000
AXPZ20 KNHC 311627
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI AUG 31 2012

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1515 UTC.

...SPECIAL FEATURE...
HURRICANE ILEANA NEAR 22.0N 115.4W 985 MB AT 1500 UTC AUG 31 
MOVING NW OR 310 DEG AT 7 KT. MINIMUM CENTRAL PRES 985 MB WITH  
MAXIMUM SUSTAINED WINDS 65 KT WITH GUSTS TO 80 KT. NUMEROUS 
STRONG CONVECTION WAS NOTED WITHIN 45 NM OF CENTER...WHILE 
SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS WITHIN 90 NM 
OF CENTER. ILEANA IS QUICKLY APPROACHING COOLER SST'S...AND 
DRIER MUCH MORE STABLE AIR IS APPARENT IS SATELLITE IMAGERY 
WITHIN 180 NM ACROSS THE W SEMICIRCLE. ILEANA HAS PEAKED IN 
INTENSITY AND WILL BEGIN TO WEAKEN SHORTLY AS IT MOVES ON A W-NW 
TRACK. AS THE SYSTEM WEAKENS SIGNIFICANTLY WITHIN 48 HOURS...A 
GRADUAL TRACK TOWARD THE WEST IS ANTICIPATED. SEE LATEST NHC 
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP4/WTPZ24 KNHC 
FOR MORE DETAILS. LARGE SOUTH AND SOUTHEAST SWELL FROM ILEANA IS 
STRONGLY IMPACTING THE SOUTH HALF OF THE BAJA CALIFORNIA PACIFIC 
COASTLINE...AS WELL AS INSIDE THE GULF OF CALIFORNIA. 

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH AXIS EXTENDS FROM COLOMBIA NEAR 10N71W TO 10N82W 
TO 14N92W TO LOW PRES 1009 MB NEAR 12N97.5W TO 18N107W TO 
10N125W TO 11N140W. SCATTERED MODERATE ISOLATED STRONG N OF 06N 
E OF 82W. SCATTERED TO LOCALLY NUMEROUS MODERATE TO STRONG N OF 
06.5N BETWEEN 89W AND 108W. SCATTERED MODERATE ISOLATED STRONG 
WITHIN 120 NM S OF TROUGH AXIS BETWEEN 110W AND 121W.

...DISCUSSION...
A BROAD MIDDLE/UPPER LEVEL TROUGH DOMINATES THE NE PACIFIC AND 
EXTENDS S TO 25N. UPPER LEVEL ANTICYCLONES WERE NOTED TO THE NE 
AND SW OF ILEANA...AND WILL BE FORCED WWD DURING THE NEXT FEW 
DAYS AS THE UPPER TROUGH LIFTS OUT TO THE NE AND UPPER RIDGING 
ACROSS THE GULF OF MEXICO BUILDS W INTO THE FAR EPAC N OF 20N. 
NELY UPPER LEVEL FLOW GENERALLY DOMINATES THE REST OF THE 
TROPICAL AREA S OF 20N E OF 130W. ABUNDANT TROPICAL MOISTURE HAS 
CONVERGED IN THE VICINITY OF THE MONSOON TROUGH E OF 107W...WITH 
A BROAD LLVL CYCLONIC CIRCULATION CENTERED NEAR 12N AND 98W. 
SEVERAL LLVL VORTICES ARE SUGGESTED WITHIN THIS CIRCULATION IN 
RECENT VISIBLE IMAGERY. GLOBAL MODELS MOVE THIS CIRCULATION ON A 
GENERAL W TO WNW TRACK OVER THE NEXT FEW DAYS...WITH MODEST 
POTENTIAL FOR IMPROVED CIRCULATION. THE PRES GRADIENT BETWEEN 
THIS CIRCULATION AND HIGH PRES RIDGING INTO THE GULF OF MEXICO 
IS EXPECTED TO PRODUCE WINDS 20 TO 25 KT ACROSS THE NE 
SEMICIRCLE OF THIS BROAD AREA DURING THE NEXT FEW DAYS.
SCATTERED TO NUMEROUS DEEP CONVECTION MENTIONED ABOVE IS 
OCCURRING NEAR THE MONSOON TROUGH...AND INDUCING DIVERGENT NE 
FLOW ALOFT...OVERHEAD OF THE DEEP CELLS.

VERY LONG PERIOD CROSS EQUATORIAL SW SWELL HAS MOVED INTO THE 
ENTIRE MARINE AREA DURING THE PAST 18-24 HOURS...AND IS EXPECTED 
TO PEAK TODAY THROUGH TONIGHT. MODERATE TO LARGE SW SWELL OF 
7-10 FT AT 14 TO 18 SECONDS WILL PRODUCE VERY LARGE AND POWERFUL 
SURF ACROSS THE SHOALS...REEFS...AND BEACHES OF ALL EXPOSED 
COASTLINES FROM COLOMBIA TO MEXICO. THIS DANGEROUS SURF WILL 
PRODUCE WIDESPREAD AND VERY STRONG RIP CURRENTS WITHIN THE SURF 
ZONE THROUGH THE WEEKEND. MORNING ALTIMETER PASSES SUGGEST WWIII 
FORECASTS FOR THE REGION ARE UP TO 2 FEET TOO LOW...AND WE ARE 
BASING OUR FORECASTS TOWARD THE WW ENSEMBLES AND ECMWF FORECASTS.

$$
STRIPLING