THESE WINDS AND SEAS ARE FORECAST TO DIMINISH BELOW ADVISORY CRITERIA BY WED AFTERNOON AS THE PRES GRADIENT SLACKENS WITH LOW PRES LOCATED SW OF THE REGION MOVING AWAY TO THE W TO NW. WINDS HAVE TEMPORARILY DIMINISHED IN THE GULF OF PAPAGAYO... WHILE RESIDUAL 8 TO 10 FT NE SWELL REMAINS DOWNWIND TO 95W. WINDS WILL RAMP UP AGAIN BY SUNRISE WED WITH THE AID OF DRAINAGE FLOW OFF OF NICARAGUA AND COSTA RICA...THEN DIMINISHING TO 20 KT OR LESS FOR THE NEXT SEVERAL LATE NIGHTS/MORNINGS THEREAFTER. MODEL GUIDANCE STILL FORECASTS NORTHERLY WINDS OF 20 TO 25 KT DEVELOPING IN THE GULF OF PANAMA LATE TONIGHT N OF THE MONSOON TROUGH AS LOW PRES OVER INTERIOR COLOMBIA DEEPENS. THESE WINDS ARE THEN FORECAST TO DIMINISH BY LATE WED NIGHT AS THE LOW AND ASSOCIATED NORTHERLY FLOW THEN WEAKENS. NW SWELL OF 8 FT WILL DIP TO 29N BETWEEN 117W AND 122W BY LATE WED NIGHT...PERSISTING OVER THE SAME GENERAL AREA INTO THU EVENING. $$ LEWITSKY