000
AXPZ20 KNHC 191535
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI OCT 19 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 
0545 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM 12N87W TO 10N106W TO 14N121W TO 
10N132W. ITCZ AXIS THEN EXTENDS FROM 13N122W TO 09N140W. 
SCATTERED MODERATE AND ISOLATED STRONG CONVECTION EXISTS WITHIN 
120 NM N OF MONSOON TROUGH AXIS E OF 95W.

...DISCUSSION...

AT THE SURFACE...A TROUGH EXTENDS FROM 32N127W TO 
24N125W...WHICH IS IN PART THE REMNANTS OF HURRICANE PAUL AS 
WELL AS FORCING INDUCED BY AN UPPER-LEVEL LOW NEAR 27N123W.
THERE IS NO SIGNIFICANT DEEP CONVECTION ASSOCIATED WITH EITHER 
THE SURFACE TROUGH OR THE UPPER LOW.  HOWEVER...SCATTERED 
SHOWERS ARE LIKELY OCCURRING WITHIN 180 NM OF THE CENTER OF THE 
UPPER LOW.  THE TROUGH SHOULD DISSIPATE WITHIN THE NEXT DAY OR 
SO AS THE UPPER LOW WEAKENS AND LIFTS OUT TO THE NORTHEAST.

CURRENTLY...NO 25 KT SURFACE WINDS ARE OCCURRING IN OUR AREA OF 
RESPONSIBILITY.  THE REGION OF DEEP CONVECTION NORTH OF THE 
MONSOON TROUGH E OF 95W HAS A LOW-LEVEL VORTICITY MAXIMUM 
ASSOCIATED WITH IT.  AS THIS PROGRESSES WESTWARD...BY TOMORROW 
THIS SHOULD INDUCE A WEAK TEHUANTEPEC GAP WIND EVENT.  THE GFS 
IS THE MOST AGGRESSIVE MODEL WITH A WEAK LOW DEVELOPING SOUTH OF 
THE MEXICO-GUATEMALA BORDER BY TOMORROW MORNING AND INDUCING N 
TO NE WINDS UP TO 25 KT.  THIS IS MAINTAINED WITHIN THE HIGH 
SEAS THOUGH IF THE OTHER MODELS ARE CORRECT IN LESS 
DEVELOPMENT...THE WINDS MAY END UP BELOW OUR 25 KT CRITERION. 
BECAUSE OF CONTINUED MODERATE HIGH PRESSURE IN THE GULF OF 
MEXICO AND LOW PRESSURES IN THE NORTHEAST PACIFIC MONSOON 
TROUGH...THIS WEAK TEHUANTEPEC EVENT MAY CONTINUE FOR ABOUT A 
WEEK.  IN GENERAL...THE GAP WINDS WILL BE MOST PROMINENT IN LATE 
NIGHT-EARLY MORNING AND WEAKEST DURING THE AFTERNOON-EARLY 
EVENING MINIMUM.

THE AFOREMENTIONED DISTURBANCE IS ROBUSTLY SPUN UP INTO A 
TROPICAL CYCLONE BY MONDAY WITHIN THE 06Z GFS SOUTH OF SOUTHERN 
MEXICO...BUT REMAINS SUBSTANTIALLY WEAKER WITHIN THE GFS 
ENSEMBLE MEAN.  THE REMAINING GLOBAL MODEL GUIDANCE ONLY SHOWS 
AN EAST-WEST EXTENDED MONSOON TROUGH THROUGH THURSDAY.  THE 
EXPERIMENTAL GRIDDED FORECAST WILL FAVOR THE MODEL CONSENSUS OF 
NO DEVELOPMENT AND DOWNPLAY...AT THIS TIME...ANY TROPICAL 
DEVELOPMENT.  YET IT IS QUITE SHOCKING TO SEE THE GFS DEPICTING 
A HURRICANE BY WEDNESDAY AND THE OTHER MODELS SHOWING ALMOST 
NOTHING.

A WEAK NW SWELL EVENT IS OCCURRING IN THE NW PORTION OF OUR AREA 
OF RESPONSIBILITY.  THIS SHOULD FADE BY SUNDAY.  NO LONG PERIOD 
HIGH SWELL ARE SUBSEQUENTLY ANTICIPATED FOR THE NEXT SEVERAL 
DAYS.

$$
LANDSEA