000
AXPZ20 KNHC 191005
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SAT NOV 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 
0945 UTC.

...SPECIAL FEATURE...

AN 1006 MB AREA OF LOW PRES IS EMBEDDED IN THE MONSOON TROUGH 
NEAR 09.5N98W MOVING W AT ABOUT 8 KT. OVERALL SYSTEM STRUCTURE 
HAS BECOME MORE SYMMETRICAL DURING THE PAST 24 HRS. THIS IS 
EVIDENT BY THE MORE PRONOUNCED BANDING TYPE FEATURES THAT HAVE 
DEVELOPED MAINLY OVER THE EASTERN SEMICIRCLE OF THE LOW. 
CONVECTION NOTED WITHIN THE BANDS CONSISTS OF THE SCATTERED 
MODERATE/ISOLATED STRONG TYPE WITHIN 30 NM OF A LINE FROM 8N98W 
TO 11N96W AND WITHIN 60 NM W OF THE CENTER. SCATTERED MODERATE 
CONVECTION IS LOCATED FROM 11N TO 12.5N BETWEEN 96W AND 
97W...AND WITHIN 45 NM OF 8N98W. THE LOW IS UNDER VERY FAVORABLE 
ANTICYCLONIC FLOW ALOFT...AND AS IT CONTINUES TO PULL FURTHER 
AWAY FROM DRIER AND MORE STABLE AIR FLOWING SW FROM THE GULF OF 
TEHUANTEPEC THE ENVIRONMENTAL CONDITIONS WILL CONTINUE TO 
PROVIDE IT WITH A HIGH CHANCE FOR IT TO DEVELOP INTO A TROPICAL 
CYCLONE DURING THE NEXT 24-48 HOURS.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
 
THE MONSOON TROUGH EXTENDS FROM NORTHERN COSTA RICA TO 11N92W TO 
LOW PRES NEAR 9.5N98W TO 9N107W TO ANOTHER LOW AT 8N114W AND
8N118W. LOW LEVEL WINDS THEN SUGGEST THAT THE INTERTROPICAL 
CONVERGENCE ZONE AXIS THEN EXTENDS FROM 8N118W TO 11N126W...AND
RESUMES FROM 10N131W TO 8N140W. SCATTERED MODERATE TO STRONG 
CONVECTION IS WITHIN 60 NM EITHER SIDE OF ITCZ BETWEEN 131W AND 
133W. SCATTERED MODERATE ISOLATED/STRONG CONVECTION IS WITHIN 60 
NM EITHER SIDE OF THE ITCZ BETWEEN 121W AND 131W AND WITHIN 60 
NM S OF THE MONSOON TROUGH BETWEEN 100W AND 104W.

...DISCUSSION...

AN UPPER LEVEL TROUGH REACHES FROM THE CALIFORNIA CHANNEL 
ISLANDS INTO THE AREA NEAR 32N123W TO NEAR 21N137W. PLENTIFUL 
MID TO UPPER LEVEL MOISTURE IS BEING ADVECTED TO THE NE WITHIN 
360-420 NM AHEAD OF THE TROUGH AXIS. ADDITIONAL MID TO UPPER 
LEVEL MOISTURE IS PRESENT FROM 16N TO 24N W OF 128W...WHICH IS 
BEING CHANNELED NORTHEASTWARD FROM THE DEEP TROPICS S OF THE 
HAWAIIAN ISLANDS. ANOTHER UPPER LEVEL TROUGH STRETCHES FROM NEAR 
23N116W TO 12N122W. TROPICAL MOISTURE IS WITHIN 240-300 NM E OF 
THE TROUGH FEEDING TO THE NE FROM THE ITCZ. WATER VAPOR 
SATELLITE IMAGERY INDICATES DRY AND STABLE AIR UNDER MODERATE TO 
STRONG SE OF A LINE FROM SRN BAJA CALIFORNIA TO 14N125W AND EWD 
TO ACROSS MEXICO. 

AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS S OF GUATEMALA NEAR 
11N92W WITH A RIDGE AXIS EXTENDING FROM IT TO NEAR 13N117W. 
UPPER LEVEL DIFFLUENCE OVER THIS REGION IS ENHANCING CONVECTION 
ASSOCIATED WITH THE LOW PRES SYSTEM DESCRIBED IN THE SPECIAL 
FEATURE SECTION ABOVE. AN ELONGATED UPPER LEVEL ANTICYCLONIC 
CIRCULATION IS NEAR 9N135W WITH A RIDGE AXIS ALONG 09N/10N W OF 
125W. UPPER LEVEL DIFFLUENCE OVER THIS REGION IS ALSO ENHANCING 
CONVECTION ALONG THE ITCZ AS IS DESCRIBED IN THE SECTION ABOVE.

ELSEWHERE AT THE SURFACE...HIGH PRES OF 1033 MB NW OF THE 
DISCUSSION AREA NEAR 37N150W EXTENDS A RIDGE THROUGH 32N138W SE 
TO NEAR 23N117W. HIGH PRES COVERS THE AREA N OF ABOUT 16N AND W 
OF 118W. NW SWELLS ARE ALLOWING FOR SEAS OF 8-11 FT TO EXIST N 
OF 28N AND W OF 120W. A NEW SET OF LARGER NW SWELL WITH PEAK 
WAVE PERIODS OF 16-18 SECONDS WILL PROPAGATE INTO THE NW PORTION 
OF THE DISCUSSION WATERS STARTING IN ABOUT 18-24 HRS. A FRONTAL 
TROUGH WILL PRECEDE THIS SWELL ALTHOUGH ASSOCIATED WINDS ARE 
FORECAST TO REMAIN LESS THAN 20 KT WITH THIS FEATURE. A 
REINFORCING COLD FRONT WILL ARRIVE EARLY SUN MORNING REACHING 
FROM 30N126W TO 28N135W TO 29N140W BY 12 UTC SUN...THEN WILL 
WEAKEN AS IT REACHES FROM 30N122W TO 27N125W TO 26N140W BY 00 
UTC MON. THE NW SWELL WILL BUILD TO 13 OR 14 FT W OF FRONT TO
135W.

A SURFACE TROUGH IS ANALYZED ALONG THE ITCZ EXTENDING FROM 
13N125W TO 9N129W. THE PRES GRADIENT BETWEEN THE TROUGH AND
THE RIDGE TO THE N IS ALLOWING FOR NE 20 KT TRADES WITH SEAS
OF 8 FT TO BE LOCATED FROM 11N-24N AND W OF 127W. THIS AREA
OF TRADES WILL SHRINK SLIGHTER OVER THE NEXT 48 HRS AS THE 
PRES GRADIENT BREAKS DOWN WITH THE ARRIVAL OF THE REINFORCING
COLD FRONT TO THE N.

GAP WINDS...THE PRES GRADIENT CONTINUES TO SLOWLY WEAKEN OVER 
THE GULF OF TEHUANTEPEC REGION ALTHOUGH N-NE 20-25 KT WINDS AND 
SEAS TO 9 FT PERSIST. THESE WINDS AND SEAS WILL DIMINISH 
TO LESS THAN 20 KT AND LESS THAN 8 FT BY 12 HRS...AND INTO
24 HRS. N WINDS OF 20 KT WILL THEN RESTART THROUGH THE GULF
SUN NIGHT.

$$
AGUIRRE