000
AXPZ20 KNHC 311543
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE AUG 31 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 
1500 UTC.

...SPECIAL FEATURE...

LOW PRES 1008 MB IS CENTERED NEAR 15N106W MOVING WNW AROUND 5 
KT. E TO SE WINDS OF 20 KT AND COMBINED SEAS TO 9 FT IN S TO SW 
SWELL ARE OCCURRING WITHIN 210 NM IN THE NE QUADRANT OF THE LOW 
CENTER. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS 
WITHIN 120 NM IN THE W SEMICIRCLE OF THE LOW CENTER. UPPER LEVEL 
WINDS APPEAR MARGINALLY CONDUCIVE FOR SOME SLOW DEVELOPMENT OF 
THIS SYSTEM AND THERE IS A MEDIUM CHANCE OF THIS SYSTEM BECOMING 
A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

...ITCZ...

INTERTROPICAL CONVERGENCE ZONE AXIS IS ANALYZED FROM 09N79W TO 
09N96W THEN RESUMES AT 12N109W TO 10N120W TO 11N130W TO 10140W. 
SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS WITHIN 300 
NM S OF THE AXIS AND E OF 81W. SIMILAR CONVECTION IS WITHIN 90 
NM S OF THE AXIS BETWEEN 81W AND 84W...AND ALSO WITHIN 90 NM N 
OF THE AXIS BETWEEN 94W TO 97W. SCATTERED MODERATE CONVECTION
IS WITHIN 120 NM N AND 90 NM S OF THE AXIS BETWEEN 109W AND 
114W. SIMILAR CONVECTION IS NEAR 11N130W.

...DISCUSSION...

ALOFT...A MID/UPPER LEVEL TROUGH EXTENDS FROM ARIZONA ACROSS
NW MEXICO AND NORTHERN BAJA CALIFORNIA TO NEAR 27N112W. A 
REINFORCING TROUGH IS MOVING SE FROM THE NE PACIFIC TOWARD 
NORTHERN CALIFORNIA. AN ANTICYCLONE IS POSITIONED JUST W OF THE 
AREA NEAR 14N142W WITH AN UPPER RIDGE EXTENDING TO A COL NEAR 
20N127W. SW FLOW EXTENDS FROM THE NORTHERN PERIPHERY OF THE 
ANTICYCLONE TO THE ABOVE MENTIONED TROUGH. WATER VAPOR SATELLITE 
IMAGERY INDICATES VERY DRY AIR UNDER MODERATE TO STRONG 
SUBSIDENCE ACROSS THE AREA N OF 20N AND W OF 116W. CONVECTION
IS BEING ENHANCED UNDER DIFFLUENT FLOW ON THE SE PERIPHERY OF 
THE RIDGE ALONG THE ITCZ W OF 126W.

ANOTHER ANTICYCLONE IS CENTERED OVER CENTRAL TEXAS WITH A RIDGE 
EXTENDING ACROSS NORTHERN MEXICO TO SOUTHERN BAJA CALIFORNIA TO 
NEAR 21N126W. AN INVERTED TROUGH HAS INTRUDED ON THE SOUTHERN 
SIDE OF THE RIDGE EXTENDING FROM 17N103W TO TO 26N99W. MAINLY 
ZONAL/NE TO E FLOW COVERS THE AREA SE OF A LINE FROM THE 
SOUTHERN TIP OF BAJA CALIFORNIA TO 10N126W WITH ABUNDANT DEEP 
LAYER TROPICAL MOISTURE OVER THE SE HALF OF THE DISCUSSION AREA.

AT THE SURFACE...THE REMNANT LOW OF FRANK IS POSITIONED NEAR 
21N111W WITH WINDS HAVING DIMINISHED TO 5-15 KT NEAR THE 
CIRCULATION CENTER AS CAPTURED BY A 0420 UTC ASCAT PASS. THIS
LOW IS NOW EXPECTED TO DISSIPATE LATER TODAY. 1035 MB HIGH PRES 
IS CENTERED WELL NW OF THE AREA NEAR 40N151W WITH A RIDGE AXIS 
EXTENDING INTO THE AREA NEAR 31N140W AND CONTINUING THROUGH 
27N129W TO 20N116W. NE TO E WINDS OF 10 TO 15 KT AND SEAS OF 4 
TO 7 FT DOMINATE THE AREA N OF THE ITCZ AND W OF 110W UNDER THE 
RIDGE. 

SW CONVERGENT FLOW S OF THE MONSOONAL TROUGH IS OCCURRING IN THE 
AREA FROM FROM 07N TO 14N BETWEEN 100W AND 113W...AND ALSO S OF 
THE ITCZ IN THE SE PORTION E OF 87W...WITH SW TO W WINDS OF 20 
TO 25 KT AND COMBINED SEAS OF 8 TO 12 FT IN SW SWELL. THESE 
CONDITIONS ARE EXPECTED TO PERSIST DURING THE NEXT 48 HOURS
OVER THE SAME GENERAL AREA.

OTHER MARINE CONCERNS...A SURGE OF CROSS-EQUATORIAL LONG PERIOD 
SOUTHERLY SWELL CONTINUES TO PROPAGATE NORTHWARD ACROSS THE 
FORECAST WATERS PRIMARILY E OF 126W. THESE SWELLS HAVE REACHED 
ALL THE WAY TO THE U.S. WEST COAST WITH PEAK WAVE PERIODS OF 15 
TO 17 SECONDS. THIS SWELL WILL START TO SIGNIFICANTLY SUBSIDE 
AROUND 48 HOURS.

$$
LEWITSKY