000
AXPZ20 KNHC 290243
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SUN AUG 29 2010

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0115 UTC.

...TROPICAL LOW...

THE REMNANT LOW OF FORMER TROPICAL DEPRESSION FRANK WAS CENTERED 
NEAR 21N112W AND CONSISTED OF A SWIRL OF LOW CLOUDS. THERE IS NO 
SIGNIFICANT CONVECTION CURRENTLY ASSOCIATED WITH THE LOW WHICH 
IS FORECAST TO DRIFT N-NE AND DIMINISH TO A TROUGH BY MON. THE 
EDGE OF A 1750 UTC ASCAT PASS INDICATED 20 KT WINDS AROUND THE 
PERIPHERAL CIRCULATION OF THE LOW OUT 120 NM FROM THE CENTER AND 
A SHIP NEAR 21N109W REPORTED 10 FT SEAS AT 0000 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 96W N OF 08N MOVING W NEAR 5 KT WITH AN 
ASSOCIATED 1008 MB LOW ALONG THE WAVE AXIS NEAR 12N. ISOLATED 
MODERATE TO STRONG CONVECTION LIES BETWEEN 90 NM AND 410 NM W OF 
THE WAVE FROM 08N TO 14N.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS IS ANALYZED FROM 09N83W 
TO 08N105W THEN RESUMES FROM 14N110W TO 11N125W TO 10N140W. 
SCATTERED MODERATE CONVECTION IS WITHIN 60 NM N AND 90 NM S OF 
THE ITCZ AXIS BETWEEN 86W AND 90W AS WELL AS BETWEEN 98W AND 
102W.

...DISCUSSION...

WATER VAPOR IMAGERY CONTINUES TO SHOW MODERATE TO STRONG 
SUBSIDENCE AND DRY AIR ALOFT OVER A LARGE PORTION OF THE AREA NW 
OF A LINE FROM 30N110W TO 15N140W. THE AREA N OF 20N IS 
DOMINATED BY A PAIR OF ANTICYCLONES...THE FIRST OVER EASTERN 
MEXICO NEAR 23N98W AND ONE OVER THE PACIFIC NEAR 24N132W. A 
NARROW RIDGE AXIS CONNECTS THE TWO ANTICYCLONES. UPPER LEVEL 
DIFFLUENT FLOW TO THE S AND E OF THE ANTICYCLONE OVER MEXICO IS 
ENHANCING CONVECTION OVER THE COASTAL AREAS S OF 20N WITH 
SCATTERED MODERATE TO STRONG CONVECTION NOTED WITHIN 45 NM OF 
THE COAST BETWEEN 96W AND 105W. 

THE SOUTHERN EXTENT OF AN AMPLIFYING BROAD UPPER LEVEL TROUGH
OFF THE CALIFORNIA COAST SPLITS THE TWO ANTICYCLONES NOTED ABOVE 
ALONG 121W WITH A COL NEAR 23N121W. MID LEVEL DEBRIS MOISTURE 
FROM THE REMNANT LOW OF FRANK IS BEING ADVECTED TO THE NE OVER 
BAJA CALIFORNIA AND NW MEXICO. UPPER LEVEL DIFFLUENCE ASSOCIATED 
WITH THE RIDGE AXIS ALOFT OVER MEXICO IS ENHANCING DIURNAL 
CONVECTION OVER THE SIERRA MADRE OCCIDENTAL MOUNTAINS FROM 21N 
TO 26N WHERE MOISTURE IS BECOMING MORE PLENTIFUL.

A STRONG SURFACE RIDGE COVERS THE AREA N OF 17N W OF 120W. THE 
PRES GRADIENT IS TIGHTENING OVER NE WATERS BETWEEN THE RIDGE AND 
ZONAL TROUGHING ALONG 34N AS WELL AS TROUGHING FROM THE REMNANTS 
OF FRANK...INCREASING WINDS TO 20 KT. THE PRES GRADIENT WILL 
RELAX AS THESE TROUGHS WEAKEN...WITH ONLY 20 KT WINDS CONFINED 
TO THE BAJA COASTLINE BY 48 HOURS. N SWELL FRONT PRES GRADIENT 
INDUCED WINDS N OF THE AREA WILL KEEP SEAS IN THE 8-9 FT RANGE 
HERE THROUGH THE PERIOD.

SURFACE TROUGHING WILL BUILD OVER WESTERN NORTH AMERICA AS THE 
REMNANT LOW OF FRANK MOVES NORTHWARD AND THE TROPICAL WAVE/LOW 
PRES CURRENTLY ALONG 96W PROGRESSES WESTWARD. IN TURN...THE 
SURFACE PRES GRADIENT BETWEEN THIS MEAN TROUGHING AND HIGHER 
PRES S OF THE ITCZ WILL BUILD...INCREASING SW WINDS TO 20 TO 25 
KT IN THE REGION GENERALLY S OF 13N BETWEEN 90W AND 110W TONIGHT 
THROUGH MON. THESE WINDS ARE EXPECTED TO FEED INTO THE TROPICAL 
WAVE AND AREA OF LOW PRES.

A NEW SURGE OF CROSS-EQUATORIAL SWELL OF 15 TO 17 SECONDS IS 
MOVING NORTHWARD ACROSS THE FORECAST WATERS S OF 10N E OF 117W. 
THESE SWELLS WILL ARRIVE ON THE COAST OF MEXICO AND CENTRAL 
AMERICA SUN AND SPREAD NWD TO BAJA CALIFORNIA MON. SEAS OFFSHORE 
OF THE COASTAL AREAS OF CENTRAL AMERICA ARE EXPECTED TO REACH 8 
FT AS FAR N AS 13N BY THE END OF THE PERIOD MON EVENING.

$$
COBB/SCHAUER