000
AXPZ20 KNHC 081539
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU OCT 08 2009

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...TROPICAL WAVE... 

A TROPICAL WAVE WAS ANALYZED ALONG 104W N OF 08N TO THE MEXICAN 
COAST....AND ESTIMATED TO BE MOVING W 15 KT. THIS WAVE IS MOVING 
PAST AN UPPER RIDGE AND IS NOW IN THE DIFFLUENT ALOFT REGION OF 
AN UPPER SHORTWAVE DISCUSSED MORE FULLY BELOW. THE DIFFLUENCE 
IS SUPPORTING CONVECTION IN A LARGE AREA NEAR THE WAVE AXIS. THE 
GFS COMPUTER FORECAST MODEL SHOWS A BROAD SURFACE LOW PRESSURE 
IN THIS AREA WHICH THE MODEL KEEPS STATIONARY FOR THE NEXT 
SEVERAL DAYS. CONVECTION NORTH OF 14N EXTENDS ABOUT 90 NM WEST 
OF THE WAVE AXIS AND 120 NM EAST OF THE WAVE AXIS AND SHOWS SOME 
INDICATIONS OF BEING ORGANIZED BY BROAD CYCLONIC CIRCULATION. 

...ITCZ...

THE ITCZ AXIS WAS CENTERED ALONG 07N77W TO 13N105W TO 10N125W TO 
06N140W. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 60 NM 
OF THE POINT 07N80W. SCATTERED MODERATE CONVECTION IS WITHIN 60 
NM OF THE POINT 08N93W. SCATTERED MODERATE TO STRONG CONVECTION 
IS WITHIN 60 NM OF THE POINT 09N97W. SCATTERED MODERATE TO 
STRONG WITHIN 200 NM NORTHWEST OF THE AXIS AND 140 NM SOUTHEAST 
OF THE AXIS FROM 125W TO 105W.

WITHIN THE ITCZ A LOW PRESSURE IS ANALYZED NEAR 12.5N114W WITH A 
CENTRAL PRESSURE OF 1010 MB. THE LOW HAS BEEN DRIFTING SLOWLY 
WEST AND HAS NOT DEVELOPED. A LARGE AREA OF CONVECTION NEAR THE 
LOW HAS DIMINISHED DURING THE LAST SEVERAL HOURS. THE GFS 
COMPUTER MODEL DOES NOT DEPICT THE LOW VERY WELL AND DOES NOT 
DEVELOP ANY CIRCULATION NEARBY.
  
ALSO WITHIN THE ITCZ IS A TROUGH FROM 15N123.5W TO 08N127W 
MOVING WEST 10 KT. A LINE OF CONVECTION IS LOCATED ABOUT 100 NM 
NORTHWEST OF THE TROUGH AND THE CONVECTION IS MOVING AWAY FROM 
THE TROUGH. THE GFS COMPUTER MODEL MAINTAINS THE TROUGH AS IT 
MOVES WEST AND DOES NOT DEVELOP A CIRCULATION.

...DISCUSSION...

UPPER LEVELS...
A DEEP LAYER SHORTWAVE IS OVER THE NORTHEAST PART OF THE PACIFIC 
OCEAN AREA AND THE NORTH HALF OF THE BAJA CALIFORNIA PENINSULA 
AND THE SOUTHWESTERN UNITED STATES. THE TROUGH IS FORECAST TO 
MOVE EAST OVER NORTHERN MEXICO AND THE U.S. STATES OF ARIZONA 
AND NEW MEXICO. THE AREA IS DRY AND CLOUD FREE. THE ONLY 
MOISTURE ASSOCIATED WITH THE SYSTEM IS OVER CALIFORNIA BUT THERE 
ARE NO CLOUDS WITH THIS SYSTEM. ASSOCIATED UPPER DIFFLUENCE IS 
ENHANCING CONVECTION WELL SOUTHEAST OF THE TROUGH OFF THE 
SOUTHWEST COAST OF CENTRAL MEXICO.

ANOTHER TROUGH LOCATED WEST OF THE AREA NEAR 150W WILL MOVE EAST 
AND OVER THE NORTHWEST PART OF THE AREA TONIGHT. THIS TROUGH 
WILL MOVE EAST TO WHERE THE ABOVE TROUGH IS SATURDAY NIGHT.

OTHERWISE A BROAD RIDGE IS OVER THE AREA.

A BROAD AREA OF MULTI LEVEL CLOUDS AND EMBEDDED AREAS OF 
CONVECTION IS NORTH OF THE ITCZ WEST OF 100W AND SOUTH OF A 
LINE FROM 12N140W TO 15N120W TO WEST TEXAS. THE CONVECTION IS 
MOSTLY OVER THE OCEAN.

SURFACE...
MODERATE RIDGE IS NORTH OF THE ITCZ WEST OF 110W. ELSEWHERE 
BESIDES THE FEATURES MENTIONED WITH THE ITCZ A BROAD TROUGH IS 
ANALYZED AT THE SURFACE.

$$
LL