000
AXPZ20 KNHC 200231
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED APR 20 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 
0300 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 07N77W TO 
06N93W TO 05N100W TO 07N108W TO 05N125W TO 03N140W. SCATTERED 
MODERATE CONVECTION IS FROM 03N TO 07N BETWEEN 87W AND 93W. 
SIMILAR CONVECTION IS WITHIN 120 NM S OF AXIS FROM 103W TO 108W.

...DISCUSSION...

A 1021 MB HIGH PRES LOCATED NEAR 27N138W EXTENDS A RIDGE SE 
ACROSS THE FORECAST WATERS TO NEAR 17N108W. THIS FEATURE IS 
FORECAST TO DISSIPATE IN ABOUT 24 HOURS. A SMALL AREA OF 20 KT 
TRADE WINDS IS NOTED ON THE SOUTHERN PERIPHERY OF THE RIDGE FROM 
05N TO 15N W OF 130W...AND FROM 05N TO 11N BETWEEN 125W AND 
130W. AN EARLIER WINDSAT PASS ALONG WITH THE MOST RECENT ASCAT 
PASS PROVIDED OBSERVATIONS OF THESE WIND SPEEDS. MODEL GUIDANCE 
INDICATES LITTLE CHANGE OF THIS WEATHER PATTERN DURING THE NEXT 
COUPLE OF DAYS. 

THE 0116 UTC EXPERIMENTAL ASCAT 25 KM COASTAL WINDS SHOWED AND 
AREA OF 20 KT NW WINDS JUST W OF THE BAJA CALIFORNIA PENINSULA 
BUT PARTICULARLY N OF 26N E OF 117W. WINDS ARE FORECAST TO 
INCREASE TO 25 KT BY THU AS PRES GRADIENT BETWEEN A BUILDING 
HIGH PRES N OF AREA AND LOWER PRES OVER MEXICO TIGHTENS.

A PAIR OF WEAK COLD FRONTS WILL CLIP THE EXTREME NW PART OF THE 
DISCUSSION AREA WITH LITTLE EFFECT OTHER THAN A SHIFT IN WIND 
DIRECTION AND SLIGHTLY HIGHER NW SWELL BEHIND THE FRONTS. THE 
FIRST COLD FRONT IS CURRENTLY NEAR 30N140W AND WILL EXTEND AS A 
DISSIPATING FRONT OVER THE FAR NW PART OF THE FORECAST REGION 
THIS WED. THE NEXT FRONT WILL BRUSH THE FAR NW PART FRI NIGHT 
INTO SAT. 

WEAK CYCLONIC CIRCULATION IS NOTED ON SATELLITE PICTURES NEAR 
06N94W. A SURFACE TROUGH IS ANALYZED ALONG 94W FROM 02N TO 09N. 
MODELS GUIDANCE SUGGESTS THAT THIS WEAK SYSTEM WILL DRIFT WNW 
OVER THE NEXT SEVERAL DAYS WITH LITTLE CHANGE IN INTENSITY. 
AS PREVIOUSLY MENTIONED IN THE ITCZ SECTION...SCATTERED MODERATE 
CONVECTION IS OBSERVED E OF THE TROUGH AXIS FROM 03N TO 07N 
BETWEEN 87W AND 93W. 

VERY LONG PERIOD 19-20 SEC CROSS-EQUATORIAL SW SWELL WILL SWEEP 
NE ACROSS THE WATERS THE REMAINDER OF THE WEEK...REACHING COASTAL
AREAS OF SOUTHERN CALIFORNIA...MEXICO AND CENTRAL AMERICA THU. 
WHILE SEA HEIGHTS WILL BE LESS THAN 8 FT AS THE SWELL PROPAGATES 
AWAY FROM THE EQUATOR...THIS HIGH ENERGY SWELL WILL STILL RESULT 
IN VERY HAZARDOUS SURF CONDITIONS AT COASTAL LOCATIONS INCLUDING 
AN ENHANCED RIP CURRENT DANGER THU THROUGH SAT.

$$
GR