000 AXPZ20 KNHC 150351 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC THU JAN 15 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0300 UTC. ...SPECIAL FEATURES... GULF OF TEHUANTEPEC GALE WARNING...NORTHERLY WIND FLOW BETWEEN A STALLED FRONTAL BOUNDARY THAT RUNS NORTH TO SOUTH ACROSS THE BAY OF CAMPECHE...AND RIDGING EXTENDING NORTH TO SOUTH ALONG THE NORTHEASTERN MEXICAN COAST...CONTINUES TO FUNNEL THROUGH THE ISTHMUS OF TEHUANTEPEC AND ACROSS THE GULF OF TEHUANTEPEC. THIS PATTERN IS MAINTAINING STRONG NORTHERLY WINDS W OF THE FRONT IN THE GULF OF MEXICO THAT SPILL THROUGH THE CHIVELA PASS AND ACCELERATE TO 25-35 KT ACROSS THE GULF OF TEHUANTEPEC AND EXTEND SOME 100-150 NM DOWNSTREAM. THIS RIDGE WILL WEAKEN SLIGHTLY OVER THE NEXT 24 HOURS...AND GALE FORCE WINDS ARE EXPECTED TO DIMINISH TO 20-30 KT BY SUNRISE THU MORNING. HOWEVER...GLOBAL MODELS SHOW THE RIDGE STRENGTHENING AGAIN ACROSS W TEXAS AND SOUTHWARD ACROSS EASTERN MEXICO...WHICH SHOULD INCREASE WINDS ACROSS TEHUANTEPEC TO GALE FORCE AGAIN THU EVENING...THEN INCREASE FURTHER TO 30-40 KT OVERNIGHT THU THROUGH FRI NIGHT. SEAS WILL FLUCTUATE AT 8 TO 11 FT ACROSS THE GULF OF TEHUANTEPEC THROUGH THU THEN INCREASE TO 9-15 FT THU NIGHT THROUGH FRI. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM 06N75W TO 07N84W TO 03.5N95W... WHERE IT TRANSITIONS TO ITCZ...THEN CONTINUES ON TO 09N124W TO 08.5N140W. SCATTERED MODERATE TO STRONG CONVECTION NOTED WITHIN 90 NM S OF TROUGH BETWEEN 86W AND 91W. NUMEROUS MODERATE TO STRONG CONVECTION NOTED WITHIN 240 NM E OF TROUGH FROM 07N11W TO 13.5N112W. NUMEROUS MODERATE TO STRONG CONVECTION NOTED WITHIN 240 NM E OF TROUGH FROM 11N122W TO 15N125W. ...DISCUSSION... A SOMEWHAT COMPLEX MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM 08N120W TO BEYOND THE N BOUNDARIES OF THE DISCUSSION AREA NEAR 30N125W...WITH A 55-65 KT JETSTREAM PASSING THROUGH THE BASE. BROAD UPPER RIDGES OCCURRING ON BOTH SIDES OF THIS TROUGH ARE ALLOWING FOR ONLY A SLOW EASTWARD SHIFT OF THE TROUGH. SHARP TURNING WITHIN THE BASE OF THE TROUGH S OF 20N CONTINUES TO WORK DOWNWARD THROUGH THE ATMOSPHERE AND NEARLY TO THE SURFACE... WHERE A SURFACE TROUGH WAS FROM 11N122W TO 15N125W...AND A SECOND TROUGH WAS LOCATED FROM 07N11W TO 13.5N112W. VERY ACTIVE CONVECTION CONTINUES ACROSS THIS REGION...WITH NUMEROUS MODERATE TO STRONG CONVECTION OCCURRING WITHIN 240 NM E OF BOTH SURFACE TROUGHS. THE MIDDLE TO UPPER TROUGH IS FORECAST TO SHIFT SLOWLY EASTWARD THROUGH FRI NIGHT...AND REORGANIZE...WITH A CUT OFF LOW DEVELOPING NEAR 13N119W BY SAT EVENING...AND A SURFACE LOW IS EXPECTED TO DEVELOP JUST TO THE W OF THE UPPER LOW. AMPLE MIDDLE TO UPPER LEVEL ENERGY IS EXPECTED TO PERSIST ABOUT THE BASE OF THIS TROUGH...AND INTERACT WITH ABUNDANT LOW LEVEL MOISTURE TO MAINTAIN VERY ACTIVE CONVECTION EAST THROUGH SOUTHEAST OF THE UPPER TROUGH DURING THE NEXT FEW DAYS. THE SUBTROPICAL RIDGE EXTENDS FROM 1023 MB HIGH PRESSURE NEAR 33N124W THROUGH 25N120W TO 17N108W. THE PRESSURE GRADIENT HAS WEAKENED A BIT BETWEEN THE SUBTROPICAL RIDGE AND THE TWO TROUGHS MENTIONED ABOVE...BUT REMAINS SUFFICIENT FOR STRONG NE TRADES TO PERSIST THIS EVENING FROM 08N TO 14.5N BETWEEN 111W AND 118W...WHERE SEAS WERE 8 TO 10 FT. THE HIGH WILL SHIFT SLIGHTLY SW OVER THE NEXT FEW DAYS AS THE SURFACE LOW DEVELOPS...AND WILL CREATE A BROAD ZONE OF FRESH TO STRONG TRADES FROM 15N TO 20N BETWEEN THE LOW AND 130W THROUGH SAT. A DISSIPATING COLD FRONT PASSES THROUGH 30N132W TO 25N140W... ACROSS THE NORTHWESTERN PORTION OF THE FORECAST AREA...AND WILL BECOME DIFFUSE OVERNIGHT. WINDS HAVE DIMINISHED TO 15 KT OR LESS ON BOTH SIDES OF THE FRONT...WITH NWLY SWELL DOMINATED NW PORTIONS OF THE AREA TONIGHT...WHERE SEAS WERE 8-11 FT. THE NW SWELL WILL CONTINUE TO SEND SEAS OF 8 FT OR GREATER SOUTHEASTWARD INTO THE FORECAST AREA. GAP WINDS... GULF OF PAPAGAYO...FRESH TO STRONG TRADEWINDS ACROSS THE WEST AND SOUTHWESTERN CARIBBEAN SEA CONTINUE TO FUNNEL THROUGH NORTHERN COSTA RICA AND ACROSS THE GULF OF PAPAGAYO. FRESH TO STRONG EAST-TO-NORTHEAST WINDS OCCURRING EARLIER TODAY HAVE DIMINISHED TO 15-20 KT THIS EVENING...BUT WILL INCREASE AGAIN OVERNIGHT THROUGH THU MORNING TO 15-25 KT DURING THE PERIOD OF MAXIMUM NOCTURNAL DRAINAGE FLOW. WINDS AND SEAS WILL BRIEFLY DIMINISH AGAIN THU DURING THE AFTERNOON AND EARLY EVENING HOURS. GULF OF CALIFORNIA...AN UPPER LOW OVER ARIZONA MOVING SLOWLY SE TODAY WILL BECOME SHEARED AND FORCED EASTWARD INTO TEXAS ON THURSDAY. AT THE SURFACE...THE PRESSURE GRADIENT WILL BUILD BETWEEN LEE SIDE TROUGHING ALONG THE W SLOPES OF THE SIERRA MADRE OCCIDENTAL AND INCREASED RIDGING OVER THE GREAT BASIN IN THE WAKE OF THE SYSTEM THU. SCATTEROMETER DATA EARLY TODAY SHOWED NW TO N WINDS 15-20 KT OCCURRING ACROSS THE NORTHERN GULF OF CALIFORNIA...AND EXPECT OCCASIONAL INCREASES IN WINDS N OF 28N MAY TO OCCUR DURING THE NEXT DAY OR SO. $$ STRIPLING