000
AXPZ20 KNHC 170322
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED SEP 17 2008

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0145 UTC.

...TROPICAL WAVES...

TROPICAL WAVE ALONG 79W N OF 05N INTO PANAMA IS MOVING W ABOUT 
12 KT. CONVECTION IN THE PACIFIC ASSOCIATED WITH THIS SYSTEM CAN 
MAINLY BE FOUND AHEAD OF THE TROPICAL WAVE BETWEEN 81W AND 88W 
WITH SCATTERED MODERATE TO STRONG CONVECTION MOVING W TOWARD THE 
COAST OF CENTRAL AMERICA IN THIS REGION.

TROPICAL WAVE ALONG 90W N OF 08N INTO CENTRAL AMERICA IS MOVING 
W ABOUT 12 KT. THE WAVE IS RELATIVELY WEAK WITH MAINLY SCATTERED 
MODERATE CONVECTION FOUND WITHIN 60 NM OF THE COAST W OF THE 
WAVE AXIS AND E OF 94W AND NEAR THE S EDGE OF THE WAVE AXIS N OF 
05N.

TROPICAL WAVE ALONG 111W FROM 04N TO 16N IS MOVING W ABOUT 10 
KT. THIS WAVE IS ALSO WEAK WITH MINIMAL CONVECTION ASSOCIATED 
WITH IT.

...ITCZ...

ITCZ AXIS IS CENTERED FROM 09N82W TO 10N98W TO 10N117W TO 
12N126W TO 10N140W. ISOLATED MODERATE TO STRONG CONVECTION CAN 
BE FOUND N OF THE ITCZ AXIS TO THE COAST BETWEEN 85W AND 88W AND 
SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION CAN BE FOUND 
WITHIN 240 NM S OF AXIS BETWEEN 81W AND 91W.

...DISCUSSION...

N OF 20N W OF 105W...
A MID TO UPPER LEVEL TROUGH CURRENTLY STRETCHED ACROSS NW WATERS 
WILL BE REINFORCED BY A DEEP TROUGH FROM THE N PAC AS IT SETTLES 
S OVER THE NEXT DAY OR TWO. NW SWELL FROM THIS COMPLEX IS 
ALREADY BEGINNING TO MOVE INTO NW WATERS. WHILE THE APPROACH OF 
THE DEEP TROUGH IS EXPECTED TO RAISE PRECIPITABLE WATER VALUES 
TO THE 1.25 INCH RANGE AS IT APPROACHES THE FAR NW WATERS 
THU...CONVECTION WILL BE MINIMAL WITH VERTICAL LIFT EXPECTED TO 
BE INHIBITED OVER THE REGION. THE STRONG SUBSIDENCE CURRENTLY 
OVER THE WATERS N OF 15N W OF 105W WILL CONTINUE TO DOMINATE THE 
SENSIBLE WEATHER OVER THE REGION. AN UPPER LEVEL RIDGE ALONG 22N 
IS STRETCHED FROM THE ANTICYCLONE CENTER AT 22N115W TO THE MORE 
DOMINATE ANTICYCLONE CENTERED NEAR 22N98W WITH THE MEAN UPPER 
RIDGE EXPECTED TO SHIFT S TOWARD 20N AS THESE ANTICYCLONES 
MERGE. ON THE S EDGE OF THE UPPER RIDGE...EASTERLY FLOW TO 40 KT 
DOMINATES THE FLOW REGIME...INHIBITING DEEP CONVECTION ALONG THE 
ITCZ...WITH THE SURFACE TROUGH ALONG 129W...AND WITH THE 
TROPICAL WAVE ALONG 111W WHERE LOW LEVEL TROPICAL MOISTURE AND 
CONVERGENCE IS PLENTIFUL.

S OF 20N E OF 105W...
CONVECTION HAS BECOME MORE ACTIVE THIS EVENING E OF 92W WHERE 
THE UPPER LEVEL FLOW IS PRIMARILY DIFFLUENT ON THE SW SIDE OF 
THE ANTICYCLONE CENTERED OVER THE W CARIBBEAN. THIS ANTICYCLONE 
IS EXPECTED TO BE ENGULFED INTO THE PRIMARY UPPER LEVEL HIGH 
CENTERED NEAR 22N98W. ELSEWHERE...A LOW LEVEL TROUGH PUSHING S 
THROUGH MEXICO AND THE GULF OF MEXICO COUPLED WITH THE 
APPROACHING TROPICAL WAVE ALONG 90W HAS TRIGGERED 20 TO 25 KT 
NORTHERLY FLOW IN THE GULF OF TEHUANTEPEC WHICH IS EXPECTED TO 
BE SUSTAINED FOR THE NEXT FEW DAYS. IN ADDITION...SW SWELL FROM 
THE SOUTHERN HEMISPHERE HAS ELEVATED SEAS TO 10 FT S OF 13N 
BETWEEN 92W AND 122W. THIS SWELL IS EXPECTED TO SLOWLY DIMINISH 
OVER THE NEXT FEW DAYS.

$$
SCHAUER CLARK