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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