000
AXPZ20 KNHC 092120
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE SEP 09 2008

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 
2100 UTC.

...SPECIAL FEATURES...

TROPICAL STORM LOWELL...AT 2100 UTC...CENTERED NEAR 20.9N 113.2W 
OR ABOUT 255 MILES W SW OF THE SOUTHERN TIP OF BAJA CALIFORNIA 
AND ABOUT 275 MILES S SW OF CABO SAN LAZARO MEXICO. LOWELL IS 
MOVING N OR 360 DEG AT 03 KT. ESTIMATED CENTRAL PRESSURE IS 
1002 MB. MAXIMUM SUSTAINED WINDS ARE 40 KT WITH GUSTS TO 50 KT. 
SCATTERED MODERATE TO STRONG CONVECTION IS NOTED WITHIN 90 NM 
OVER THE SW QUADRANT. LOWELL IS FORECAST TO REMAIN A MINIMAL 
TROPICAL STORM MOVING GENERALLY NORTHWARD TONIGHT... WEAKENING 
TO A TROPICAL DEPRESSION AND TURNING TO THE NE TOWARDS THE BAJA 
PENINSULA ON WED AND CROSSING THE SOUTHERN BAJA PENINSULA EARLY 
THU...AND INTO THE GULF OF CALIFORNIA AS A REMNANT LOW PRES FRI 
AND EVENTUALLY DISSIPATING OVER INTERIOR NW OLD MEXICO ON SAT. 
PLEASE REFER TO THE LATEST NHC PUBLIC ADVISORY UNDER AWIPS 
HEADER MIATCPEP3 OR WMO HEADER WTPZ33 KNHC AND THE FULL FORECAST 
ADVISORY UNDER AWIPS HEADER MIATCMEP3 OR WMO HEADER WTPZ23 KNHC 
FOR MORE DETAILS. 

...ITCZ...

ITCZ AXIS ALONG 09N83W TO 06N94W TO 13N110W TO 09N130W TO 
10N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 30 
NM OF 06.5N79W AND WITHIN 90 NM EITHER SIDE OF LINE 07N84W TO 
06N88W.

...DISCUSSION...

AN UPPER TROUGH HAS PUSHED SE INTO THE DISCUSSION AREA ALONG 
POINTS 33N122W TO 30N130W MERGING WITH ANOTHER STALLED UPPER 
TROUGH EXTENDING FROM 31N139W WHERE THE TROUGH TURNS SW INTO AN 
UPPER CYCLONE FILLING NEAR 23N148W. IMMEDIATELY TO THE S OF 
THESE UPPER TROUGHS...AN UPPER ANTICYCLONE HAS SHIFTED W TO NEAR 
22N136W WITH ITS EASTERN RIDGE ERODING WESTWARD TO NEAR 23N125W 
AT THE MOMENT AS THE STRONG UPPER TROUGH DIGS FURTHER S AND 
EXPECTED TO AMPLIFY S ALONG 122W STEERING TS LOWELL EASTWARD.
THE UPPER ANTICYCLONE ASSOCIATED WITH TROPICAL STORM LOWELL IS 
CENTERED NEAR 22N113W AND HAS BECOME THE DOMINATE ANTICYCLONE 
...WITH ITS RIDGE EXTENDING NE ACROSS NORTHERN OLD MEXICO 
CRESTING AT OVER TEXAS NEAR 29N98W. A RIDGE ALSO EXTENDS SW TO A 
CREST AT 17N148W. THESE UPPER FEATURES ALL COMBINE DRYING OUT 
THE UPPER LEVELS OF THE DISCUSSION AREA TO THE W OF A WELL 
DEFINED LINE FROM 32N105W TO 22N120W TO 12N140W. AT THE LOW 
LEVELS...A BROAD SURFACE RIDGE LIES ROUGHLY ALONG 32N138W TO 
25N118W. 

THE UPPER FLOW IS NE TO E...RESPONDING TO THE UPPER RIDGE 
DESCRIBED ABOVE...OVER THE TROPICAL E PACIFIC BETWEEN 96W AND 
140W. THE ASSOCIATED UPPER DIFFLUENCE IS ENHANCING CONVECTION 
OVER THE WESTERN GULF OF MEXICO ALONG THE E COAST OF OLD MEXICO 
FROM 18N TO 26N. CONVECTION IS ALSO ENHANCED UNDER THE UPPER 
RIDGE ALONG THE W COAST OF OLD MEXICO FROM 17N WELL UP INTO THE 
GULF OF CALIFORNIA NEAR 27N...BOTH AREAS WEAKENING AT THE 
MOMENT. THE RESULTANT DEBRIS MOISTURE IS ADVECTED SW...MERGING 
WITH DEBRIS FROM LOWELL...INTO A PLUME ROUGHLY WITHIN 540 NM 
EITHER SIDE OF LINE 22N107W TO 07N127W...WITH SOME OF THE 
MOISTURE SPREADING S TO ALONG THE EQUATOR BETWEEN 114W AND 
132W.  

A BROAD UPPER TROUGH IS NOTED OVER THE DEEP TROPICS TO THE S OF 
08N ALONG 107W. CONVECTION IS ENHANCED E OF 90W AND IS 
DISSIPATING NEAR 06N100W. OTHERWISE DRY UPPER AIR IS INDICATED S 
OF 11N BETWEEN 90W AND 110W.

$$
NELSON