000
AXPZ20 KNHC 210920
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU APR 21 2011

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS WAS ANALYZED ALONG 
03N78W TO LOW PRES 1010 MB NEAR 08N95W TO 04N96W TO 08N117W THEN 
RESUMED FROM 05N122W TO 04N140W. SCATTERED MODERATE AND ISOLATED 
STRONG CONVECTION WAS FROM 06N TO 10N BETWEEN 124W AND 133W.

...DISCUSSION...

A MID TO UPPER LEVEL TROUGH EXTENDS FROM SOUTHERN CALIFORNIA 
THROUGH 30N120W TO 25N140W. AN ASSOCIATED COLD FRONT IS AT THE 
SURFACE AND WSR-88D RADAR AT VANDENBERG CALIFORNIA INDICATES 
SCATTERED SHOWERS AHEAD OF THE FRONT NOW MOVING ONSHORE. ANY 
ASSOCIATED SIGNIFICANT WEATHER WITH THIS FRONT SHOULD REMAIN N 
OF THE DISCUSSION AREA. ELSEWHERE N OF 20N...MAINLY ZONAL FLOW 
DOMINATES ALOFT. S OF 20N...UPPER LEVEL RIDGING IS THE DOMINANT 
PLAYER EXTENDING ALONG 08N E OF 110W...AND ALONG 12N W OF 110W. 
CLUSTERS OF CONVECTION AS DESCRIBED ABOVE ARE OCCURRING ALONG 
THE ITCZ S OF THE RIDGING.

1021 MB SURFACE HIGH PRES IS POSITIONED NEAR 27N126W WITH A 
RIDGE AXIS EXTENDING SE TO NEAR 18N112W. A TIGHT PRES GRADIENT 
PERSISTS NE OF THIS RIDGE WITH TROUGHING LOCATED INLAND OVER 
CENTRAL MEXICO. AS A RESULT OF THIS PRES PATTERN...NW 20 KT WINDS
ARE OCCURRING WITHIN 180 NM OF THE N BAJA CALIFORNIA COAST AND 
THESE WINDS MAY BRIEFLY STRENGTHEN TO 20-25 KT DURING THE NEXT 
24 HOURS ALTHOUGH WILL CHANGE LITTLE OVERALL DURING THE NEXT 48 
HOURS. A SMALL AREA OF 20 KT NE TRADE WINDS IS SW OF THE RIDGE 
FROM 07N TO 15N W OF 125W AS INDICATED BY A RECENT 0540 UTC 
ASCAT PASS. THESE TRADES WILL CHANGE LITTLE IN COVERAGE AND
STRENGTH DURING THE NEXT 48 HOURS.

1010 MB SURFACE LOW PRES IS LOCATED NEAR 08N95W WITH A TROUGH 
REACHING FROM THE LOW TO 12N96W. THIS LOW HAS BEEN LINGERING IN 
THIS SAME GENERAL AREA FOR THE PAST WEEK OR SO...OCCASIONALLY 
OPENING UP INTO JUST A TROUGH. A 0356 UTC ASCAT PASS WAS JUST E 
OF THE LOW CENTER AND ONLY INDICATED 5-10 KT WINDS NEAR THE 
CIRCULATION WHICH MATCHES WELL WITH GLOBAL MODEL GUIDANCE. THIS
LOW WILL REMAIN WEAK WHILE FINALLY MOVING MORE QUICKLY OFF TO 
THE W DURING THE NEXT FEW DAYS.

ANOTHER SURFACE TROUGH IS EMBEDDED IN THE ITCZ EXTENDING FROM 
10N119W TO 04N120W. NUMEROUS MODERATE AND SCATTERED STRONG 
CONVECTION WAS OCCURRING N OF 07N WITHIN 180 NM EITHER SIDE OF 
THE TROUGH AXIS. THIS TROUGH IS FORECAST TO DISSIPATE BY 48 
HOURS.

VERY LONG PERIOD 19-21 SECOND CROSS-EQUATORIAL SW SWELL 
CONTINUES TO PROPAGATE NE ACROSS THE WATERS WITH 8 FT SEAS 
CONFINED S OF 04N IN THE CENTRAL PORTION. THIS HIGH ENERGY SWELL 
WILL REACH THE COASTLINES OF SOUTHERN CALIFORNIA...MEXICO AND 
CENTRAL AMERICA DURING THE NEXT SEVERAL HOURS WITH HEIGHTS OF 4 
TO 6 FT. EVEN THOUGH SEAS WILL BE LESS THAN 8 FT...VERY 
HAZARDOUS SURF CONDITIONS ARE EXPECTED AT EXPOSED COASTAL 
LOCATIONS...INCLUDING AN ENHANCED RIP CURRENT THREAT TODAY
THROUGH SAT.

$$
LEWITSKY