000 AXPZ20 KNHC 282143 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC SUN DEC 28 2008 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2115 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 08N82W 05N98W 08N112W 07N130W 09N140W. SCATTERED MODERATE CONVECTION IS WITHIN 45 NM OF THE AXIS BETWEEN 93W-96W AND WITHIN 180 NM N OF AXIS BETWEEN 118W- 133W. ...DISCUSSION... A W TO SWLY UPPER-LEVEL JET LIES OVER MUCH OF THE TROPICS W OF 105W ENHANCED BY A RIDGE ALONG 138W AND A SHORTWAVE TROUGH EXTENDING SW FROM THE CENTRAL CONUS THRU BAJA CALIFORNIA. INSTABILITY ASSOCIATED WITH THE JET COUPLED WITH LOW-LEVEL DIRECTIONAL AND SPEED CONVERGENCE IS PRODUCING SCATTERED SHOWERS AND TSTMS FROM 13N-21N BETWEEN 105W-120W. SIMILAR ACTIVITY EXISTS FARTHER SW WITHIN THE ITCZ (OUTLINED ABOVE). DEEP LAYER HIGH PRES HAS BUILT IN BEHIND THE SHORTWAVE CENTERED OFF THE SO CALIFORNIA COAST. THE PRESSURE GRADIENT BETWEEN THIS HIGH AND LOWER PRES ASSOCIATED WITH THE ITCZ IS GENERATING A SWATH OF 20-25 KT NE/E TRADES FROM 10N-26N W OF 114W. WIND GENERATED WAVES COMBINED WITH LONG PERIOD NW TO N SWELL IS ELEVATING SEAS TO 8-14 FT OVER MUCH OF THE EPAC W OF 110W. WHILE WINDS ARE NOT EXPECTED TO CHANGE MUCH OVER THE NEXT COUPLE OF DAYS...NLY SWELL WILL DIMINISH SOME ALLOWING SEAS TO REDUCE SLIGHTLY. A 1009 MB LOW PRES SYSTEM IS NEARLY STATIONARY OFF THE COAST OF COLOMBIA NEAR 05N79W. THIS LOW HAS BECOME MORE DETACHED FROM THE ITCZ AND HAS A WELL DEFINED LOW-LEVEL CENTER WITH CURVED BANDS ROTATING ABOUT IT. WHILE ITS LOW-LEVEL STRUCTURE IS IMPRESSIVE ON VISIBLE IMAGERY...IR IMAGERY SUGGESTS THAT IT IS SHALLOW IN NATURE DEVOID OF DEEP CONVECTION. ABUNDANT DRY AIR IN THE MID AND UPPER LEVELS ARE LIKELY LIMITING THE DEVELOPMENT OF DEEP CLOUDINESS AND EVEN IF DEEPER ACTIVITY DOES DEVELOP IT WILL LIKELY BE QUICKLY SHEARED OFF BY STRONG S WINDS IN THE MID-UPPER LEVELS. NONETHELESS...20-25 KT WINDS HAVE BEEN REVEALED ON SCATTEROMETER DATA...STRONGEST S OF THE CENTER. GAP WINDS... A RECENT ASCAT PASS REVEALED 20-25 KT NE WINDS FUNNELING THROUGH THE GULF OF PAPAGAYO. THESE WINDS MAY EXPAND W OVER THE NEXT COUPLE OF DAYS ENHANCED BY THE TIGHTENED PRES PATTERN S/SW OF A FRONTAL BOUNDARY. THIS FRONTAL BOUNDARY WILL ALSO HAVE INFLUENCE ON THE GULF OF TEHUANTEPEC. A GALE WARNING IS POSTED FOR THIS GAP BEGINNING MON AS THE FRONT CONTINUES ITS SURGE S IN THE W BAY OF CAMPECHE. MODEL GUIDANCE IS IN AGREEMENT IN SHOWING A MINIMAL GALE EVENT LIKELY ENDING LATE TUE AS THE FRONT LIFTS BACK N AND DISSIPATES. GULF OF CALIFORNIA...NW TO N 20-30 KT WINDS WERE REVEALED IN EARLIER QSCAT DATA. THIS ENHANCED WIND REGIME WILL LIKELY DIMINISH OVER THE NEXT COUPLE OF DAYS AS THE TAIL END OF THE FRONT OVER N MEXICO AND THE GREAT BASIN HIGH WEAKENS. $$ CANGIALOSI