000
AXPZ20 KNHC 230317
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
0405 UTC TUE APR 23 2013

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 ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0300 UTC.

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

THE MONSOON TROUGH AXIS EXTENDS FROM 09N79W TO WEAK 1011 MB LOW 
PRES NEAR 06N101W TO 07N118W. THE ITCZ AXIS EXTENDS FROM 07N118W 
TO 06N140W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS 
WITHIN 120 NM S OF THE ITCZ BETWEEN 90W AND 94W...WITHIN 60 NM N 
OF THE ITCZ BETWEEN 93W AND 96W...WITHIN 120 NM S OF A LINE FROM 
07N111W TO 04N116W...FROM 06N TO 10N BETWEEN 114W AND 118W...AND 
ALSO WITHIN 60 NM EITHER SIDE OF THE ITCZ BETWEEN 130W AND 133W.

...DISCUSSION...                                                 

AN UPPER LEVEL RIDGE IS OVER THE SE PORTION OF THE DISCUSSION 
WATERS EXTENDING FROM NEAR 08N77W THROUGH 22N111W...WHERE IT IS 
DISRUPTED TO THE W-NW BY AN UPPER LEVEL TROUGH. ANOTHER UPPER 
RIDGE EXTENDS INTO THE SW PORTION OF THE AREA FROM 02N140W TO 
08N116W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION    
UNDER UPPER DIFFLUENCE IS NOTED BELOW BOTH UPPER RIDGES AS IS 
DESCRIBED IN THE SECTION ABOVE. THIS REGION ALSO CORRESPONDS TO 
THE HIGHEST PRECIPITABLE WATER VALUES OBSERVED ACROSS THE 
FORECAST AREA. 

AN UPPER LEVEL CYCLONE IS CENTERED NEAR 31N131W AND IS MOVING TO 
THE E...WITH THE AFOREMENTIONED UPPER TROUGH REACHING S-SE FROM 
THE CYCLONE CENTER THROUGH 27N128W WHERE IT FLATTENS WITH SEMI-
ZONAL FLOW PRESENT FROM 22N TO 27N W OF 120W...THEN CONTINUING 
FROM NEAR 22N120W TO 08N113W. A WEAK SURFACE REFLECTION OF THE 
TROUGH THAT WAS NOTED EARLIER SW OF THE CALIFORNIA COAST HAS 
BECOME DIFFUSE DURING THE PAST SEVERAL HOURS. LITTLE SENSIBLE 
WEATHER IMPACT BY THE UPPER TROUGH IS EXPECTED WITH REGARD TO 
WINDS AND SEAS...WITH THE TROUGH CONTINUING TO ENHANCE 
PRECIPITATION ALONG THE ITCZ.

1038 MB HIGH PRES IS CENTERED WELL N OF THE DISCUSSION WATERS W 
OF VANCOUVER ISLAND NEAR 50N133W...EXTENDING A SURFACE RIDGE 
THROUGH 42N136W TO 32N139W...THEN SOUTHEASTWARD TO 20N107W. 
MAINLY LIGHT TO MODERATE TRADE WINDS EXIST ACROSS THE DISCUSSION 
WATERS OUTSIDE OF ANY CONVECTION...EXCEPT FOR LOCALLY FRESH 
WINDS NEAR 10N140W. WINDS ARE FORECAST TO REMAIN 20 KT OR LESS 
OVER THE ENTIRE FORECAST AREA THROUGH AT LEAST WED EVENING...BUT 
NORTHERLY WINDS ALONG THE CALIFORNIA COAST N OF THE AREA SHOULD 
BECOME STRONG ENOUGH ON TUE TO GENERATE AND THEN PROPAGATE N-NE 
SWELL WITH 8-9 FT SEAS INTO THE WATERS N OF 29N BETWEEN 130W AND 
137W BY LATE TUE NIGHT INTO AT LEAST WED EVENING.

$$
LEWITSKY