000
AXPZ20 KNHC 120328
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SAT OCT 12 2013

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 
0300 UTC.

...SPECIAL FEATURES...
LOW PRES 1007 MB EMBEDDED IN MONSOON TROUGH AT 14N107W HAS 
MODERATE TO FRESH WINDS BUT INCREASING TO STRONG WITHIN NEXT
12 HOURS MAINLY ON ITS NORTHERN SEMICIRCLE.  SYSTEM IS A TOSS UP
BETWEEN A FAVORABLE LOWER LEVEL CONDITIONS...WARM SST AND PLENTY
OF TROPICAL MOISTURE WITH GOOD MECHANICAL UPLIFT...AND UPPER
LEVEL ANTICYCLONE WHICH PUMPS AN INCREASING SOUTHEAST SHEAR OVER
IT.  CONVECTION REMAINS DISORGANIZED...BUT ABUNDANT.  MODEL
GUIDANCE HAVE DIVERGENT SOLUTIONS WITH STATISTICAL ONES BUILDING
A SHORT-LIVED TROPICAL STORM...BUT DYNAMICAL MODELS HOLDING A 
STEP SHY OF IT.  THERE IS A MEDIUM CHANCE OF TROPICAL CYCLONE
DEVELOPMENT DURING THE NEXT 48 HOURS.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...           
MONSOON TROUGH EXTENDS FROM 11N86W TO 10N93W TO 14N103W TO 1007
MB LOW PRES AT 14N107W TO 11N125W THEN RESUMES FROM REMNANT 1009
MB LOW PRES NARDA AT 15N132W TO 12N134W TO BEYOND 09N140W.
SCATTERED MODERATE CONVECTION WITHIN 240 NM N AND 270 S OF AXIS
E OF 120W.

...DISCUSSION...
UPPER LEVEL TROUGH CUTS DEEP INTO BASIN FROM 32N118W TO 14N125W
WITH VERY DRY AND STABLE SUBSIDING AIR MASS W OF AXIS.  STUBBORN
MID-UPPER LEVEL DOWNSTREAM RIDGE OVER CENTRAL MEXICO BLOCKS ANY
FURTHER EASTWARD MOVEMENT OF TROUGH AND IS IN TURN SQUEEZED ON
ITS WESTERN PERIPHERY INCREASING SOUTHERLY WINDS INCLUDING S-SE 
WINDS OVER SURFACE LOW PRES 1007 MB AT 14N107W.  THIS INCREASED 
SHEAR OVER LOW PRES HINDERS...OR MAY EVEN PREVENT ITS POSSIBLE
DEVELOPMENT INTO A TROPICAL CYCLONE.  ON THE OTHER HAND...RIDGE
ALSO ALLOWS ABUNDANT TROPICAL MOISTURE TO MOVE INTO E PAC ALONG
MONSOON TROUGH E OF 122W. 

UPPER LEVEL SHORTWAVE ROTATING AROUND TROUGH AT 32N INCREASES
NW WINDS N OF 32N AND ALLOWS MODERATE N-NW SWELL TRAIN TO MOVE S
AS FAR AS TO REACH 14N W OF 130W DURING THE WEEKEND.  

...ELSEWHERE AT THE LOWER LEVELS...
FARTHER W...REMNANT LOW PRES 1009 MB OF NARDA PERSISTS AT
16N132W WITH A DEFINITELY WELL DEFINED CYCLONIC CIRCULATION...
BUT TOTAL ABSENCE OF CONVECTION WITHIN 200 NM OF ITS CENTER.
STILL...THE SYSTEM IS ABLE TO TIGHTEN PRES GRADIENT ENOUGH TO
PROMPT FRESH NE BREEZE ON ITS NW QUADRANT THROUGH FORECAST
PERIOD.  
 
$$
WALLY BARNES