000 AXPZ20 KNHC 121020 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC THU JAN 12 2012 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 0900 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH EXTENDS FROM 07N75W TO 03N78W TO 06N85W TO 03N91W...WHERE IT TRANSITIONS TO ITCZ...CONTINUING ON TO LOW PRES NEAR 05N100W 1010 MB TO 08N114W TO 06N120W TO 07N128W TO BEYOND 05N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED FROM 150 TO 360 NM N OF AXIS BETWEEN 106W AND 114W. ISOLATED TO SCATTERED MODERATE TO STRONG CONVECTION NOTED WITHIN 240 NM OF AXIS BETWEEN 114W AND 121W. OTHER SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS NOTED OCCURRING WELL REMOVED FROM ITCZ FROM 12N TO 19N BETWEEN 132W AND 137W. ...DISCUSSION... AT UPPER LEVELS...A BLOCKING UPPER LEVEL TROUGH PERSISTS THIS MORNING ALONG ABOUT 137W...FROM 25N EXTENDING S TO JUST S OF THE EQUATOR ALONG 140W. BROAD UPPER RIDGING PREVAILS W AND E OF THIS FEATURE TO 90W...WHERE A SHARP UPPER TROUGH EXTENDS FROM NEAR PANAMA SSE ACROSS THE EQUATOR NEAR 80W. THIS BLOCKING UPPER TROUGH WILL FINALLY BEGIN TO WEAKEN AND SHIFT OFF TO THE E-NE DURING THE NEXT 24 HOURS...AND EXIT THE AREA OVER THE WEEKEND. NE OF THIS UPPER TROUGH...A DEEP LAYER CYCLONE WAS CENTERED NEAR 30N130.5W...WITH AN ASSOCIATED WEAK 1018 MB SURFACE LOW DIRECTLY BELOW. THIS CYCLONE WILL REMAIN RELATIVELY STATIONARY ALOFT OVER THE NEXT 24 HOURS AND AID IN KICKING OUT THE LINGER UPPER TROUGH TO ITS SW. AT LOW LEVELS...A WEAKNESS IN THE FORM OF A BROAD TROUGH EXTENDS FROM THE SURFACE LOW SE TO NEAR 24N126W. COLD AIR SPILLING DOWN TO THE W OF THE SURFACE LOW FORMS A WEAK AND BENIGN REINFORCING COLD FRONT FROM 28N128W TO 24N138W...WITH NLY WINDS AROUND 20 KT DEPICTED BY A 0540 UTC ASCAT PASS N OF 29N BETWEEN 132W AND 136W. SURFACE HIGH PRES LOCATED ACROSS THE FAR NE PACIFIC EXTENDS SW TO THE HAWAIIAN ISLANDS...WITH SUFFICIENT PRES GRADIENT TO THE S BETWEEN THE HIGH AND LOWER PRES ASSOCIATED WITH THE ITCZ TO PRODUCE A VERY SMALL AREA OF 20 KT NE TRADEWINDS FROM 06N TO 09N W OF 135W...AND ALONG A CONVERGENCE LINE FARTHER N FROM 16N TO 22N W OF 137W. AS THE UPPER PATTERN BREAK DOWN OVER THE WEEKEND...THE E PACIFIC HIGH PRES RIDGE WILL BUILD ACROSS THE REGION AND BRING A RETURN TO FRESH TRADEWINDS S OF 16N AND W OF 130W BY SUNDAY EVENING. OTHERWISE...A VERY WEAK PRES PATTERN PREVAILS ACROSS THE REMAINDER OF THE AREA. ACTIVE CONVECTION CONTINUES INVOF OF STRONG CYCLONIC TURNING OCCURRING WITHIN THE BLOCKING UPPER TROUGH ALONG 137W...WITH DOWNSTREAM UPPER DIFFLUENCE AIDING IN VENTING MODERATE TO DEEP CONVECTION N OF THE ITCZ MENTIONED ABOVE. SHIP AND ALTIMETER DATA VERIFY PERSISTENT NW SWELL DOMINATING MARINE CONDITIONS OVER MUCH OF THE AREA W OF 105W...WHILE A NEW PULSE OF W-NW SWELL HAS BEGUN TO ENTER THE FAR NW PORTIONS OF THE AREA OVERNIGHT...AND WILL RAISE SEAS TO 9 TO 10 FT BY FRI MORNING. OTHERWISE...LITTLE CHANGE IS EXPECTED THROUGH 48 HOURS. THE 20 KT NORTHERLY WINDS W OF THE LOW WILL DIMINISH AS THE LOW WEAKENS AND LIFTS OUT TO THE NE THIS AFTERNOON AND TONIGHT....WHILE THE NW SWELL WILL LARGELY DECAY BELOW 8 FT OVER ALL BUT NW PORTIONS THROUGH FRI. GULF OF TEHUANTEPEC...A COLD FRONT HAS STALLED ACROSS THE YUCATAN PENINSULA OVERNIGHT AND IS QUICKLY DISINTEGRATING. A NEW REINFORCING COLD FRONT WAS MOVING OFF THE UPPER TEXAS COAST THIS MORNING AND WILL PUSH THROUGH THE GULF OF MEXICO THROUGH FRI. COLD AIR ADVECTION AND STRONG HIGH PRES BUILDING OVER THE WESTERN GULF BEHIND THE FRONT WILL PROMPT NLY GAP WIND FLOW THROUGH THE CHIVELA PASS TONIGHT...WITH WINDS EXPECTED TO REACH MINIMAL GALE FORCE FRI MORNING...AND PERSIST THROUGH SAT MORNING. AS HIGH PRES BEHIND THE FRONT SINKS S INTO THE GULF OF MEXICO ON SAT...THE PRES GRADIENT WILL INCREASE ACROSS THE ENTIRE CARIBBEAN AND EPAC...AND GALES COULD INCREASE TO 40 KT THROUGH THE GULF OF TEHUANTEPEC BY SAT EVENING. GAP WIND FLOW E OF 90W IS CURRENTLY MILD...REACHING 15-20 KT IN THE OVERNIGHT HOURS DUE TO NOCTURNAL DRAINAGE FLOW. NLY WINDS HAVE INCREASED TO NEAR 20 KT THROUGH THE GULF OF PANAMA AS INDICATED BY SHIP OBSERVATIONS OVERNIGHT...AND IS EXPECTED TO REMAIN SO THROUGH FRI. GAP WINDS THROUGH THE GULF OF PAPAGAYO ARE EXPECTED TO INCREASE TO 20-25 KT FRI NIGHT AS THE PRES GRADIENT INCREASES ACROSS THE CARIBBEAN...AND GENERALLY PERSIST INTO EARLY NEXT WEEK. $$ STRIPLING