000
AXPZ20 KNHC 302156
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI APR 30 2010

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2145 UTC.

...ITCZ...

AXIS ANALYZED FROM 08N96W TO 05N140W. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION IS NOTED WITHIN 180 NM EITHER SIDE OF 
A LINE FROM 03N82W TO 06N112W TO 05N137W.

...DISCUSSION...

A LONGWAVE UPPER TROUGH DOMINATES THE WESTERN CONUS WITH ITS 
MEAN AXIS EXTENDING INTO THE DISCUSSION AREA ALONG 32N114W TO A 
BASE NEAR 23N120W. UPPER MOISTURE IS NOW SPREADING SE INTO THE 
TROUGH OVER THE AREA N OF 30N BETWEEN 128W AND 140W. OTHERWISE 
THE UPPER LEVELS ARE DRY N OF 20N ACROSS THE ENTIRE AREA. AN 
UPPER SHORTWAVE TROUGH IS EXPECTED PASS THROUGH THE LONGER 
PATTERN EFFECTIVELY AMPLIFYING THE LONGWAVE SW FROM ARIZONA TO 
NEAR 09N133W.

AN UPPER ANTICYCLONE IS QUASI STATIONARY NEAR 13N84W WITH AN 
UPPER RIDGE EXTENDING W ACROSS THE TROPICAL PACIFIC TO A SHARP
CREST AT 09N142W. ITCZ CONVECTION HAS BEEN ENHANCED UNDER THE 
ENTIRE UPPER RIDGE ESPECIALLY BETWEEN 82W AND 115W. THE 
RESULTANT DEBRIS MOISTURE FROM CONVECTION BETWEEN 120W AND 140W 
IS ADVECTED NE...BUT FOR THE MOST PART EVAPORATES COMPLETELY BY 
THE TIME IT REACHES ALONG 20N IN THE DRY AIR ACCOMPANYING UPPER 
TROUGH PREVIOUSLY DESCRIBED. ITCZ CONVECTION ENHANCED BETWEEN 
120W AND 100W IS FAINING OUT OVER THE AREA FROM 11N TO THE 
EQUATOR. SOME OF THE DEBRIS MOISTURE FROM CONVECTION E OF 100W 
IS SPREADING SW ACROSS THE EQUATOR WHILE SOME OF THE MOSITURE IS 
ADVECTED NE ACROSS THE NW CARIBBEAN. 

ELSEWHERE AT THE SURFACE...
A RIDGE IS BECOMING STATIONARY FROM 32N140W TO NEAR 12N110W. NE 
TRADES THE S OF THE RIDGE AXIS ARE AT 15 TO 20 KT...WITH SEAS 8 
TO 11 FT IN MIXED NE AND NW SWELL. NORTHERLY WINDS TO THE E OF 
THE RIDGE REACH THE WESTERN BAJA PENINSULA AND HAVE INCREASED 
20 TO 30 KT WITH SEAS HEIGHTS TO ABOUT 16 FT ALONG 29N NEAR 
119W. SOUTHERLY WINDS CONTINUE AROUND THE SOUTHERN TIP OF THE 
BAJA PENINSULA OVER THE GULF OF CALIFORNIA TO ABOUT 25N...WITH 
SEAS TO ABOUT 7 FT IN REFRACTIVE SWELL OVER THE SOUTHERN GULF
WATERS. THESE NW SWELLS SHOULD REACH THE DEEP TROPICS SAT AND 
EVENTUALLY MIX WITH A NEW SERIES OF LONG PERIOD SW SWELL 
CROSSING THE EQUATOR ON SUN. THE SOUTHERLY MONSOON FLOW OVER 
THE FAR SE WATERS HAS DIMINISHED BELOW 20 KT AND SEAS HAVE ALSO 
SUBSIDED TO ABOUT 7 FT. CURRENTLY A SURFACE TROUGH EXTENDS FROM 
13N94W TO 07N88W. SCATTERED MODERATE ISOLATED STRONG CONVECTION 
EXISTS N OF 08N BETWEEN 85W AND 93W.
   
$$
NELSON