000 AXPZ20 KNHC 170338 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC WED DEC 17 2008 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0315 UTC. ...ITCZ... INTERTROPICAL CONVERGENCE ZONE...6N78W 5N90W 7N100W 8N115W 10N130W 7N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM 8N-13N BETWEEN 128W-132W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM S OF THE AXIS BETWEEN 120W-124W...AND ALSO WITHIN 30 NM EITHER SIDE OF THE AXIS BETWEEN 132W-136W. ...DISCUSSION... RATHER PRONOUNCED AND PROGRESSIVE FLOW REGIME EXISTS OVER THE AREA MARKED BY A POSITIVELY-TILTED LONGWAVE TROUGH EXTENDING FROM THE NORTHERN U.S. SW THROUGH 32N126W TO 24N131W TO 12N138W. A SURFACE COLD FRONT ASSOCIATED WITH THE TROUGH EXTENDS FROM ARIZONA SW ACROSS NORTHERN BAJA CALIFORNIA TO 26N122W TO 25N130W ...THEN NW TO W OF THE AREA AT 26N140W. SHIP OBSERVATIONS FROM EARLY THIS EVENING SHOWED STRONG NW-N WINDS OF 20-30 KT WITH HIGHER GUSTS ALONG AND N OF THE AREA. ALONG WITH THESE WINDS...VERY HIGH SEAS IN THE RANGE OF 15 TO 16 FT IN N SWELL ARE SPREADING SWD TOWARDS THE NORTHERN PORTION OF THE AREA BEHIND THE FRONT. N OF 25N E OF FRONT WINDS ARE SW 20 KT WITH SEAS TO 8 FT. LATEST MODEL GUIDANCE SUGGESTS THAT A LOW WILL FORM ON THE FRONT IN THE VICINITY OF FAR NORTHERN BAJA CALIFORNIA AND FAR SOUTHERN CALIFORNIA OVER THE NEXT 24 HOURS AS SURFACE PRESSURES DECREASE TO THE E OF THE LONGWAVE TROUGH. THE FRONT IS FORECAST TO MOVE INLAND SOUTHERN CALIFORNIA AND NORTHERN BAJA CALIFORNIA AND WEAKEN IN ABOUT 36 HOURS AS THE ATTENDANT LOW QUICKLY LIFTS NE OVER THE SW U.S. FOLLOWING THE AREA OF SYNOPTIC SCALE ASCENT WHICH SHIFTS TO THE WESTERN U.S. AT THAT TIME. THE LOW WILL ALLOW FOR SW-W WINDS TO INCREASE TO 25 KT E OF THE FRONT NEAR NORTHERN BAJA CALIFORNIA ON WED. THE MAIN IMPACT ON MUCH OF THE AREA WILL BE LINGERING LARGE SWELLS...IN THE RANGE OF 9-13 FT SPREADING SSE OVER THE WATERS W OF ABOUT 120W THROUGH THU THEN SUBSIDING TO 8 FT S OF 21N. GLOBAL MODELS HINT THAT YET ANOTHER PRONOUNCED LONGWAVE TROUGH SETS UP OVER THE FAR NE PART OF THE AREA BY FRI WITH AN UPPER LOW DROPPING SWD INTO THE NORTHERN PORTION OF THE AREA NEAR 28N130W. THIS LOW IS THEN FORECAST TO CUT-OFF AS IT BECOMES LARGER AND DRIFTS SW WHILE A HIGHLY AMPLIFIED UPPER LEVEL RIDGE REMAINS W OF THE AREA BRINGING CONFLUENT FLOW AND DESCENDING STABLE AIR IN MODERATE SUBSIDENCE OVER A PORTION OF THE WESTERN PORTION OF THE AREA. ELSEWHERE ACROSS THE FORECAST AREA...TRADE WIND CONVERGENCE ZONE ALONG THE ITCZ REMAINS QUITE ACTIVE FROM 9N-18N W OF 118W WHERE QUIKSCAT DATA FROM 1500 UTC THIS MORNING SHOWED NE 20-25 KT WINDS. STRONGER WINDS WERE NOTED AS RAIN-FLAGGED VECTORS IN CONVECTION OCCURRING ALONG THIS PORTION OF THE ITCZ. THIS CONVECTION IS EXPECTED TO REMAIN ACTIVE THROUGH THE END OF THE WEEK AS UPPER LEVEL DIVERGENCE TO THE SE OF THE TROUGHS CONTINUES TO SUPPORT THE DEVELOPMENT OF THIS CONVECTION. THERE MAY SOME INDICATION THAT A WEAK SURFACE TROUGH IS FORMING ALONG OR NEAR 128W. GLOBAL MODELS EVEN SHOW A POSSIBLE WEAK LOW FORMING THERE AS WELL OVER THE NEXT 12-18 HOURS. DEEP TROPICAL PACIFIC MOISTURE CONTINUES TO STREAM NE TOWARDS BAJA CALIFORNIA...AND MUCH OF MEXICO. GAP WINDS...QUIKSCAT DATA FROM JUST PAST 0000 UTC TONIGHT SHOWED A COUPLE OF 20 KT WIND BARBS WITHIN ABOUT 60 NM OF THE GULF OF TEHUANTEPEC COAST. THESE WINDS SHOULD LAST ABOUT 48 HOURS BUT COULD END SOONER IF PRES GRADIENT OVER SE MEXICO WEAKENS FURTHER. QUIKSCAT DATA ALSO SHOWED GULF OF PAPAGAYO NE WINDS TO JUST LESS THAN 20 KT. THESE WINDS ARE EXPECTED TO PICK UP TO 20-25 KT IN THE MORNING WITH THE TYPICAL DIURNAL CYCLE FOR THESE WINDS. EXPECT THIS WINDS TO VARY SLIGHTLY THROUGH THE NEXT 48 HOURS. $$ AGUIRRE