000
AXPZ20 KNHC 031532
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU JAN 03 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 
1500 UTC.

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

THE MONSOON TROUGH IS ALONG 07N78W TO 06N99W. THE INTERTROPICAL 
CONVERGENCE ZONE AXIS EXTENDS FROM 06N99W TO 07N114W TO 06N130W 
TO 05N140W. SCATTERED MODERATE CONVECTION IS WITHIN 180 NM S OF 
THE MONSOON TROUGH E OF 81W...WITHIN 120 NM S OF THE MONSOON 
TROUGH BETWEEN 86W AND 89W...AND ALSO FROM 06N TO 08N BETWEEN 
98W AND 101W.

...DISCUSSION...

MAINLY ZONAL WESTERLY FLOW DOMINATES THE DISCUSSION WATERS IN 
THE UPPER LEVELS. AN EXCEPTION IS A MID-LEVEL TROUGH EXTENDING 
FROM THE FAR NORTHERN GULF OF CALIFORNIA ACROSS CENTRAL BAJA 
CALIFORNIA TO 22N124W. THIS TROUGH IS SUPPORTING A WEAK 1016 MB 
SURFACE LOW NEAR 26N123W WHICH IS FORECAST TO DISSIPATE DURING 
THE NEXT 24 HOURS. ELSEWHERE OVER THE NORTHWESTERN PORTIONS OF 
THE WATERS...A MID TO UPPER LEVEL LOW IS CENTERED WELL NORTH OF 
THE AREA NEAR 42N128W WITH A SHARP UPPER TROUGH EXTENDING FROM 
THE LOW THROUGH 37N125W TO 30N137W. 

THIS TROUGH IS SUPPORTING A SURFACE COLD FRONT FROM THE LOW TO 
30N129W THEN STATIONARY TO 25N140W. WINDS ARE 20 KT OR LESS S OF 
30N IN THE VICINITY OF THE FRONT...ALTHOUGH NW SWELL UP TO 13 FT 
IS W OF THE FRONT. MOST OF THE STRONGER UPPER LEVEL DYNAMICS 
WILL REMAIN N OF 30N WITH THE COLD FRONT BECOMING DIFFUSE AS IT 
SLOWLY MOVES EASTWARD. MEANWHILE THE STATIONARY FRONT WILL HANG 
AROUND THROUGH FRI MORNING WHILE BECOMING ILL-DEFINED. THE 
STATIONARY FRONT WILL DISSIPATE BY SAT MORNING...WITH A NEW AND 
MORE VIGOROUS COLD FRONT PUSHING INTO THE NW WATERS BY THEN. 
FRESH TO STRONG NORTHERLY WINDS WILL FOLLOW THIS NEW COLD FRONT 
ALONG WITH A NEW SET OF NW SWELL UP TO 12 FT BY 12 UTC SAT.

WEAK SURFACE RIDGING EXTENDS SW FROM A 1022 MB HIGH CENTERED 
NEAR 32N125W TO 22N135W. A TIGHT PRES GRADIENT EXISTS BETWEEN 
THE RIDGE AND LOWER PRES TO THE S ASSOCIATED WITH THE ITCZ...AND 
AN AREA OF FRESH TO STRONG TRADES IS PRESENT FROM 06N TO 18N W 
OF 128W ALONG WITH SEAS TO 11 FT IN MIXED NE WIND WAVES AND NW 
SWELL. THE STRENGTH AND COVERAGE OF THESE TRADES WILL NOT VARY 
MUCH THROUGH 48 HOURS...ALTHOUGH SEAS WILL SUBSIDE SLIGHTLY TO 
10 FT AS THE COMMINGLING SET OF NW SWELL DECAYS SOMEWHAT.

A TIGHT PRES PATTERN IS ALSO IN PLACE OVER THE NORTHERN GULF OF 
CALIFORNIA BETWEEN HIGH PRES OVER THE U.S. GREAT BASIN REGION 
AND WEAK TROUGHING ALONG THE W COAST OF MEXICO. THIS IS ENOUGH 
TO PRODUCE AN AREA OF FRESH TO STRONG NORTHERLY WINDS IN THE 
GULF OF CALIFORNIA N OF 28N. THESE WINDS WILL DIMINISH TO 20 KT 
OR LESS BY SAT MORNING AS THE PRES PATTERN RELAXES.

NW SWELL OF 8 FT OR GREATER COVERS THE REMAINDER OF THE WATERS W 
OF 111W. THIS SWELL WILL GRADUALLY DECAY THROUGH THE NEXT 48 
HOURS.

GAP WINDS...GULF OF TEHUANTEPEC...THE NEXT GALE FORCE WIND EVENT 
IS EXPECTED TO START 06 UTC FRI AS NORTHERLY WINDS SURGE THROUGH 
THE CHIVELA PASS FROM THE SW GULF OF MEXICO BEHIND A FRONT. GALE 
FORCE WINDS WILL THEN PULSE THROUGH SAT MORNING...WITH THE 
STRONGEST WINDS OCCURRING DURING THE LATE NIGHT AND EARLY 
MORNING HOURS DURING ENHANCED DRAINAGE. WIND DRIVEN SEAS WILL 
BUILD TO UP TO 13 FT DURING THE EVENT.

GULF OF PAPAGAYO...FRESH TO STRONG NE-E WINDS IN THE GULF OF 
PAPAGAYO WILL EASE A BIT THIS AFTERNOON...THEN WILL PULSE AGAIN 
UP TO 25 KT DURING THE NEXT FEW MORNINGS AS NE-E TRADES IN THE W 
CARIBBEAN SEA SHIFT SLIGHTLY WESTWARD TOWARD CENTRAL AMERICA.

$$
LEWITSKY