000
AXPZ20 KNHC 272201
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SUN DEC 27 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...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE...05N77W TO 
04N105W TO 08N120W TO 06N140W. SCATTERED MODERATE TO ISOLATED 
STRONG CONVECTION IS NOTED FROM 05N TO 09N W OF 129W. 

...DISCUSSION...

ALOFT...ZONAL FLOW PREVAILS ACROSS MUCH OF THE FORECAST AREA 
WITH A SHORTWAVE TROUGH MOVING EWD ACROSS THE N WATERS. THE 
TROUGH AXIS IS CURRENTLY N OF 24N ALONG 128W. A JET STREAM 
BRANCH WITH CORE WINDS OF 90-110 KT ROUNDS THE BASE OF THE 
SHORTWAVE TROUGH. MID AND UPPER LEVEL MOISTURE IS N OF 21N 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. MODERATE TO STRONG SUBSIDENCE AND 
THE IMPLIED DRY AIR MASS COVERS MUCH OF THE AREA W OF 100W WITH 
THE EXCEPTION OF THE CONVECTION ASSOCIATED WITH THE ITCZ. AN 
UPPER LEVEL ANTICYCLONE CENTERED OVER THE SOUTH-CENTRAL 
CARIBBEAN EXTENDS A RIDGE ACROSS THE E PART OF THE FORECAST AREA 
E OF 100W. UPPER DIFFLUENCE ASSOCIATED WITH THIS FEATURE IS 
HELPING TO INDUCE SOME CONVECTION NEAR A 1010 MB LOW LOCATED 
WITHIN THE ITCZ NEAR 06N83W. SW TO W WINDS OF 20 KT ARE NOTED 
WITHIN 120 NM SE QUADRANT OF LOW AND S OF THE ITCZ AXIS. 

AT THE SURFACE...A COLD FRONT IN RESPONSE TO THE SHORTWAVE 
TROUGH IS ACROSS THE FAR NW PORTION OF THE FORECAST AREA ALONG 
30N131W 25N135W 25N140W. NW TO N WINDS IN THE 20 TO 25 KT RANGE 
ARE BLOWING BEHIND THE FRONT. THE COLD FRONT WILL DISSIPATE... 
AND THE SURFACE HIGH PRESSURE CENTERED NEAR 31N140W WILL SHIFT E 
BEHIND THE FRONT MAINTAINING THE AREA OF FRESH TO STRONG TRADE 
WINDS BETWEEN 08N AND 20N W OF 125W THROUGH AT LEAST TUE 
MORNING. 

REGIONAL SEAS ARE DOMINATED BY LONG PERIOD NW SWELL...WAVE 
PERIODS OF UP TO 18 SECONDS...WITH SIGNIFICANT WAVE HEIGHTS AS 
HIGH AS 16 FT PARTICULARLY W OF 115W. THIS SWELL EVENT WILL 
CONTINUE TO SPREAD SE REACHING AROUND 100W IN 48 HOURS.
 
GAP WINDS...
GULF OF TEHUANTEPEC...N WINDS ARE EXPECTED TO INCREASE TO 20 TO 
25 KT ACROSS THE AREA OVER THE NEXT 48 HOURS AS HIGH PRES BUILDS 
ACROSS THE EASTERN SLOPES OF THE SIERRA MADRE MOUNTAINS IN 
MEXICO.

GULF OF PAPAGAYO...E WINDS ARE FORECAST TO INCREASE TO 20 TO 25 
KT DURING THE NEXT COUPLE OF DAYS AND SPREAD EAST BY MONDAY 
NIGHT AS FRESH TRADE WIND FLOW IN THE SW CARIBBEAN FUNNELS 
THROUGH THE GAP.

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