000
AXPZ20 KNHC 070930
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SAT AUG 07 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.

...SPECIAL FEATURE...

AT 07/0900 UTC...THE CENTER OF TROPICAL STORM ESTELLE IS LOCATED 
NEAR 16.8N 106.2W MOVING TOWARD THE WEST OR 270 DEGREES AT 9 KT. 
A WEST-NORTHWESTWARD MOTION IS EXPECTED TO RESUME LATER TODAY 
FOLLOWED BY A DECREASE IN FORWARD SPEED. ON THIS TRACK...ESTELLE 
WILL CONTINUE TO MOVE WELL AWAY FROM THE COAST OF SOUTHWEST 
MEXICO. 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 0344 UTC TRMM PASS AND A 0416 UTC AMSU PASS 
INDICATE THAT THE LOW-LEVEL CENTER OF ESTELLE REFORMED ABOUT 50 
MILES TO THE SOUTH OF THE PREVIOUSLY ESTIMATED LOCATION. 
CONVECTION HAS INCREASED AGAIN NEAR THE CENTER WITH A DEVELOPING 
CENTRAL DENSE OVERCAST. NUMEROUS MODERATE TO STRONG CONVECTION 
IS NOTED WITHIN 40 NM OF CENTER.

...ITCZ...

THE ITCZ AXIS IS ALONG 09N85W TO 09N100W TO 12N115W TO 10N132W 
TO 09N140W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS  
WITHIN 120 NM EITHER SIDE OF AXIS BETWEEN 102W AND 118W. 
SCATTERED MODERATE CONVECTION IS WITHIN 50 NM OF AXIS BETWEEN 
85W AND 88W. SIMILAR CONVECTION IS ALSO NOTED FROM 08N TO 11N W 
OF 130W.
 
...DISCUSSION...

AN UPPER LEVEL ANTICYCLONE DOMINATING THE NW WATERS IS CENTERED 
NEAR 26N138W WITH AN UPPER RIDGE EXTENDING BEYOND 32N138W. A 
SECOND UPPER LEVEL ANTICYCLONIC CIRCULATION IS LOCATED OVER NE 
TEXAS WITH THE ASSOCIATED RIDGE EXTENDING ACROSS NORTHERN 
MEXICO. ANOTHER ANTICYCLONE HAS DEVELOPED OVER SE MEXICO NEAR 
18N99W WITH A RIDGE EXTENDING NW BETWEEN ESTELLE AND SOUTHERN 
BAJA CALIFORNIA. 

AN UPPER LEVEL TROUGH ENTERS THE FORECAST AREA NEAR 31N122W AND 
CONTINUES SW TO A COL NEAR 22N133W. VERY DRY AIR ALOFT WITH 
MODERATE TO STRONG SUBSIDENCE IS PRESENT ACROSS THE REGION N OF 
20N AND W OF 117W. AN INVERTED TROUGH EXTENDS FROM 20N140W TO 
THE COL. 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 
126W.  

AT THE SURFACE...A RIDGE DOMINATES THE NORTHERN WATERS MAINLY N 
OF 18N. PRES GRADIENT BETWEEN THE RIDGE AND LOWER PRES OVER NW 
MEXICO IS STILL PRODUCING NW WINDS OF 20 KT N OF 26N E OF 118W 
TO THE COAST OF BAJA CALIFORNIA...AND N OF 29N BETWEEN 118 AND 
128W. AN 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 13N132W TO 09N137W. 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 
DISSIPATE THEREAFTER. 

ITCZ DISTURBANCES CONTINUE TO PRODUCE A BELT OF SW WINDS 20 KT 
PARTICULARLY 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 DURING THE NEXT 24 TO 48 HOURS. 

$$
GR