000 AXPZ20 KNHC 190341 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC MON JAN 19 2009 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 0245 UTC. ...ITCZ... AXIS WAS ALONG 3N79W TO 01N91W TO 04N97W TO 05N108W TO 08N124W TO 06N140W. SCATTERED MODERATE ISOLATED DEEP CONVECTION WAS OCCURRING WITHIN 90 NM N AND 60 NM S OF AXIS FROM 112W TO 128W. ISOLATED MODERATE CONVECTION 60 NM OF AXIS FROM 102W TO 112W. SCATTERED MODERATE TO DEEP CONVECTION WITHIN 90 NM OF 04N95.5W. ...DISCUSSION... A HIGH AMPLITUDE REX BLOCK PATTERN DOMINATES THE HEMISPHERE FROM THE EAST CENTRAL PACIFIC TO THE EXTREME WEST ATLC TONIGHT. THE MAIN FEATURE ACROSS THE AREA CONTINUES TO BE THE CUT OFF LOW IN THIS PATTERN...IN THE FORM OF AN ELONGATED AND DEEP LAYERED CYCLONIC CIRCULATION ALONG 122/123W BETWEEN 06N AND 28N. AN EMBEDDED VORTEX EARLIER TODAY HAS FILLED AND HAS BECOME MORE ELONGATED AS IT STRETCHES AND EJECTS TO THE NE ATTM...WHILE ANOTHER VORTEX FORMED NEAR THE SOUTHERN END NEAR 14N123W..AND IS SHIFTING NNE. RIDGING TO THE E CONTINUES TO BLOCK THIS TROUGH FROM MOVING FORWARD...AND IS ALSO AIDING IN STRETCHING THIS ELONGATED CIRCULATION NE. THIS TROUGH IS FORECAST TO BE NUDGED GRADUALLY FORWARD TO ALONG 118W BY 48 HOURS AS THE BROAD MID LATITUDE UPPER TROUGH N OF THE HAWAIIAN ISLANDS APPROACHES THE W COAST OF THE U.S. DURING THE NEXT FEW DAYS. DEEP TROPICAL MOISTURE IS CURRENTLY BEING ADVECTED N AND NEWD ON THE E SIDE OF THE TROUGH BETWEEN 104W AND 122W...RESULTING IN SCATTERED TO NUMEROUS MODERATE AND ISOLATED DEEP CONVECTION S OF 24N BEING ENHANCED DUE TO UPPER DIVERGENCE. MEANWHILE...BROKEN TO OVERCAST MID AND HIGH CLOUDS CONTINUE TO STREAM NE ACROSS BAJA CALIFORNIA AND THE NEARBY GULF AND INTO MEXICO...N OF 24N...AND ARE LIKELY PRODUCING STRATIFORM PRECIP. AN ASSOCIATED 1013 MB SURFACE LOW CONTINUES THIS EVENING NEAR 17.5N128W WITH SEVERAL SMALL EMBEDDED MESO VORTICES SEEN ROTATING AROUND THE INNER CIRCULATION IN VISIBLE IMAGERY TODAY. SCATTEROMETER WINDS EARLIER THIS AFTERNOON REVEALED 20 TO 25 KT WINDS ACROSS THE N SEMICIRCLE. ISOLATED MODERATE CONVECTION WAS PERSISTING WITHIN 300 NM IN THE ERN SEMICIRCLE OF THIS SURFACE LOW. THE LOW APPEARS TO BE GRADUALLY SPINNING DOWN AND BEING SHEARED OR STRETCHED TO THE NE...AND IS EXPECTED TO GRADUALLY WEAKEN...AS THE UPPER SUPPORT HAS LONG SINCE LIFTED OUT. ACTIVE CONVECTION E OF THE DEEP LAYERED TROUGH IS ALSO FORECAST TO GRADUALLY DIMINISH OVER THE NEXT 24 TO 36 HOURS. A STRONG COLD FRONT HAS ENTERED THE AREA FROM THE NW...EXTENDING SW INTO THE TROPICS S OF HAWAII. THE CENTRAL PACIFIC UPPER TROUGH MENTIONED ABOVE WILL SUPPORT A FURTHER E TO SE PROGRESS OF THIS FRONT DURING THE NEXT 48 HOURS...AND AS IT MOVES TO WITHIN 8-10 DEGREES OF THE DEEP LAYERED TROUGH TO ITS SE BY 24 HOURS...MOISTURE AND ENERGY FROM THE DEEP LAYERED TROUGH WILL BE FURTHER SHEARED N AND NE...WHICH WILL INDUCE ACTIVE CONVECTION ALONG THE FRONT N OF 20N. SEAS BEHIND THE FRONT WILL BUILD 14 TO 18 FT IN LARGE NW SWELL WITHIN THE AREA...AND IN EXCESS OF 20 FT JUST TO THE NW OF THE AREA. ...GAP WINDS... THE GULF OF TEHUANTEPEC GALE EVENT HAS EXPIRED AND N-NE WINDS ARE SLOWLY WEAKENING THROUGH THE PASS...AND EXPECTED TO DROP TO AROUND 20 KT BETWEEN 24 AND 36 HOURS AS HIGH PRES OVER GULF OF MEXICO DRIFTS E. AT 48 HOURS...VERY COLD AIR SPREADING ACROSS THE GULF COAST REGION WILL BEGIN TO SPILL INTO THE BAY OF CAMPECHE AND THEN MOVE ACROSS THE GULF OF TEHUANTEPEC TO START ANOTHER EVENT. COMPUTER MODEL GUIDANCE...WHICH IS TYPICALLY LOW...IS INDICATING A HIGH GALE EVENT BY 54-60 HOURS...AND MAY REACH STORM STRENGTH. GULF OF PAPAGAYO STRONG NE WINDS HAVE WEAKENED SOMEWHAT AND ARE EXPECTED TO BECOME MORE NE TO E AND FLUCTUATE UP AND DOWN DURING THE NEXT 48 HOURS...BUT GENERALLY REMAIN AT 20 KT OR GREATER WITH SEAS AROUND 8 FT. WINDS THROUGH THE GULF OF PANAMA WERE NLY AROUND 20 KT EARLIER TODAY BUT ARE EXPECTED TO DIMINISH DURING THE NEXT 12 TO 24 HOURS. NW TO N WINDS HAVE ALSO BEGUN TO INCREASE TO 20 TO 25 KT ACROSS THE EXTREME SRN GULF OF CALIFORNIA EXTENDING INTO THE OPEN PACIFIC...WITH 20 KT EXPECTED TO DEVELOP ACROSS THE REMAINDER OF THE GULF IN THE NEXT 24 HOURS AS HIGH PRESSURE EAST OF THE APPROACHING PACIFIC FRONT NUDGES UP ALONG THE COAST AND SIERRA MADRE OCCIDENTALES. SEAS WITHIN THE GULF WILL LIKELY BUILD TO 6 FT BY 12 HOURS AND TO 7 FT S HALF BY 24 HOURS. SEVERAL PULSES OF LONG PERIOD NW SWELL ARE EXPECTED DURING THE NEXT SEVERAL DAYS. ONE PULSE CURRENTLY MOVING THROUGH THE MIDDLE OF THE AREA IS PRODUCING SEAS OF 8 FT AND GREATER ACROSS MOST OF THE AREA W OF 110W. PEAK SEAS ACROSS THE AREA ARE CURRENTLY BEHIND THE FRONT AT 14 TO 18 FT...WHILE SEAS ACROSS THE N SEMICIRCLE OF THE 1014 MB LOW ARE RUNNING 10 TO 12 FT IN NW SWELL. THIS PULSE OF NW SWELL WILL REACH 90W BY 48 HOURS...WHILE SEAS REMAIN 10 TO 15 FT W OF 127W AND N OF 15N THROUGH THAT PERIOD. A PULSE OF LONG PERIOD SSW SWELL MOVING ACROSS THE EQUATOR HAS BEGUN TO MERGE WITH THE NW SWELL AND IS PRODUCING SEAS OF 8 TO 9 FT S OF 14S AND W OF 112W. COLD AND DRIER YET MODIFIED POLAR AIR WORKING INTO THE GULF OF MEXICO AND WRN CARIB LATER IN THE WEEK WILL REACH CENTRAL AMERICA TUE THROUGH THU TO ALLOW FOR ONLY VERY SHALLOW MOISTURE AND LIGHT PRECIP AMOUNTS ALL THE WAY INTO EXTREME NW COSTA RICA. $$ STRIPLING