000
AXPZ20 KNHC 040335
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED NOV 04 2009

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 ITCZ AXIS FLUCTUATES FROM 10N TO 12N W OF CENTRAL AMERICA TO 
140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED TO 
THE N OF 06N E OF 98W TO THE COAST OF CENTRAL AMERICA. ISOLATED 
MODERATE TO STRONG CONVECTION IS ALSO OBSERVED WITHIN 30 NM OF 
12N107W AND ALSO FROM 08N TO 12N BETWEEN 120W AND 132W.

...DISCUSSION...

AN UPPER LEVEL ANTICYCLONE IS CENTERED NEAR 13N121W WITH A RIDGE 
AMPLIFYING N TO A CREST AT 30N115W. A RIDGE ALSO EXTENDS SW TO A 
SHARP CREST OVER THE ITCZ AT 09N136W AND A RIDGE EXTENDS E FROM 
THE ANTICYCLONIC CENTER TO 12N109W. DEBRIS MOISTURE FROM ITCZ 
CONVECTION BETWEEN 130W AND 150W IS ADVECTED NE ALONG THE 
RIDGE... WITHIN 150 NM EITHER SIDE OF LINE 08N150W TO 15N127W 
THEN FANNING OUT AS IT SPREADS ACROSS THE YUCATAN PENINSULA NEAR 
28N112W. SUBSIDENCE IS INDICATED OVER THE E SEMICIRCLE OF THE 
ANTICYCLONE AND IS SUPPRESSING ITCZ CONVECTION BETWEEN 108W AND 
120W. 

TO THE NW OF THE ANTICYCLONE IS A QUASI STATIONARY UPPER CYCLONE 
CENTERED NEAR 27N128W....MOVING NE...WITH A TROUGH EXTENDING SW 
TO BEYOND 16N140W. FURTHER NW...A SECOND UPPER TROUGH IS 
APPROACHING THE AREA AND IS CURRENTLY ALONG 32N142W TO 30N145W. 
UPPER MOISTURE PRECEDES THIS SECOND TROUGH BY ABOUT 180 NM AND 
IS NOW SPREADING OVER THE EXTREME NW PORTION OF THE DISCUSSION 
AREA. OTHERWISE...THE UPPER LEVELS ARE DRY NW OF THE MOISTURE 
PLUME PREVIOUSLY MENTIONED. 

A LONG WAVE TROUGH DOMINATES CENTRAL N AMERICA WITH ITS AXIS 
EXTENDING S ALONG 99W ACROSS CENTRAL OLD MEXICO TO A SMALL UPPER 
CYCLONE AT 18N99W THEN THE TROUGH TURNS SE TO A BASE OVER THE E 
PAC NEAR 11N95W. A DEEP LAYERED CYCLONE IS OVER THE SW CARIBBEAN 
NEAR 11N81W. CONVECTION ALONG THE ITCZ IS SLIGHTLY ENHANCED E OF 
THE UPPER TROUGH AND ALSO NEAR THE CARIBBEAN CYCLONE. SOME OF 
THE RESULTANT DEBRIS MOISTURE SPREADING N AND NE ACROSS THE 
WESTERN GULF OF MEXICO AND THE SW CARIBBEAN.    

AT THE LOW LEVELS...A SURFACE HIGH PRES IS NEAR 27N123W 1016 MB. 
NE TRADES ARE AT 20 KT SW OF THE RIDGE BY EXPECTED TO DIMINISH 
BELOW 20 KT WED. A COLD FRONT IS APPROACHING THE NW PORTION BUT 
THE SOUTHERLY FLOW AHEAD OF THE FRONT IS EXPECTED TO ONLY 
BRIEFLY INCREASE TO 20 KT ON WED. NW WINDS ARE EXPECTED TO 
INCREASE BRIEFLY TO 20 KT OVER THE DISCUSSION AREA NW OF THE 
FRONT WITH NW SWELLS CONTINUING TILL A SECOND COLD SURGE ARRIVES 
FRI WITH EVEN LARGER SEAS...PERHAPS TO 13 FT. BROAD LOW PRES 
ANALYZED AS A SURFACE LOW NEAR 11N91W IS EXPECTED CONTINUE FOR A 
FEW DAYS WITH THE SOUTHWESTERLY MONSOON FLOW ENHANCED OVER THE S 
SEMICIRCLE OF THE LOW AT 20 TO 25 KT.  

GAP WINDS...
GALE FORCE WINDS EXPECTED TO CONTINUE THROUGH THE GULF OF 
TEHUANTEPEC AND INCREASE TO NEAR STORM FORCE THU NIGHT AND FRI.

$$
NELSON