000 AXPZ20 KNHC 181558 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC SUN DEC 18 2011 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1500 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH AXIS CROSSES CENTRAL AMERICA AND ENTERS EPAC NEAR 08.5N84W TO 05N101W TO 06110W WHERE IT TRANSITIONS TO ITCZ... CONTINUING TO 10N120W TO 06.5N137W TO BEYOND 07N140W. SCATTERED MODERATE CONVECTION NOTED WITHIN 180 NM EITHER SIDE OF AXIS E OF 85W. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED WITHIN 240 NM N AND 150 NM S OF AXIS BETWEEN 111W AND 134W. ...DISCUSSION... A DEEP LAYERED UPPER CYCLONE OVER FAR SW CALIFORNIA AND FAR NW MEXICO HAS FINALLY BEGUN TO MOVE SLOWLY EASTWARD INTO FAR W ARIZONA THIS MORNING...AND IS FORECAST TO EXIT THE AREA TO THE E MON NIGHT AND TUE...WITH SHORTWAVE ENERGY DROPPING INTO THE SAME GENERAL AREA AND FORMING ANOTHER SE SINKING TROUGH TUE THROUGH WED. SATELLITE IMAGERY AND SURFACE OBSERVATIONS CONTINUE TO SUGGEST AN ASSOCIATED 1019 MB LOW PRES SYSTEM NEAR 30.5N117W... BUT WILL DISSIPATE TODAY AS ITS UPPER SUPPORT SHIFTS INLAND. LIGHTNING DATA THIS MORNING CONTINUES TO SHOW ISOLATED LIGHTNING STRIKES ALONG THE COASTAL WATERS FROM SRN CALIFORNIA TO NRN BAJA N OF 30N...INDUCED BY THE UPPER LEVEL LOW. ELEVATED CONVECTION IN THE FORM OF SHOWERS AND THUNDERSTORMS ASSOCIATED WITH THE CYCLONE WILL CONTINUE TO IMPACT THE FORECAST AREA OVER THE NORTHERN GULF OF CALIFORNIA...BAJA CALIFORNIA NORTE AND SONORA TODAY AS THE UPPER LOW SHIFTS E. A DISSIPATING COLD FRONT JUST NW OF THE AREA ASSOCIATED WITH A WEAKENING DEEP LAYER TROUGH HAS USHERED IN A NEW PULSE OF NW SWELL ENTERING THE FAR NW WATERS THIS MORNING...WITH THE LEADING FORERUNNERS OF THIS PULSE FORECAST AT 17 SECONDS. THE FRONT SEPARATES A WEAK HIGH PRES SYSTEM JUST N OF THE AREA FROM STRONGER HIGH PRES TO IT NW. AS A RESULT OF THE COMPROMISED SUBTROPICAL HIGH...TRADE WINDS HAVE SHRUNK WEST OF 135W ACCORDING TO THE OVERNIGHT 0556 UTC ASCAT PASS. THE STRONGER HIGH PRES MOVING IN BEHIND THE FRONT WILL MERGE TODAY WITH THE WEAK HIGH PRES TO THE E...ALLOWING TRADES TO EXPAND EASTWARD TO 111W THROUGH MON MORNING. THE PRES GRADIENT BETWEEN THIS WEAKER EASTERN HIGH PRES AND TROUGHING IN THE LEE OF THE SIERRA MADRE OCCIDENTAL MOUNTAINS HAS BROUGHT FRESH TO STRONG NW TO N WINDS TO THE AREA OFFSHORE OF CABO CORRIENTES...MEXICO. THESE WINDS WILL WEAKEN SOMEWHAT AS THE HIGH PRES SYSTEMS MERGE...BUT WILL REMAIN FRESH THROUGH AT LATE MONDAY NIGHT. MOISTURE IS POOLED ALONG THE ITCZ/MONSOON TROUGH AXIS WITH PRECIPITABLE WATER VALUES HIGHEST ALONG THE EASTERN EDGE OF THE AXIS E OF 90W. SHOWERS AND TSTMS CONTINUE TO PULSE OVER PORTIONS OF PANAMA AND COSTA RICA AND THEIR ADJACENT COASTAL WATERS ON BOTH SIDES OF THE MONSOON TROUGH AXIS...AND SHOULD CONTINUE FOR THE NEXT DAY OR SO. GAP WINDS... GULF OF TEHUANTEPEC...THE 0412 UTC ASCAT PASS CAPTURED WINDS IN THE 30-40 KT RANGE IN THE GULF OF TEHUANTEPEC. THE CURRENT GALE EVENT IS EXPECTED TO CONTINUE UNTIL EARLY MON MORNING WHEN HIGH PRES OVER THE SOUTHERN PLAINS/LOWER MISSISSIPPI VALLEY SHIFTS EASTWARD...REDUCING THE PRES GRADIENT BY SUNRISE ACROSS SOUTHERN MEXICO BETWEEN THIS HIGH AND THE MONSOON TROUGH TO THE S. GULF OF PAPAGAYO...THE SAME PRES GRADIENT THAT IS FORCING GALE WINDS IN THE GULF OF TEHUANTEPEC IS ALSO YIELDING FRESH TO STRONG WINDS IN THE GULF OF PAPAGAYO. THE 0410 UTC ASCAT PASS CAUGHT THE FAR WESTERN EDGE OF THE FRESH NE TO E WINDS THAT EXTEND FROM PAPAGAYO TO NEAR 09N94W...WITH MODEL GUIDANCE SUGGESTING WINDS AS HIGH AS 30 KT BRIEFLY THIS MORNING. THESE WINDS WILL BEGIN TO DIMINISH OVERNIGHT TONIGHT AS HIGH PRES TO THE N SHIFTS EASTWARD...BUT WILL REMAIN FRESH THROUGH AT LEAST TUE MORNING...BEFORE DROPPING TO BELOW 20 KT TUE AFTERNOON. $$ STRIPLING