000
AXPZ20 KNHC 302143
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 04N90W TO 
03N120W TO 03N140W. SCATTERED MODERATE CONVECTION IS FROM 04N TO 
07N BETWEEN 90W AND 95W.

...DISCUSSION...

A NEARLY ZONAL UPPER LEVEL JET BETWEEN 30N AND 40N WITH WINDS IN 
EXCESS OF 150 KT IS KEEPING THE NORTHERN STREAM PATTERN ALOFT 
ACROSS THE NE PACIFIC PROGRESSIVE...ALTHOUGH AN UPPER LEVEL 
SHORTWAVE TROUGH APPROACHING FROM THE W ALONG 142W CONTINUES TO 
AMPLIFY AND DIG SOUTHWARD IN THE VICINITY OF 38N140W. A 
POSITIVELY TILTED UPPER LEVEL TROUGH LIES OVER THE FORECAST AREA 
FROM WEST TEXAS THROUGH SOUTHERN BAJA CALIFORNIA TO 21N130W THEN 
SOUTHWESTWARD TO A STRONG UPPER LEVEL LOW CENTERED W OF THE 
DISCUSSION AREA NEAR 13N145W. THIS DEEP LAYERED LOW WILL BEGIN 
TO WEAKEN...GRADUALLY BECOME ELONGATED BY SUNDAY AND SHIFT 
SLOWLY EAST-NORTHEAST OVER THE UPCOMING WEEKEND. THE NORTHERN 
STREAM PATTERN WILL BECOME MORE AMPLIFIED OVER THE WEEKEND 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 THIS EVENING INTO THE OVERNIGHT HOURS. 

SYNOPTIC SCALE LIFT AND DEEP LAYERED CONVERGENCE ASSOCIATED WITH 
THE UPPER LEVEL LOW CONTINUES TO PRODUCE MULTI-LAYERED 
CLOUDINESS AND WIDELY SCATTERED SHOWERS AND TSTMS FROM 01N TO 
13N W OF 125W. HOWEVER...WATER VAPOR IMAGERY INDICATES DRY AIR 
WRAPS AROUND THE LOW AND IS ADVECTING NE INTO THE MIDDLE LEVELS 
ACROSS THIS AREA AND TO THE NORTH LIMITING THE NORTHWARD EXTENT 
OF CONVECTION. UPPER LEVEL RIDGING CURRENTLY OVER THE 
NORTHWESTERN CORNER OF THE DISCUSSION AREA 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 
OVERNIGHT.

AT THE LOWER LEVELS...A 1022 MB SUBTROPICAL HIGH CONTINUES TO 
INFLUENCE THE NORTHERN PORTION OF THE DISCUSSION AREA CENTERED 
NEAR 27N130W THAT EXTENDS A RIDGE AXIS TO 15N110W. N OF THE 
RIDGE AXIS...NORTHWESTERLY WINDS REMAIN IN THE 10 TO 15 KT RANGE 
HOWEVER ARE FORECAST TO GRADUALLY INCREASE OVERNIGHT INTO 
SATURDAY OVER THE AREA N OF 24N E OF 117W. SOUTH OF THE RIDGE 
AXIS...FRESH TO STRONG NE TRADEWINDS PREVAIL FROM 05N TO 18N W 
OF 126W WITH CONFUSED SEAS OF 9 TO 11 FT IN A BROAD MIX OF NE... 
SW...AND NW SWELL. THIS AREA OF FRESH TRADEWINDS IS FORECAST TO 
CONTRACT WESTWARD SLIGHTLY THROUGH SATURDAY AND EVENTUALLY MERGE 
INTO A LARGER AND WIDER SWATH OF N TO NE WINDS IN ASSOCIATION 
WITH A DISSIPATING COLD FRONT AND NE TRADES SOUTH OF HIGH 
PRESSURE BUILDING WESTWARD FROM THE CENTRAL PACIFIC. STRONG NW 
WINDS OF 20 TO 25 KT WILL ACCOMPANY THE FRONT BUT THE BIGGER 
STORY IS THE LARGE NW SWELL YIELDING SEAS TO 20 FEET EXPECTED 
OVER THE NORTHWESTERN WATERS FRIDAY INTO SATURDAY. 

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 
CONTINUES TO IMPACT THE ADJACENT COASTAL WATERS OF CENTRAL 
AMERICA AND WILL CONTINUE TO PRODUCE HEAVY SURF ALONG REEFS AND 
BEACHES. POWERFUL MODERATE SIZED SURF IS EXPECTED ALONG THE 
CENTRAL AMERICAN COASTS THROUGH SATURDAY...CREATING STRONG RIP 
CURRENTS.

$$
HUFFMAN