000 AXPZ20 KNHC 200252 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC FRI NOV 20 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0230 UTC. ...SPECIAL FEATURES... TROPICAL STORM RICK CENTERED NEAR 15.2N 108.1W AT 20/0300 UTC OR 317 NM SW OF MANZANILLO MEXICO AND 474 NM SSE OF THE SOUTHERN TIP OF BAJA CALIFORNIA MOVING WNW AT 9 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1002 MB. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP1/WTPZ21 KNHC FOR MORE DETAILS. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS WITHIN 240 NM IN THE NW SEMICIRCLE. RICK REMAINS SHEARED WITH THE LOW LEVEL CENTER NEAR THE SE EDGE OF THE DEEP CONVECTION AS CAPTURED NICELY BY EARLIER SCATTEROMETER PASSES. SLOW STRENGTHENING IS STILL POSSIBLE THROUGH FRI...THEN RICK IS FORECAST TO WEAKEN TO A TROPICAL DEPRESSION BY SUN AFTERNOON...BECOMING POST-TROPICAL BY MON AFTERNOON...WITH DISSIPATION EXPECTED BY TUE AFTERNOON. GALE WARNING FOR GULF OF TEHUANTEPEC...HIGH PRES IS BUILDING BEHIND A COLD FRONT IN THE WESTERN GULF OF MEXICO N OF THE AREA WITH AN EARLIER SCATTEROMETER PASS ALREADY SHOWING FRESH TO STRONG NORTHERLY WINDS IN THE IMMEDIATE GULF. WINDS WILL CONTINUE TO INCREASE TO MINIMAL GALE FORCE AROUND SUNSET THIS EVENING. WINDS MAY BRIEFLY DIMINISH TO 30 KT DURING THE AFTERNOON HOURS HOWEVER MINIMAL GALE FORCE WINDS WILL BE LIKELY THROUGH SAT MORNING...DIMINISHING BY SAT AFTERNOON. LOOKING AHEAD...A STRONGER GALE FORCE EVENT IS LIKELY SUN MORNING THROUGH EARLY NEXT WEEK AS A MUCH STRONGER COLD FRONT MOVES THROUGH THE GULF OF MEXICO WITH WINDS TO AT LEAST 45 KT POSSIBLE. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM 09N79W TO 09N90W TO 13N101W THEN RESUMES FROM 13N110W TO LOW PRES NEAR 11N114W TO LOW PRES NEAR 11N129W TO 07N137W. THE ITCZ AXIS EXTENDS FROM 07N137W TO 06N140W. SCATTERED MODERATE CONVECTION IS WITHIN 240 NM S OF THE AXIS BETWEEN 79W AND 89W...WITHIN 150 NM S OF THE AXIS BETWEEN 94W AND 98W...WITHIN 60 NM SE OF THE AXIS BETWEEN 130W AND 133W ...FROM 05N TO 07N BETWEEN 129W AND 134W...AND ALSO FROM 07N TO 09N BETWEEN 135W AND 139W. ...DISCUSSION... N OF 15N E OF 120W...A TIGHT PRES GRADIENT REMAINS OVER NW MEXICO WITH FRESH TO STRONG WINDS STILL IN THE GULF OF CALIFORNIA FROM 25N TO 29N W OF 110W. AS A RESULT...SEAS OF 4-7 FT ARE STILL POSSIBLE IN THE GULF. THE PRES GRADIENT WILL WEAKEN DURING THE NEXT SEVERAL HOURS ALLOWING FOR CONDITIONS IN THE GULF TO IMPROVE BY SUNRISE FRI. A TIGHT PRES GRADIENT IS FORECAST TO RETURN BY SAT MORNING WITH FRESH TO STRONG WINDS AND SEAS TO 8 FT LIKELY N OF 29N SAT MORNING AND AFTERNOON. MODEL GUIDANCE SHOWS STRONGER WINDS THAN THIS PAST EVENT...NEAR GALE BY 12 UTC SAT. SCATTEROMETER DATA AND SHIP OBSERVATIONS SHOWED MAINLY MODERATE N-NE WINDS SW OF THE BAJA CALIFORNIA PENINSULA ALONG WITH 4-7 FT SEAS. S OF 15N E OF 110W...DEEP LAYER DRY AIR IS IN PLACE ACROSS MUCH OF THE AREA N OF 10N OUTSIDE OF THE INFLUENCE OF RICK...INDUCED BY A BROAD UPPER ANTICYCLONE CENTERED OVER SOUTHERN MEXICO KEEPING CONVECTION MINIMAL OFF THE CENTRAL AMERICAN COAST NORTH OF COSTA RICA. SCATTERED CONVECTION PERSISTS S OF THE MONSOON TROUGH AS DESCRIBED ABOVE...DUE TO CONVERGENCE OF MODERATE SW FLOW IN THE LOWER LEVELS AND WEAK UPPER DIVERGENCE ON THE SOUTHERN PERIPHERY OF THE MID/UPPER RIDGE. NO MAJOR CHANGES ARE EXPECTED OVER THE NEXT 2 TO 3 DAYS. LOOKING AHEAD...THERE IS SOME DISAGREEMENT WITH GLOBAL MODEL GUIDANCE WITH REGARDS TO THE DEVELOPMENT OF LOW PRES ALONG THE MONSOON TROUGH EAST OF COSTA RICA BY SAT. THE GFS IS AN OUTLIER SHOWING VERY AGGRESSIVE DEVELOPMENT OF A LOW PRESSURE SYSTEM BETWEEN 90W AND 100W MON THROUGH WED...AND HAS BEEN DISCOUNTED AT THE PRESENT TIME. ELSEWHERE...SCATTEROMETER DATA SHOWED FRESH TO STRONG TRADES ACROSS MUCH OF THE WATERS N OF 10N W OF 120W BETWEEN RIDGING ASSOCIATED WITH 1029 MB HIGH PRES NEAR 35N136W AND LOWER PRES ALONG THE MONSOON TROUGH/ITCZ. VARIOUS ALTIMETER DATA CONTINUE TO SHOW SEAS AS HIGH AS 11 FT IN THE AREA OF THE STRONG TRADE WINDS...HELPED IN PART PRIMARILY BY LONG PERIOD NW SWELL PREVAILING ACROSS MUCH OF THE REGION. THIS IS PRODUCING A LARGE AREA OF CONFUSED SEAS OF 8 FT OR GREATER...ROUGHLY W OF 103W. THE RIDGE WILL GRADUALLY WEAKEN THROUGH THE REMAINDER OF THE WEEK INTO THE WEEKEND WHICH WILL ALLOW FOR THE TRADE WINDS TO DIMINISH ACCORDINGLY. AS A RESULT...WINDS AND SEAS WILL SUBSIDE ACROSS MOST OF THIS AREA. $$ LEWITSKY