000 AXPZ20 KNHC 251612 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC WED NOV 25 2015 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 FEATURES... HURRICANE SANDRA WAS CENTERED NEAR 12.6N 109.5W...OR ABOUT 560 MILES SW OF MANZANILLO MEXICO AND ABOUT 710 MILES S OF THE SOUTHERN TIP OF THE BAJA CALIFORNIA PENINSULA...AT 1500 UTC. SANDRA IS MOVING W-NW OR 295 DEGREES AT 9 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE WAS 975 MB. MAXIMUM SUSTAINED WINDS HAVE INCREASED TO 85 KT WITH GUSTS TO 105 KT WITH ADDITIONAL STRENGTHENING TO A MAJOR HURRICANE FORECAST DURING THE NEXT 24 HOURS. CURRENTLY NUMEROUS STRONG CONVECTION IS OBSERVED WITHIN 180 NM N AND 150 NM S SEMICIRCLES OF CENTER. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED IN A BAND E AND SE OF CENTER WITHIN 90 NM EITHER SIDE OF A LINE FROM 07N102W TO 15N105W. SIMILAR CONVECTION IS OBSERVED NE OF THE CENTER WITHIN 120 NM EITHER SIDE OF A LINE FROM 15N100W TO 19N106W. SANDRA IS FORECAST TO TURN TOWARD THE NW LATER TODAY...WITH A TURN TOWARD THE N EXPECTED ON THU. INTERESTS IN THE SOUTHERN PORTIONS OF THE BAJA PENINSULA SHOULD MONITOR THE PROGRESS OF SANDRA AS WATCHES AND WARNINGS MAY BE REQUIRED LATER TODAY. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP2/WTPZ22 KNHC FOR MORE DETAILS. GULF OF TEHUANTEPEC GALE WARNING...MINIMAL GALE FORCE NORTHERLY WINDS AT SUNRISE THIS MORNING ARE EXPECTED TO DIMINISH TO A MAXIMUM OF 30 KT THIS AFTERNOON. THE MAXIMUM NOCTURNAL DRAINAGE TONIGHT IS FORECAST TO INCREASE TO MINIMAL GALE CONDITIONS LATE TONIGHT AND CONTINUE THROUGH SUNRISE ON THU. ALTHOUGH THE PRESSURE GRADIENT WILL GRADUALLY WEAKEN ACROSS SOUTHERN MEXICO OVER THE NEXT SEVERAL DAYS...THE MAXIMUM DRAINAGE FLOW SHOULD REACH NEAR GALE FORCE ON THU...FRI AND SAT NIGHTS. ...TROPICAL LOWS... A 1008 MB LOW PRESSURE IS EMBEDDED IN THE MONSOON TROUGH NEAR 07N95W WITH ISOLATED MODERATE TO STRONG CONVECTION NOTED WITHIN 120 NM OVER THE N SEMICIRCLE. THIS LOW WILL MOVE SLOWLY W ALONG THE MONSOON TROUGH OVER THE NEXT FEW DAYS. A 1009 MB LOW IS ANALYZED AT 21N125W AND IS THE REMNANTS OF TROPICAL CYCLONE RICK. BROKEN TO LOCALLY OVERCAST STRATOCUMULUS CLOUDS SURROUND THE CENTER. THE LOW IS FORECAST TO OPEN UP TO A TROUGH BY TONIGHT. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A 1008 MB SURFACE LOW IS MEANDERING ALONG THE CARIBBEAN COAST OF COLOMBIA AT 09N77W. THE MONSOON TROUGH EXTENDS SW FROM THIS LOW INTO THE EPAC NEAR 06N81W...THEN TURNS WESTWARD THROUGH THE PREVIOUSLY MENTIONED EMBEDDED SURFACE LOW AT 07N95W AND CONTINUES W TO 09N100W WHERE IT LOSES IDENTITY IN THE BROAD CYCLONIC CIRCULATION ASSOCIATED WITH TROPICAL CYCLONE SANDRA. THE MONSOON TROUGH RESUMES SW OF SANDRA AT 08N112W AND CONTINUES SW TO 05N118W WHERE SCATTEROMETER WINDS INDICATE A TRANSITION TO AN ITCZ. THE ITCZ THEN CONTINUES W TO 04N135W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 90 NM EITHER SIDE OF A LINE FROM 06N79W TO 04N85W. ...DISCUSSION... A COLD FRONT ENTERS THE DISCUSSION AREA AT 32N117W AND EXTENDS SW TO 29N130W...THEN TURNS NW TO BEYOND 32N140W. NORTHERLY WINDS AT 15-20 KT ACCOMPANY THE FRONT TO THE S OF 32N...WITH LONG PERIOD NW SWELL MIXING WITH LONG PERIOD SE SWELL...RESULTING IN COMBINED SEAS TO 7-9 FT TO THE N OF THE FRONT. ALTHOUGH THE FRONT IS EXPECTED TO CONTINUE S AND WASH OUT BY LATE THU...THE GRADIENT WILL TIGHTEN INCREASING THE NE FLOW TO 20-25 KT ACROSS THE WATERS FROM 19-23N BETWEEN 122-132W. BY THEN THE LONG PERIOD NW SWELL WILL PROPAGATE S ACROSS THE DISCUSSION WATERS N OF 18N W OF 118W BY LATE THU WITH SEAS OF 8-11 FT. THE NW SWELL WILL MIX WITH THE BROAD MIX OF SWELL ASSOCIATED WITH TROPICAL CYCLONE SANDRA ON THU NIGHT ACROSS THE WATERS FROM ABOUT 13-27N BETWEEN 112-120W. GAP WINDS... GULF OF PAPAGAYO...A TIGHT PRESSURE GRADIENT WILL CONTINUE TO SUPPORT PULSES OF NE-E 20-25 KT WINDS TONIGHT AND AGAIN ON THU NIGHT WITH SEAS BUILDING TO 7 FT DOWNSTREAM OF THE GULF OF PAPAGAYO TO NEAR 09N90W. GUIDANCE SUGGESTS STRONG NE WINDS WILL RESUME ON SAT NIGHT. $$ NELSON