000
AXPZ20 KNHC 190935
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC WED OCT 19 2011

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0715 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS WAS ANALYZED FROM 12N105W TO 09N120W TO 
08N140W. SCATTERED MODERATE CONVECTION LIES WITHIN 300 NM S OF 
THE MONSOON TROUGH AXIS BETWEEN 103W AND 110W.

...DISCUSSION...

FORECAST GUIDANCE SUGGESTS A GALE FORCE WIND EVENT ACROSS THE 
GULF OF TEHUANTEPEC WILL BEGIN LATER THIS MORNING AFTER A STRONG 
COLD FRONT MOVES ACROSS THE BAY OF CAMPECHE INTO THE ISTHMUS OF 
TEHUANTEPEC...WITH NLY WINDS THEN EXPECTED TO FUNNEL THROUGH THE 
CHIVELA PASS INTO THE GULF OF TEHUANTEPEC. A GALE WARNING IS IN 
EFFECT FROM AROUND SUNRISE TODAY UNTIL THU AFTERNOON WHEN THE 
DEEP LAYER TROUGHING OVER THE GULF OF MEXICO SWINGS 
NORTHEASTWARD AND WINDS IN THE SW GULF OF MEXICO WEAKEN.

NUMEROUS MODERATE TO STRONG CONVECTION LIES WITHIN 120 NM OF THE 
MEXICAN COAST BETWEEN 99W AND 103W AND SCATTERED MODERATE WITH 
ISOLATED STRONG CONVECTION IS FOUND FROM 10N TO 14N BETWEEN 96W 
AND 103W. THIS CONVECTION IS ASSOCIATED WITH A MID LEVEL LOW 
CENTERED NEAR 13N100W. PRECIPITABLE WATER VALUES ARE HIGHEST 
NEAR THIS MID LEVEL LOW AND UNDER A REGION OF UPPER LEVEL 
DIFFLUENCE ASSOCIATED BETWEEN SE WINDS ALOFT TO THE N ALONG THE 
MEXICAN COAST AND NE WINDS ALOFT TO THE S. THE COLD FRONT 
PASSING THROUGH THE ISTHMUS OF TEHUANTEPEC TODAY SHOULD PROVIDE 
ADDED VORTICITY TO THIS BROAD MID LEVEL LOW WHILE ENERGY 
ASSOCIATED WITH THE REMNANT LOW OF IRWIN...WHICH WAS STILL 
EVIDENT ON VISIBLE SATELLITE IMAGERY BEFORE SUNSET TUE EVENING 
NEAR 13N100W...SHOULD ALSO BECOME ENGULFED IN THIS GYRE. THE 
FORECAST CALLS FOR THE MID LEVEL LOW TO TRACK W AND DEVELOP A 
WEAK SURFACE REFLECTION THAT WILL DRIFT W ALONG THE MONSOON 
TROUGH TODAY THROUGH THE END OF THE PERIOD FRI MORNING. FRESH TO 
STRONG SW WINDS CURRENTLY OCCUPY THE AREA FROM 05N TO 14N 
GENERALLY E OF 110W. THESE WINDS ARE SUPPLYING TROPICAL MOISTURE 
TO THE BROAD MID LEVEL LOW. THE AREA OF STRONGEST WINDS AND THE 
BEST CHANCE OF PRECIPITATION WILL DRIFT W WITH THE GYRE THROUGH 
THE FORECAST PERIOD. 

1021 MB HIGH PRES LIES NEAR 31N128W. THE PRES GRADIENT BETWEEN 
THIS HIGH AND TROUGHING OVER NW MEXICO AT THE SURFACE IS STRONG 
ENOUGH TO SUPPORT A SMALL AREA OF FRESH N WINDS OFF THE COAST OF 
BAJA CALIFORNIA NORTE WITH SEAS TO 9 FT ACCORDING TO SHIP DDIJ 
NEAR 27N118W AT 0200 UTC. WINDS ARE EXPECTED TO DIMINISH HERE BY 
THIS EVENING AS THE HIGH PRES OVER THE SUBTROPICAL EASTERN NORTH 
PACIFIC SHIFTS NW...WEAKENING THE PRES GRADIENT.

$$
SCHAUER