000 AXPZ20 KNHC 200951 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC SUN JAN 20 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0930 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH FROM 09N84W TO 07N92W THEN ITCZ TO 06N109W TO 07N116W TO 06N126W TO 09N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 180 NM OF AXIS FROM 98W TO 110W. ...DISCUSSION... NEGATIVELY-TILTED UPPER LEVEL TROUGH FROM 32N125W TO WEAK CYCLONE AT 30N122W TO 17N118W BRING A DRY SWATH FROM 118W TO 128W. BURST OF TROPICAL MOISTURE E OF 118W ADVECTED NE BY DOWNSTREAM RIDGE CREST AND SECOND REGION OF MOISTURE N OF 22N W OF 128W FORCED INTO BASIN BY NEXT DEEP LAYER CYCLONE. MODEL GUIDANCE MOVE FIRST CYCLONE E ALONG 30N WITH MINOR AREA OF SCATTERED MODERATE CONVECTION IN SE QUADRANT MOVING OVER NORTHERN BAJA CALIFORNIA LATE SUN. SECOND NEGATIVELY TILTED LONGWAVE...DEEP LAYERED AND VIGOROUS... CROSSING 140W INTO E PAC BRING SERIES OF SHORTWAVES ROTATING AROUND ITS BASE. FIRST SHORT WAVE PRESENTLY HAS COLD FRONT EXTENDING FROM 1002 MB SURFACE LOW PRES NW OF AREA TO 32N140W TO 26N139W TO 20N140W. VERY STRONG SE-S WINDS N OF 23N W OF 133W WITH SEAS APPROACHING 12 FT NOTED. FRONT MOVES NE WITH DIMINISHING WIND BUT BUILDING SEAS IN NW SWELLS SUN. SECOND SHORTWAVE SWINGS AROUND DEEP LAYER TROUGH BASE WITH 1002 MB SURFACE LOW PRES ENTERING E PAC NEAR 25N140W SUN NIGHT DRAGGING COLD FRONT INTO BASIN. LOW PRES 1003 MB NEAR 24N133W WITH ATTENDANT COLD FRONT TO 23N130W TO 20N1328W TO 06N134W BY LATE MON. STRONG TO NEAR GALE FORCE WINDS...MAINLY IN NORTHERN SEMICIRCLE OF LOW PRES...POSSIBLE WITH SEAS OVER 20 FT IN NW LONG PERIOD SWELL. LOW PRES DRIFT NE WITH SIMILAR CONDITIONS WELL BEYOND FORECAST PERIOD. VERY LONG PERIOD NW SWELLS PROPAGATE ACROSS W HALF OF BASIN AND ACROSS EQUATOR INTO S PAC. ELSEWHERE AT THE LOW LEVELS... CONTINUED STRONG NORTHERLY WINDS IN SW GULF OF MEXICO ACROSS CHIVELA PASS BRING GALE FORCE N-NE WINDS INTO GULF OF TEHUANTEPEC. WINDS DIMINISH IN COVERAGE AND MAY WEAKEN BELOW GALE FORCE CRITERIA MOMENTARILY LATE SUN BEFORE NEXT BLAST OF COLD AIR IN GULF OF MEXICO INCREASES IT AGAIN LATE IN FORECAST PERIOD. GALE FORCE WINDS WILL REMAIN IN REDUCED AREA BEYOND FORECAST PERIOD. CURRENT GALE FORCE WINDS OVER SW CARIBBEAN REINFORCE FRESH TO STRONG NE WINDS ALONG GULFS OF PAPAGAYO AND FONSECA THROUGH FORECAST PERIOD WITH STRONGEST USUALLY NOTED IN EARLY MORNINGS AS DOWNSLOPE DRAINAGE WINDS ADD STRENGTH TO WIND FIELD. CARIBBEAN GALE ALSO CONTRIBUTES TO FRESH N BREEZE OVER GULF OF PANAMA THROUGH LATE MON. $$ WALLY BARNES