000
AXPZ20 KNHC 160925
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC WED DEC 16 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 6N77W 7N90W 5N100W 7N1110W 6N140W. SCATTERED 
MODERATE ISOLATED STRONG CONVECTION WITHIN 120 NM N OF AXIS FROM 
103W-106W. SCATTERED MODERATE TO STRONG CONVECTION WITHIN 100 NM 
EITHER SIDE OF AXIS FROM 129W-134W AND WITHIN 120 NM S OF AXIS 
FROM 134W-140W.

...DISCUSSION...
A MID TO UPPER LEVEL TROUGH IS OVER THE NW PORTION OF THE 
DISCUSSION AREA. A 95 KT JETSTREAM IS S OF THE TROUGH FROM 
25N140W TO 25N135W. MID TO UPPER LEVEL RIDGE IS E OF THE TROUGH 
WITH AXIS FROM NORTHERN GULF OF CALIFORNIA TO  TO 17N125W. 
MODERATE TO STRONG SUBSIDENCE WITH DRY STABLE AIR AT THE MIDDLE 
AND UPPER LEVELS OF THE ATMOSPHERE COVERS THE AREA N OF THE ITCZ 
TO 25N W OF 120W. SOME HIGH LEVEL MOISTURE IS N OF 25N WITH
SCATTERED TO BROKEN CIRRUS CLOUDS.

A SHARP MID TO UPPER LEVEL TROUGH EXTENDS FROM NW MEXICO THROUGH 
SOUTHERN GULF OF CALIFORNIA TO 15N110W. A 95-100 KT JETSTREAM IS 
SE OF THE TROUGH FROM 17N105W ACROSS CENTRAL MEXICO TO JUST S OF 
THE BIG BEND OF TEXAS. OVERCAST HIGH CLOUDS ARE WITHIN 300 NM SE 
OF THE JET. A WEAK UPPER LEVEL RIDGE IS S OF THE JET FROM 
SOUTHERN MEXICO NEAR THE GULF OF TEHUANTEPEC TO 5N95W. MODERATE 
TO STRONG SUBSIDENCE IS N OF THE ITCZ E OF 95W. THE SUBSIDENCE 
SUPPRESSED ANY SIGNIFICANT CONVECTION ALONG THE ITCZ...WITH ONLY 
ISOLATED AREAS OF SHOWERS.

A 1023 MB HIGH PRES IS CENTERED NEAR 31N122W. A BROAD AREA OF 
MODERATE TO STRONG TRADE WINDS ON THE SOUTHERN PERIPHERY OF THE 
HIGH PRES...MAINLY FROM 08N TO 20N W OF 115W. WEAKENING COLD 
FRONT FROM  32N132W TO 30N135W THEN STATIONARY TO 27N138W, 
OVERCAST LOW CLOUDS ARE WITHIN AROUND 30 NM EITHER SIDE OF THE 
FRONT. THE FRONT SHOULD DISSIPATE WITHIN THE NEXT 24 HOURS. A 
COUPLE OF TROUGHS ARE ANALYZED ALONG THE ITCZ. THE FIRST ONE 
EXTENDS FROM 12N107W TO A 1009 MB LOW PRES NEAR 7N109W TO 
3N109W. A FEW SHOWERS ARE NEAR LOW. THE SECOND TROUGH WITH AXIS 
FROM 10N129W TO 5N131W. SCATTERED MODERATE TO STRONG CONVECTION 
WITHIN 300 NM E OF THE TROUGH ALONG THE ITCZ.

SEA HEIGHTS ARE INCREASING ACROSS THE NW PORTION OF THE AREA W 
OF THE FRONT. SEAS OF UP TO 16 FT ARE EXPECTED OVER THE NW 
PORTION OF THE AREA BY THIS EVENING.

NE WINDS 20 KT CONTINUE THROUGH THE GULF OF TEHUANTEPEC. MODEL 
GUIDANCE SUGGESTS THAT THIS WIND EVENT WILL CONTINUE AND THEN 
BECOME STRONGER THIS EVENING INTO THU AS A COLD FRONT PUSHES 
INTO THE SW GULF.

NE TO E WINDS OF 20 TO 25 KT ARE STILL BLOWING ACROSS THE 
GULF OF PAPAGAYO AS A TIGHT PRES GRADIENT ACROSS THE WESTERN 
CARIBBEAN IS ALLOWING ELY TRADE WINDS TO FUNNEL ACROSS COSTA 
RICA AND NICARAGUA INTO THE EASTERN PACIFIC. THESE WINDS ARE 
EXPECTED TO DECREASE DURING THE NEXT 24 TO 48 HOURS. 

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