000
AXPZ20 KNHC 020905
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC WED DEC 02 2009

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 
0900 UTC.

...ITCZ...
THE ITCZ AXIS IS ALONG 07N77W TO 09N98W TO 06N107W TO 0N117W TO 
07N130W TO 10N140W. SCATTERED MODERATE TO ISOLATED STRONG 
CONVENTION IS FROM 08N TO 12N BETWEEN 130W AND 134W...AND FROM 
10N TO 13N W OF 138W. SIMILAR CONVECTION IS ALSO NOTED NEAR 
12N114W AND NEAR 06N124W. 

...DISCUSSION...
AN UPPER LEVEL SHORTWAVE TROUGH CONTINUES TO MOVE ACROSS THE N 
PORTION OF THE FORECAST AREA N OF 24N...NEAR 120W. THIS FEATURE 
HAS WEAKENED THE SURFACE HIGH PRESSURE THAT HAS PREVAILED OVER 
THE FORECAST AREA...AND HAS BROUGHT A DECREASE IN THE AREAL 
COVERAGE OF TRADES GREATER THAN 20 KT. THE SURFACE HIGH 
PRESSURE...ANALYZED 1020 MB NEAR 28N131W...WILL REMAIN WEAK OVER 
THE NEXT SEVERAL DAYS AS A PROGRESSIVE UPPER LEVEL PATTERN... 
WITH TWO MORE SHORTWAVE TROUGHS...EXPECTED TO MOVE ACROSS THE 
AREA THROUGH THIS WEEKEND. 

THREE LOW PRES CENTERS ARE NOTED ALONG THE ITCZ. FROM EAST TO 
WEST...THEY ARE LOCATED NEAR 09N100W...08N118W AND 08N134W. THE 
LAST ONE IS FORECAST BY THE COMPUTER MODELS TO PERSIST AS A 
CLOSED CIRCULATION JUST WEST OF THE FORECAST AREA. CURRENTLY... 
A DIFFLUENT PATTERN ALOFT ASSOCIATED WITH AN UPPER ANTICYCLONE 
CENTERED NEAR 08N126W IS ENHANCING CONVECTION RELATED TO THIS 
FEATURE. PRES GRADIENT BETWEEN THIS LOW PRES AND THE RIDGE TO 
THE N WILL PRODUCE AN AREA OF E TO SE WINDS OF 20 TO 25 KT 
PARTICULARLY FROM 15N TO 25N W OF 130W DURING THE NEXT 24 TO 48 
HOURS. 

REGIONAL SEAS ARE DOMINATED BY LONG PERIOD NW SWELLS. SEAS IN 
EXCESS OF 8 FT ARE NOTED MAINLY W OF 110W. ANOTHER PULSE OF 
LARGE AND LONG PERIOD NW SWELLS WILL REACH THE NW CORNER OF THE 
AREA AT ABOUT 03/0600 UTC AND SPREAD SE DURING THE LATER PART OF 
THE FORECAST PERIOD.

GAP WINDS...
NE TO E WINDS OF 20 KT CONTINUES OVER THE GULF OF PAPAGAYO AS 
FRESH TRADEWIND FLOW IN THE SW CARIBBEAN FUNNELS THROUGH THE 
GAP. THE WINDS ARE GREATEST DURING THE OVERNIGHT AND EARLY 
MORNING HOURS WITH THE AID OF DRAINAGE FLOW. THIS WEATHER 
PATTERN WILL PERSIST DURING THE NEXT 48 HOURS.

$$
GR