000
AXPZ20 KNHC 260923
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU MAY 26 2011

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 
0730 UTC.
 
...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE WAS ANALYZED FROM 12N87W TO 
13N94W TO 07N130W TO 04N140W. SCATTERED MODERATE WITH ISOLATED 
STRONG CONVECTION LIES WITHIN 300 NM S OF THE ITCZ AXIS BETWEEN 
90W AND 98W AND FROM 05N TO 10N BETWEEN 86W AND 90W. ISOLATED 
MODERATE CONVECTION LIES WITHIN 30 NM N AND 210 NM S OF THE ITCZ 
AXIS BETWEEN 110W AND 116W. SCATTERED MODERATE CONVECTION ALSO 
LIES WITHIN 120 NM W OF TROUGH FROM 08N107W TO 13N106W EMBEDDED 
IN THE ITCZ.

...DISCUSSION...
THE SUBTROPICAL RIDGE EXTENDS FROM 1027 MB HIGH PRES NW OF THE 
AREA NEAR 32N149W THROUGH 32N127W TO 15N112W. THE PRESSURE 
GRADIENT BETWEEN THE SUBTROPICAL RIDGE AND TROUGHING ASSOCIATED 
WITH A COLD FRONT OVER THE WESTERN UNITED STATES IS GENERATING 
FRESH NW OFF THE W COAST OF BAJA CALIFORNIA TO 122W AS OBSERVED 
BY THE 0518 UTC ASCAT PASS. THE SUBTROPICAL HIGH WILL MOVE 
EASTWARD TODAY...PASSING 130W TONIGHT AS A COLD FRONT ENCROACHES 
ON IT FROM THE N. ON FRI...THE HIGH WILL RETREAT BACK TO ITS 
CURRENT POSITION AND STRENGTHEN AS THE COLD FRONT MOVES E OF IT 
AND THE MID-LATITUDE PATTERN AMPLIFIES. THE AREA OF FRESH 
INCREASING TO STRONG NW WINDS OFF THE BAJA CALIFORNIA AND 
SOUTHERN CALIFORNIA COAST WILL EXPAND WESTWARD AS THE PRES 
GRADIENT BETWEEN THE RIDGE AND SLOW MOVING TROUGHING OVER THE 
INTERIOR WESTERN UNITED STATES BUILDS. NW SWELL WILL BRING 
SIGNIFICANT WAVE HEIGHTS TO AS HIGH AS 12 FT OFF THE BAJA 
CALIFORNIA NORTE COAST BY THE START OF THE WEEKEND.

FRESH TRADE WINDS LIE OVER CENTRAL WATERS W OF 125W AS INDICATED 
BY THE 0250 UTC WINDSAT PASS AND 0516 UTC ASCAT PASS. THE AREA 
OF FRESH TRADES WILL REMAIN RELATIVELY UNCHANGED DESPITE THE 
GYRATIONS SEEN IN THE SUBTROPICAL HIGH POSITION AND STRENGTH. A 
40-50 KT SOUTHWESTERLY UPPER JET LIES OVER THE REGION OF TRADE 
WINDS ON THE E SIDE OF AN UPPER LOW CENTERED NEAR 21N138W. THIS 
JET IS TRANSPORTING UPPER MOSITURE MANIFESTED AS CIRRUS 
CLOUDS...PRIMARILY FROM 15N TO 29N W OF 125W...THAT OVERLAY THE 
SCATTERED STRATOCUMULUS THAT EXTENDS OVER MUCH OF THE AREA FROM 
15N TO 26N BETWEEN 120W AND 135W.

THE REMNANTS OF A FRONTAL BOUNDARY HAVE MOVED INTO THE NW 
PORTION OF THE FORECAST AREA AND A NEW BATCH OF NW SWELL IS 
ACCOMPANYING THEM. THIS SWELL WILL MERGE WITH THE TRADE WINDS 
AREA TO THE S AND THE AREA OF FRESH TO STRONG NW WINDS OFF BAJA 
CALIFORNIA BY EARLY FRI.

CONVECTION ALONG THE ITCZ IS STRONGEST SE OF A 1011 MB LOW PRES 
SYSTEM NEAR 12N95W. THIS CONVECTION IS DESCRIBED IN THE ITCZ 
SECTION. DIFFLUENT FLOW ALOFT BETWEEN THE LEADING EDGE OF AN 
UPPER TROUGH FROM 10N92W INTO EL SALVADOR AND THE LEFT FRONT 
QUADRANT OF AN EAST-NORTHEASTERLY UPPER JET TO ITS S IS 
ENHANCING THE CONVECTION. THE UPPER TROUGH WILL PULL 
NORTHEASTWARD OUT OF THE PACIFIC TODAY AND THIS LOW IS FORECAST 
TO DISSIPATE.

CROSS-EQUATORIAL SW SWELL WITH 14-16 SECOND PERIODS HAS BROUGHT 
SEAS TO 8 FT OVER S CENTRAL WATERS S OF 07N. THE 1840 UTC JASON2 
AND 1750 UTC ENVISAT PASSES CONFIRM THESE CONDITIONS. THIS SWELL 
WILL DAMPEN AS IT PROPAGATES NORTHWARD...KEEPING THE SEAS ABOVE 
ADVISORY CRITERIA OVER THE SAME GENERAL AREA THROUGH THE 
FORECAST PERIOD.

$$
SCHAUER