000 AXPZ20 KNHC 162136 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC SAT MAY 16 2015 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1900 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A SURFACE TROUGH AXIS WAS ANALYZED FROM 08N79W TO 05N83W TO 06N90W. THE MONSOON TROUGH AXIS WAS ANALYZED FROM 07N95W TO 07N108W TO 06N115W TO LOW PRES NEAR 10N125W 1010 MB TO LOW PRES NEAR 08N139W 1010 MB. N OF THE TROUGH AXIS TO 10N E OF 87W. SCATTERED MODERATE CONVECTION WAS BETWEEN 150 NM-390 NM S OF AXIS BETWEEN 86W-111W. SCATTERED MODERATE CONVECTION WAS WITHIN 75 NM N AND 210 NM S OF THE AXIS BETWEEN 112W-118W. SCATTERED MODERATE CONVECTION WAS WITHIN 450 NM NE AND 240 NM W QUADRANTS OF LOW PRES NEAR 10N125W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION WAS WITHIN 150 NM N OF THE AXIS BETWEEN 130W AND 134W. SCATTERED MODERATE CONVECTION WAS WITHIN 240 NM NE AND OVER FORECAST WATERS WITHIN 120 NM W QUADRANTS OF LOW PRES NEAR 08N139W. ...DISCUSSION... THE SUBTROPICAL RIDGE EXTENDS THROUGH N WATERS FROM 30N140W TO 27N116W. A COLD FRONT LIES TO THE N OF THIS RIDGE AXIS. THE COLD FRONT WILL DIP S OF 32N OVER NW WATERS THIS EVENING AND STRETCH FROM 32N130W TO 29N133W TO 28N140W BY SUN AFTERNOON. THE FRONT WILL BE DISSIPATING FROM WEAK 1020 MB LOW PRES NEAR 31N126W TO 25N131W SUN AFTERNOON. WINDS NEAR THE FRONT ARE EXPECTED TO REMAIN BELOW A FRESH BREEZE AND SEAS TO 8 FT SHOULD BE CONFINED N OF 30N BEHIND THE FRONT. 1029 MB HIGH PRESSURE CURRENTLY LIES BEHIND THE FRONT NEAR 37N152W. THE HIGH IS FORECAST TO WEAKEN AS IT SHIFTS SE WITH THE FRONT. THIS SHOULD KEEP THE PRESSURE GRADIENT RELATIVELY CONSTANT AND MAINTAIN THE AREA OF FRESH TRADES FOUND W OF 120W. MEAN TROUGHING ALOFT OVER NW MEXICO AND THE SW UNITED STATES WILL CONTINUE THROUGH THE PERIOD. AN UPPER LOW OVER NW WYOMING WILL CARRY ITS TROUGH AXIS E OUT OF NW MEXICO TONIGHT. THE ASSOCIATED COLD FRONT AT THE SURFACE IS CURRENTLY DISSIPATING FROM ACROSS THE GULF OF CALIFORNIA NEAR 29N...ALONG THE BORDER OF BAJA CALIFORNIA NORTE AND BAJA CALIFORNIA SUR AND INTO THE PACIFIC TO 23N124W. A SMALL AREA OF SEAS TO 8 FT OFFSHORE JUST N OF THE FRONT WILL SUBSIDE BY SUNSET. THE NEXT SHORTWAVE UPPER TROUGH IS DROPPING INTO THE BACKSIDE OF THE MEAN TROUGH AND WILL HELP CUT OFF AN UPPER LOW OFF THE CENTRAL CALIFORNIA COAST BY SUN NIGHT BEFORE MOVING INTO CALIFORNIA...BUT THE COLD FRONT AT THE SURFACE EXPECTED TO DISSIPATE WELL OFFSHORE BY SUN AFTERNOON AS DESCRIBED IN THE PREVIOUS PARAGRAPH. A VAST ANTICYCLONE ALOFT CENTERED NEAR 11N116W EXTENDS ITS PRIMARY RIDGE AXIS W TO 11N140W. CONVECTION UNDER THIS ANTICYCLONE IS DESCRIBED IN THE SECTION ABOVE. THE BULK OF THE DEEP CONVECTION IN THE WESTERN PORTION OF THE AREA CAN BE FOUND UNDER THE UPPER LEVEL DIVERGENCE ASSOCIATED WITH THIS RIDGE AXIS...WHICH IS ENHANCING LIFT IN THE ATMOSPHERE...AND NEAR THE MONSOON TROUGH AXIS AT THE SURFACE...WHICH IS AN AREA OF PLENTIFUL LOW- AND MID-LEVEL MOISTURE. CONVECTION IN THE SE PORTION OF THE AREA IS OVER COSTA RICA AND PANAMA AND OFFSHORE AS DESCRIBED IN THE SECTION ABOVE. THIS AREA LIES IN THE REAR RIGHT QUADRANT OF A SOUTHWESTERLY JET THAT EXTENDS INTO THE CARIBBEAN. THE JET AXIS IS FORECAST TO SHIFT N OVER THE NEXT TWO DAYS...AND THE FORECAST CALLS FOR THE CHANCE OF PRECIPITATION TO INCREASE OVER NICARAGUA AS A RESULT. GAP WINDS... GULF OF PAPAGAYO...THE PRESSURE GRADIENT BETWEEN RIDGING OVER THE NW CARIBBEAN AND TROUGHING TO THE SW WILL SUPPORT A FRESH TO STRONG BREEZE IN THE GULF OF PAPAGAYO TO 89W BY THE EARLY MORNING HOURS SUN WITH THE ASSISTANCE OF NOCTURNAL DRAINAGE FLOW. THESE WINDS WILL DIMINISH AFTER SUNRISE AND RETURN AGAIN EARLY MON MORNING ONLY TO DIMINISH AGAIN AFTER SUNRISE MON. $$ SCHAUER