000
AXPZ20 KNHC 052151
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SAT DEC 05 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...

AXIS ANALYZED ALONG 05N80W TO 10N107W TO 06.5N118W TO 9.5N127W 
TO 07.5N135W TO 10N140W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION WITHIN 170 NM S OF AXIS E OF 84W. SCATTERED MODERATE  
CONVECTION WITHIN 130 NM S OF AXIS BETWEEN 87W AND 89W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 110 NM N OF 
AXIS BETWEEN 94W AND 98W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION WITHIN 130 NM EITHER SIDE OF AXIS BETWEEN 103W AND 
126W. NUMEROUS MODERATE SCATTERED STRONG CONVECTION WITHIN 60 NM 
N AND 130 NM S OF AXIS W OF 134W. 

...DISCUSSION...
WEAK HIGH PRESSURE RIDGE ACROSS THE N PART OF THE AREA REMAINS. 
AS A RESULT...ONLY A SMALL AREA OF FRESH TRADES REMAIN FROM 11N 
TO 20N BETWEEN 125W AND 135W. THIS IS DUE TO CONVECTIVE ACTIVITY 
AND RESULTING PRESSURE FALLS AROUND A 1010 MB LOW PRESSURE 
CENTER EMBEDDED IN THE ITCZ NEAR 09N129W WHICH IS TIGHTENING THE 
PRESSURE GRADIENT BETWEEN THE TWO FEATURES. 

WINDS OVER THE GULF OF CALIFORNIA WILL VEER TO THE SW AND 
INCREASE TO 20 TO 25 KT LATE TONIGHT N OF 29N IN ADVANCE OF A 
COLD FRONT DIVING DOWN THROUGH THE U.S. GREAT BASIN.

NW SWELL CONTINUES TO PREVAIL ACROSS THE WATERS N OF 07N AND W 
OF 113W...MIXING WITH NE SWELL IN AFOREMENTIONED REGION OF 
STRONGEST TRADES. S OF 07N W OF 116W...NW SWELL IS MIXED WITH SE 
SWELL. A COLD FRONT NW OF THE AREA HAS GENERATED ANOTHER PULSE 
OF LONG PERIOD NW SWELL. THIS COLD FRONT...AND ASSOCIATED SWELL 
WILL MOVE INTO THE FAR NW PART OF THE FORECAST AREA 
OVERNIGHT...WITH SEAS TO 14 FT BY SUN AFTERNOON.  

GAP WINDS...
GULF OF TEHUANTEPEC...STRONG N WINDS IN THE BAY OF CAMPECHE ARE 
BEING FUNNELED ACROSS THE ISTHMUS OF TEHUANTEPEC AND OVER THE 
GULF OF TEHUANTEPEC...WITH GALE FORCE CONDITIONS NOW OCCURRING 
THERE. HIGH PRESSURE WILL RAPIDLY SHIFT EASTWARD...AND WINDS 
ACROSS THE BAY OF CAMPECHE WILL QUICKLY VEER TO THE E TO SE OVER 
THE NEXT 12 HOURS. THIS WILL RESULT IN A DECREASE OF THE COLD 
DENSE AIR THAT IS CURRENTLY FUNNELING THROUGH THE ISTHMUS OF 
TEHUANTEPEC AND DIMINISH WINDS BELOW GALE FORCE ACROSS THE GULF 
OF TEHUANTEPEC LATER TONIGHT. 

GULF OF PAPAGAYO...FRESH EASTERLY TRADEWINDS WILL CONTINUE TO 
FUNNEL THROUGH THE GULF OF PAPAGAYO INTO DOWNSTREAM WATERS TO 
90W DURING THE NEXT FEW DAYS. THESE WINDS WILL BE STRONGEST...20 
TO 25 KT...DURING THE MORNING HOURS WITH THE AID OF DRAINAGE 
FLOW. 

$$

AL