000
AXPZ20 KNHC 301556
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON AUG 30 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.

...ITCZ...

INTERTROPICAL CONVERGENCE ZONE AXIS ANALYZED FROM 11N86W TO 
15N97W THEN RESUMES FROM 10N101W TO 09N106W TO 12N130W TO 
11N140W. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 90 NM 
OF THE AXIS E OF 97W. SCATTERED MODERATE AND ISOLATED STRONG 
CONVECTION IS WITHIN 60 NM OF THE AXIS FROM 102W TO 112W. 
SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 60 NM OF THE 
AXIS FROM 112W TO 130W.

...DISCUSSION...

ALOFT...A DEEP TROUGH EXTENDS FROM NEAR THE U.S. CALIFORNIA AND 
MEXICO BORDER NEAR 32N117W TO 28N120W TO 18N124W. THIS TROUGH IS 
CREATING A WEAKNESS IN THE SUBTROPICAL RIDGE WHICH EXTENDS FROM 
AN ANTICYCLONE LOCATED IN THE RIO GRANDE VALLEY TO 25N108W 
ACROSS THE SOUTHERN TIP OF BAJA CALIFORNIA TO 18N120W THEN 
FLATTENS AS IT REACHES TO 21N140W. DIFFLUENT EASTERLY FLOW 
PREVAILS NEAR THE MEXICAN COAST BETWEEN THIS ANTICYCLONE AND AN 
INVERTED TROUGH EXTENDING FROM NEAR THE GULF OF TEHUANTEPEC TO 
23N92W. 

SURFACE...THE REMNANT LOW OF FRANK IS POSITIONED NEAR 20N111W 
WITH WINDS HAVING DIMINISHED TO 10-15 KT NEAR THE CIRCULATION 
CENTER. THIS LOW IS EXPECTED TO FINALLY DISSIPATE BY TONIGHT. A 
TIGHT PRES GRADIENT EXISTS N OF 27N W OF BAJA CALIFORNIA TO 118W 
BETWEEN THE SEMI-PERMANENT TROUGH OF LOW PRES OVER THE GULF OF 
CALIFORNIA AND A RIDGE WHICH EXTENDS FROM 1035 MB HIGH PRES 
CENTERED WELL NW OF THE AREA NEAR 42N155W TO 32N136W TO 25N127W 
TO 16N117W. NW-N WINDS OF 20 KT ARE OCCURRING IN THIS AREA WITH 
SEAS TO 8 FT PRIMARILY IN NW SWELL. THE WINDS WILL DIMINISH AND 
SEAS WILL SUBSIDE TONIGHT AS THE PRES GRADIENT RELAXES. 

A 1008 MB AREA OF LOW PRES IS CENTERED NEAR 14N100W. THE LOW IS 
EXPECTED TO GRADUALLY DEEPEN AS IT MOVES NW AROUND 5 KT DURING 
THE NEXT 48 HOURS. WEST TO SOUTHWESTERLY LOW LEVEL CONVERGENT 
FLOW WITH WINDS OF 20-25 KT EXISTS S OF THE LOW AND S OF THE 
ITCZ IN THE AREA FROM 03N TO 12N BETWEEN 92W AND 118W WITH 
COMBINED SEAS OF 8-11 FT IN SW SWELL. CONVECTION NEAR THE LOW IS 
AS DESCRIBED IN THE ITCZ SECTION ABOVE.

OTHER MARINE CONCERNS...A SURGE OF CROSS-EQUATORIAL LONG PERIOD
SOUTHERLY SWELL CONTINUES TO PROPAGATE NORTHWARD ACROSS THE 
FORECAST WATERS E OF 120W. THESE SWELLS HAVE REACHED ALL THE WAY 
TO THE COAST OF U.S. SOUTHERN CALIFORNIA WITH PEAK WAVE PERIODS 
OF 15-18 SECONDS. NW SWELL GENERATED BY A LOW PRES SYSTEM 
OFFSHORE OF THE U.S. PACIFIC NW COAST WILL PROPAGATE INTO THE NE 
PORTION OF THE AREA DURING THE NEXT FEW DAYS CONVERGING WITH THE 
SOUTHERLY SWELL RESULTING IN CONFUSED SEAS.

$$
LEWITSKY