000
AXPZ20 KNHC 072159
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...SPECIAL FEATURES...
TROPICAL STORM GILMA CENTERED AT 15.1N 113.9W AT 2100 UTC MOVING 
W-NW OR 295 DEGREES AT 10 KT AND EXPECTED TO CONTINUE OVER NEXT 
COUPLE OF DAYS THEN SLOW DOWN ITS PACE TO A CRAWL AS STEERING 
CURRENTS WEAKEN.  MINIMUM CENTRAL PRES IS 1001 MB WITH MAXIMUM 
WIND SPEED 40 GUSTS TO 50 KT.  NUMEROUS MODERATE TO STRONG 
CONVECTION WITHIN 45 NM OF CENTER.  SCATTERED MODERATE ISOLATED 
STRONG CONVECTION ELSEWHERE FROM 13N TO 16N BETWEEN 112W AND 
118W.  PRESENTLY GILMA REMAINS UNDER FAVORABLE UPPER LEVEL 
ENVIRONMENT AND OVER 29 DEGREES SST INDICATING ITS POTENTIAL  
FOR STRENGTHENING REMAINS HIGH FOR THE NEXT 48 HRS.  AFTER THAT 
...BOTH UPPER AND LOWER LEVELS BECOME LESS CONDUCIVE FOR 
DEVELOPMENT AND GILMA IS EXPECTED TO HOLD OR DAMPER ITS INITIAL 
INTENSIFICATION.  GUIDANCE SOLUTIONS CARRY VERY LOW CONFIDENCE 
DUE TO THEIR DIVERSITY...UNCERTAINTY AND POSSIBLY THE ADDITION 
OF CURRENT ATLC HURRICANE 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 139W FROM 09N TO 14N MOVES W AT 10 KT. 
CONVECTION ALL BUT GONE AS DRY AIR MASS UNDER MID TO UPPER LEVEL 
RIDGE COVERS REGION W OF 128W.  TIGHT PRES GRADIENT BETWEEN WAVE 
CREST AND RIDGE ALONG 28N PROMPTS FRESH NE BREEZE W OF 132W.  
WAVE EXPECTED TO MOVE OUT OF AREA TONIGHT AND WINDS DIMINISH 
WITHIN NEXT 24 HRS.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...MONSOON 
TROUGH AXIS FROM 108N78W TO 11N90W TO 1009 MB LOW AT 10N101W TO 
13N106W. THEN CONTINUES FROM 13N116W TO 10N120W TO 10N130W. ITCZ 
EXTENDS FROM 10N130W TO BEYOND 11N140W.  SCATTERED MODERATE FROM 
07N TO 12N BETWEEN 100W AND 104W...AND FROM 05N TO 09N BETWEEN 
120W AND 128W.

...DISCUSSION...
BROAD ANTICYCLONE AT 18N140W EXTENDS RIDGE SOUTHEASTWARD TO 
13N125W WITH VERY DRY SUBSIDING AIR MASS COVERING LARGE REGION  
N OF 10N W OF 128W.  WELL DEFINED CYCLONE AT 20N125W CONTRIBUTES 
TO EXTEND DRY AIR MASS TO 118W N OF 16N.  SECOND ANTICYCLONE N 
OF AREA ALONG 114W PROVIDES TROPICAL STORM GILMA WITH MODERATE 
DIVERGENT FLOW ALOFT TO ENHANCE ITS OUTFLOW ALOFT AND MAINTAIN 
ITS DEEP CONVECTION.  THIRD ANTICYCLONE OVER GULF OF HONDURAS 
AND CARIBBEAN HURRICANE ERNESTO MAINTAINS STEADY FLOW OF WARM 
AND MOIST TROPICAL AIR MASS INTO E PAC E OF 92W INCREASING 
CONVECTIVE ACTION IN THE AREA. 

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 WED INDUCED BY 
PRES GRADIENT BETWEEN HIGHER PRES IN SW GULF OF MEXICO.  FLOW IS 
ENHANCED BY APPROACH OF HURRICANE ERNESTO...BUT FLOW IS CUT OFF 
ONCE ERNESTO MOVES W OF 93W-94W EARLY THU.

$$
WALLY BARNES