000
AXPZ20 KNHC 202200
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC THU NOV 20 2008

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 
2145 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE 07N77W 
07N110W 08N140W. SCATTERED MODERATE WITHIN 60-90 NM N OF AXIS 
BETWEEN 101W AND 113W. 

...DISCUSSION...
UPPER LEVELS
MID TO UPPER LEVEL TROUGH NW OF THE AREA EXTENDS FROM THE 
CENTRAL CALIFORNIA COAST WSW TO 31N140W. THIS TROUGH IS 
AFFECTING THE NW PART OF THE AREA WITH UPPER MOISTURE AND 
BROKEN HIGH CLOUDS NORTHWEST OF A LINE THROUGH 32N115W TO 
25N140W. THIS FEATURE IS FORECAST TO MOVE EAST AND IMPACT THE 
NRN PART OF THE AREA THROUGH AT LEAST 48 HOURS. 

FURTHER E...MID TO UPPER TROUGH AXIS IS ALONG AN AXIS FROM 
W TEXAS SW THROUGH 28N100W TO 20N120W TO THE ITCZ NEAR 124W. A
PORTION OF THE TROUGH HAS FRACTURED AND EXTENDS TO THE SE TO 
NEAR 3N115W. THE AREA BETWEEN THE TROUGH AXIS AND THE CLOUDS 
ASSOCIATED WITH THE TROUGH TO THE WEST IS DRY AND CLOUD FREE IN 
THE MIDDLE AND UPPER LEVELS. THE AREA EAST OF THIS LINE AND 
NORTH OF THE ITCZ IS MOIST IN THE MIDDLE AND UPPER LEVELS 
BECAUSE OF MOISTURE EMANATING FROM ITCZ CONVECTION ADVECTING 
NORTHWARD. DIFFLUENT FLOW IN THE VICINITY WAS ALSO AIDING IN 
CONVECTIVE DEVELOPMENT AS WELL. 

SURFACE
DISSIPATING COLD FRONT IS SWEEPING JUST TO THE N OF THE AREA 
ALONG 130W AND WILL DISSIPATE ENTIRELY WITHIN THE NEXT 6 HOURS. 
OTHERWISE MODERATE RIDGE IS N OF ABOUT 12N W OF 112W. 

GAP WINDS...
PRES GRADIENT ACROSS ISTHMUS OF TEHUANTEPEC HAS RELAXED WITH
THE LATEST HIGH RESOLUTION SCATTEROMETER PASSES 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 1540 UTC HIGH RESOLUTION ASCAT PASS INDICATED 25-30 KT WINDS 
IN THE GULF OF PAPAGAYO. THESE WINDS ARE FORECAST TO WEAKEN ON 
FRI BEFORE ANOTHER SURGE SETS IN SAT WITH WINDS ONCE AGAIN
REACHING 30 KT.  

$$
COBB