000
AXPZ20 KNHC 142206
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC WED JAN 14 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 
2145 UTC.

...ITCZ...

ITCZ IS CENTERED ALONG 6N78W 8N86W 6N91W 6N102W 7N111W 7N122W 
7N134W 5N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
WITHIN 120 NM N OF THE AXIS BETWEEN 130W-135W. SCATTERED MODERATE
CONVECTION IS WITHIN 60 NM OF THE AXIS BETWEEN 79W-82W.

...DISCUSSION...

THE REGION REMAINS IN BETWEEN TWO RATHER LARGE SCALE FEATURES.
THE FIRST IS THE TAIL END OF BROAD UPPER LEVEL TROUGHING 
CENTERED OVER MID-WEST REGION OF THE UNITED STATES WHICH REACHES 
INTO THE FAR EASTERN SECTION OF THE AREA TO N OF ABOUT 22N AND E 
OF 118W. W OF THE TROUGH...THE AREA IS UNDER MID AND UPPER LEVEL 
RIDGING PRESENT N OF 22N WITH AN ANTICYCLONIC CENTER NEAR 
32N125W. A RIDGE EXTENDS FROM THIS ANTICYCLONE TO WELL NW OF THE 
REGION. THE SECOND FEATURE IS A RATHER EXTENSIVE DEEP LAYER 
TROUGH DIGGING SWD JUST W OF THE AREA ALONG 142W IN RESPONSE TO 
LOW PRES WELL NW OF THE AREA. THE ASSOCIATED SURFACE COLD FRONT
IS ALSO WELL W OF THE AREA TO THE NE OF THE HAWAIIAN ISLANDS...
HOWEVER...STRONG SOUTHERLY FLOW AHEAD OF THIS SYSTEM IS BEING
OBSERVED JUST TO THE NW OF THE AREA AS REVEALED IN SHIP 
OBSERVATIONS FROM DURING THE AFTERNOON HOURS. A FEW OBSERVATIONS
OF 20 KT S WINDS ARE NOW BEING NOTED IN THE FAR NW CORNER OF 
THE AREA. DATA INFERRED FROM SATELLITE-DERIVED WINDS SHOWS 
MODERATE TO STRONG UPPER LEVEL WINDS AHEAD OF TROUGH AXIS NOW 
ENCROACHING TO THE FAR WESTERN PORTION OF THE REGION. THESE 
WINDS ARE TRANSPORTING DEEP TROPICAL MOISTURE IN THE FORM OF 
HIGH LEVEL CLOUDS NWD TO THE GENERAL AREA OF THE GULF OF ALASKA. 
THE MAIN ENERGY WITH THE TROUGH IS FORECAST TO PASS N OF THE 
AREA WITHIN THE NEXT 48-72 HOURS WHILE THE COLD FRONT IS ALSO 
EXPECTED TO STAY N OF THE AREA. THE MAIN 
PROBLEM...HOWEVER...WILL BE LONG PERIOD NW SWELLS GENERATED BY 
THE PARENT LOW OF THIS SYSTEM ARE FORECAST TO MIGRATE INTO THE 
NW SECTION OF THE REGION BY THE END OF THE WEEK WITH POSSIBLE 
MAXIMUM HEIGHTS OF 15 OR 15 FT IN THE FAR NW CORNER.

ELSEWHERE...A WEAK UPPER LEVEL CYCLONIC CIRCULATION MOVING 
WESTWARD IS EMBEDDED IN THE AREA OF MID/UPPER LEVEL RIDGING NEAR 
25N129W WITH A TROUGH STRETCHING SE THROUGH 21N119W TO 16N112W 
TO NEAR 8N105W. MODERATE TO STRONG SW FLOW E OF THE UPPER TROUGH 
BECOMES CONFLUENT ALONG 22N E OF 118W OR ALONG THE BASE OF THE 
BROAD UPPER LEVEL TROUGH OVER THE EASTERN PART OF THE AREA. A 
JET STREAM BRANCH WITH MAXIMUM WINDS OF UP TO 75 KT ROUNDS THE 
BASE OF THE THIS TROUGH. POSSIBLE HIGH LEVEL TURBULENCE IN 
TRANSVERSE BANDING OF CIRRUS CLOUDS IS NOTED FROM 10N TO 20N E 
OF THE 117W. THE CONFLUENT FLOW ASSOCIATED WITH THE BROAD UPPER 
LEVEL TROUGH IS RESULTING IN MODERATE TO STRONG SUBSIDENCE 
INDUCING DRY STABLE AIR OVER MUCH OF THE AREA N OF 22N E OF 
135W. BROAD UPPER LEVEL ANTICYCLONIC FLOW COVERS THE AREA S OF 
20N AND TO THE W OF THE ABOVE MENTIONED TROUGH.

AT THE SURFACE...HIGH PRES RIDGING SWD OVER THE WESTERN GULF OF
MEXICO AND MEXICO HAS CREATED A TIGHT PRES GRADIENT ALONG THE
MEXICAN COAST BRINGING MINIMAL STORM FORCE WINDS TO THE GULF
GULF OF TEHUANTEPEC EARLY THIS MORNING. THESE WINDS HAVE SINCE 
DIMINISHED SLIGHTLY TO GALE FORCE AS OF THE AFTERNOON HOURS...
AND ARE EXPECTED TO REMAIN AT THAT STRAIGHT THROUGH 48 HOURS
WITH SOME INCREASE IN SPEEDS AS INDICATED BY THE LATEST 10M AND
30M MODEL WIND GUIDANCE. MODEL GUIDANCE ALSO INDICATES THAT 
THESE CONDITIONS SHOULD PERSIST THROUGH AT LEAST THE END OF
THE WEEK.
 
NE WINDS OF 20-25 KT THROUGH THE GULF OF PAPAGAYO ARE EXPECTED
TO CHANGE LITTLE OVER THE NEXT 24 HOURS THEN INCREASE TO 30 KT
IN 48 HOURS AS STRONG CARIBBEAN TRADE WINDS CHANNEL W ACROSS 
CENTRAL AMERICA WHILE HIGH PRES RIDGING PRESSES SWD OVER CENTRAL
AMERICA. ELSEWHERE HIGH PRES COVERS THE AREA N OF ABOUT 16N W OF 
110W.

$$
AGUIRRE