000
AXPZ20 KNHC 210924
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
1005 UTC SUN APR 21 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0645 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...              
THE MONSOON TROUGH AXIS WAS ANALYZED FROM 11N86W TO 06N102W TO 
07N107W. THE ITCZ AXIS WAS ANALYZED FROM 07N107W TO 08N111W TO 
05N120W TO 07N129W TO 04N140W. ISOLATED MODERATE CONVECTION WAS 
WITHIN 210 NM N AND 180 NM S OF THE AXIS BETWEEN 96W AND 102W. 

...DISCUSSION...                                                 
A VAST ANTICYCLONE CENTERED NEAR 15N103W EXTENDS A RIDGE AXIS 
NORTHWESTWARD THROUGH 16N112W TO 32N121W AS WELL AS EASTWARD 
ALONG 15N INTO GUATEMALA. SCATTERED MODERATE WITH ISOLATED 
STRONG CONVECTION FOUND WITHIN 90 NM OF THE COAST OF GUATEMALA 
AND SOUTHERN MEXICO BETWEEN 91W-93W IS BEING ENHANCED BY THE 
UPPER LEVEL DIFFLUENCE ASSOCIATED WITH THE RIDGE AXIS. DIFFLUENT 
CONDITIONS ALOFT ALSO EXIST S OF THE ANTICYCLONE ALONG 100W 
BETWEEN THE E-SE WINDS AROUND THE ANTICYCLONE AND NE WINDS NEAR 
THE EQUATOR. DIFFLUENCE HERE IS LIFTING SOME OF THE MOISTURE 
POOLED IN THIS AREA AND ENHANCING THE CONVECTION ALONG THE 
MONSOON TROUGH AXIS THAT IS DESCRIBED IN THE SECTION ABOVE. THE 
ANTICYCLONE IS EXPECTED SHIFT EASTWARD AND WEAKEN OVER THE NEXT 
TWO DAYS...DRAGGING THE WESTERN RIDGE AXIS EASTWARD THROUGH THE 
BAJA CALIFORNIA PENINSULA AND INTO MEXICO. THIS WILL MAKE ROOM 
FOR THE UPPER LOW THAT IS CURRENTLY NEAR 29N141W TO MAKE ITS WAY 
OVER NW WATERS...REACHING NEAR 32N129W BY THE END OF THE 
FORECAST PERIOD EARLY TUE MORNING. THIS UPPER LOW EXTENDS A 
TROUGH SOUTHEASTWARD TO 10N122W. DRY AIR AND IMPLIED SUBSIDENCE 
DOMINATE MUCH OF THE REGION N OF 12N...EXCEPT WHERE SOUTHERLY 
FLOW IS TRANSPORTING TROPICAL MOISTURE ALOFT BETWEEN THE UPPER 
TROUGH AXIS AND THE RIDGE AXIS TO ITS E. THIS MOISTURE IS BEING 
OVERTAKEN BY THE 50-80 KT W-SW UPPER JET N OF 20N. THIS MOISTURE 
IS MANIFESTED BY A BAND OF PATCHY CIRRUS FROM NEAR 20N120W 
THROUGH THE CENTRAL GULF OF CALIFORNIA INTO NW MEXICO.

THE 1032 MB SUBTROPICAL HIGH LIES WELL N OF THE AREA NEAR 
39N136W AND EXTENDS A RIDGE AXIS SOUTHEASTWARD THROUGH 25N125W 
TO 16N110W. MODERATE NE TRADE WINDS LIE BETWEEN THE RIDGE AXIS 
AND THE ITCZ OVER WESTERN WATERS. SEAS THAT ARE CURRENTLY TO 9 
FT UNDER NE SWELL IN THE CLIMATOLOGICAL TRADE WIND AREA WILL 
SUBSIDE BELOW 8 FT OVERNIGHT SUN NIGHT. WINDS ARE EXPECTED TO 
REMAIN BELOW 25 KT OVER THE ENTIRE FORECAST AREA THROUGH AT 
LEAST EARLY TUE MORNING...BUT N WINDS ALONG THE CALIFORNIA COAST 
N OF THE AREA SHOULD REMAIN STRONG ENOUGH TO CONTINUE TO 
PROPAGATE N SWELL WITH 8-9 FT SEAS INTO WATERS N OF 29N BETWEEN 
120W AND 131W THROUGH TUE MORNING. SOME RESIDUAL NE SWELL FROM 
THE FORMER GALE IN THE GULF OF TEHUANTEPEC CONTINUES TO KEEP 
SEAS IN THE 8-9 FT RANGE SE OF THE GULF. THIS SWELL IS MERGING 
WITH 16-18 SECOND PERIOD CROSS-EQUATORIAL SW SWELL WHICH HAS 
ALSO BUMPED SEAS UP ABOVE 8 FT OVER S CENTRAL WATERS W OF THE 
GALAPAGOS. SEAS FROM BOTH SWELL SOURCES WILL GRADUALLY SUBSIDE 
BELOW 8 FT THROUGH MON MORNING.

$$
SCHAUER