000
AXPZ20 KNHC 281554
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT AUG 28 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 
1545 UTC.

...SPECIAL FEATURES...

TROPICAL DEPRESSION FRANK IS CENTERED NEAR 20.8N 112.3W MOVING N 
OR 010 DEG AT 5 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1005 
MB. MAXIMUM SUSTAINED WINDS ARE 30 KT WITH GUSTS TO 40 KT.  
FRANK CONSISTS OF A SWIRL OF LOW CLOUDS AND IS EXPECTED TO 
DEGENERATE INTO A REMNANT LOW LATER TODAY. THE LAST ADVISORY HAS 
BEEN ISSUED FOR FRANK UNDER AWIPS/WMO HEADERS MIATCMEP4/ WTPZ24 
KNHC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 94W/95W N OF 08N MOVING W NEAR 10 KT
WITH AN ASSOCIATED 1007 MB LOW ALONG THE WAVE AXIS NEAR 14N. 
SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 120 NM W OF 
THE WAVE AXIS AND LOW PRES FROM 13N TO 15.5N. 

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS IS ANALYZED FROM 09N84W 
TO 05N94W TO 08N105W THEN RESUMES NEAR 12N112W TO 08N118W TO 
11N130W TO 09N140W. SCATTERED MODERATE WITHIN 120 NM EITHER SIDE 
OF AXIS BETWEEN 112W AND 120W. 

...DISCUSSION...

WATER VAPOR IMAGERY SHOWS 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 22N100W AND 
A LARGER ONE NEAR 24N133W. 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 EAST 
PACIFIC FROM 09N TO THE COAST OF MEXICO BETWEEN 95W AND 105W.

THE SOUTHERN EXTENT OF AN AMPLIFYING BROAD UPPER LEVEL TROUGH
SPLITS THE TWO ANTICYCLONES NOTED ABOVE ALONG 123W WITH A COL 
NEAR 23N123W. MID AND UPPER LEVEL DEBRIS MOISTURE FROM T.S. 
FRANK AND CONVECTION NOTED EARLIER ALONG THE SIERRA MADRE WAS 
BEING ADVECTED TO THE NE OVER BAJA CALIFORNIA AND NW MEXICO. 

STRONG SURFACE RIDGE COVERS THE AREA N OF 18N W OF 120W. PRES 
GRADIENT IS FORECAST TO TIGHTEN THUS INCREASING WINDS TO 20 KT 
AND BUILDING SEAS TO 9 FT OVER THE NEXT 24 HOURS MAINLY N OF 25N 
E OF 120W. THE RIDGE WILL THEN RELAX WITH ONLY 20 KT WINDS ALONG 
THE BAJA COASTLINE BY 48 HOURS.  

SURFACE TROUGHING WILL BUILD OVER WESTERN NORTH AMERICA AS THE 
REMNANT LOW OF FRANK MOVES NORTHWARD AND THE TROPICAL WAVE/LOW 
PRES CURRENTLY ALONG 94W PROGRESSES WESTWARD. IN TURN...THE 
SURFACE PRES GRADIENT BETWEEN THIS MEAN TROUGHING AND HIGHER 
PRES S OF THE ITCZ WILL BUILD INCREASING SW WINDS 20 TO 25 KT IN 
THE REGION S OF 11N BETWEEN 90W AND 105W DURING THE WEEKEND. 
THESE WINDS ARE EXPECTED TO FEED INTO THE TROPICAL WAVE AND AREA 
OF LOW PRES OVER THE WEEKEND INTO THE FIRST OF THE WEEK.

THE LAST ROUND OF S SWELL THAT MOVED NORTHWARD OVER E FORECAST 
WATERS THE PAST FEW DAYS IS BEGINNING TO SUBSIDE. A NEW SURGE OF 
CROSS-EQUATORIAL SWELL IS MOVING INTO THE AREA BUT SEAS WILL 
REMAIN BELOW 9 FT OVER THE EASTERN AND CENTRAL WATERS THROUGH 
SUN NIGHT.

$$
COBB