000
AXPZ20 KNHC 071607
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE AUG 07 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 
1500 UTC.

...SPECIAL FEATURES...
TROPICAL DEPRESSION SEVEN-E HAS BECOME TROPICAL STORM GILMA AT 
07/1500 UTC CENTERED AT 14.8N 112.6W.  GILMA MOVES W-NW OR 295 
DEGREES AT 10 KT AND EXPECTED TO CONTINUE OVER NEXT COUPLE OF 
DAYS.  MINIMUM CENTRAL PRES IS 1005 MB WITH MAXIMUM SUSTAINED 
WIND SPEED 35 KT GUSTS TO 45 KT.  NUMEROUS MODERATE TO STRONG 
CONVECTION WITHIN 45 NM OF CENTER.  SCATTERED MODERATE ISOLATED 
STRONG CONVECTION ELSEWHERE FROM 12N TO 17N BETWEEN 111W AND 
116W.  PRESENTLY GILMA REMAINS UNDER FAVORABLE UPPER LEVEL 
ENVIRONMENT AND OVER 29 DEGREES SST INDICATING ITS POTENTIAL  
FOR STRENGTHENING REMAINS HIGH FOR THE NEXT 72 HRS.  AFTER THAT 
...BOTH UPPER AND LOWER LEVELS BECOME LESS CONDUCIVE FOR 
DEVELOPMENT AND IS EXPECTED TO HOLD OR DAMPER ITS INITIAL 
INTENSIFICATION.  GUIDANCE SOLUTIONS CARRY VERY LOW CONFIDENCE 
DUE TO THEIR DIVERSITY...UNCERTAINTY AND THE ADDITION OF THE 
POSSIBILITY OF CURRENT ATLC TROPICAL STORM ERNESTO SURVIVING THE 
MOUNTAINS OF MEXICO AND INTRUDING INTO THE E PAC. SEE LATEST NHC 
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP2/WTPZ22 KNHC 
FOR MORE DETAILS. 

...TROPICAL WAVES...
WEAK TROPICAL WAVE ALONG 138W FROM 09N TO 17N MOVES W AT 15 KT. 
CONVECTION HAS DECREASED SIGNIFICANTLY AS DRY AIR MASS UNDER MID 
TO UPPER LEVEL RIDGE COVERS REGION W OF 130W.  TIGHT PRES 
GRADIENT BETWEEN WAVE CREST AND RIDGE ALONG 30N PROMPTS FRESH NE 
BREEZE W OF 132W.  WAVE EXPECTED TO MOVE OUT OF AREA WITHIN NEXT 
24 HRS. 

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...MONSOON 
TROUGH AXIS FROM 11N87W TO 09N99W T0 12N107W THEN RESUME FROM 
12N113W TO 11N118W TO 11N132W TO 10N135W...ITCZ THEREAFTER TO 
BEYOND 08N140W.  ISOLATED MODERATE CONVECTION WITHIN 90 NM OF 
AXIS E OF 103W AND WITHIN 240 NM S OF AXIS FROM 113W TO 126W. 

...DISCUSSION...
ALOFT...
BROAD ANTICYCLONE AT 18N140W EXTENDS RIDGE SOUTHEASTWARD TO 
14N130W WITH VERY DRY SUBSIDING AIR MASS COVERING LARGE REGION  
N OF 10N W OF 130W.  WELL DEFINED CYCLONE AT 20N123W CONTRIBUTES 
TO EXTEND DRY AIR MASS TO 118W.  SECOND ANTICYCLONE N OF AREA 
ALONG 110W PROVIDES TROPICAL STORM GILMA WITH MODERATE DIVERGENT 
FLOW ALOFT TO ENHANCE ITS CONVECTION. 

ELSEWHERE AT THE LOWER LEVELS...
SUBTROPICAL RIDGE EXTENDS ALONG 30N AS HIGH PRES IS FORCED E BY 
APPROACHING COLD FRONT CURRENTLY WELL W OF BASIN.  RIDGE 
MAINTAINS FRESH NE TRADES FROM 13N TO 18N W OF 132W. HIGH PRES 
WEAKENS WED DIMINISHING TRADES. 

GAP WINDS...FRESH TO STRONG NORTHERLY WINDS FUNNEL THROUGH 
CHIVELA PASS INTO GULF OF TEHUANTEPEC THROUGH EARLY WED INDUCED 
BY PRES GRADIENT BETWEEN RELATIVELY HIGHER SURFACE PRES IN SW 
GULF OF MEXICO AHEAD OF ATLANTIC TROPICAL STORM ERNESTO AND 
LOWER PRES ALONG MONSOON TROUGH S OF TEHUANTEPEC.

$$
WALLY BARNES