000
AXPZ20 KNHC 210314
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC FRI NOV 21 2008

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0315 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE 08N82W 
06N92W 08N110W 06N130W 08N140W. SCATTERED MODERATE WITHIN 90-120 
NM N OF AXIS BETWEEN 104W AND 110W. 

...DISCUSSION...

UPPER LEVELS...
MID TO UPPER LEVEL TROUGH IS JUST ENTERING THE FAR NW CORNER OF 
THE AREA AND EXTENDS FROM THE CENTRAL CALIFORNIA COAST WSW 
THROUGH 32N135W TO 28N140W. SWLY DIFFLUENT FLOW E OF THE TROUGH 
IS SPREADING HIGH LEVEL MOISTURE ACROSS THE NRN PART OF THE AREA 
BETWEEN 115W AND 138W. THE TROUGH IS FORECAST TO MOVE EAST AND 
IMPACT THE NRN PART OF THE AREA THROUGH AT LEAST 48 HOURS. 

FURTHER E...SHEARED MID TO UPPER TROUGH IS ALONG AN AXIS FROM W 
TEXAS SW THROUGH 28N102W TO 20N120W TO THE ITCZ NEAR 120W. A 
PORTION OF THE TROUGH HAS FRACTURED AND EXTENDS TO THE SE TO 
NEAR 3N112W. STRONG UPPER LEVEL SUBSIDENCE/DRY AIR ALOFT WAS 
NOTED WITHIN 90 NM EITHER SIDE OF THE TROUGH AXIS N OF 20N AND 
WAS MOST PRONOUNCED OVER BAJA CALIFORNIA. THE AREA S AND E OF THE
TROUGH AXIS NOTED ABOVE IS MOIST IN THE MIDDLE AND UPPER LEVELS 
DUE TO MOISTURE EMANATING FROM ITCZ CONVECTION BETWEEN 104W AND 
110W. DIFFLUENT FLOW IN THE VICINITY OF THE ITCZ WAS ALSO AIDING 
IN CONVECTIVE DEVELOPMENT AS WELL. 

SURFACE...
1029 MB HIGH NEAR 36N134W WITH RIDGING EXTENDING SE THROUGH 
32N127W TO 18N109W DOMINATED THE FLOW OVER THE N PORTION OF THE 
AREA. SCATTEROMETER DATA INDICATED AN AREA OF MODERATE 20-25 KT 
TRADES S OF THE RIDGE FROM 07N TO 20N W OF 117W.  

GAP WINDS...
PRES GRADIENT ACROSS ISTHMUS OF TEHUANTEPEC HAS RELAXED WITH 
HIGH RESOLUTION SCATTEROMETER PASSES FROM EARLIER TODAY 
INDICATING N TO NE WINDS OF 20-25 KT IN THE GULF OF TEHUANTEPEC. 
ANOTHER COLD SURGE IS FORECAST TO MOVE INTO THE AREA WITH GALE 
FORCE WINDS ONCE AGAIN DEVELOPING ON FRI AND CONTINUING INTO 
SAT. WINDS MAY REACH 40-45 KT FRI NIGHT. 

A 2346 UTC HIGH RESOLUTION QUIKSCAT PASS INDICATED 20-25 KT 
WINDS IN THE GULF OF PAPAGAYO. THESE WINDS ARE FORECAST TO 
WEAKEN TO AROUND 20 KT ON FRI BEFORE ANOTHER SURGE SETS IN SAT 
WITH WINDS REACHING 25-30 KT WITH NWP MODELS SUGGESTING THE 
POSSIBILITY OF A BRIEF PERIOD OF GALE FORCE WINDS.  

$$
COBB