000
AXPZ20 KNHC 071605
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE APR 07 2009

...HURRICANE FORCE WIND WARNING IN EFFECT FOR THE GULF OF 
TEHUANTEPEC THROUGH 07/1500 UTC...

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 
0900 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE LIES ALONG A LINE FROM 04N77W 
TO 06N95W TO 00N113W... THEN FROM 01N129W TO 04N134W TO 04N140W. 
SCATTERED MODERATE FROM 05N TO 07N BETWEEN 132W AND 136W. 

...DISCUSSION...

GAP WINDS...
A HURRICANE FORCE WIND WARNING HAS BEEN POSTED FOR THE GULF OF 
TEHUANTEPEC...WHERE A LATE SEASON GAP WIND EVENT IS CURRENTLY 
UNDERWAY FOR THE NEXT 3 HOURS. THE NAM APPEARS TO HANDLE THIS 
WIND EVENT THE BEST AMONG VARIOUS COMPUTER MODEL GUIDANCE. 
FOLLOWING THE NAM FORWARD IN TIME...WINDS WILL LIKELY FALL BELOW 
STORM FORCE BY 08/0000 UTC...AND THEN FALL BELOW GALE FORCE BY 
08/1200 UTC. THE STRONG WINDS WILL BUILD SEAS UP TO 18 FT BASED 
ON WAVEWATCH GUIDANCE TODAY...WITH SEAS UP TO 9 FT IN 
NORTHEASTERLY SWELL PROPAGATING AS FAR DOWNSTREAM AS 05N102W BY 
LATE WEDNESDAY.

INCREASING TRADE WINDS OVER THE CARIBBEAN REGION ARE FORECAST TO 
EXTEND INTO THE GULF OF PAPAGAYO AND PANAMA DURING THE NEXT FEW 
DAYS...WHEN SURFACE WINDS ARE EXPECTED TO REACH 20 KT. 
ALSO...ACROSS THE GULF OF CALIFORNIA...SW TO W WINDS WILL LIKELY 
DOWNSLOPE OFF THE BAJA CALIFORNIA MOUNTAINS IN RESPONSE TO 
INCREASING PRESSURE FALLS OVER WESTERN MEXICO BY MIDWEEK. 

ELSEWHERE...
A SURFACE TROUGH IS OVER THE NW DISCUSSION AREA FROM 30N123W TO 
25N130W CURRENTLY BEING SUPPORTED BY A CLOSED UPPER LOW CENTERED 
NEAR 35N130W. COMPUTER MODEL GUIDANCE SUGGESTS THAT THIS LOW 
WILL BE PUSHED EASTWARD DURING THE NEXT DAY AND WEAKEN AS AN 
UPPER LEVEL RIDGE TO ITS WEST MOVES EASTWARD AND AN UPPER LEVEL 
JET MAXIMUM PROPAGATES AROUND THE LOW. IN RESPONSE...THE TROUGH 
WILL CONTINUE TO DISSIPATE...WITH THE CORRESPONDING STRONGER 
WIND FIELD CONTRACTING AND WEAKENING IN INTENSITY. 
ALSO...WAVEWATCH GUIDANCE SUGGESTS THAT NW SWELL CONTAINING SEAS 
UP TO 14 FT IS MOVING SOUTHEASTWARD ACROSS THE NW DISCUSSION 
AREA. AS THIS SWELL DEPARTS IT SOURCE REGION...MAXIMUM SEAS WILL 
SUBSIDE... THOUGH NORTHWESTERLY SWELL OF 8 TO 11 FT WILL 
OVERTAKE A LARGE PART OF THE DISCUSSION AREA THROUGH MIDWEEK. BY 
LATE WEEK...A SURFACE COLD FRONT WILL APPROACH THE NORTHERN 
PORTIONS OF THE DISCUSSION AREA...BRINGING WINDS UP TO 25 KT 
EITHER SIDE OF THE FRONT...WITH AN REINFORCEMENT OF HIGHER SEAS.

FARTHER TO THE S...THE AXIS OF THE SUBTROPICAL JET STREAM 
STRETCHES ALONG A LINE FROM 19N140W TO 24N120W TO CENTRAL BAJA 
CALIFORNIA INTO N MEXICO AND TEXAS...WHERE A MAIN CORE OF 130 KT 
IS NOTED. THIS JET IS ADVECTING ABUNDANT MID TO UPPER LEVEL 
MOISTURE EASTWARD ACROSS THE DISCUSSION AREA. SE OF THIS 
JET...ATMOSPHERIC STABILITY AND DEEP LAYERED DRY AIR IN THE 
VICINITY OF AN UPPER HIGH NEAR 11N101W IS SUPPORTING FAIR 
WEATHER ACROSS MUCH OF THE SE PORTION OF THE DISCUSSION AREA.

$$
FORMOSA