000
AXPZ20 KNHC 310905
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI DEC 31 2010

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0700 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE WAS ANALYZED FROM A 1007 MB 
LOW PRES NEAR 08N79W TO 06N99W TO 09N110W TO 08N122W TO 07N140W. 
SCATTERED MODERATE CONVECTION WAS WITHIN 90 NM S OF THE ITCZ 
AXIS BETWEEN 103W AND 111W AND WITHIN 360 NM N OF THE ITCZ AXIS 
BETWEEN 108W AND 113W.


...DISCUSSION...

THE UPPER TROUGH CURRENTLY CENTERED OVER THE U.S. GREAT BASIN 
THROUGH NW MEXICO INTO NE WATERS WILL BE REINFORCED BY A SYSTEM 
WELL N OF THE AREA THAT IS EXPECTED TO DROP INTO THE BACKSIDE OF 
THE TROUGH OFF THE CALIFORNIA COAST BY SAT...BROADENING THE 
TROUGHING OVER N WATERS. THE REINFORCING SYSTEM IS REFLECTED AS 
A 986 MB SURFACE LOW NEAR 50N145W ON THE 0600 UTC SURFACE 
ANALYSIS AND IS FORECAST TO DRAG A COLD FRONT EASTWARD THROUGH N 
WATERS OVER THE WEEKEND. WINDS AND SEAS ARE EXPECTED TO REMAIN 
BELOW ADVISORY CRITERIA THROUGH THE NEXT 48 HOURS NEAR THE FRONT 
WITH THE 13-15 SECOND LONG PERIOD SWELL ASSOCIATED WITH THE 
SYSTEM NOT FORECAST TO REACH N WATERS UNTIL SUN.

1024 MB HIGH PRES CURRENTLY RESIDES NEAR 32N133W. THE PRES 
GRADIENT BETWEEN THIS HIGH AND LOWER PRES ALONG THE ITCZ IS 
RESPONSIBLE FOR AN AREA OF FRESH TRADE WINDS W OF 130W PRIMARILY 
BETWEEN 15N AND 20N. THESE TRADES ARE EXPECTED TO RETREAT W OF 
135W THROUGH SAT MORNING AS THIS HIGH PRES TO THE N IS WEAKENED 
BY THE AFOREMENTIONED APPROACHING COLD FRONT. BY SAT 
NIGHT...HIGH PRES WILL REBUILD W OF THE FRONT AND FRESH TRADES 
WILL EXPAND E TO 115W. MEANWHILE...THE PRES GRADIENT BETWEEN THE 
1024 MB HIGH AND LOWER PRES OVER THE U.S. GREAT BASIN AND N 
CENTRAL MEXICO IS GENERATING FRESH TO STRONG NW TO N WINDS OFF 
THE COAST OF BAJA CALIFORNIA OUT TO 133W OVER N WATERS. SHIP 
A8JS7 NEAR 29N126W AT 0600 UTC REPORTED 20 KT N WINDS AND 10 FT 
SEAS WHILE THE 0540 UTC ASCAT PASS SHOWED AN AREA OF NW WINDS TO 
25 KT PRIMARILY N OF 29N WITHIN 240 NM W OF BAJA CALIFORNIA. 
WINDS HERE ARE EXPECTED TO DIMINISH BELOW 20 KT DURING THE DAY 
FRI AS THE HIGH PRES OVER THE PACIFIC WEAKENS AND THE TROUGHING 
OVER THE U.S. AND MEXICO PUSHES NORTHEASTWARD. FRESH NW TO N 
WINDS ARE EXPECTED IN THE GULF OF CALIFORNIA BY SAT NIGHT AS 
HIGH PRES BUILDS OVER THE U.S. GREAT BASIN BEHIND THE 
NORTHEASTWARD MOVING SURFACE SYSTEM AND INCREASES THE PRES 
GRADIENT OVER THE GULF OF CALIFORNIA BETWEEN THIS HIGH AND 
TROUGHING OVER THE EASTERN SHORE OF THE GULF ON THE LEE SIDE OF 
THE SIERRA MADRE OCCIDENTAL.

GAP WINDS...
N TO NE WINDS THROUGH THE GULF OF PAPAGAYO ARE EXPECTED TO PULSE 
TO 20 KT IN THE EARLY MORNING HOURS THROUGH THE FORECAST PERIOD 
AS TRADE WINDS FROM THE WESTERN CARIBBEAN BLEED THROUGH CENTRAL 
AMERICAN AND ARE ENHANCED BY MORNING MOUNTAIN DRAINAGE FLOW. 

$$
SCHAUER