000
AXPZ20 KNHC 130321
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU AUG 13 2009

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0330 UTC.

...SPECIAL FEATURES...

TROPICAL STORM GUILLERMO NEAR 16.2 119.2W OR ABOUT 600 NM SW OF 
THE SOUTHERN TIP OF BAJA CALIFORNIA AT 0300 UTC AUG 13. 
GUILLERMO WAS MOVING TOWARD THE WEST-NORTHWEST OR 290 DEGREES AT 
14 KT. MAXIMUM SUSTAINED WINDS WERE NEAR 35 KT WITH GUSTS TO 45 
KT. ESTIMATED MINIMUM CENTRAL PRESSURE WAS 1004 MB. SEE THE 
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS 
MIATCMEP5/WTPZ25 KNHC FOR MORE DETAILS. CONVECTION IS BECOMING A 
LITTLE MORE ORGANIZED WRAPPING AROUND GUILLERMO AS THE STORM 
MOVES WEST INTO A MORE FAVORABLE ENVIRONMENT ON THE SOUTHWEST 
SIDE OF AN UPPER LEVEL ANTICYLONE. T.S GUILLERMO IS EXPECTED TO 
STRENGTHEN FURTHER INTO FRIDAY.

...TROPICAL WAVES...

A TROPICAL WAVE WAS ANALYZED ALONG 87W N OF 03N MOVING W NEAR 15 
KT. NO SIGNIFICANT CONVECTION WAS NOTED WITH THIS FEATURE.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE WAS ANALYZED ALONG THE 
LINE...07N78W TO 07N100W TO 14N115W TO 09N130W TO 08N140W. 
SCATTERED MODERATE WITHIN 210 NM S OF AXIS BETWEEN 95W AND 110W.

...DISCUSSION...

E OF 110W...AN UPPER LEVEL LOW IS CENTERED OVER THE MEXICAN 
COAST NW OF ACAPULCO. DIVERGENCE ALOFT ON THE SE SIDE OF THE LOW 
IS ENHANCING POCKETS OF MODERATE CONVECTION N OF THE ITCZ 
BETWEEN 95W AND 100W. SSMI IMAGERY FROM THIS MORNING HINTED OF 
CONTINUED 20 KT WINDS THROUGH THE GULF OF TEHUANTEPEC...LIKELY 
RELATED TO A WEAK SURFACE FEATURE ASSOCIATED WITH THE UPPER LOW. 
THESE WINDS WILL GRADUALLY DIMINISH THROUGH THU AS THE UPPER LOW 
MOVES EAST. SCATTEROMETER DATA ALSO INDICATED 20 KT WINDS 
PERSISTING THROUGH THE GULF OF PAPAGAYO DUE TO ENHANCED TRADE 
WIND FLOW IN THE CARIBBEAN. SCATTERED CONVECTION WAS FLARING OFF 
THE COASTS OF PANAMA AND COSTA RICA...WHERE THE AFOREMENTIONED 
TROPICAL WAVE WAS MIGRATING WEST ALONG THE ITCZ. LITTLE CHANGE 
IS EXPECTED THROUGH 48 HOURS.

W OF 110W...A WEAK UPPER TROUGH EXTENDS FROM 30N122W TO 23N125W. 
THIS SPLITS TWO UPPER ANTICYCLONES...ONE OFF THE SOUTHERN BAJA 
COAST...AND THE OTHER CENTERED OVER 21N135W. DIVERGENT FLOW TO 
THE SW THE UPPER ANTICYCLONE OFF BAJA IS ENHANCING CONVECTION 
OVER TROPICAL STORM GUILLERMO. DEEP LAYER DRY SUBSIDENT FLOW IS 
SUPPRESSING CONVECTION OVER WHAT WAS T.D. NINE-E. CONVECTION HAS 
DIMINISHED SO MUCH THAT THE DEPRESSION IS NOW LITTLE MORE THAN A 
WEAK SWIRL NEAR 15N133W.

A MIX OF CROSS-EQUATORIAL SE AND SW SWELLS CONTINUE TO BE THE 
DOMINANT WAVE ENERGY AFFECTING THESE EASTERN PACIFIC WATERS... 
WITH A NEW PULSE OF LONG PERIOD SRN HEMISPHERE SWELL TO REACH 
THE CENTRAL AMERICAN COAST LATE SAT INTO EARLY SUN. BROAD FIELDS 
OF 20 KT WINDS ACROSS THE NRN PORTIONS OF TROPICAL WAVES AND LOW 
TRANSITING THE BASIN CONTINUE TO RAISE SEAS A FEW FEET 
HIGHER...TO 8 FT AND GREATER ACROSS THESE ZONES. 

$$
CHRISTENSEN