000
AXPZ20 KNHC 071900 RRA
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT AUG 07 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 
1530 UTC.

...SPECIAL FEATURE...

AT 07/1500 UTC...THE CENTER OF TROPICAL STORM ESTELLE IS LOCATED 
NEAR 17.1N 107.6W MOVING TOWARD THE WEST OR 280 DEGREES AT 8 KT.
A GENERAL WEST NORTHWEST MOTION IS EXPECTED OVER THE NEXT FEW 
DAYS. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1000 MB. MAXIMUM 
SUSTAINED WINDS ARE 45 KT WITH GUSTS TO 55 KT. SEE LATEST NHC 
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP2/WTPZ22 KNHC 
FOR MORE DETAILS. A LARGE BURST OF SCATTERED STRONG CONVECTION 
IS OCCURRING NEAR THE APPARENT LOW LEVEL CENTER CENTER OF 
ESTELLE DURING THE PAST FEW HOURS AND EXTENDS OUT TO 90 NM IN 
THE SW SEMICIRCLE. ESTELLE HAS ABOUT 24 HOURS OF STRENGTHENING 
BEFORE INCREASING SOUTHEASTERLY SHEAR...COOLER WATERS...AND A 
MORE STABLE ATMOSPHERE TAKES ITS TOLL ON THE SYSTEM.     

...ITCZ...

THE ITCZ AXIS IS ALONG 09N75W TO 10N85W TO 13N96W TO 14N106W TO 
10N129W TO 11N136W TO 09N140W. SCATTERED MODERATE TO STRONG 
CONVECTION WAS NOTED WITHIN 75 NM N AND 240 NM S OF AXIS BETWEEN 
87W AND 118W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS 
NOTED WITHIN 60 NM N AND 90 NW S OF AXIS BETWEEN 130W AND 137W. 
SCATTERED MODERATE TO STRONG N OF 05N E OF 85W TO THE COAST OF 
PANAMA. 

...DISCUSSION...

AN UPPER LEVEL ANTICYCLONE DOMINATING THE NW WATERS REMAINS 
ANCHORED NEAR 26N138W WITH AN UPPER RIDGE EXTENDING BEYOND 
32N135W. A SECOND UPPER LEVEL ANTICYCLONIC CIRCULATION IS 
LOCATED OVER NE TEXAS WITH THE ASSOCIATED RIDGE EXTENDING ACROSS 
NORTHERN MEXICO. AN ELONGATED RIDGE AXIS IS OVER SOUTHERN MEXICO 
EXTENDING FROM NEAR THE ISTHMUS OF TEHUANTEPEC WNW TO A SMALL 
ANTICYCLONE JUST TO THE NW OF ESTELLE NEAR 21N111W. ESTELLE IS 
EMBEDDED IN THE UPPER LEVEL SOUTHEASTERLY FLOW TO THE S OF THE
RIDGE. 

AN UPPER LEVEL TROUGH ENTERS THE FORECAST AREA NEAR 32N121W AND 
CONTINUES SW THROUGH 23N125W THEN CONTINUES AS A SHEAR AXIS 
THROUGH 21N135W TO A SMALL CYCLONIC CIRCULATION W OF THE AREA 
NEAR 19N142W. VERY DRY AIR ALOFT WITH MODERATE TO STRONG 
SUBSIDENCE IS PRESENT ACROSS THE REGION N OF 18N AND W OF 115W.  
EASTERLY FLOW PREVAILS ACROSS THE REMAINDER OF THE DISCUSSION 
AREA IN THE DEEP TROPICS S OF 10N. UPPER LEVEL MOISTURE 
RESULTING FROM ITCZ CONVECTION IS BEING ADVECTED TO THE WEST AS 
A RESULT OF THE PERSISTENT EASTERLY WINDS. UPPER LEVEL 
DIFFLUENCE IS HELPING TO INDUCE CONVECTION ALONG THE ITCZ W OF 
132W...AND ALSO BETWEEN 105W AND 118W.  

AT THE SURFACE...A RIDGE DOMINATES THE NORTHERN WATERS MAINLY N 
OF 18N AND W OF 115W. PRES GRADIENT BETWEEN THE RIDGE AND LOWER 
PRES OVER NW MEXICO IS PRODUCING DIURNALLY ENHANCED NW WINDS OF 
20 KT WITHIN 120 NM OF THE COAST OF BAJA CALIFORNIA. A MUCH 
EARLIER ASCAT PASS FROM 0428 UTC AND SHIP OBSERVATIONS VERIFIED 
THE EXISTENCE OF THESE WINDS. EXPECT N TO NE WINDS OF 20 KT 
ACROSS THE NW WATERS MAINLY N OF 23N AND W OF 125W OVER THE NEXT 
COUPLE OF DAYS AS THE PRES GRADIENT CONTINUES TO TIGHTEN BETWEEN 
HIGH PRES LOCATED NW OF AREA AND LOWER PRES OVER THE SW CONUS 
AND NW MEXICO.

A SURFACE TROUGH EXTENDS FROM 13N135W TO 09N136W. WINDS OF 20 KT 
AND SEAS TO 8 FT ARE OCCURRING WITHIN 150 NM NW OF THE TROUGH 
AXIS N OF 11N. THESE MARINE CONDITIONS WILL PERSIST AHEAD OF THE 
TROUGH DURING THE NEXT 24-36 HOURS WITH THE TROUGH EXPECTED TO 
MOVE W OF THE AREA THEREAFTER. 

ITCZ DISTURBANCES CONTINUE TO PRODUCE A BELT OF SW WINDS OF 20 
KT IN AN AREAS FROM 09N TO 13N BETWEEN 95W AND 123W. THIS 
WEATHER PATTERN WILL PERSIST DURING THE NEXT FEW DAYS. 

CROSS EQUATORIAL SW SWELLS WITH PERIODS OF 14-16 SECONDS 
DOMINATE THE MAJORITY OF THE FORECAST WATERS. THESE SWELLS WILL 
GRADUALLY DECAY THROUGH MON AS A NEW SWELL TRAIN CROSSES THE 
EQUATOR BETWEEN 105W AND 125W. 

$$
COBB