000
AXPZ20 KNHC 061541
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN OCT 06 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1515 UTC.

...SPECIAL FEATURE...

DEEP CONVECTION ASSOCIATED WITH  A 1007 MB LOW NEAR 13N116W WAS 
BECOMING BETTER ORGANIZED THIS MORNING. FIRST VISIBLE SATELLITE 
IMAGES SHOW INCREASED BANDING FEATURES AND A FAIRLY WELL DEFINED 
LOW LEVEL CIRCULATION. HOWEVER...EASTERLY SHEAR OVER THE SYSTEM 
IS DISPLACING MOST OF THE DEEP CONVECTION TO THE WEST OF THE 
CENTER. CURRENTLY...SCATTERED MODERATE ISOLATED STRONG 
CONVECTION WAS NOTED WITHIN 240 NM OF THE LOW IN THE NW 
SEMICIRCLE. THERE IS A MEDIUM PROBABILITY OF TROPICAL CYCLONE 
FORMATION ASSOCIATED WITH THIS SYSTEM OVER THE NEXT 48 HOURS. 

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

MONSOON TROUGH AXIS EXTENDS FROM 09N85W TO 1010 MB LOW PRES NEAR 
13N100W TO 14N111W TO 1007 MB LOW PRES NEAR 13N116W TO 10N132W. 
ITCZ FROM 10N132W TO 10N140W. SCATTERED MODERATE TO STRONG 
WITHIN 180 NM OF COAST CENTRAL AMERICA BETWEEN 89W AND 92W. 
SCATTERED MODERATE 180 NM EITHER SIDE OF MONSOON TROUGH BETWEEN 
100W AND 108W. 
 
...DISCUSSION...

SHARP MID TO UPPER LEVEL TROUGH WAS OVER THE NW PORTION OF THE 
DISCUSSION AREA EXTENDING FROM NEAR 32N130W SW A BASE NEAR 
22N138W. THE TROUGH APPEARED  TO BE SHEARING OUT TO THE NE AROUND 
A FAIRLY AMPLIFIED RIDGE N OF 20N ALONG 120W WHICH WAS TIED TO 
AN EXPANSIVE UPPER LEVEL ANTICYCLONE NEAR 22N111W. 

THE ANTICYCLONE AND ASSOCIATED EASTERLY FLOW TO THE S OF THE 
FEATURE GOVERNED THE FLOW OVER THE TROPICAL PACIFIC E OF 125W 
AND CENTRAL AMERICA. SURFACE LOW PRES NEAR 13N116W WAS EMBEDDED 
WITHIN THIS EASTERLY FLOW ALOFT WHICH IS DISPLACING THE DEEP 
CONVECTION TO THE W OF THE CENTER. ADDITIONAL THE LOW WAS   
SITUATED IN AN AREA OF UPPER DIFFLUENCE WHICH WAS ENHANCING  
DEEP CONVECTION NEAR THE LOW AND ELSEWHERE ALONG THE MONSOON 
TROUGH BETWEEN 115W-127W. 

ANOTHER AREA OF WEAK UPPER DIFFLUENCE IS CENTERED OVER THE 
TRANSITIONAL AREA OF THE MONSOON TROUGH AND ITCZ...BUT ONLY 
SUPPORTED ISOLATED SHOWERS AND TSTMS OVER THE PAST SEVERAL 
HOURS. THE UPPER DEBRIS MOISTURE IS CURRENTLY FANNING OUT ACROSS 
THE TROPICS FROM 05-11N BETWEEN 130W-140W. OTHERWISE THE UPPER 
LEVELS APPEAR VERY DRY OVER THE DISCUSSION AREA N OF 20N AND S 
OF 20N W OF 130W. 
   
GULF OF CALIFORNIA...AN EARLIER 0728 UTC OCEAN SAT SCATTEROMETER 
PASS INDICATED 20-30 KT WINDS IN THE GULF.  HIGHEST SEAS WERE 
ESTIMATED TO BE IN THE 8-9 FT RANGE. PRES GRADIENT BETWEEN HIGH 
PRES OVER THE PACIFIC AND A SURFACE TROUGH ALONG THE COAST OF 
MEXICO IS EXPECTED TO RELAX ENOUGH SO WINDS SHOULD DIMINISH TO 
LESS THAN 20 KT BY TONIGHT...THEN FURTHER DIMINISHING TO 5-10 KT 
WITH SEAS OF 1-3 FT BY LATE MON.  

GULF OF TEHUANTEPEC...LIGHT AND VARIABLE WINDS ARE EXPECTED TO 
CONTINUE ACROSS THE GULF OF TEHUANTEPEC AREA THROUGH THIS 
EVENING. AN UPPER SHORTWAVE TROUGH OVER CENTRAL N AMERICA 
CONTINUES S ACROSS THE WESTERN GULF OF MEXICO WITH SOME EVIDENCE 
OF THE TROUGH BASE CURRENTLY OVER THE BAY OF CAMPECHE. THE 
ASSOCIATED SURFACE COLD FRONT IS OVER THE NW GULF OF 
MEXICO...AND WILL RACE SE REACHING THE ISTHMUS OF TEHUANTEPEC 
LATE TONIGHT. NORTHERLY 15-20 KT DRAINAGE FLOW IS EXPECTED TO 
BEGIN ACROSS THE GULF OF TEHUANTEPEC WATERS LATE TONIGHT...THEN 
INCREASE TO 20 TO 25 KT LATE MON. THE GRADIENT IS EXPECTED TO 
SUPPORT PULSES OF N-NE 20-30 KT WINDS RESULTING IN COMBINED SEAS 
OF 8-10 FT BEGINNING LATE MON NIGHT.

ELSEWHERE AT THE SURFACE...A BROAD RIDGE COVERS THE WATERS N OF 
13N W OF 113W WITH AN EMBEDDED INVERTED TROUGH ANALYZED TO THE N 
OF 27N ALONG 130W. THE TROUGH WILL LIFT OUT TO THE NE TODAY 
ALLOWING THE RIDGE TO BUILD E AGAIN ACROSS THE NORTHERN PORTION. 
NE 15-20 KT TRADES CONTINUE S OF THE RIDGE ACROSS THE WATERS 
FROM 14-17N BETWEEN 124-130W WITH SEAS 6-8 FT PRIMARILY IN MIXED 
LONG PERIOD NW AND CROSS EQUATORIAL SE SWELL. THE AFFECTED AREA 
IS EXPECTED TO SHIFT W ACROSS THE TROPICAL WATERS FROM 12-16N 
BETWEEN 128-135W LATE TONIGHT...THEN FROM 11-17N BETWEEN 133-
140W ON MON NIGHT. THESE CONDITIONS ARE EXPECTED TO SHIFT W OF 
140W BY TUE NIGHT.

COBB