000
AXPZ20 KNHC 212159
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC WED JAN 21 2009

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE LIES ALONG A LINE FROM 
04N78W TO 03N90W TO 06N114W TO 04N128W TO 06N140W. THERE IS NO 
SIGNIFICANT CONVECTION CURRENTLY ASSOCIATED WITH THE ITCZ.

...DISCUSSION...

A GALE WARNING IS IN EFFECT FOR THE GULF OF TEHUANTEPEC.  THE 
QUIKSCAT PASS FROM 1246 UTC...NEAR THE PEAK OF THE EVENT... 
SHOWED GALE FORCE WINDS AS FAR AS 120 NM FROM THE COAST WITH 
WIND SPEEDS AS HIGH AS 50 KT.  HOWEVER...THE BULK OF THE 
NON-RAIN FLAGGED RETURNS SUGGESTED WINDS TO 45 KT.  WINDS SHOULD 
GRADUALLY DIMINISH BELOW GALE FORCE TOMORROW MORNING AND DROP 
BELOW 20 KT AROUND FRI AFTERNOON.  TO THE SOUTH...THE ASCAT PASS 
FROM 1558 UTC SHOWS WINDS IN THE GULF OF PAPAGAYO AND THE GULF 
OF FONSECA IN THE 20 TO 25 KT RANGE.  THIS AREA OF WIND IS 
EXPECTED TO EXPAND WEST OVER THE NEXT DAY BEFORE CONTRACTING AND 
WEAKENING AS THE PRESSURE GRADIENT BETWEEN THE DISSIPATING HIGH 
PRESSURE OVER CENTRAL AMERICA AND LOW PRESSURE OVER COLOMBIA 
SLACKENS.

A DEEP LAYERED LOW PRESSURE SYSTEM HAS A SURFACE LOW CENTERED 
NEAR 28N124W.  THE QUIKSCAT PASS FROM 1430 UTC SHOWED WINDS IN 
THE 20 TO 25 KT RANGE PRIMARILY WITHIN 180 NM N QUADRANT OF THE 
LOW.  WINDS SHOULD DIMINISH WITH THIS SYSTEM OVER FORECAST 
WATERS AS IT IS GRADUALLY OVERTAKEN BY ANOTHER DEEP LAYERED LOW 
PRESSURE SYSTEM NW OF THE AREA.  EXPECT THE LOW CURRENTLY OVER 
FORECAST WATERS TO WEAKEN AS ITS SURFACE TROUGH IS FORCED CLOSER 
TO THE BAJA CALIFORNIA COAST OVER THE NEXT TWO DAYS.  THE COLD 
FRONT ASSOCIATED WITH THE LOW NW OF THE FORECAST AREA WILL MOVE 
INTO NW WATERS OVERNIGHT TONIGHT.  LONG PERIOD NW SWELL...IN THE 
16 TO 18 SECOND RANGE...WILL MOVE INTO NW WATERS AND PUSH AHEAD 
OF THE FRONT.  SEAS ARE EXPECTED TO BE AS HIGH AS 14 TO 16 FT IN 
NW WATERS BEHIND THE FRONT ON FRI.  

SCATTERED MODERATE CONVECTION CAN CURRENTLY BE FOUND WITHIN 210 
NM OF 12N112W.  THIS CONVECTION IS ASSOCIATED WITH A BROAD AREA 
OF UPPER LEVEL DIFFLUENCE ON THE SE EDGE OF THE UPPER TROUGH 
FROM 30N125W TO 05N110W...THE SAME TROUGH SUPPORTING THE SURFACE 
LOW NEAR 28N124W.  THE NORTHERN PORTION OF THIS TROUGH IS 
EXPECTED TO MOVE INTO NW MEXICO OVERNIGHT THU NIGHT WHILE SOME 
MID TO UPPER LEVEL ENERGY WILL BE LEFT BEHIND S OF 20N AND IS 
EXPECTED TO BE DRAWN WEST TOWARD THE AFOREMENTIONED DEEP LAYER 
TROUGH APPROACHING FROM THE NW.  THE BEST CHANCE OF CONVECTION 
WILL REMAIN S OF 15N...WHERE MOISTURE IS MORE PLENTIFUL... 
BETWEEN 95W AND 120W AS THE LINGERING MID TO UPPER LEVEL ENERGY 
AND RESULTING TROUGHING AND DIFFLUENCE WILL BE SLOWER TO MOVE 
OVER THE NEXT DAY OR TWO THAN THE N EDGE OF THE TROUGH.

$$
SCHAUER CLARK