Tropical Weather Discussion
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000
AXPZ20 KNHC 200348
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SAT DEC 20 2014

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
0315 UTC.

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

THE MONSOON TROUGH EXTENDS NW FROM THE PACIFIC COAST OF COLOMBIA
AT 07N78W TO 10N85W TO 07N92W WHERE SCATTEROMETER WINDS INDICATE
A TRANSITION TO AN ITCZ WHICH WIGGLES WESTWARD TO BEYOND 05N140W.
SCATTERED MODERATE CONVECTION IS OBSERVED S OF THE MONSOON TROUGH
WITHIN 30 NM EITHER SIDE OF A LINE FROM 05N77W TO 06N81W...ALONG
THE ITCZ WITHIN 90 NM EITHER SIDE OF A LINE FROM 07N99W TO
07N118W WHERE THE CONVECTION IS CURRENTLY INCRESING TO ISOLATED
STRONG...AND ALONG THE ITCZ WITHIN 90 NM EITHER SIDE OF A LINE
FROM 07.5N131W TO 07N135W.

...DISCUSSION...

AN UPPER LEVEL CONTINUES OVER THE CENTRAL PORTION OF THE
DISCUSSION AREA WITH ITS MEAN AXIS CURRENTLY EXTENDING SW FROM
32N111W ACROSS NORTHERN MEXICO TO A BASE OVER THE DEEP TROPICS
AT 10N128W. UPPER MOISTURE IS SPREADING E ACROSS THE DISCUSSION
AREA TO THE N OF 27N TO INCLUDE SOUTHERN CALIFORNIA...THE
NORTHERN BAJA PENINSULA AND THE NORTHERN GULF OF CALIFORNIA.
SCATTERED MODERATE CONVECTION IS ENHANCED E OF THE UPPER TROUGH
WITHIN 120 NM OF A LINE FROM 10N129W TO 16N116W. A PLUME OF
UPPER MOISTURE ORIGINATING WELL W OF THE DISCUSSION AREA STREAMS
E ACROSS THE DISCUSSION AREA FROM 04-14N BETWEEN 140-125W...THEN
TURNS NE IN RESPONSE TO THE UPPER TROUGH WITHIN ABOUT 330 NM
EITHER SIDE OF A LINE FROM 10N125W TO 20N104W WHERE THE PLUME
NARROWS AS IT CONTINUES NE ACROSS CENTRAL MEXICO AND THE CENTRAL
GULF OF MEXICO AND ACROSS CENTRAL FLORIDA. DEBRIS MOISTURE FROM
THE PREVIOUSLY DESCRIBED CONVECTIVE CLUSTERS E OF THE UPPER
TROUGH IS RE-ENFORCING THE PLUME.

AT THE LOW LEVELS LONG PERIOD NW SWELL CONTINUES TO MIX WITH
LONG PERIOD SOUTHERLY SWELL ACROSS THE ENTIRE OPEN WATERS WATERS
N OF THE ITCZ W OF 115W. A SURFACE RIDGE EXTENDS FROM 28N140W TO
14N100W. NE 15-20 KT TRADES ARE OBSERVED ACROSS THE TROPICS
BETWEEN THE ITCZ AND THE RIDGE WITH AN AREA OF EMBEDDED 20-25 KT
NE WINDS ACROSS THE WATERS FROM 08-20N W OF 132W. THE GRADIENT
SHOULD CONTINUE TO TIGHTEN OVER THE NEXT SEVERAL DAYS WITH THE
20-25 KT CONDITIONS SPREADING E TO ALONG 120W. THE GRADIENT IS
EXPECTED TO WEAKEN EARLY NEXT WEEK WITH THE TRADES RELAXING
BELOW 20 KT LATE MON.

A COLD FRONT IS WEAKENING AS IT PASSES E ACROSS THE DISCUSSION
WATERS N OF THE RIDGE. ALTHOUGH ONLY A W-NW 10 KT WIND SHIFT IS
OCCURRING ALONG THE FRONT...LARGE POST-FRONTAL NW SWELLS HAVE
BUILT COMBINED SEAS UP TO 17 FT NEAR 30N135W. THIS LONG PERIOD
NW SWELL WILL ARRIVE ALONG THE PACIFIC COAST OF THE BAJA
PENINSULA IN THE FORM OF 8-13 FT SEAS ON SAT AFTERNOON...WITH 7-
10 FT SEAS EXPECTED ALONG THE ENTIRE PACIFIC COAST OF THE BAJA
PENINSULA ON SUN. THE SWELLS WILL SUBSIDE WITH 6-8 FT CONDITIONS
EXPECTED ALONG THE ENTIRE PACIFIC COAST OF THE BAJA PENINSULA ON
MON AND MON NIGHT...THEN SUBSIDING TO 4-6 FT ON TUE ACROSS THE
COASTAL WATERS S OF 28N.

GULF OF TEHUANTEPEC...EXPECTING A MAX OF 10-15 KT NOCTURNAL
DRAINAGE FLOW ACROSS THE GULF OF TEHUANTEPEC TONIGHT AND 15-20
KT ON SAT NIGHT. MODEL GUIDANCE SUGGESTS THE THE NEXT GALE EVENT
WILL BEGIN AROUND SUNRISE ON WED INCREASING TO NEAR STORM
STRENGTH ON WED NIGHT.

GULF OF PAPAGAYO...NE 15-20 KT NOCTURNAL PULSES EXPECTED THROUGH
EARLY MON...THEN ONLY 10-15 KT DRAINAGE FLOW EARLY TUE.

GULF OF CALIFORNIA...15-25 KT NW WINDS ARE EXPECTED TONIGHT...
THEN DIMINISH TO 15-20 KT ON SUN...FURTHER DIMINISHING TO 15 KT
ON MON.

$$
NELSON



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