000 AXPZ20 KNHC 130355 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC SUN FEB 13 2011 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0200 UTC. ...ITCZ... THE INTERTROPICAL CONVERGENCE ZONE AXIS ANALYZED FROM 01N78W TO 02N86W TO 02S98W TO 06N122W TO 04N130W TO 07N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS NOTED WITHIN 210 NM N OF AXIS BETWEEN 117W AND 124W. ...DISCUSSION... AN UPPER LEVEL BLOCKING PATTERN CONTINUES ACROSS THE EPAC BETWEEN 100W AND 150W...WITH A CUT OFF UPPER CYCLONE CENTERED NEAR 18N134W...AND A NEGATIVE TILT MID TO UPPER LEVEL TROUGH TO ITS SE EXTENDING FROM 13N123W TO NEAR 04N109W. THIS PATTERN CONNECTED WITH A BROAD UPPER CYCLONE S OF THE EQUATOR NEAR 17S150W TO PRODUCE A BROAD WLY JETSTREAM STRADDLING THE EQUATOR FROM 10N TO 05S BETWEEN 125W AND 160W...WITH RECENT SCATTEROMETER WINDS INDICATING WEAK TRADES ACROSS THIS ZONE. THE UPPER CYCLONE NEAR 18N134W HAS INDUCED A WEAKNESS IN THE LOW LEVEL FLOW TO ITS S AND SW...PRODUCING A BROAD AND WEAK INVERTED TROUGH...WHILE BROAD UPPER DIVERGENCE E OF THE UPPER TROUGH WAS VENTING ISOLATED MODERATE ELEVATED CONVECTION OFF THE ITCZ BETWEEN 12N AND 22N. TWO TROUGHS WERE NOTED EMBEDDED IN THE ITCZ THIS EVENING...ONE ALONG 141W AND A SECOND 123W. NO SIGNIFICANT CONVECTION WAS NOTED NEAR THE TROUGH ALONG 141W AS IT HAS ENTERED A REGION OF UPPER CONVERGENCE AND SINKING MOTION. THE TROUGH ALONG 123W HOWEVER WAS MOVING UNDERNEATH THE SE TAIL OF THE NEGATIVE TILT TROUGH...AND WAS IN A MOIST AND UNSTABLE ENVIRONMENT WHERE SCATTERED CONVECTION WAS FIRING DUE TO GOOD LOW LEVEL CONVERGENCE OF THE TRADES. IN FACT THIS AREA WAS THE MAIN REGION OF FRESH TRADE WINDS ACROSS THE AREA TODAY. AS THIS SECOND TROUGH MOVES WWD IT WILL ENCOUNTER A MORE HOSTILE AND SHEARED UPPER ENVIRONMENT AND BEGIN TO WEAKEN CONSIDERABLY. A COLD FRONT WAS APPROACHING FAR NW PORTIONS OF THE AREA THIS EVENING...EXTENDING FROM 32N140W TO 23N150W AND WILL MOVE E-SE INTO THE NW PORTION OF THE AREA IN ABOUT 12 HOURS...WITH S WINDS 20 TO 25 KT IMMEDIATELY AHEAD OF THE FRONT AND NW WINDS TO 20-25 KT BEHIND THE FRONT. SEAS ASSOCIATED WITH THE FRONT WILL BUILD TO AROUND 13-14 FT IN NW SWELL IN EXTREME NW PART OF THE FORECAST AREA DURING THE NEXT 30-60 HOURS. GLOBAL MODELS SHOW THE FRONT LIFTING N OF 30N NEAR 128W IN ABOUT 48 HOURS. A HIGH PRES RIDGE EXTENDS SW FROM A 1024 MB HIGH OFF THE CENTRAL CALIFORNIA COAST TO 20N150W. THE RIDGE WILL ACT TO BUFFER THE APPROACH OF THE COLD FRONT INTO THE FORECAST AREA. EXPECT RIDGE TO REMAIN FIRMLY IN PLACE FROM SOUTHERN CALIFORNIA THROUGH A HIGH CENTERED NEAR 25N125W TO AROUND 22N137W THROUGH MON NIGHT ALLOWING THE COLD FRONT TO RIDE UP AND OVER THE RIDGE. GAP WINDS... GULF OF TEHUANTEPEC...COLD AIR CONTINUES TO SURGE ACROSS THE ISTHMUS OF TEHUANTEPEC. AFTERNOON AND EARLY EVENING OBSERVATIONS AT LAND STATION IXTEPEC MEXICO HAVE REPORTED N WINDS AT 40 KT WITH GUSTS OF 50 TO 60 KT. HIGH PRES OVER SE TEXAS THIS AFTERNOON HAS SHIFTED INTO THE NW GULF OF MEXICO AND IS FORCING A REINFORCING SURGE OF COLD AIR THROUGH THE PASS. WINDS ARE PRESENTLY INCREASING TO STORM FORCE AND ARE EXPECTED TO REMAIN AT STORM FORCE THROUGH EARLY SUN AFTERNOON. A SLIGHT LESSENING OF THE GRADIENT ON SUN AFTERNOON SHOULD ALLOW FOR THE WINDS TO DIMINISH BELOW 50 KT AND RETURN TO GALE FORCE. SEAS WILL BUILD TO UP TO 19 FT COINCIDENT WITH THE STORM FORCE CONDITIONS. NE SWELL GENERATED BY THESE WINDS WILL SPREAD SW TO 04N BY SUN NIGHT. GULF OF PAPAGAYO...WINDS ARE EXPECTED TO INCREASE TO 20 TO 25 KT TONIGHT AS COOL DRAINAGE FLOW RESUMES OFF OF CENTRAL AMERICA BY THE EARLY MORNING HOURS. THESE FRESH WINDS WILL PERSIST THROUGH AT LEAST SUN NIGHT AS TRADES INCREASE IN THE WESTERN CARIBBEAN SEA. GULF OF PANAMA...NE TRADE WINDS TO 20 KT ARE FILTERING ACROSS THE ISTHMUS OF PANAMA AND BECOMING NLY ACROSS THE GULF OF PANAMA N OF 06N BETWEEN 78W AND 80W...AND ARE EXPECTED REMAIN STATUS QUO THROUGH 24 HOURS. GULF OF CALIFORNIA...THE PRES GRADIENT BETWEEN HIGH PRES OVER THE U.S. INTER-MOUNTAIN WEST AND BROAD SURFACE TROUGH OVER NW MEXICO IS GENERATING 20 TO 25 KT NW WINDS FUNNELING THROUGH THE S HALF OF THE GULF OF CALIFORNIA THIS EVENING. THESE WINDS WILL PERSIST OVERNIGHT THEN DIMINISH BELOW 20 KT BY SUN AFTERNOON AS THE GRADIENT RELAXES. $$ STRIPLING