000 AXPZ20 KNHC 121551 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC SUN JAN 12 2014 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1545 UTC. ...SPECIAL FEATURE... GULF OF TEHUANTEPEC...A NORTHERLY DRAINAGE SURGE OF 20-30 KT OCCURRED EARLY THIS MORNING CONFIRMED BY A SCATTEROMETER PASS AND A SHIP THAT REPORTED 9 FT SEAS DOWNSTREAM OF THE GULF WATERS. THE WINDS ARE CURRENTLY DIMINISHING AND SHOULD BE AT 10- 15 KT BY SUNSET TODAY...WITH THE DIURNAL MAXIMUM DRAINAGE EXPECTED TO MAX AT ONLY 15 KT LATE TONIGHT. A COLD FRONT WILL PASS THROUGH THE SOUTHERN GULF OF MEXICO TONIGHT INTO MON... WITH THE POST-FRONTAL GRADIENT SENDING A 20-25 KT SURGE THROUGH THE CHEVILA PASS AROUND MIDNIGHT ON MON NIGHT...INCREASING TO MINIMAL GALE BY SUNRISE TUE. THE NORTHERLY FLOW WILL INCREASE TO AT LEAST STRONG GALE WINDS...IF NOT MINIMAL STORM CONDITIONS... BY LATE WED. THIS GALE EVENT SHOULD PERSIST THROUGH MIDDAY ON THU BEFORE DIMINISHING BELOW GALE FORCE THU NIGHT INTO FRI. GUIDANCE IS HINTING AT ANOTHER MINIMAL GALE AGAIN FRI NIGHT INTO SAT. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS WSW FROM THE COAST OF COLOMBIA AT 06N78W TO 05.5N94W WHERE SCATTEROMETER WINDS INDICATE A TRANSITION TO AN ITCZ. THE ITCZ CONTINUES WNW THROUGH 07N120W TO BEYOND 07N140W. ISOLATED MODERATE CONVECTION IS NOTED WITHIN 240 NM S OF THE MONSOON TROUGH TO THE E OF 92W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS OBSERVED N OF THE ITCZ WITHIN 75 NM OF 07N101W AND WITHIN 120 NM EITHER SIDE OF A LINE FROM 11N120W TO 07N129W...WITH A CLUSTER NOTED N OF THE ITCZ WITHIN 90 NM OF 11N116W. ...DISCUSSION... ALOFT...AN UPPER CYCLONE IS CENTERED OVER THE W COAST OF OLD MEXICO AT 25N108W WITH AN UPPER TROUGH EXTENDING SW TO A BASE OVER THE DEEP TROPICAL PACIFIC AT 06N116W. AN UPPER SHORTWAVE RIDGE IS OVER THE WESTERN PORTION OF DISCUSSION AREA WITH THE RIDGE AXIS EXTENDING ROUGHLY FROM 07N140W TO 32N120W. UPPER MOISTURE IS NOTED TO THE N OF 23N WITHIN 480 NM EITHER SIDE OF THIS UPPER RIDGE AXIS. AN UPPER TROUGH IS SWINGING SE INTO THE NORTHERN PORTION FROM SE NEVADA AT 35N114W TO 32N130W TO 32N145W...AND IS ERODING THE NORTHERN PORTION OF THE UPPER RIDGE NEAR 32N130W. UPPER SOUTHWESTERLY FLOW AHEAD OF THE TROUGH IS TAPPING THE MOISTURE ALONG THE NORTHERN PORTION OF THIS UPPER RIDGE...RESULTING IN A VERY DENSE 240 NM WIDE PLUME ADVECTED NE ACROSS SOUTHERN CALIFORNIA...THE NORTHERN BAJA CALIFORNIA PENINSULA AND THE NORTHERN GULF OF CALIFORNIA...WITH THE PLUME CONTINUING NE ACROSS NEVADA AND NEW MEXICO. UPPER MOISTURE IS OBSERVED OVER THE E SEMICIRCLE OF THE CYCLONE AT 25N108W...AND IS SPREADING NE ACROSS NE OLD MEXICO AND SW TEXAS ATTM. WEAK UPPER DIFFLUENCE IS INDUCED OVER THE DEEP TROPICS TO THE E OF THE UPPER RIDGE AND W OF THE SOUTHERN EXTENSION OF THE UPPER TROUGH. THIS AREA OF UPPER DIFFLUENCE IS IN PHASE WITH THE LOWER LEVEL ITCZ AND IS ENHANCING THE PREVIOUSLY MENTIONED CONVECTION ALONG AND THE N OF THE ITCZ. THE DEBRIS MOISTURE IS ADVECTED E TROUGH THE BASE OF THE UPPER TROUGH...THEN TURNS NE CONCENTRATING INTO 240 NM WIDE TROPICAL PLUME THAT CONTINUES NE ACROSS CENTRAL OLD MEXICO...THEN TURNS NE ACROSS THE W-CENTRAL GULF MEXICO AND FINALLY EVAPORATES OVER THE EASTERN GULF OF MEXICO NEAR 28N84W. AN LARGE UPPER ANTICYCLONE IS OBSERVED OVER HAITI IN N-CENTRAL CARIBBEAN WITH ITS ANTICYCLONIC ENVELOPE DOMINATING THE DISCUSSION AREA E OF 100W...AND SUPPRESSING CONVECTION ALONG THE MONSOON TROUGH AND ITCZ EXCEPT AS PREVIOUSLY NOTED. THE UPPER CYCLONE OVER THE SOUTHERN TIP OF THE BAJA PENINSULA WILL LIFT NE LATER TODAY AND LOSE IDENTITY IN A DEEP LAYERED TROUGH THAT WILL SHIFT EASTWARD ACROSS EASTERN N AMERICA OVER THE NEXT COUPLE OF DAYS. THE UPPER SHORTWAVE RIDGE CURRENTLY OVER THE WESTERN PORTION OF THE DISCUSSION AREA WILL AMPLIFY NE INTO A LONGWAVE RIDGE THAT WILL ANCHOR OVER THE EASTERN N PACIFIC IN THE WAKE OF THE AMPLIFYING LONGWAVE TROUGH SETTING UP OVER N AMERICA. THE CARIBBEAN ANTICYCLONE WILL REMAIN EMBEDDED IN A BROAD ANTICYCLONE THAT WILL CONTINUE TO DOMINATE THE EASTERN PORTION OF THE DISCUSSION AREA. AT LOWER LEVELS...A RIDGE EXTENDS FROM 32N130W TO 15N107W. A 1013 MB SURFACE LOW IS OVER SW ARIZONA WITH A WEAK COLD FRONT OR TROUGH EXTENDING W TO NEAR 31N130W. THIS WEAK FRONT WILL SWING SE ACROSS THE NORTHERN BAJA CALIFORNIA PENINSULA TODAY AND ACROSS THE NORTHERN GULF OF CALIFORNIA EARLY TONIGHT. ALTHOUGH ANTICYCLONIC LOW LEVEL WINDS ARE CURRENTLY ONLY 15-20 KT AROUND THE SURFACE RIDGE ACROSS THE PACIFIC WATERS TO THE W OF 115W...A NORTHERLY SURGE WILL SPREAD S ACROSS THE NORTHERN WATERS BEHIND THE WEAK COLD FRONT TONIGHT WITH N-NE-E WINDS INCREASING TO 20- 25 KT/SEAS 10-16 FT ACROSS THE AREA N OF 24N W OF 120W. THE GRADIENT WILL QUICKLY WEAKEN ON MON WITH WINDS DIMINISHING TO 15- 20 KT AND SEAS GRADUALLY SUBSIDING TO 7-9 FT BY MIDDAY TUE. GULF OF CALIFORNIA...LIGHT AND VARIABLE 5-10 KT WINDS ACROSS THE ENTIRE GULF WILL SHIFT TO NW TONIGHT OVER THE NORTHERN WATERS BEHIND A WEAK COLD FRONT OR TROUGH THAT WILL QUICKLY PASS THROUGH. STRENGTHENING POST-FRONTAL HIGH PRESSURE WILL INCREASE THE NW FLOW TO 20-25 KT ACROSS THE GULF WATERS N OF 29N LATE TONIGHT...WITH THESE CONDITIONS SPREADING SE ACROSS THE ENTIRE GULF BY LATE MON. LITTLE CHANGE EXPECTED THROUGH LATE TUE NIGHT AS SEAS BUILD TO 9 FT IN LONG NW-SE FETCH ACROSS THE CENTRAL WATERS. THE GRADIENT WILL RELAX WED SUPPORTING 10-15 KT AGAIN BY EARLY THU. GULF OF PAPAGAYO...FRESH EASTERLY TRADES ACROSS THE WESTERN CARIBBEAN ARE SPILLING ACROSS CENTRAL AMERICA MAINTAINING LATE NIGHT NE-E SURGES OF 20-25 KT THROUGH...AND DOWNSTREAM OF THE GULF OF PAPAGAYO. LITTLE CHANGE EXPECTED THROUGH LATE FRI NIGHT. $$ NELSON