000
AXPZ20 KNHC 011558
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT JAN 01 2011

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1545 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ANALYZED FROM 07N78W TO 
04N90W TO 08N120W TO 07N140W. SCATTERED MODERATE WITHIN 120 NM 
EITHER SIDE OF AXIS BETWEEN 115W AND 124W.  

...DISCUSSION...
THE UPPER TROUGH CURRENTLY CENTERED OVER THE CENTRAL U.S. 
THROUGH NORTHERN MEXICO INTO N WATERS IS BEING REINFORCED BY A
VIGOROUS SHORTWAVE TROUGH WELL N OF THE AREA THAT IS DROPPING
INTO THE BACKSIDE OF THE TROUGH OFF THE NORTHERN CALIFORNIA 
COAST...BROADENING THE TROUGHING OVER THE FAR NORTHERN WATERS. 
A 110 KT UPPER JET IS FOUND ON THE LEADING EDGE OF THIS TROUGH 
AND THE REAR RIGHT QUADRANT OF THIS JET IS RESPONSIBLE FOR UPPER 
LEVEL DIFFLUENCE NEAR THE CENTRAL MEXICAN COAST THAT IS 
ENHANCING THE SCATTERED MODERATE CONVECTION FOUND FROM 12N TO 
15N BETWEEN 110W AND 114W. THE REINFORCING SYSTEM MOVING INTO 
THIS TROUGH IS REFLECTED AS A 1001 MB SURFACE LOW NEAR 43N132W
ON THE 1200 UTC SURFACE ANALYSIS AND IS FORECAST TO DRAG A COLD 
FRONT SOUTHEASTWARD THROUGH THE FAR NRN WATERS LATE SUN BEFORE 
WEAKENING ALONG 30N118W TO 26N130W MON. NW WINDS WILL INCREASE 
TO 20 KT BEHIND THE FRONT AND ALLOW SEAS TO BUILD TO 13 FT DUE 
TO A COMBINATION OF WIND WAVES AND 14 TO 16 SECOND PERIOD NW 
SWELL BY LATE SUN INTO MON.

1021 MB HIGH PRES CURRENTLY RESIDES NEAR 30N127W. THE PRES 
GRADIENT BETWEEN THIS HIGH AND LOWER PRES ALONG THE ITCZ IS 
RESPONSIBLE FOR AN AREA OF FRESH TRADE WINDS W OF 125W FROM JUST 
N OF THE ITCZ TO 12N. BY LATE SUN...HIGH PRES W OF THE 
AFOREMENTIONED COLD FRONT WILL BECOME THE DOMINANT RIDGE CENTER 
AND FRESH TRADES WILL EXPAND E TO 115W AS THE FORMER HIGH CENTER 
MOVES E AND WEAKENS. CURRENTLY...THE PRES GRADIENT BETWEEN THIS 
1022 MB HIGH AND LOWER PRES OVER N CENTRAL MEXICO HAS WEAKENED 
AND THEREFORE ALLOWED WINDS TO DIMINISH BELOW 20 KT THIS 
MORNING. FRESH NW TO N WINDS HAVE DEVELOPED IN THE GULF OF 
CALIFORNIA IN THE WAKE OF BUILDING HIGH PRES OVER THE U.S. GREAT 
BASIN BEHIND THE DEEP LAYER TROUGH AXIS. 

GAP WINDS...
N TO NE WINDS THROUGH THE GULF OF PAPAGAYO ARE EXPECTED TO PULSE 
TO 20 KT THROUGH THE FORECAST PERIOD AS TRADE WINDS FROM THE 
WESTERN CARIBBEAN BLEED THROUGH CENTRAL AMERICA AND ARE 
ENHANCED BY MORNING MOUNTAIN DRAINAGE FLOW...MAKING THE EARLY 
MORNING HOURS THE MOST LIKELY TIME TO SEE THE STRONGEST WINDS.

NORTHERLY WINDS ARE EXPECTED TO BEGIN FILTERING THROUGH THE 
CHIVELA PASS INTO THE GULF OF TEHUANTEPEC BY SUN AS THE COLD 
FRONT ASSOCIATED WITH THE DEEP LAYER TROUGHING OVER THE CENTRAL 
U.S. SWEEPS ACROSS THE WESTERN GULF OF MEXICO. THIS EVENT WILL 
INTRODUCE N WINDS INITIALLY IN THE 20-25 KT RANGE EARLY SUN AND 
INCREASING TO 30 KT SUN NIGHT AND MON. THE ONLY MODEL 
FORECASTING GALE FORCE WINDS IN THE AREAS IS THE GLOBAL FORECAST 
SYSTEM (GFS) WHICH DEPICTS WINDS VERY BRIEFLY REACHING GALE 
FORCE BEFORE OVERNIGHT SUN NIGHT...BEFORE DECREASING MON. HAVE 
THEREFORE ELECTED TO NOT POST A GALE FOR THE GULF OF TEHUANTEPEC
WITH THIS SURGE.
  
$$
COBB