000
AXPZ20 KNHC 271535
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN DEC 27 2009

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE...04N81W TO 
04N106W TO 08N128W TO 06N140W. SCATTERED MODERATE ISOLATED 
STRONG WITHIN 90 NM EITHER SIDE OF AXIS W OF 128W.

...DISCUSSION...

ZONAL FLOW PREVAILS ACROSS MUCH OF THE UPPER LEVELS ACROSS THE 
FORECAST AREA. A SHORTWAVE TROUGH IS IN THE FAR NW PORTION OF 
THE FORECAST AREA...WITH AXIS N OF 22N ALONG 134W. MID AND UPPER 
LEVEL MOISTURE IS EAST OF THE TROUGH AXIS EXTENDING TO CENTRAL 
TEXAS. THE SHORTWAVE IS FORECAST TO MOVE EAST ABOUT 30 KNOTS AND 
STRENGTHEN AND REACH BAJA CALIFORNIA LATE MONDAY. SOME 
CONVECTION IS NOTED NEAR AND WITHIN ABOUT 150 NM EAST OF THE 
SHORTWAVE. MID AND UPPER LEVEL MOISTURE FROM ITCZ CONVECTION W 
OF 128W IS BEING ADVECTED NE IN THE SUBTROPICAL JET ACROSS S 
MEXICO INTO THE GULF OF MEXICO. UPPER LEVEL RIDGING PREVAILS 
ACROSS THE E PART OF THE FORECAST AREA E OF 100W. 

AT THE SURFACE...A COLD FRONT IN RESPONSE TO THE SHORTWAVE 
TROUGH IS ACROSS THE FAR NW PORTION OF THE FORECAST AREA...FROM 
30N132W TO 26N140W. SURFACE HIGH PRESSURE 1021 MB IS CENTERED 
NEAR 27N122W. THE COLD FRONT WILL DISSIPATE...AND THE HIGH 
PRESSURE WILL WEAKEN TODAY AS THE SHORTWAVE SHIFTS RAPIDLY TO 
THE E. SURFACE HIGH PRESSURE CENTERED NEAR 31N140W WILL SHIFT E 
BEHIND THE SHORTWAVE. THIS WILL MAINTAIN THE AREA OF FRESH TO 
STRONG TRADEWINDS BETWEEN 08N AND 20N W OF 125W THROUGH AT LEAST 
TUE MORNING. 

A SURFACE LOW 1009 MB IS ANALYZED NEAR 05N80W WITH SCATTERED 
MODERATE AND ISOLATED STRONG CONVECTION WITHIN 150 NM OF THE 
CENTER. LATENT HEAT RELEASE FROM THE CONVECTION IS HELPING 
MAINTAIN THE UPPER LEVEL RIDGE E OF 100W.

GAP WINDS...
GULF OF TEHUANTEPEC...WITH N WINDS INCREASING ACROSS THE GULF OF 
MEXICO INTO THE BAY OF CAMPECHE TODAY...WINDS WILL FUNNEL 
THROUGH THE ISTHMUS OF TEHUANTEPEC INTO THE GULF TONIGHT. WINDS 
WILL INCREASE TO 20 TO 25 KT TONIGHT AND SPREAD SOUTHWEST BY 
MONDAY.

GULF OF PAPAGAYO...E WINDS ARE EXPECTED TO INCREASE TO 20 KT 
TONIGHT AND INCREASE TO 20 TO 30 KT AND SPREAD EAST BY MONDAY 
NIGHT.

FOR ADDITIONAL INFORMATION PLEASE VISIT 
HTTP://WWW.HURRICANES.GOV/MARINE
  
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AL