000
AXPZ20 KNHC 081600
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC WED AUG 08 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 
1545 UTC.

...SPECIAL FEATURES...
GILMA IS NEARING HURRICANE STRENGTH. AT 08/1500 UTC...GILMA WAS 
CENTERED NEAR 16.0N 117.1W MOVING W-NW OR 285 DEGREES AT 11 KT. 
ESTIMATED MINIMUM CENTRAL PRESSURE IS 989 MB. MAXIMUM SUSTAINED 
WINDS REMAIN 60 KT WITH GUSTS TO 75 KT. PLEASE SEE LATEST NHC 
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP2/WTPZ22 KNHC 
FOR MORE DETAILS. THERE HAS BEEN LITTLE CHANGE IN THE OVERALL 
ORGANIZATION OF THE CYCLONE OVERNIGHT. CURRENTLY NUMEROUS 
MODERATE TO STRONG CONVECTION IS NOTED WITHIN 60 NM OF THE 
CENTER. SIMILAR CONVECTION CAN BE FOUND IN A BAND WITHIN 90 NM 
IN TH SW QUADRANT OF THE CENTER ALONG 15N119W 14.5N117W 
15N116W...AN OUTER BAND WAS LOCATED WELL S OF THE CENTER FROM 
12N TO 14N BETWEEN 113W AND 117W. GILMA CONTINUES TO BECOME 
BETTER ORGANIZED OVER WARM WATERS AND IN A LOW SHEAR 
ENVIRONMENT. THEREFORE...IT IS FORECAST TO BECOME A HURRICANE 
LATER TODAY.  

A 1008 MB LOW PRES EMBEDDED IN THE MONSOON TROUGH IS LOCATED 
NEAR 11N103W. SHOWER AND THUNDERSTORM ACTIVITY ASSOCIATED WITH 
THIS SYSTEM HAVE ONCE AGAIN INCREASED AND WAS CONCENTRATED 
WITHIN 90 NM OF THE CENTER IN THE W SEMICIRCLE. THIS SYSTEM HAS 
A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE AS IT DRIFTS 
GENERALLY WESTWARD DURING THE NEXT 48 HOURS.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...MONSOON 
TROUGH EXTENDS FROM 14N89W TO 1008 MB LOW PRES NEAR 11N103W THEN 
CONTINUES W OF T.S. GILMA FROM 13N119W TO 09N130W. ITCZ AXIS IS 
FROM 09N130W TO BEYOND 10N140W. SCATTERED MODERATE FROM 05N TO 
14N BETWEEN 85W AND 95W...AND FROM 06N TO 08N BETWEEN 128W AND 
135W.

...DISCUSSION...
ALOFT...AN BROAD ANTICYCLONE OVER ARIZONA AND THE FOUR CORNERS 
OF THE SW CONUS EXTENDS A RIDGE SOUTHWESTWARD ACROSS BAJA 
CALIFORNIA THROUGH 27N130W TO 24N140W...GENERALLY TO THE NORTH
OF T.S. GILMA. UPPER DIFFLUENCE ASSOCIATED WITH THIS RIDGE IS 
HELPING TO SUSTAIN THE DEEP CONVECTION ASSOCIATED WITH THIS 
TROPICAL CYCLONE. WW OF THE RIDGE...THERE IS AN UPPER LEVEL LOW 
SPINNING NEAR 23N129W. STRONG W TO SW FLOW AHEAD OF A LONG WAVE 
TROUGH IS AFFECTING THE NW CORNER OF THE AREA. THESE WINDS ARE 
TRANSPORTING ABUNDANT MID/UPPER LEVEL MOSITURE. NE WINDS ALOFT 
ARE MAINLY S OF 12N AND E OF 110W. THESE WINDS ARE ENHANCING THE 
CONVECTION NEAR THE MONSOON TROUGH. 

AT THE SURFACE...A 1025 MB HIGH PRES LOCATED NEAR 33N142W 
EXTENDS A RIDGE OVER THE NORTHERN WATERS TO NEAR 24N115W. THE 
HIGH PRESSURE IS FORECAST TO MOVES NE AND SLIGHTLY INTENSIFY. 
TRADE WINDS IN THE 20 TO 25 KT RANGE ARE SEEN PER THE 0654 UTC 
ASCAT PASS COVERING THE AREA FROM 11N TO 17N W OF 134W. AS THE 
HIGH PRES MOVES NE...EXPECT THE AREA OF TRADES TO GRADUALLY MOVE 
W OF THE DISCUSSION AREA BY THU. AT THE SAME TIME...THE PRESSURE
GRADIENT WILL TIGHTEN NEAR THE COAST OF CALIFORNIA AND JUST N OF 
THE FORECAST REGION RESULTING IN NLY WINDS OF 20 KT OVER THE N 
WATERS MAINLY N OF 27N AND W OF 120W. SEAS OF AROUND 8 FT 
GENERATED BY THESE WINDS WILL REACH 30N THU NIGHT.  

CROSS EQUATORIAL LONG PERIOD SW SWELLS OF 17-18 SECONDS ARE NOW 
IMPACTING THE SOUTH-CENTRAL WATERS RAISING SEAS TO 8 FT MAINLY  
S OF 06N BETWEEN 115W AND 126W. THIS SWELL EVENT WILL CONTINUE 
TO PROPAGATE NWD OVER THE NEXT COUPLE OF DAYS...BUT SEAS WILL 
SUBSIDE TO LESS THAN 8 FT IN ABOUT 36-48 HOURS. 

GAP WINDS...NORTHERLY WINDS IN THE OUTER CIRCULATION OF T.S 
ERNESTO CURRENTLY OVER THE SOUTHERN YUCATAN PENINSULA ARE 
FUNNELING THROUGH THE CHIVELA PASS INTO THE GULF OF 
TEHUANTEPEC. HOWEVER AS THE STORM MOVES WESTWARD ACROSS THE 
SOUTHERN BAY OF CAMPECHE THE WINDS WILL BACK INTO THE NW AND W
AS EARLY AS LATE THIS AFTERNOON. 

$$
COBB