000
AXPZ20 KNHC 250925
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SUN JUL 25 2010

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...ITCZ...

AXIS IS ALONG 10N86W TO 07N94W TO 14N109W TO 12N117W TO 13N127W 
TO 10N138W. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 60 
NM OF THE AXIS BETWEEN 92W AND 95W. SCATTERED MODERATE TO STRONG 
CONVECTION IS WITHIN 150 NM S OF THE AXIS BETWEEN 102W AND 108W. 
SCATTERED MODERATE CONVECTION IS WITHIN 75 NM S OF THE AXIS 
BETWEEN 116W AND 120W.

...DISCUSSION...

AN UPPER LEVEL TROUGH PERSISTS OVER THE NORTHERN PORTION OF THE 
DISCUSSION AREA FROM NEAR 32N128W TO 22N129W TO 20N140W WITH THE 
SOUTHERN PORTION OF THE TROUGH DRIFTING E-SE AS AN UPPER 
UPSTREAM RIDGE EDGES INTO THE FAR NW PORTION OF THE AREA. A PAIR 
OF UPPER LEVEL ANTICYCLONES ARE E THROUGH S OF THE TROUGH WITH 
THE NORTHERN ONE POSITIONED NEAR 25N119W JUST W OF BAJA 
CALIFORNIA. ANOTHER ANTICYCLONE IS CENTERED NEAR 18N135W. VERY 
DRY AND STABLE AIR IS IN PLACE OVER THE AREA N OF 10N BETWEEN 
BAJA CALIFORNIA AND 130W. 

UPPER LEVEL EASTERLIES PREVAIL OVER THE MAJORITY OF THE 
REMAINDER OF THE DISCUSSION AREA S OF 20N EXTENDING FROM CENTRAL 
AMERICA W TO 130W WHERE WINDS TURN SE TO S AROUND THE ABOVE 
MENTIONED UPPER ANTICYCLONE. AMPLE CONVECTION THAT DEVELOPED 
OVER INTERIOR MEXICO AND CENTRAL AMERICA HAS DRIFTED OFFSHORE 
DURING THE OVERNIGHT HOURS TO WITHIN 120 NM OF THE COASTLINE. 
THE REMAINDER OF THE AREA IS MAINLY VOID OF CONVECTION EXCEPT 
ALONG THE ITCZ MAINLY BETWEEN 100W AND 107W WHICH IS BEING 
FORCED AND INDUCED BY 20 KT SOUTHERLY WINDS ON THE S SIDE OF THE 
ITCZ AXIS BETWEEN 107W AND 117W.

ELSEWHERE AT THE SURFACE...BROAD 1032 MB HIGH PRES WELL NW OF 
THE AREA HAS A RIDGE AXIS ENTERING 30N140W TO ANOTHER HIGH OF 
1019 MB NEAR 25N133W WITH ANOTHER RIDGE TO 18N118W. A WEAK 
TROUGH IS TRAPPED BETWEEN THE TWO HIGHS/RIDGES AND WILL MAINTAIN 
FRESH NW BREEZE WITHIN 90 NM OF THE W COAST OF BAJA CALIFORNIA 
FROM 24N TO 28N DURING THE NEXT 36 HOURS AS THE HIGH CENTER IN 
THE DISCUSSION AREA DRIFTS E-SE. A TIGHTENING PRES GRADIENT MAY 
PRODUCE FRESH SOUTHERLY WINDS INSIDE THE GULF OF CALIFORNIA FROM 
24N TO 27N BY 18 HOURS THEN DIMINISHING TO LESS THAN 20 KT BY 48 
HOURS AS THE PRES GRADIENT WEAKENS. 

CROSS EQUATORIAL SOUTHERLY SWELL UP TO 9 FT WITH PERIODS OF 
12-14 SECONDS WILL CONTINUE TO PROPAGATE ACROSS THE MAJORITY OF 
THE SOUTHERN THIRD OF THE AREA THROUGH 48 HOURS WHILE POCKETS OF 
SOUTHERLY 20 KT WINDS OCCUR S OF THE ITCZ AXIS.

$$
LEWITSKY