000 AXPZ20 KNHC 070341 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC WED DEC 07 2011 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0315 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH EXTENDS FROM LOW PRES NEAR 05N78W 1008 MB TO 08N86W TO 05N98W TO 06N104W WHERE LOW LEVEL WINDS SUGGEST THAT THE ITCZ THEN EXTENDS TO LOW PRES NEAR 09N117W 1010 MB TO 07N130W TO 07N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION EXISTS WITHIN 60 NM N OF THE TROUGH...AND WITHIN 60 NM OF THE ITCZ BETWEEN 136W-139W. ...DISCUSSION... A COUPLE OF UPPER LEVEL LOWS N OF THE AREA BLOCKED BETWEEN LARGE HIGH PRES OVER THE NW U.S. AND A NARROW RIDGE ALONG 147W ARE SWINGING A COUPLE OF SHORTWAVE TROUGHS THROUGH THE CENTRAL AND NW PORTIONS OF THE AREA. A RATHER PRONOUNCED JET STREAM BRANCH ENTERS THE AREA THROUGH 14N140W...AND ROUNDS THE SOUTHERN PERIPHERIES OF THE TROUGHS AS IT STRETCHES NE TO 15N120W TO 19N110W AND TO ACROSS NRN MEXICO AND THE SE U.S. THE JET IS TAPPING ABUNDANT DEEP TROPICAL CENTRAL PACIFIC MOISTURE IN THE FORM OF BROKEN TO SCATTERED HIGH CLOUDS OBSERVED STREAMING NORTHEASTWARD TO ACROSS BAJA CALIFORNIA...AND NORTHERN/CENTRAL MEXICO. A LARGE UPPER ANTICYCLONE IS ANCHORED JUST TO THE SW OF GUATEMALA WITH A RIDGE W TO 14N105W. STABLE ATMOSPHERIC CONDITIONS PREVAIL OVER THE REMAINDER OF THE AREA TO THE S AND SE OF THE JET RELATED UPPER LEVEL MOISTURE WITH THE EXCEPTION OF THE FAR SE PORTION WHERE LOW LEVEL CONVERGENCE TO THE S OF THE MONSOON TROUGH IS NOTED AS ENHANCED TROPICAL MOISTURE PRODUCING SCATTERED SHOWERS AND ISOLATED TSTMS FROM 4N-6N E OF 89W. IN ADDITION A 1009 MB LOW IS ALONG THE MONSOON TROUGH NEAR 07N78W...JUST TO THE S OF THE TAIL END OF AN UPPER LEVEL TROUGH THAT EXTENDS INTO THE AREA FROM THE CARIBBEAN SEA. THE OVERALL BROAD SCALE PATTERN WILL CHANGE LITTLE OVER THE DISCUSSION AREA THROUGH THE NEXT 24-48 HRS AS A REX-TYPE OF PATTERN SETS UP N OF THE REGION TO THE W OF THE PACIFIC NW U.S. ALLOWING FOR BROAD RIDGING TO PREVAIL WITH NO FRONTS EXPECTED TO CROSS S OF 32N. GULF OF TEHUANTEPEC...HIGH PRES BUILDING OVER THE CENTRAL PLAINS OF THE UNITED STATES HAS INCREASED THE PRES GRADIENT BETWEEN THE NORTHERN COAST OF THE ISTHMUS OF TEHUANTEPEC AND ITS SOUTHERN TERMINUS. SEA LEVEL PRES AT MINATITLAN ON THE NORTHERN COAST HAS RISEN TO 1020 MB COMPARED WITH 1012 MB AT IXTEPEC ON THE SOUTHERN PORTION OF THE GULF. MEANWHILE A STALLED COLD FRONT OVER THE SW GULF OF MEXICO WILL RECEIVE A REINFORCING SHOT OF COLD AIR TONIGHT INTO WED MORNING...AND FUNNEL INTO THE GULF. THIS WILL ALLOW A SHARP INCREASE IN GAP FLOW THROUGH THIS EVENING...WITH WINDS LIKELY REACH STRONG GALE FORCE. LATEST MODEL WIND GUIDANCE HINTS AT WINDS PEAKING TO JUST BELOW STORM STRENGTH WED EVENING BEFORE GOING ON THE DECREASING TREND. GLOBAL MODELS SHOW A LARGE SWATH OF NE-E 20-30 KT REACHING AS FAR W AS 105W BY THU. SEAS ARE EXPECTED TO REACH A MAXIMUM OF 18 FT BY WED EVENING BEFORE SLOWLY SUBSIDING TO 15 FT THU AFTERNOON. GULF OF CALIFORNIA...HIGH RESOLUTION ASCAT DATA FROM YESTERDAY AFTERNOON REVEALED NW-N WINDS OF 20-30 KT SWEEPING THROUGH THE GULF TO AS FAR S AS 22N E OF 110W WHERE THEY TURN MORE TO THE N AND NE. A ZONE OF NE-E WINDS IS ALREADY BEING FORCED ACROSS AND THROUGH PASSES IN THE BAJA CALIFORNIA PENINSULA AND INTO THE OPEN PACIFIC WATERS TO THE W OF THE PENINSULA WITH WINDS OF 20-25 KT. AS THE GRADIENT SLACKENS OVER THE NEXT 24-48 HRS...WINDS WILL RESPONSE BY DIMINISHING TO 20 KT AND LESS THAN 20 KT AT 48 AROUND 48 HRS. FURTHER SOUTH...A PERSISTENT 1010 MB LOW PRES SYSTEM CENTERED NEAR 09N117W IS MOVING WESTWARD AT 10 KT...WITH A TROUGH EXTENDING NE TO 13N113W. STRONG SW UPPER SHEAR HAS TOTALLY DISSIPATED THE PREVIOUS LARGE CLUSTER OF STRONG CONVECTION NOTED TO THE E OF THE LOW. AS STATED IN PREVIOUS FORECASTS ...THE LOW WILL BE FORECAST TO CONTINUE ON A WESTWARD MOTION TO NEAR 09N123W IN 24 HRS AND TO NEAR 09N128W BY 48 HRS. THERE IS A POSSIBILITY THAT THE LOW MAY BECOME DIFFUSE NEAR OR SHORTLY AFTER 24 HRS AS MOST OF THE GLOBAL MODELS INDICATE. THE PRES GRADIENT BETWEEN THE LOW AND HIGH PRES RIDGING TO ITS N WILL ALLOW FOR WINDS 0F 20-25 KT IN THE 210 NM NE QUADRANT ...THEN OVER AN AREA FROM 10N-17N BETWEEN 121W-130W IN 24 HRS AND FROM 10N-18N BETWEEN 121W-130W IN 48 HRS WITH SEAS OF 8-10 FT THROUGH 24 HRS. A MODERATE PRES GRADIENT IS OVER THE NW WATERS BETWEEN A STRONG 1035 MB HIGH PRES WELL N OF THE AREA AT 45N138W AND LOWER PRES ASSOCIATED WITH THE ITCZ INCLUDING A WEAK SURFACE ALONG 134W/135W FROM 09N TO 12N. THE TROUGH WILL BE THE KEY PLAYER IN HELPING TO MAINTAIN THE MODERATE PRES GRADIENT OVER THESE WATERS THROUGH THE NEXT 24-48 HRS. NE TRADE WINDS ARE GENERALLY BELOW THE 20 KT THRESHOLD...EXCEPT FOR 20 KT WINDS FROM 14N TO 21N W OF 131W... AND FROM 12N TO 20N BETWEEN 119W-131W. SEAS THERE ARE IN THE RANGE OF 9-10 FT IN A MIXED NE AND NW SWELL. AS THE TROUGH PROGRESSES WESTWARD THE 9-10 FT SEAS WILL SHIFT WESTWARD AS WELL AND BE RESTRICTED TO W OF 130W BY 48 HOURS. THE NEXT LARGE SWELL EVENT SHOULD COMMENCE BEYOND THE DISCUSSION PERIOD ON FRIDAY WITH LONG PERIOD NW SWELL REACHING THE NORTHWEST CORNER OF THE AREA IN ADVANCE OF A FRONTAL SYSTEM. GULF OF PAPAGAYO...NE 20 KT WINDS WILL CONTINUE TO PULSE UP AND DOWN DOWNWIND OF THE GULF OF PAPAGAYO THROUGH THE NEXT 48 HOURS IN THE LATE NIGHT AND EARLY MORNING HOURS DURING PEAK DRAINAGE FLOW OFF CENTRAL AMERICA. THESE OCCURRENCES SHOULD NOT LAST LONG ENOUGH TO BE INCLUDED IN THE HIGH SEAS FORECAST. $$ AGUIRRE