000
AXPZ20 KNHC 121940
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL 
1605 UTC THU DEC 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1545 UTC.

...SPECIAL FEATURES...

GULF OF TEHUANTEPEC...AN ASCAT PASS FROM 0412 UTC LAST NIGHT 
CAPTURED A SWATH OF N-NE 30-40 KT WINDS OVER THE MID-SECTION OF 
THE GULF WITH NE WINDS OF 25-30 KT ELSEWHERE FROM 12N TO 15N 
BETWEEN 94W AND 98W. MAX WAVE HEIGHTS ARE IN THE 10-16 FT RANGE 
IN THE IMMEDIATE GALE FORCE WIND AREA WITH SEAS 10-14 FT 
ELSEWHERE WITHIN 75 NM EITHER SIDE OF A LINE FROM 16N95W TO 
15N95W TO 13N96W TO 12N97W...AND 8-12 FT ELSEWHERE FROM 12N TO 
15N BETWEEN 94W AND 98W.

THE PEAK WIND SPEED WILL DIMINISH SLIGHTLY THROUGH TODAY...BUT 
THEN INCREASE BACK TO 40 KT DURING THE LATE NIGHT AND EARLY 
MORNING HOURS OF FRI WITH THE AID OF NOCTURNAL DRAINAGE FLOW. 
THESE WINDS WILL THEN DIMINISH SLIGHTLY TO 30-35 KT NEAR 
DAYBREAK FRI...AND TO JUST BELOW GALE FORCE BY EARLY FRI 
EVENING. WITH THE PRES GRADIENT WEAKENING FURTHER DURING FRI AND 
INTO FRI NIGHT...THE WINDS WILL DIMINISH FURTHER TO 20 KT OR 
LESS BY EARLY SAT WITH SEAS LESS THAN 8 FT. SINCE THIS HAS BEEN 
A LONG DURATION ONGOING EVENT...THE ASSOCIATED PLUME OF NE 
SWELLS WILL CONTINUE TO MIGRATE TO THE SW AND W WELL AWAY FROM 
THE GULF OF TEHUANTEPEC...EXPECTED TO REACH TO NEAR 116W AND 
EXTEND EASTWARD TO 99W.

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

MONSOON TROUGH AXIS EXETNDS FROM 07N78W TO 04N90W WHERE LOW 
LEVEL WINDS SUGGEST THE ITCZ AXIS BEGINS AND CONTINUES TO 
07N100W TO 08N110W TO 10N120W TO 10N131W TO 08N140W. SCATTERED 
STRONG CONVECTION IS WITHIN 120 NM N OF THE ITCZ BETWEEN 110W-
114W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 
120 NM N OF THE ITCZ BETWEEN 100W AND 104W...BETWEEN 116W AND 
121W AND WITHIN 60 NM N OF THE ITCZ BETWEEN 90W-104W

...DISCUSSION... 

ALOFT...                                                    
LATEST SATELLITE WATER VAPOR IMAGERY SHOWS AN UPPER LOW MOVING 
INLAND OVER SRN CALIFORNIA WITH A TROUGH SSW TO NEAR 23N119W. A 
SHORTWAVE RIDGE IS TO THE W OF THE TROUGH FROM NEAR 22N125W NW 
TO 32N129W. AN UPPER LOW IS DIVING SEWD TO THE NW OF THE RIDGE 
AT 33N135W WITH A TROUGH SSW TO ANOTHER UPPER LOW AT 24N136W... 
AND CONTINUING SW TO SW OF THE AREA AT 14N140W. A VERY ACTIVE 
JET STREAM BRANCH IS NOTED TO THE SE OF AFOREMENTIONED FEATURES 
ROUNDING THE BAS OF THE WESTERN MOST TROUGH...AND STRETCHING 
NEWD THROUGH 23N128W TO ACROSS THE BASE OF THE FIRST 
TROUGH...AND NEWD TO ACROSS SRN BAJA CALIFORNIA. IT CONTINUES 
INLAND TO OVER FAR NRN MEXICO AND THE TEXAS PANHANDLE. MODERATE 
TO STRONG SW WINDS ASSOCIATED WITH THIS JET STREAM BRANCH ARE 
TRANSPORTING AMPLE MID AND UPPER LEVEL CLOUDS WITHIN 500 NM SE 
AND S OF THE JET STREAM NEWD TOWARDS THE SRN BAJA CALIFORNIA 
PENINSULA...AND NORTHWESTERN MEXICO. LOWER CLOUDS UNDERNEATH THE 
MID AND UPPER CLOUDS MAY CONTAIN WIDELY SCATTERED SHOWERS AND 
SMALL CELLS OF ISOLATED TSTMS. OTHERWISE...MODERATE TO STRONG 
SUBSIDENCE RESULTING IN RATHER STABLE ATMOSPHERIC CONDITIONS IS 
NOTED TO THE NW AND N OF THE JET STREAM CLOUDINESS.

OVER THE EASTERN PORTION OF THE AREA...A MID/UPPER TROUGH 
EXTENDS FROM MEXICO NEAR 20N98W SSW TO THE EQUATOR NEAR 100W. 
MOSTLY MODERATE SUBSIDENCE IS OBSERVED TO THE E OF THIS TROUGH 
WITH ONLY ISOLATED SHOWERS AND TSTMS NOTED OVER THAT SECTION OF 
THE DISCUSSION AREA.

SURFACE...A STATIONARY FRONT CROSSES SW ACROSS THE FAR NW CORNER 
OF THE AREA. WITH ITS UPPER SUPPORT WEAKENING...THE FRONT WILL 
WEAKEN TO A TROUGH AND SHIFT BACK W TO W OF THE 140W BY FRI 
AFTERNOON. A WEAK TROUGH IS ALONG 121W FROM 09N TO 13N. 
SCATTERED CONVECTION IS WITHIN 180 NM W OF THE TROUGH. THE 
TROUGH SHOULD DISSIPATE BY FRI EVENING AS IT TRACKS W AROUND
10 KT. 

A RIDGE EXTENDS FROM A 1025 HIGH CENTER NEAR 33N129W SW TO 
23N140W. THE COMBINATION OF THE RIDGE WITH LOWER LOWER PRES 
ALONG THE ITCZ IS SUPPORTING AN AREA OF FRESH TRADES OVER THE W 
CENTRAL WATERS. THESE WINDS COMBINED WITH LONGER PERIOD NE 
SWELLS ARE RESULTING IN COMBINED SEAS OF 8 FT W OF A LINE FROM 
20N140W TO 14N129W TO 09N140W. THESE SWELLS WILL MIX WITH SW 
SWELLS BY 48 HOURS FROM 12N TO 16N BETWEEN 118W AND 128W.

GULF OF PAPAGAYO...NOCTURNAL PULSING OF WINDS OF 20-25 KT CAN BE 
EXPECTED TONIGHT AGAIN...THEN DIMINISH TO 20 KT OR LESS DURING 
FRI AFTERNOON.

$$
AGUIRRE