000
AXPZ20 KNHC 281532
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI SEP 28 2007

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 
1515 UTC.
  
...SPECIAL FEATURE...

A 1007 MB LOW IS LOCATED ALONG A TROPICAL WAVE AXIS NEAR 14.2N 
106.9W...OR ABOUT 330 NM SSW OF MANZANILLO MEXICO...MOVING W AT 
5-10 KT. THE LOW STILL APPEARS TO BE UNDER THE INFLUENCE OF 
ABOUT 20 KT OF EASTERLY SHEAR...WHICH HAS CAUSED MOST OF THE 
DEEP CONVECTION TO BE LOCATED OVER THE WESTERN SIDE OF THE 
LOW-LEVEL CIRCULATION. SCATTERED MODERATE/ISOLATED STRONG 
CONVECTION IS FROM 9N-16N BETWEEN 106W-110W. UPPER LEVEL WINDS 
MAY RELAX JUST ENOUGH FOR THIS SYSTEM TO BECOME A LITTLE BETTER 
ORGANIZED...AND A TROPICAL DEPRESSION COULD FORM WITHIN THE NEXT 
24-48 HOURS. 

...TROPICAL WAVES...

TROPICAL WAVE ALONG 117W S OF 16N MOVING W 10-15 KT. THE AREA OF 
LOW PRESSURE WHICH WAS ALONG THE WAVE YESTERDAY HAS DEGENERATED 
AND BECAME ABSORBED INTO THE ITCZ. CONVECTION ALONG THE ITCZ 
DOES STILL SHOW A WEAK MID-LEVEL CIRCULATION IN THE VICINITY OF 
THE WAVE AXIS. SEE ITCZ FOR RELATED CONVECTION.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 8N77W 7N82W 14N106W 11N130W 12N140W. 
WIDELY SCATTERED MODERATE CONVECTION WITHIN 120 NM OF AXIS 
BETWEEN 81W-90W AND FROM 7N-12N BETWEEN 94W-102W. SCATTERED 
MODERATE/ISOLATED STRONG WITHIN 150 NM OF AXIS BETWEEN 
112W-127W. SCATTERED MODERATE/ISOLATED STRONG FROM 10N-16N W OF 
134W.

...DISCUSSION...

E OF 110W...
AN UPPER LEVEL RIDGE EXTENDS ACROSS S/CENTRAL MEXICO FROM THE 
UPPER LEVEL ANTICYCLONE CREATED BY T.D. LORENZO SW TO NEAR 
18N110W...AND IS COLLOCATED WITH A MID-LEVEL RIDGE OVER THE SAME 
VICINITY. AS A RESULT...THE DEEP EASTERLY FLOW IS PRODUCING 
STRONG EASTERLY SHEAR S OF ABOUT 15N...INCREASING TO THE 30-40 
KT RANGE S OF 10N. DEEP MOISTURE IS QUITE ABUNDANT BETWEEN 
90W-110W DUE TO THE PRESENCE OF T.D. LORENZO AND THE AREA OF LOW 
PRESSURE NEAR 14N107W. N OF THE LOW...AN AXIS OF LOW-LEVEL 
CONVERGENCE EXTENDS FROM NEAR PUERTO VALLARTA SW TO 
17N110W...AND NUMEROUS MODERATE/STRONG CONVECTION HAS FORMED 
JUST OFFSHORE FROM 19N-22N BETWEEN 105W-108W. WESTERLY 
MID-LATITUDE FLOW IS IN PLACE OVER THE CONTINENTAL UNITED 
STATES...AND THIS FLOW EXTENDS FAR ENOUGH S TO SPREAD ACROSS 
NORTHERN MEXICO N OF 24N.

W OF 110W...
AN EXTENSIVE MID/UPPER LEVEL RIDGE AXIS EXTENDS ACROSS THE REST 
OF THE PACIFIC WATERS FROM 18N110W TO 18N140W. A FAIRLY VIGOROUS 
UPPER TROUGH IS MOVING INLAND OVER THE W COAST OF THE UNITED 
STATES AND THE TRAILING TROUGH AXIS IS JUST REACHING THE 
DISCUSSION AREA ALONG 30N W OF 128W. WESTERLY FLOW HAS 
STRENGTHENED JUST S OF THE TROUGH AXIS WITH A 70-95 KT JET 
STREAK RUNNING FROM 28N140W TO 30N123W THEN TO THE 
CALIFORNIA/MEXICO BORDER. THE TROUGH AND AFOREMENTIONED RIDGE 
AXIS ARE PRODUCING A LARGE AREA OF MODERATE SUBSIDENCE N OF 
17N...AN AREA DOMINATED BY STABLE LOW-LEVEL STRATOCUMULUS. 
FARTHER S...THE ITCZ IS CONVECTIVELY ACTIVE AND COULD BE THE 
RESULT OF SLIGHT UPPER LEVEL DIVERGENCE WHERE UPPER LEVEL WINDS 
ARE ACCELERATING S OF 10N TO THE EQUATOR.

$$
BERG