000
AXPZ20 KNHC 120311
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC FRI SEP 12 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 
0245 UTC.

...SPECIAL FEATURES...

TROPICAL DEPRESSION LOWELL DISSIPATING NEAR 26.0N 109.0W OR 
ABOUT 15 MILES N OF LOS MOCHIS MEXICO AT 12/0300 UTC MOVING N OR 
10 DEG AT 9 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB.
MAXIMUM SUSTAINED WIND SPEED IS 20 KT WITH GUSTS TO 25 KT. ALL
ASSOCIATED CONVECTIVE ACTIVITY HAS JUST ABOUT DISSIPATED. ONLY
WEAK ISOLATED SHOWERS OVER NW MEXICO. THE REMNANT LOW WILL
CONTINUE TO TRACK NE OVER NW MEXICO THROUGH THE NEXT 24-48 HOURS.

...TROPICAL WAVES...

TROPICAL WAVE HAS ENTERED THE FAR ERN WATERS ALONG 85W N OF 4N
MOVING W ABOUT 18 KT. ISOLATED MODERATE CONVECTION IS WITHIN 120 
NM W OF THE WAVE WITHIN 30 NM OF 10N87W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 10N85W 8N92W 9N100W 8N110W 10N119W
13N124W 13N140W. NO SIGNIFICANT CONVECTION IS NOTED.

...DISCUSSION...

A MID/UPPER LEVEL CYCLONIC CIRCULATION DROPPING SSE ABOUT 17 KT 
IS OVER SRN CALIFORNIA. THIS CIRCULATION IS EMBEDDED IN A RATHER
SHARP TROUGH THAT EXTENDS INTO THE AREA THROUGH 32N118W...AND 
CONTINUES TO 27N119W TO 23N125W. A NEARLY STATIONARY UPPER LEVEL 
ANTICYCLONE IS CENTERED NEAR 22N136W...WHILE A SECOND ONE IS E 
OF THE DISCUSSION AREA OVER ERN TEXAS NEAR 29N98W. A RIDGE 
EXTENDS SW FROM THIS ANTICYCLONE SW ACROSS CENTRAL MEXICO TO 
23N108W...AND TO 20N120W WHERE A COL REGION EXISTS BETWEEN BOTH 
ANTICYCLONES. MID/UPPER LEVEL MOISTURE IS CIRCULATING 
ANTICYCLONICALLY AROUND THE WRN PERIPHERY OF THE ANTICYCLONE 
OVER ERN TEXAS. THIS MOISTURE CONSISTS OF RESIDUAL MOISTURE FROM 
DISSIPATING TROPICAL DEPRESSION LOWELL AND MOISTURE FROM 
SCATTERED MODERATE/ISOLATED STRONG CONVECTION OCCURRING OVER THE 
INTERIOR PORTION OF MEXICO. THE MID/UPPER LEVEL TROUGH IS 
FORECAST TO LIFT NE OVER THE SW UNITED STATES IN ABOUT 48-72W 
HOURS.

MODERATE E-SE UPPER FLOW IS NOTED ON THE SW SIDE OF THE MEXICAN
RIDGE...WHILE SIMILAR FLOW IS IN BETWEEN THE RIDGE AND THE TROUGH
TO ITS NW. UPPER LEVEL MOISTURE...TO A LESSER EXTENT AS MENTIONED
ABOVE...IS ADVECTING WWD BY THE ELY FLOW TO THE S OF THE RIDGE.
THIS MOISTURE REACHES AS FAR W AS 120W.

THE REMAINDER OF THE DISCUSSION AREA IS UNDER AMPLE MODERATE TO 
STRONG SUBSIDENCE AND ASSOCIATED DRY STABLE CONDITIONS AS 
OBSERVED ON WATER VAPOR IMAGERY...MAINLY N OF 19N W OF A LINE 
FROM 30N110W TO 20N119W TO 15N125W IS INHIBITING ANY CONVECTION 
FROM DEVELOPING WITHIN THIS AREA.

AT THE SURFACE...WEAK RIDGE EXTENDS FROM 32N137W TO 25N128W TO
21N118W. HIGH PRES COVERS THE AREA N OF 20N W OF 125W. A SMALL 
AND SHEARED 1010 MB LOW IS NEAR 13N130W MOVING W 8 KT...BUT 
SHOULD DISSIPATE WITHIN THE NEXT 12-18 HOURS OR SOONER.

IN REFERENCE TO THE HIGH SEAS MARINE FORECAST...LONG PERIOD 
CROSS-EQUATORIAL SW SWELLS FROM THE SOUTHERN HEMISPHERE IN THE 
RANGE OF 6-8 FT CONTINUE TO IMPACT MUCH OF THE TROPICAL E 
PACIFIC WATERS...EXCEPT W OF 125W WHERE SE SWELLS PREVAILS UNDER 
SE WINDS TO 20 KT. WAVE GUIDANCE SUGGESTS THAT WAVE HEIGHTS ARE 
FORECAST TO CHANGE LITTLE THROUGH EARLY SUN...THEN MAYBE 
INCREASE TO 9 FT ALONG AND NEAR THE EQUATOR.

$$
AGUIRRE