000
AXPZ20 KNHC 110915
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI DEC 11 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...
AXIS IS ALONG 08N83W TO 06N105W TO 08N125W TO 07N140W.
NO SIGNIFICANT CONVECTION.

...DISCUSSION... 
A BROAD MID/UPPER LEVEL RIDGE COVERS THE FAR W PORTION OF THE 
DISCUSSION AREA N OF 15N W OF 130W. A 95-105 KT JET STREAM
ENTERS THE AREA NEAR 32N140W TO 28N121W. BROKEN HIGH CLOUDS
ARE N OF 28N W OF 125W. OTHERWISE MODERATE TO STRONG SUBSIDENCE
WITH DRY AND STABLE AIR IN THE MIDDLE AND UPPER LEVELS OF THE
ATMOSPHERE COVER THE AREA N OF THE ITCZ W OF 120W. A BROAD
UPPER TROUGH IS E OF THE RIDGE WITH AXIS FROM 32N117W TO 15N118W.
A 105-125 KT JET STREAM IS E OF THE TROUGH FROM SOUTHERN TIP
OF THE BAJA PENINSULA ACROSS NORTHERN MEXICO. BROKEN TO OVERCAST
CIRRUS CLOUDS ARE WITHIN 200 NM SE OF THE JET AXIS.

AN UPPER-LEVEL ANTICYCLONE...CURRENTLY CENTERED OVER THE NW 
CARIBBEAN...WITH RIDGE EXTENDING ACROSS SE MEXICO AND NORTHERN 
CENTRAL AMERICA INTO THE EASTERN PACIFIC TO 13N106W. STRONG 
UPPER LEVEL SUBSIDENCE IS ASSOCIATED WITH RIDGE. THE SUBSIDENCE
IS LIMITING THE CONVECTION OVER THE ITCZ.

THREE TROUGHS ARE ANALYZED ALONG THE ITCZ. THE FIRST IS FROM
4N-10N ALONG 102W SCATTERED SHOWERS ARE ALONG THE TROUGH AXIS.
SECOND TROUGH WITH AXIS FROM 6N-13N ALONG 116W. ISOLATED
SHOWERS ARE ALONG AND JUST W OF THE TROUGH. ANOTHER TROUGH IS 
ALONG 127W FROM 6N-13N. ISOLATED SHOWERS ALONG THE TROUGH S
OF THE ITCZ. A 1019 MB SURFACE HIGH PRES IS CENTERED NEAR
26N132W. 

MARINE CONDITIONS W OF 110W ARE BEING DOMINATED BY LARGE AND 
LONG PERIOD NW SWELL...WITH WAVE PERIODS OF UP TO 20 SECONDS AND 
SIGNIFICANT WAVE HEIGHTS AS HIGH AS 18 FT. THIS SWELL EVENT 
WILL CONTINUE TO PROPAGATE SE BEYOND THE EQUATOR OVER THE NEXT 
TWO DAYS. HOWEVER...THE SEA HEIGHTS ARE EXPECTED TO GRADUALLY 
SUBSIDE.

THE NEXT COLD FRONT WILL ENTER THE FAR NW PORTION OF THE 
FORECAST REGION FRI AFTERNOON .WITH SW WINDS OF 20 TO 25 KT 
AHEAD OF THE FRONT.

WINDS ARE HAVE INCREASED TO 20 KT ACROSS THE GULF OF PAPAGAYO AS 
THE DRAINAGE FLOW OFF THE CENTRAL AMERICA LANDMASS INCREASES AND 
THE PRES GRADIENT BUILDS ACROSS THE WESTERN CARIBBEAN...ALLOWING 
EASTERLY TRADE WINDS TO FUNNEL ACROSS COSTA RICA AND NICARAGUA 
INTO THE EPAC.

N WINDS OF 20 KT ACROSS THE GULF OF TEHUANTEPEC IS TO CONTINUE
THROUGH AT LEAST 24 HOURS THEN DECREASE BY 48 HOURS.

$$
DGS