000
AXPZ20 KNHC 070304
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0045 UTC.

...SPECIAL FEATURES...
1008 MB LOW PRES IS NEAR 13.5N110W WITH AN ATTENDANT TROPICAL 
WAVE EXTENDING N OF THE LOW TO 20N110W. THIS WAVE AND LOW ARE 
MOVING W-NW AROUND 10 KT. SCATTERED MODERATE WITH ISOLATED 
STRONG CONVECTION WAS WITHIN 120 NM NW QUADRANT OF THE LOW PRES 
CENTER WHILE SCATTERED MODERATE CONVECTION WAS ELSEWHERE WITHIN 
210 NM NW SEMICIRCLE OF LOW PRES AND WITHIN 180 NM EITHER SIDE 
OF THE WAVE FROM 15N TO 17N. 20-25 KT WINDS ARE BELIEVED TO BE 
WITHIN 60 NM OF THE CENTER OF THE LOW. HOWEVER...THERE HAVE BEEN 
FEW SHIP OBSERVATIONS AND THE 1646 UTC ASCAT PASS JUST CLIPPED 
THE WESTERN SIDE OF THE CIRCULATION THIS AFTERNOON. 
ENVIRONMENTAL CONDITIONS APPEAR CONDUCIVE FOR DEVELOPMENT...AND 
THIS LOW MAY BECOME A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

...TROPICAL WAVES...
A TROPICAL WAVE EXTENDS ALONG 135W FROM 09N TO 17N. THIS 
TROPICAL WAVE IS MOVING W AROUND 10-15 KT. SIGNIFICANT DEEP 
CONVECTION ASSOCIATED WITH THE WAVE IS CONFINED TO NEAR THE 
WESTERN EDGE OF ITCZ FOUND JUST S OF THE WAVE...WITH SCATTERED 
MODERATE CONVECTION FOUND FROM 07N TO 10N W OF 132W. THE PRES 
GRADIENT BETWEEN THE SURFACE TROUGHING ASSOCIATED WITH THE WAVE 
AND THE SUBTROPICAL RIDGE SHOULD BE STRONG ENOUGH FOR FRESH TO 
STRONG WINDS TO BUILD NEAR THE WAVE OVER THE W CENTRAL WATERS 
DURING THE NEXT FEW DAYS JUST BEFORE IT MOVES W OF THE AREA.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH AXIS WAS ANALYZED FROM 08N78W TO 10N90W TO 
09N98W TO 13N109W TO 10N116W TO 10N130W. THE ITCZ AXIS WAS 
ANALYZED FROM 10N130W TO 09N140W. SCATTERED MODERATE CONVECTION 
WAS WITHIN 180 NM NE AND SW OF THE AXIS BETWEEN 101W AND 104W AS 
WELL AS BETWEEN 75 NM AND 180 NM S OF THE AXIS BETWEEN 108W AND 
113W.

...DISCUSSION...
A WEAK SUBTROPICAL RIDGE EXTENDS OVER MUCH OF THE AREA N OF 10N 
W OF 115W. THE RIDGE WILL BUILD THROUGH TUE AS THE SUBTROPICAL 
HIGH CONSOLIDATES NW OF THE FORECAST AREA AND WILL SLOWLY BEGIN 
TO WEAKEN WED AS A COLD FRONT APPROACHES THE HIGH FROM THE NW. 
LIGHT TO MODERATE WINDS ARE CURRENTLY UNDERNEATH THIS RIDGE. 
MODERATE TO FRESH WINDS ARE EXPECTED TO BUILD NEAR THE TROPICAL 
WAVE ALONG 135W ON TUE. 

AN ANTICYCLONE OVER NEW MEXICO EXTENDS A RIDGE SOUTHWARD THROUGH 
THE MOUTH OF THE GULF OF CALIFORNIA AND S OF THE UPPER LOW NEAR 
20N122W TO ANOTHER ANTICYCLONE CENTERED NEAR 19N137W. DIFFLUENCE 
ASSOCIATED THIS RIDGE AXIS CAN BE FOUND OVER THE TROPICAL WAVE 
AND LOW ALONG 110W. THIS WAVE IS ASSOCIATED WITH THE HIGHEST 
PRECIPITABLE WATER VALUES IN THE FORECAST AREA AND THE 
DIFFLUENCE ALOFT IS HELPING TO LIFT THIS MOISTURE AND SUSTAIN 
DEEP CONVECTION NEAR THE WAVE AND LOW. BROAD DIFFLUENCE CAN BE 
FOUND OVER W WATERS BETWEEN THE WESTERN ANTICYLONE ALOFT AND A 
30-40 KT NORTHEASTERLY UPPER JET S OF 05N BETWEEN 105W AND 130W. 
THESE CONDITIONS ARE ENHANCING THE CONVECTION NEAR ITCZ AND ON 
THE S EDGE OF THE TROPICAL WAVE ALONG 135W.

GAP WINDS...FRESH TO STRONG NORTHERLY WINDS WILL CONTINUE TO 
FUNNEL THROUGH CHIVELA PASS INTO THE GULF OF TEHUANTEPEC THROUGH 
WED MORNING. THIS GAP WIND EVENT WAS INDUCED BY THE PRESSURE 
GRADIENT BETWEEN RELATIVELY HIGHER SURFACE PRESSURES OVER THE SW 
GULF OF MEXICO AHEAD OF ATLANTIC TROPICAL STORM ERNESTO AND 
LOWER PRESSURE WITH THE MONSOON TROUGH SOUTH OF TEHUANTEPEC 
WHICH WILL BE DRIFTING NORTHWARD BEFORE ERNESTO MOVES INTO THE 
YUCATAN PENINSULA LATE TUE NIGHT OR EARLY WED.

$$
SCHAUER