000 AXPZ20 KNHC 301605 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC FRI MAR 30 2012 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1515 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE ITCZ AXIS EXTENDS FROM 05N88W TO 04N106W TO 04N115W TO 01N136W. SCATTERED MODERATE TO STRONG CONVECTION WITHIN 120 NM N AND 60 NM S OF AXIS BETWEEN 89W AND 93W. SCATTERED MODERATE WITHIN 150 NM N OF AXIS W OF 93W. ...DISCUSSION... A NEARLY ZONAL UPPER JET BETWEEN 30N AND 40N WITH WINDS IN EXCESS OF 150 KT IS KEEPING THE NORTHERN STREAM PATTERN ALOFT ACROSS THE NE PACIFIC REASONABLY PROGRESSIVE THIS MORNING... ALTHOUGH UPPER TROUGHING APPROACHING FROM THE W ALONG 149W HAS BEGUN TO AMPLIFY AND DIG S TOWARD HAWAII. A POSITIVELY TILTED UPPER TROUGH LIES OVER THE FORECAST AREA FROM THE TEXAS PAN HANDLE THROUGH CENTRAL BAJA CALIFORNIA TO 22N134W THEN SOUTHWESTWARD TO A STRONG UPPER LOW JUST W OF THE AREA NEAR 14N146W. THIS ANOMALOUSLY DEEP LOW IS FOUR STANDARD DEVIATIONS DEEPER THAN THE CLIMATOLOGICAL PATTERN AT 250 MB AND FIVE STANDARD DEVIATIONS AT 500 MB. THIS DEEP LAYERED LOW WILL BEGIN TO WEAKEN...AND GRADUALLY BECOME ELONGATED AND SHIFT SLOWLY EASTWARD THIS AFTERNOON AND EVENING AS THE SUPPORTING TROUGH IS PROPELLED EASTWARD BY THE STRONG NORTHERN STREAM JET ALOFT. THE NORTHERN STREAM PATTERN WILL BECOME MORE AMPLIFIED AS RIDGING BUILDS OVER THE SOUTHWESTERN U.S. BEHIND THE TROUGH...SLOWING DOWN AND INTENSIFYING THE NEXT TROUGH TO ENTER THE FORECAST AREA FROM THE NW ON THIS EVENING AND TONIGHT. SYNOPTIC SCALE LIFT AND DEEP LAYERED CONVERGENCE ASSOCIATED WITH THE UPPER LOW HAS BEEN PRODUCING MULTI-LAYERED CLOUDINESS AND WIDELY SCATTERED SHOWERS AND TSTMS FROM ABOUT 15N TO 20N W OF 130W THE PAST 24 HOURS. HOWEVER...DRY AIR HAS WRAPPED AROUND THE LOW AND IS ADVECTING NE INTO THE MIDDLE LEVELS ACROSS THIS AREA...AND HAS ACTED TO QUICKLY LIMIT CONVECTION IN THE PAST SEVERAL HOURS. UPPER LEVEL RIDGING TO THE N IS EXPECTED TO CUT OFF THE COLD AIR ALOFT SPILLING INTO THE BACKSIDE OF THIS CYCLONE BY EARLY SATURDAY AS THE LOW CENTER CROSSES EAST OF 140W INTO THE DISCUSSION AREA. GRADUAL WEAKENING OF THE CYCLONE WILL OCCUR OVER THE WEEKEND AS IT MOVES E-NE. AT THE LOWER LEVELS...A 1021 MB SUBTROPICAL HIGH REMAINS ACROSS N PORTIONS...CENTERED NEAR 27N129W AND EXTENDS A RIDGE AXIS TO 20N107W. N OF THE RIDGE AXIS...STRONG NORTHWESTERLY WINDS CURRENTLY OFF THE W COAST OF THE BAJA PENINSULA N OF 27N ARE EXPECTED TO GRADUALLY DIMINISH THROUGH MIDDAY FRI. SOUTH OF THE RIDGE AXIS...FRESH TO STRONG NE TRADEWINDS PREVAIL FROM 04N TO 17N W OF 130W WITH CONFUSED SEAS OF 8 TO 11 FT FOUND THERE IN A BROAD MIX OF NE...SW...AND NW SWELL. MORE FRESH TRADES LIE FROM 08N TO 16N BETWEEN 126W AND 130W. THIS AREA OF FRESH TRADEWINDS WILL CONTRACT WESTWARD A BIT ON FRI AND REBUILD SAT AS HIGH PRES BOTH BEHIND AND AHEAD A COLD FRONT MOVING IN FROM THE NW. STRONG NW WINDS WILL ACCOMPANY THE FRONT BUT THE BIGGER STORY IS THE LARGE NW SWELL YIELDING SEAS TO 20 FEET EXPECTED OVER NW WATERS SAT. LIGHT TO MODERATE WINDS OTHERWISE PREVAIL E OF 110W...WITH GAP WIND FLOW PULSING TO NEAR 20 KT DURING THE OVERNIGHT HOURS IN THE GULF OF PAPAGAYO. LITTLE CHANGE IN THIS PATTERN IS EXPECTED DURING THE NEXT 48 HOURS. LONG PERIOD SW SWELL HAS MOVED INTO THE ADJACENT COASTAL WATERS OF CENTRAL AMERICA AND WILL CONTINUE TO PRODUCE BUILDING SURF ALONG REEFS AND BEACHES. POWERFUL MODERATE SIZED SURF IS EXPECTED ALONG THE CENTRAL AMERICAN COASTS THROUGH SAT...CREATING STRONG RIP CURRENTS. $$ STRIPLING