000 AXPZ20 KNHC 272217 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC FRI NOV 27 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2130 UTC. ...SPECIAL FEATURES... HURRICANE SANDRA IS CENTERED NEAR 20.4N 108.4W AT 2100 UTC...OR ABOUT 125 NM SW OF LAS ISLAS TRES MARIAS MEXICO...MOVING N-NE OR 020 DEG AT 9 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 978 MB. MAXIMUM SUSTAINED WIND SPEED IS 70 KT WITH GUSTS TO 85 KT. STRONG SOUTHWESTERLY UPPER LEVEL WIND SHEAR CONTINUES TO IMPACT SANDRA...AND IS BEGINNING TO DISPLACE THE ASSOCIATED THUNDERSTORMS TO THE NE OF THE SURFACE CENTER. SCATTERED TO NUMEROUS MODERATE TO STRONG CONVECTION IS OCCURRING WITHIN 270 NM ACROSS THE NE SEMICIRCLE AND 240 NM ACROSS THE S QUADRANT. SANDRA IS EXPECTED TO CONTINUE TO WEAKEN AND BECOME A TROPICAL STORM TONIGHT AS IT VEERS MORE NORTHEASTERLY AND ACCELERATES...AND WILL MOVE ASHORE ALONG THE COAST OF SINALOA MEXICO SATURDAY AFTERNOON. DETERIORATING MARINE CONDITIONS SHOULD BE EXPECTED ACROSS THE SOUTH HALF OF THE GULF OF CALIFORNIA TONIGHT AND SATURDAY. BANDS AND CLUSTERS OF SHOWERS AND THUNDERSTORMS WILL ALSO IMPACT THE MEXICAN COASTAL STATES FROM MICHOACAN TO SINALOA THROUGH LATE SATURDAY...PRODUCING THE POTENTIAL FOR FLASH FLOODING AND LANDSLIDES. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPEP2/WTPZ32 KNHC AND THE FULL FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP2/WTPZ22 NHC FOR MORE DETAILS. GULF OF TEHUANTEPEC...STRONG HIGH PRESSURE ACROSS THE EASTERN SEABOARD OF THE U.S. WILL SHIFT SLIGHTLY SW THROUGH SATURDAY AND FORCE THE STRONG E-NE WIND FLOW CURRENTLY ACROSS THE SOUTHEAST GULF OF MEXICO AND NW CARIBBEAN TO BECOME MORE NORTHEASTERLY TONIGHT AND SATURDAY. THIS WILL ALLOW THE GAP WIND FLOW ACROSS CENTRAL AMERICA TO INCREASE ACROSS THE EASTERN PACIFIC COASTALZONES OF CENTRAL AMERICA TONIGHT THROUGH THE WEEKEND. NORTHERLY WINDS OF 20-25 KT ACROSS THE GULF OF TEHUANTEPEC LATETHIS AFTERNOON ARE EXPECTED TO STRENGTHEN THIS EVENING AND TONIGHT AND INCREASE TO MINIMAL GALE FORCE DURING THE LATE NIGHTAND EARLY MORNING HOURS...AND SLOWLY DIMINISH TO AROUND 30 KT BY LATE SATURDAY MORNING...BEFORE INCREASING TO GALE FORCE AGAIN SATURDAY NIGHT THROUGH SUNDAY MORNING. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM 06N77W TO 06N79W TO 08N85W TO07N94W...THEN RESUMES NEAR 15N112W TO 07N122W. THE ITCZ THEN EXTENDS FROM 07N122W TO 05N126W TO 04N140W. ISOLATED TO SCATTERED MODERATE CONVECTION NOTED FROM 02N TO 07N E OF 92W... AND FROM 06N TO 10N BETWEEN 123W AND 125W. ...DISCUSSION... A COLD FRONTAL BOUNDARY THAT MOVED THROUGH BAJA CALIFORNIA ANDMOST OF THE EASTERN WATERS THE PAST FEW DAYS HAS MERGED ACROSS CENTRAL PORTIONS ALONG ABOUT 19N WITH THE REMNANTS OFFORMER TROPICAL CYCLONE RICK. A STRONG PRESSURE GRADIENT BETWEEN HIGH PRESSURE TO THE NORTH AND THIS MERGED FEATURES IS SUPPORTING A BROAD BAND OF FRESH TO STRONG NE WINDS FROM GENERALLY 19N TO 25N BETWEEN 121W AND 131W AND FROM 15N TO 25N W OF 131W...WITH COMBINED SEAS OF 8 TO 14 FT PREVAILING IN MIXED NW SWELL AND NE WIND WAVES. ELSEWHERE THIS LONG PERIOD NW SWELL IS MIXING WITH NE WIND WAVES AND SE SWELL FROM SANDRA... RESULTING IN COMBINED SEAS OF 8 TO 11 FT GENERALLY FROM 14N TO 26N BETWEEN 112W AND 125W. THE AREA OF FRESH TO STRONG TRADES IS EXPECTED TO SHIFT WEST-SOUTHWESTWARD AS RIDGING BUILDS SOUTHEASTWARD ACROSS THE NORTHERN FORECAST WATERS THROUGH SUN. BY SUN AS THE AREA OF TRADES WEAKENS AND SHRINKS IN AREAL COVERAGE...WHILE 8 TO 11 FT COMBINED SEAS ARE FORECAST TO PREVAIL W OF LINE FROM 06N125W TO 18N116W TO 25N133W TO 30N133W. GAP WINDS... AS MENTIONED ABOVE...THE GAP WIND FLOW ACROSS CENTRAL AMERICA AND INTO THE EASTERN PACIFIC IS EXPECTED TO INCREASE MODESTLY TONIGHT THROUGH THE WEEKEND AS HIGH PRESSURE BUILDS ACROSS THE GULF OF MEXICO AND THE NW CARIBBEAN...AND WINDS THERE TURN MORE NORTHEASTERLY. THIS NORTHEAST DIRECTION WILL AID IN PRODUCING STRONGER WINDS BLOWING ACROSS AND DOWNSTREAM OF THE GULF OF PAPAGAYO FOR THE NEXT FEW DAYS...AND WILL ALSO RESULT IN NORTHERLY WINDS AROUND 20 KT SPILLING ACROSS PANAMA AND THE GULF OF PANAMA TONIGHT THROUGH THE WEEKEND. LOOK FOR OTHER GAP WIND PRONE AREAS SUCH AS THE GULF OF FONSECA TO ALSO REACH NEAR 20 KT EACH NIGHT AND EARLY MORNING. $$ STRIPLING