000
AXPZ20 KNHC 271553
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE JUL 27 2010

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...ITCZ...
AXIS ALONG 10N85W TO 11N100W TO 09N130W TO 11N140W.  SCATTERED 
MODERATE ISOLATED STRONG CONVECTION WITHIN 60 NM OF AXIS E OF 
95W.  ISOLATED MODERATE CONVECTION WITHIN 120 NM OF S OF AXIS 
FROM 95W TO 107W AND WITHIN 45 NM OF AXIS FROM 113W TO 128W. 

...DISCUSSION...
LARGE AMPLITUDE UPPER LEVEL TROUGH EXTENDS FROM WELL N OF BASIN 
TO 32N126W TO 16N133W AS BROAD RIDGE RESISTS ANY FURTHER 
EASTWARD DRIFT OF TROUGH.  MODEL GUIDANCE REINFORCES ANTICYCLONE 
NOW AT 23N110W FORCING TROUGH TO RETREAT W AS RIDGE EXTENDS IT 
DOMAIN TO 135W BY THU.  VERY DRY AND STABLE AIR MASS DUE TO 
MODERATE TO STRONG SUBSIDENCE N OF 18N W OF 115W AND FROM 12N TO 
18N W OF 120W.  MID TO UPPER LEVEL MOISTURE ADVECTED SW BY 
ANTICYCLONE FINDING ITS WAY ALONG ITCZ TO 130W BY QUASI ZONAL 
EASTERLIES ALOFT S OF 18N.  LACK OF LOW LEVEL UPLIFTING FEATURES 
HINDER DEVELOPMENT OF DEEP CONVECTION.  ONLY ISOLATED TSTMS 
NOTED W OF 95W.  SCATTERED CONVECTION ASSOCIATED TO TAIL END OF 
WEAK SURFACE TROUGH OVER GULF OF TEHUANTEPEC IS MAIN CONVECTION 
CENTER AT THIS TIME.  THIS MIGHT CHANGE IN NEAR FUTURE AS MOST
DYNAMICAL MODELS FOCUS ON MID LEVEL TROUGH MEANDERING ALONG 
105W-110W...BUT ANY POSSIBILITY OF DEVELOPMENT DEPEND ON LESS 
HOSTILE UPPER LEVEL ENVIRONMENT WHICH COULD OCCUR BEYOND 
FORECAST PERIOD.   

ELSEWHERE AT THE SURFACE...
WEAK TROUGH...REMNANTS OF TROPICAL WAVE...EXTEND FROM 20N95W TO 
14N94W.  THIS COULD BE THE TRIGGER NEEDED BY MID LEVEL TROUGH TO 
BRING SOME VORTICITY TO SURFACE...BUT AGAIN...IT WOULD BE LATE 
IN FORECAST PERIOD OR BEYOND.

BROAD 1028 MB HIGH PRES CENTER WELL NW OF AREA HAS RIDGE AXIS 
EXTEND SE TO 15N125W.  FRESH NW BREEZE CONTINUES TO FUNNEL DOWN 
ALONG W COAST OF BAJA CALIFORNIA PENINSULA FROM 24N TO 28N.
IN ADDITION...PRES GRADIENT OVER FAR NW MEXICO EXPECTED TO EASE 
AS RIDGE DRIFT W DIMINISHING THE PRESENT FRESH SE BREEZE IN GULF 
OF CALIFORNIA BELOW 20 KT WITHIN 24 HOURS.

FRESH TO STRONG BREEZE OVER S PAC CONTINUE TO GENERATE LONG 
PERIOD SOUTHERLY CROSS EQUATORIAL SWELL WITH SEAS UP TO 9 FT 
ENCROACHING INTO E PAC WATERS S OF 10N.  SEAS EXPECTED TO 
PERSIST DURING NEXT 48 HOURS.

$$
WALLY BARNES