000
AXPZ20 KNHC 190312
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC FRI SEP 19 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 0215 UTC.

...TROPICAL WAVES...

TROPICAL WAVE ALONG 91W N OF 08N TO THE SE COAST OF GUATEMALA 
MOVING W ABOUT 10 KT. SCATTERED MODERATE WITH ISOLATED STRONG 
CONVECTION LIES AHEAD OF THE TROPICAL WAVE WITHIN 75 NM OF THE 
COAST BETWEEN 91W AND 95W. THIS WAVE WILL MOVE CLOSER TO THE 
AREA OF DISTURBED WEATHER DESCRIBED IN THE PARAGRAPH BELOW OVER 
THE NEXT FEW DAYS.

TROPICAL WAVE ALONG 101W FROM 06N TO 16N MOVING W ABOUT 05 TO 10 
KT. THIS WAVE IS ASSOCIATED WITH A BROAD MID LEVEL CYCLONIC 
CIRCULATION AND SCATTERED MODERATE WITH ISOLATED STRONG 
CONVECTION FROM 93W TO 108W BETWEEN 04N AND 17N. 20 TO 40 KT 
EASTERLY FLOW ALOFT IS PASSING OVER THE NORTHERN PORTION OF THIS 
REGION ON THE SOUTHERN SIDE OF THE BROAD ANTICYCLONE CENTERED IN 
THE VICINITY OF THE WESTERN BAY OF CAMPECHE COAST. THIS STRONG 
FLOW ALOFT IS INHIBITING DEEP CONVECTION BY GENERATING VERTICAL 
SHEAR. THE SYSTEM WILL MOVE INTO A SLIGHTLY MORE FAVORABLE 
ENVIRONMENT FOR DEVELOPMENT OVER THE NEXT FEW DAYS.

TROPICAL WAVE ALONG 120W FROM 06N TO 16N MOVING W 05 KT. VERY 
LITTLE CONVECTION IS ASSOCIATED WITH THIS SYSTEM.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 12N91W TO 09N109W TO 11N118W TO 
08N126W TO 09N140W. SCATTERED MODERATE WITH ISOLATED STRONG 
CONVECTION LIES WITHIN 270 NM S OF THE AXIS BETWEEN 93W AND 108W.

...DISCUSSION...

W OF 115W...
THE SOUTHERN EDGE OF THE DEEP LAYER TROUGH PUSHING INTO THE 
WESTERN CONUS IS CURRENTLY MOVING INTO NW WATERS AND WILL 
DISSIPATE SAT.  WHILE SURFACE WINDS ARE NOT EXPECTED TO EXCEED 
20 KT...ELEVATED SEAS TO 8 FT WITH NW SWELL WILL PUSH INTO NW 
WATERS OVERNIGHT.  THERE IS NO ACTIVE CONVECTION ASSOCIATED WITH 
THIS TROUGH.  IN THE WAKE OF THIS TROUGH...DEEP HIGH PRESSURE 
WILL BUILD INTO THE REGION FROM N OF THE AREA LATE SAT. THE 
REBUILDING RIDGE WILL LIMIT ANY NW PROGRESS FOR THE INVERTED MID 
LEVEL TROUGH CURRENTLY S OF 20N CENTERED ALONG 130W. THE 
TROPICAL WAVE ALONG 120W HAS SLOWED OVER THE LAST 24 HOURS AS IT 
HAS ENCOUNTERED THIS MID LEVEL TROUGH.  THE TROUGH SHOULD TURN 
THE WAVE ON A MORE NORTHERLY PATH WHERE IT WILL ENCOUNTER 
INCREASING SHEAR AND DISSIPATE OVER THE NEXT FEW DAYS.  
ELSEWHERE W OF 115W...A SUBSIDENT REGION IS CENTERED FROM THE 
CENTRAL COAST OF BAJA CALIFORNIA WSW TOWARD 20N140W.

E OF 115W...
ASIDE FROM THE AREA OF DISTURBED WEATHER ASSOCIATED WITH THE 
TROPICAL WAVE ALONG 101W MENTIONED ABOVE...DISSIPATING 
CONVECTION SPURRED ON BY AFTERNOON HEATING OVER LAND AND PUSHED 
W TOWARD THE COAST ON THE SOUTHERN EDGE OF THE UPPER TO MID 
LEVEL RIDGE STRETCHED ACROSS MEXICO ALONG 20N CAN BE FOUND 
WITHIN 45 NM OF THE COAST BETWEEN 20N AND 16N. 

NORTHERLY LOW TO MID LEVEL FLOW ASSOCIATED WITH THE STRONG 
PRESSURE GRADIENT BETWEEN THE RIDGING OVER NE MEXICO AND THE 
WEAKENING TROUGH OVER THE BAY OF CAMPECHE IS PUSHING SOUTHWARD 
INTO THE GULF OF TEHUANTEPEC.  AN ASCAT PASS AT 1544 UTC 
CONFIRMS A SWATH OF 20 TO 30 KT WINDS WITHIN 60 NM EITHER SIDE 
OF A LINE FROM 16N94W TO 13N97W.  THESE WINDS AND ASSOCIATED 
SEAS ARE EXPECTED TO SLOWLY SUBSIDE AS THE TROUGHING IN THE BAY 
OF CAMPECHE WEAKENS.

$$
SCHAUER CLARK