000 AXPZ20 KNHC 280334 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC MON NOV 28 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... THE MONSOON TROUGH EXTENDS SW FROM COSTA RICA AT 10N83W TO THE E PACIFIC AT 06N92W...THEN TURNS W-NW THROUGH A CYCLONIC SWIRL NEAR 09N103W ANALYZED AS A 1010 MB SURFACE LOW. THE MONSOON TROUGH THEN CONTINUES W TO NEAR 09N110W WHERE LOW LEVEL WINDS SUGGEST A TRANSITION TO AN ITCZ. THE ITCZ CONTINUES W THROUGH AN EMBEDDED 1009 MB SURFACE LOW PRESSURE AT 10N123W...THEN TURNS W TO BEYOND 09N140W. ISOLATED MODERATE TO OCCASIONALLY STRONG CONVECTION...VERIFIED BY LIGHTNING DATA...IS FLARING OVER AND ALONG PACIFIC COAST OF PANAMA. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 15 NM OF 09N102W AND WITHIN 30 NM OF EITHER SIDE OF A LINE FROM 08N113W TO 10N121W. ISOLATED MODERATE CONVECTION IS NOTED WITHIN 30 NM OF 06.5N130W. THE REMNANT TROUGH OF KENNETH IS ALONG 140W FROM 10N TO 16N... AND IS EXPECTED TO MOVE W OF 140W TONIGHT. LOW PRES AT 10N123W...NE TO E WINDS AT 20 KT AND SEAS 8 TO 12 FT ARE NOTED WITHIN 300 NM NW SEMICIRCLE OF CENTER. THE LOW IS EXPECTED TO DRIFT W OVER THE NEXT 24 HOURS WEAKENING TO NE TO SW ORIENTATED TROUGH FROM 12N121W TO 09N126W WITH THE PRESSURE GRADIENT SUPPORTING SW WINDS AT 15 TO 20 KT WITHIN 180 NM SE OF THE TROUGH. THE NEWLY FORMED SURFACE LOW EMBEDDED WITHIN THE MONSOON TROUGH AT 09N103W IS ACCOMPANIED BY 15 KT WINDS AND A FEW THUNDERSTORMS. ...DISCUSSION... A LONG WAVE UPPER TROUGH DISSECTS N AMERICA WITH ITS MEAN AXIS EXTENDING SW INTO THE DISCUSSION AREA OVER TEXAS AT 32N96W...SW ACROSS CENTRAL OLD MEXICO...THROUGH EMBEDDED UPPER CYCLONES OVER THE PACIFIC AT 20N112W AND 17N118W...THEN CONTINUING S OVER THE PACIFIC TO A BASE AT 10N119W. THE ASSOCIATED SURFACE COLD FRONT IS OVER THE EASTERN GULF OF MEXICO EXTENDING ACROSS GUATEMALA. POST FRONTAL STRONG COLD AIR ADVECTION IS SURGING THROUGH THE ISTHMUS OF TEHUANTEPEC RESULTING IN THE STORM FORCE WINDS IN AND DOWNSTREAM OF THE GULF OF TEHUANTEPEC...FURTHER DISCUSSED BELOW. AN UPPER ANTICYCLONE IS QUASI STATIONARY OVER THE DEEP TROPICS AT 12N136W WITH A LONGWAVE RIDGE EXTENDING NE AND COLLAPSING EASTWARD ACROSS WESTERN N AMERICA. UPPER MOISTURE FROM FORMER ITCZ CONVECTION BETWEEN 139W AND 164W...AND FROM OTHER CONVECTION FURTHER W OVER THE CENTRAL TROPICAL PACIFIC...IS ALL ADVECTED NE ALONG THE NW PERIPHERY OF THIS LARGE RIDGE... SPILLING OVER THE RIDGE ACROSS CENTRAL N AMERICA INTO THE LONGWAVE TROUGH AXIS PREVIOUSLY MENTIONED. AS THE RIDGE COLLAPSES SE...A STRONG UPPER TROUGH...CURRENTLY ALONG 32N140W TO 25N145W...WILL CONTINUE E TO OVER THE NW PORTION OF CONUS WITH ITS SOUTHERN EXTENT JUST REACHING THE NW PORTION OF THE DISCUSSION AREA AND STALLING NEAR 32N140W. THE ASSOCIATED SURFACE FRONT HAS STALLED FROM 32N134W TO 26N141W...AND IS EXPECTED TO RETRACT W AS THE UPPER RIDGE AMPLIFIES N AGAIN CUTTING OFF AN UPPER CYCLONE NEAR 29N140W MON NIGHT INTO TUE. AN UPPER CYCLONE IS NOTED NEAR 06N112W. AN UPPER ANTICYCLONE IS NEAR 07N85W WITH A RIDGE EXTENDING SW TO A SHARP CREST JUST E OF THE CYCLONE...NEAR 04N109W. DEBRIS MOISTURE ASSOCIATED WITH THE ITCZ CONVECTION BETWEEN 114W AND 121W...FANS OUT BOTH N AND S OF THE ITCZ. SOME OF THE MOISTURE...IN THE FORM OF THIN BROKEN CIRRUS...CONTINUES ACROSS CENTRAL OLD MEXICO ALONG 20N. THE DEBRIS MOISTURE ASSOCIATED WITH THE MONSOON TROUGH CONVECTION JUST TO THE S OF PANAMA ALSO EVAPORATES AS THE UPPER LEVELS ARE VERY DRY S OF 22N E OF 132W. GULF OF CALIFORNIA...N TO NE WINDS AT 15 TO 20 KT WILL DIMINISH BELOW 20 KT ON MON. GULF OF TEHUANTEPEC...NORTHERLY WINDS AT STRONG GALE FORCE ARE REPORTED AT THE LAND STATIONS IN THE ISTHMUS OF TEHUANTEPEC AREA...AND OVER THE SW GULF OF MEXICO...AND ARE SURGING THROUGH THE CHIVELA PASS AT MINIMAL STORM FORCE. EXPECT STORM FORCE WINDS TO CONTINUE THROUGH MIDDAY MON...THEN DIMINISH TO STRONG GALE FORCE THROUGH TUE MORNING. BEST GUESS FOR NOW IS MINIMAL GALE CONDITIONS WILL CONTINUE THROUGH SUNRISE THU IN DRAINAGE FLOW...THEN QUICKLY DIMINISH AS LOW LEVEL WINDS FINALLY VEER TO THE SE IN THE BAY OF CAMPECHE. $$ NELSON