000
AXPZ20 KNHC 200319
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SAT OCT 20 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 
0230 UTC.

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

THE MONSOON TROUGH IS ALONG 14N90W TO 10N106W TO 12N118W TO 
12N126W TO 10N134W. THE INTERTROPICAL CONVERGENCE ZONE AXIS 
EXTENDS FROM 10N134W TO 09N140W. SCATTERED MODERATE AND ISOLATED 
STRONG CONVECTION IS N OF 10N E OF 89W. SCATTERED MODERATE 
CONVECTION IS WITHIN 90-150 NM EITHER SIDE OF THE MONSOON TROUGH 
BETWEEN 89W AND 94W...AND ALSO WITHIN 75 NM EITHER SIDE OF THE 
MONSOON TROUGH BETWEEN 127W AND 130W.

...DISCUSSION...

THE REMNANTS OF PAUL...IN THE FORM OF A TROUGH...REACHES FROM 
31N125W TO 24N126W. THIS SURFACE FEATURE IS IN ASSOCIATION WITH 
A NEARLY STATIONARY UPPER LEVEL LOW NEAR 29N123W. NEARBY 
SCATTEROMETER PASSES INDICATED PRIMARILY LIGHT TO MODERATE WINDS 
N OF 20N E OF 130W INCLUDING IN THE VICINITY OF THE TROUGH. 
SCATTERED SHOWERS ARE STILL POSSIBLE N OF 20N BETWEEN 118W AND 
130W IN ASSOCIATION WITH THE TROUGH. THIS TROUGH IS FORECAST TO 
DISSIPATE THIS WEEKEND AFTER REMAINING NEARLY STATIONARY.

1026 MB SURFACE HIGH PRES 36N147W EXTENDS A RIDGE TO THE SE TO 
NEAR 24N137W. MODERATE TO LOCALLY FRESH WINDS ARE UNDER THIS 
RIDGE N OF THE ITCZ W OF 130W. THE EXCEPTION IS IN THE NW CORNER 
WHERE FRESH TO MODERATE WINDS ALONG WITH 8 TO 10 FT SEAS IN 
MIXED NE WIND WAVES AND NW SWELL IS PRESENT WHERE THE PRESSURE 
GRADIENT IS WELL PACKED. THESE WINDS ARE FORECAST TO DIMINISH TO 
20 KT OR LESS BY 24 HOURS WHILE THE ASSOCIATED SEAS SUBSIDE TO 
LESS THAN 8 FT SHORTLY THEREAFTER.

A REGION OF CONVECTION NEAR THE MONSOON TROUGH BETWEEN 90W AND 
95W HAS A LOW-LEVEL VORTICITY MAXIMUM ASSOCIATED WITH IT. AS 
THIS AREA PROGRESSES WESTWARD...THIS SHOULD INDUCE A WEAK 
TEHUANTEPEC GAP WIND EVENT COMMENCING EARLY SAT. THE GFS IS THE 
MOST AGGRESSIVE MODEL WITH A WEAK LOW DEVELOPING SOUTH OF THE 
MEXICO-GUATEMALA BORDER BY SAT MORNING AND INDUCING N TO NE 
WINDS UP TO 25 KT. BECAUSE OF CONTINUED MODERATE HIGH PRES IN 
THE GULF OF MEXICO AND LOW PRES IN THE NORTHEAST PACIFIC MONSOON 
TROUGH...THIS WEAK TEHUANTEPEC EVENT MAY CONTINUE TO PULSE TO 25 
KT THROUGH NEXT WEEK. IN GENERAL...THE GAP WINDS WILL BE MOST 
PROMINENT DURING THE LATE NIGHT-EARLY MORNING HOURS...AND THE 
WEAKEST DURING THE AFTERNOON-EARLY EVENING HOURS MINIMUM.

THE AFOREMENTIONED DISTURBANCE IS ROBUSTLY SPUN UP INTO A 
TROPICAL CYCLONE BY MON OR TUE WITHIN THE 18Z GFS S OF SOUTHERN 
MEXICO BUT REMAINS SUBSTANTIALLY WEAKER WITHIN THE GFS ENSEMBLE 
MEAN. THE REMAINING GLOBAL MODEL GUIDANCE ONLY SHOWS AN E TO W 
EXTENDED MONSOON TROUGH ACROSS THE SAME REGION THROUGH EARLY 
NEXT WEEK WITH NO TROPICAL DEVELOPMENT. THE GRIDDED FORECAST 
WILL CONTINUE TO FAVOR THE MODEL CONSENSUS OF NO TROPICAL 
DEVELOPMENT AT THIS TIME.

$$
LEWITSKY