000
AXPZ20 KNHC 072122
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SUN SEP 07 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 
2115 UTC.

...SPECIAL FEATURES...

TROPICAL STORM LOWELL...AT 2100 UTC...CENTERED NEAR 17.9N 108.8W 
W...OR ABOUT 355 NM S SE OF THE SOUTHERN TIP OF THE BAJA 
PENINSULA...MOVING NW OR 305 DEG AT 10 KT. ESTIMATED CENTRAL 
PRESSURE IS 996 MB. MAXIMUM SUSTAINED WINDS 45 KT WITH GUSTS TO 
55 KT. NUMEROUS MODERATE TO STRONG CONVECTION IS NOTED WITHIN 
240 NM OVER THE SW QUADRANT. SCATTERED MODERATE CONVECTION IS 
OBSERVED ELSEWHERE FROM 13N TO 18N BETWEEN 108W AND 114W. LOWELL 
IS FORECAST TO STRENGTHEN SLIGHTLY REMAINING A TROPICAL STORM 
THROUGH TUE THEN TURN NE TOWARDS THE BAJA PENINSULA ON WED. 
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 LIES ALONG 07N77W TO 11N100W TO 10N120W TO 10N135W TO 
08N140W. SCATTERED MODERATE CONVECTION NOTED WITHIN 120 NM OF 
THE AXIS E OF 83W. SCATTERED MODERATE CONVECTION OBSERVED FROM 
08N TO 10N BETWEEN 127W AND 130W.

...DISCUSSION...

AN UPPER TROUGH LIES ALONG THE N AND NW PERIPHERY OF THE 
DISCUSSION AREA...FROM 33N117W TO 32N130W TO 26N140W THEN SW 
INTO A SMALL UPPER CYCLONE AT 21N150W. THIS UPPER TROUGH SPLITS 
TWO UPPER RIDGES...ONE ORIENTATED NE TO SW BASICALLY N AND NE OF 
THE HAWAIIAN ISLANDS. THE SECOND UPPER RIDGE LIES NE TO SW 
ACROSS MOST OF THE DISCUSSION AREA. EMBEDDED UPPER ANTICYCLONES 
ARE CENTERED AT 26N125W AND AT 21N132W WITH A RIDGE EXTENDING SW 
TO A CREST NEAR 14N143W. AN UPPER TROUGH NOW EXTENDS S OVER 
WESTERN MEXICO FROM 32N117W TO 23N112W. THIS TROUGH HAS 
SEPARATED THE ANTICYCLONIC FLOW DESCRIBED ABOVE OVER THE PACIFIC 
FROM ANOTHER ANTICYCLONE OVER THE WESTERN GULF OF MEXICO WITH 
ITS RIDGE EXTENDING SW TO YET ANOTHER UPPER ANTICYCLONE 
DEVELOPING OVER TROPICAL STORM LOWELL. THE TROUGH IS EXPECTED TO 
AMPLIFY S ALONG 120W BECOMING THE PRIMARY STEERING MECHANISM FOR 
TROPICAL STORM LOWELL LATER THIS WEEK. FOR NOW...THESE UPPER 
FEATURES COMBINE TO DRY OUT THE UPPER LEVELS OF THE DISCUSSION 
AREA TO THE W OF A LINE FROM 31N105W TO 19N119W TO 14N140W. AT 
THE LOW LEVELS...A BROAD SURFACE RIDGE LIES ROUGHLY ALONG 
32N143W TO 27N115W.

THE UPPER FLOW IS NE TO E OVER THE TROPICAL E PACIFIC BETWEEN 
92W AND 115W. THE ASSOCIATED UPPER DIFFLUENCE IS ENHANCED 
CONVECTION ASSOCIATED WITH LOW PRES OVER THE BAY OF CAMPECHE... 
AND OF COURSE ENHANCING CONVECTION OVER AND NEAR THE TROPICAL 
STORM. THE DEBRIS MOISTURE IS ADVECTED SW BETWEEN 99W AND 
117W...WITH SOME SPREADING S OF THE EQUATOR NEAR 100W AND 110W. 
CONVECTION WAS ALSO ENHANCED EARLIER ALONG THE PACIFIC COAST OF 
COLOMBIA...WITH THE DEBRIS MOISTURE BEGINNING TO SPREAD W OVER 
THE AREA N OF 03N E OF 84W.

$$
NELSON