000 AXPZ20 KNHC 141610 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC THU MAR 13 2013 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 1515 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH AXIS EXTENDS FROM 08.5N84W TO 00N96W...WHERE IT TRANSITIONS TO ITCZ AXIS...CONTINUING TO 00N110W TO 03.5N122W TO 01.5N140W. SCATTERED MODERATE TO STRONG CONVECTION NOTED WITHIN 150 NM S OF TROUGH E OF 96W. SCATTERED MODERATE TO STRONG CONVECTION NOTED WITHIN 150 NM N OF ITCZ BETWEEN 96W AND 125W. ...DISCUSSION... GULF OF TEHUANTEPEC...STRENGTHENING HIGH PRESSURE IS SINKING SLOWLY S TOWARDS THE N GULF OF MEXICO COASTS...BEHIND YET ANOTHER COLD FRONT ACROSS THE NW CARIBBEAN THIS MORNING. THE INDUCED PRESSURE GRADIENT AND SURGE OF COOL AIR HAS STRENGTHENED OVERNIGHT...THROUGH THE CHIVELA PASS INTO AND DOWNSTREAM OF THE GULF OF TEHUANTEPEC...REACHING MINIMAL STORM FORCE...WITH MAXIMUM SEAS OF 19 FT NEAR 14N95.5W. THE GRADIENT WILL BEGIN TO RELAX LATER THIS MORNING...ALLOWING WINDS TO RELAX TO STRONG GALE STRENGTH...AROUND 40 KT BY EARLY AFTERNOON. THE GRADIENT WILL CONTINUE TO RELAX VERY SLOWLY TONIGHT AND FRI. HOWEVER NOCTURNAL DRAINAGE FLOW WILL ENHANCE THESE GALES TO PEAK NEAR 45 KT EARLY FRI THROUGH SUNRISE...BEFORE FALLING QUICKLY BELOW GALE FORCE SHORTLY AFTER SUNRISE. THIS PROLONGED STRONG GAP WIND EVENT WILL SPREAD A BROAD AREA OF N TO NE SWELLS DOWNWIND OF TEHUANTEPEC BETWEEN 92W AND 104W BY SAT...WITH SEAS TO 8 FT REACHING ALONG THE EQUATOR NEAR 101W FRIDAY EVENING. EXPECT WINDS TO DROP OFF TO LIGHT AND VARIABLE ON SAT NIGHT ACROSS THE GULF OF TEHUANTEPEC...WITH FAVORABLE CROSSING CONDITIONS PERSISTING THROUGH AT LEAST TUE. GULFS OF PAPAGAYO AND FONSECA...NE WINDS ARE PULSING AT 20 TO 25 KT WITH A SMALL AREA OF 30 KT WINDS IN AND JUST DOWNSTREAM OF THE GULF OF PAPAGAYO TO AS FAR W AS 08.5N90W. LITTLE CHANGE EXPECTED THROUGH LATE MORNING ON SAT...THEN THE GRADIENT WILL SUPPORT NE PULSES AT 15 TO 20 KT THROUGH THROUGH MON. N WINDS SHOULD INCREASE TO 15 TO 20 KT ACROSS THE GULF OF FONSECA THIS EVENING AND PERSIST THROUGH MIDDAY SAT. GULF OF PANAMA...NORTHERLY WINDS AT 10 TO 20 KT WILL PERSIST THROUGH AND DOWNWIND TO 05N THROUGH SAT EVENING...THEN FINALLY PULSE 20 TO 25 KT EARLY SUN. THEN GUIDANCE SUGGESTS PERSISTENT 10 TO 15 KT NORTHERLY WINDS THROUGH TUE. GULF OF CALIFORNIA...THE GRADIENT BETWEEN A PACIFIC RIDGE AND A TROUGH OVER MEANDERING N TO S ALONG THE SIERRA MADRE OCCIDENTALES...AND OCCASIONALLY OVER THE GULF OF CALIFORNIA... WILL SUPPORT NW WINDS AT 10 TO 15 KT ACROSS THE GULF OF CALIFORNIA TODAY INTO EARLY FRI MORNING. THE GRADIENT WILL RELAX ON FRI WITH LIGHT AND VARIABLE WINDS THEN EXPECTED THROUGH MON. A LONGWAVE TROUGH HAS SHIFTED E ACROSS EASTERN N AMERICA. A SHORTWAVE TROUGH NOW PROGRESSING E THROUGH THE SE CONUS APPEARS TO BE LEAVING A WEAK TROUGH EXTENDING W TO A CUT OFF CYCLONE OVER THE S BAJA CALIFORNIA PENINSULA...WITH A MIDDLE TO UPPER TROUGH EXTENDING SW FROM THERE TO A BASE OVER THE TROPICAL PACIFIC NEAR 08N116W. AN UPPER ANTICYCLONE HAS MOVED INTO THE DEEP TROPICS NEAR 06N140W WITH A LONGWAVE UPPER RIDGE AMPLIFYING NNE ACROSS THE CENTRAL PORTION OF THE DISCUSSION AREA... WITH THE RIDGE CONTINUING ACROSS WESTERN N AMERICA. UPPER MOISTURE CONTINUES TO SPILL E ACROSS THE RIDGE AXIS TO THE N OF 24N BETWEEN 120W AND 140W...AND WILL MOVE ACROSS SOUTHERN CALIFORNIA TODAY. OTHERWISE...VERY DRY UPPER AIR IS INDICATED W OF A LINE FROM 30N93W TO 00N130W. AN UPPER RIDGE EXTENDS NW ACROSS THE WESTERN CARIBBEAN FROM COLOMBIA TO A CREST ACROSS THE SE GULF OF MEXICO. UPSTREAM...A BROAD NEGATIVE TILT UPPER TROUGH EXTENDS FROM CUT OFF LOW OVER S BAJA CALIFORNIA SE TO A POSITION JUST S OF THE GALAPAGOS ISLANDS. CYCLONIC TURNING IN THE BASE OF THIS TROUGH AND THE SW EXTENSION DESCRIBED TO THE W ARE YIELDING LIFT AND UPPER DIFFLUENCE...AND AIDING DEEP CONVECTION ALONG AND N OF THE ITCZ BETWEEN 90W AND 115W. GLOBAL MODELS SHOW THE CUT OFF LOW OVER S BAJA TO STRENGTHEN SLIGHTLY OVER THE NEXT FEW DAYS AND DRIFT SSE WHICH WILL MAINTAIN FAVORABLE CONDITIONS FOR DEEP CONVECTION TO THE S AND SE THROUGH THE WEEKEND. A SURFACE RIDGE EXTENDS FROM A 1024 MB HIGH NEAR 31N131W TO 19N110W. THE ANCHORED RIDGE IS BLOCKING THE FORWARD ADVANCE OF AN APPROACHING COLD FRONT WHICH SHOULD BECOME STATIONARY NEAR 30N140W TODAY. THE GRADIENT SW OF THE RIDGE IS SUPPORTING NE TRADES AT 15 TO 20 KT ACROSS THE TROPICS FROM 04N TO 14N BETWEEN 130W AND 140W...WITH SEAS 7 TO 9 FT IN NE SWELL. THE GRADIENT IS EXPECTED TO FURTHER RELAX TONIGHT WITH SEAS SUBSIDING TO 8 FT...AND SUBSIDE FURTHER TO 7 FT FRI. $$ STRIPLING