000
AXPZ20 KNHC 230931
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC MON AUG 23 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 FEATURES...

AT 23/0900 UTC...TROPICAL STORM FRANK IS CENTERED NEAR 14.3N 
97.5W MOVING WEST OR 285 DEGREES AT 7 KT. A TURN TOWARD THE 
WEST-NORTHWEST IS EXPECTED TODAY. ON THE FORECAST TRACK...FRANK 
WILL BE MOVING PARALLEL TO THE COAST OF SOUTHERN MEXICO THROUGH 
TUESDAY. ESTIMATED MINIMUM CENTRAL PRESSURE IS 998 MB. MAXIMUM 
SUSTAINED WINDS ARE 50 KT WITH GUSTS TO 60 KT. SEE LATEST NHC 
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP4/WTPZ24 KNHC 
FOR MORE DETAILS. NUMEROUS MODERATE TO STRONG CONVECTION IS 
NOTED WITHIN 120 NM W SEMICIRCLE. ENVIRONMENTAL CONDITIONS 
APPEAR CONDUCIVE FOR INTENSIFICATION SO FRANK IS FORECAST TO 
BECOME A HURRICANE TONIGHT. TROPICAL STORM WARNING AND WATCH ARE 
EXTENDED WESTWARD ALONG THE COAST OF MEXICO.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS IS ALONG 11N98W TO 
09N110W TO 11N122W THEN FROM 11N127W TO 10N140W. NO SIGNIFICANT 
CONVECTION.

...DISCUSSION...

ALOFT...AN UPPER LEVEL ANTICYCLONE IS CENTERED OVER N CENTRAL 
NEW MEXICO EXTENDING A RIDGE TO ACROSS NW MEXICO TO 30N129W TO 
BEYOND 18N140W. AN INVERTED UPPER-LEVEL TROUGH EXTENDS FROM 
31N122W TO 22N124W. ABUNDANT MID/UPPER LEVEL MOISTURE IS N OF 
18N BETWEEN 120W AND 132W. VERY DRY AIR ALOFT UNDER MODERATE TO 
STRONG SUBSIDENCE COVERS THE AREA N OF 16N AND W OF 132W AS 
INDICATED BY WATER VAPOR SATELLITE IMAGERY. AN UPPER-LEVEL LOW 
HAS DEVELOPED NEAR 20N108W AND IS HELPING TO INDUCE SOME SHOWER 
AND TSTM ACTIVITY ALONG THE COAST OF MEXICO BETWEEN JALISCO AND 
SINALOA. NE TO E FLOW PREVAILS OVER THE MAJORITY OF THE TROPICS 
WITH THE EXCEPTION OF THE REGION SURROUNDING T.S. FRANK WHICH IS 
UNDER AN UPPER RIDGE EXTENDING FROM AN ANTICYCLONIC CIRCULATION 
LOCATED IN THE NW GULF OF MEXICO TO THE GULF OF TEHUANTEPEC. 

AT THE SURFACE...A RIDGE DOMINATES THE AREA ROUGHLY N OF 20N AND 
W OF 120W PRODUCING MODERATE TO FRESH BREEZE. SOME SHIP REPORTS 
INDICATED N TO NE WINDS OF 20N COVERING THE AREA N OF 24N W OF 
120W. A 1010 MB AREA OF LOW PRES...THE REMNANT OF T.D. 
EIGHT-E...IS CENTERED NEAR 21N115W. A SWIRL OF LOW LEVEL CLOUD 
IS STILL ASSOCIATED WITH THIS FEATURE. A SURFACE TROUGH IS 
ANALYZED FROM 14N126W TO 11N123W. SCATTERED MODERATE CONVECTION 
IS WITHIN 90 NM E OF TROUGH. ANOTHER WEAK LOW IS LOCATED NEAR 
14N130W. NO SIGNIFICANT CONVECTION IS NOTED WITH THIS LOW WHICH 
IS EXPECTED TO DISSIPATE WITHIN THE NEXT 24 HOURS.

CROSS EQUATORIAL S AND SW SWELL WITH PEAK WAVE PERIODS OF 18-20 
SECONDS CONTINUES TO AFFECT THE SOUTH WATERS MAINLY S OF 15N 
WITH COMBINED SEAS OF 8-11 FT. THIS SWELL EVENT WILL CONTINUE TO 
PROPAGATE AND EXPAND TO THE N-NE THROUGH THE NEXT 48 HOURS WHILE 
NORTHERLY SWELL OF 8-9 FT MOVES S OF 30N OVER THE N CENTRAL 
WATERS BEGINNING AROUND 18 HOURS AND CONTINUING THROUGH AT LEAST 
48 HOURS.

$$
GR