000
AXPZ20 KNHC 151600
TWDEP 

TROPICAL WEATHER DISCUSSION      
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT SEP 15 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 
1545 UTC.

...TROPICAL WAVES...

TROPICAL WAVE ALONG 94W N OF 9N MOVING W 10-15 KT. THE FIRST 
VISIBLE IMAGES OF THE DAY REVEAL A BROAD MID-LEVEL CIRCULATION 
OVER THE WATERS SW OF CENTRAL AMERICA WITH A LOW LEVEL VORTICITY 
CENTER NEAR 9N94W. THE ITCZ RUNS THROUGH THIS AREA AND THERE IS
STILL NOT A CLEAR INDICATION OF A SURFACE LOW. CONVECTION HAS 
FORMED NEAR THE WAVE BUT IS GENERALLY DISPLACED ABOUT 100-200 NM 
AWAY FROM THE VORTICITY CENTER. SCATTERED MODERATE/ISOLATED 
STRONG CONVECTION FROM 6N-16N BETWEEN 90W-101W.

TROPICAL WAVE ALONG 109W/110W FROM 6N TO 17N MOVING W 10 KT. A 
1008 MB LOW IS ALONG THE WAVE AXIS NEAR 12N. EASTERLY SHEAR 
CONTINUES TO AFFECT THE SYSTEM AND IS DISPLACING A CONVECTIVE 
BAND ABOUT 180 NM W OF THE LOW. SCATTERED MODERATE CONVECTION 
FROM 8N-12N BETWEEN 110W-115W...AND FROM 14N-16N BETWEEN 108W 
AND 112W.

TROPICAL WAVE WAS MOVED W OF THE DISCUSSION AREA ALONG 141W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 10N86W 12N94W 14N105W 12N110W 
15N117W 11N128W 11N140W. SCATTERED MODERATE/ISOLATED STRONG 
CONVECTION FROM 6N-11N BETWEEN 88W-101W. SCATTERED MODERATE FROM 
10N-15N BETWEEN 110W-115W. SCATTERED MODERATE FROM 10N-14N 
BETWEEN 125W-131W...AND FROM 14N-16N BETWEEN 119W-125W.

...DISCUSSION...

E OF 110W...
MID/UPPER LEVEL RIDGING REMAINS ANCHORED ACROSS NORTHERN MEXICO 
WITH AN ANTICYCLONIC CENTER JUST NE OF MAZATLAN. THE UPPER FLOW 
S OF THE RIDGE IS MAINLY EASTERLY TO NORTHEASTERLY...EXTENDING 
FROM CENTRAL AMERICA WWD TO 110W. HOWEVER...A DECAYING CYCLONIC 
SHEAR AXIS IS NOTED IN WATER VAPOR IMAGERY FROM THE ISTHMUS OF 
TEHUANTEPEC SW TO 13N100W. ABUNDANT MOISTURE LIES ACROSS THE 
ENTIRE REGION N OF 5N EXTENDING INTO SRN MEXICO AND MOST OF 
CENTRAL AMERICA. SCATTERED MODERATE CONVECTION IS FROM 
13N-17N BETWEEN 95W-108W...AND WITHIN 90 NM OF THE COAST BETWEEN 
20N-24N. A COUPLE OF TROPICAL WAVES ARE MOVING THROUGH THE AREA 
AT THE MOMENT BUT NEITHER ARE EXPECTED TO SHOW MUCH DEVELOPMENT 
IN THE COMING DAYS.

W OF 110W...
THE SURFACE RIDGE IS BECOMING RE-ESTABLISHED NEAR 30N AND AS A 
RESULT IS STRENGTHENING THE PRESSURE GRADIENT WITHIN THE TRADE 
WIND BELT FROM 16N-25N. ELSEWHERE...THE SURFACE WIND FIELD IS 
MUCH WEAKER WITH WESTERLIES NOTED NEAR A DISSIPATING 1008 MB LOW 
NEAR 19N118W AND A 1009 MB LOW NEAR 13N123W. THE SECOND LOW IS 
EXPECTED TO MOVE W OVER THE NEXT FEW DAYS AND LIKELY FURTHER 
INCREASE THE PRESSURE GRADIENT TO ITS NW IN THE TRADE WIND ZONE. 
LOW-LEVEL CONVERGENCE NEAR THE LOW IS CURRENTLY PRODUCING WIDELY 
SCATTERED MODERATE CONVECTION FROM 10N-15N BETWEEN 125W-131W. 
THE UPPER LEVELS ARE DOMINATED BY AN EXTENSIVE RIDGE AXIS FROM 
BAJA CALIFORNIA SW TO 12N140W. A LARGE MID/UPPER LOW IS CENTERED 
NEAR THE CALIFORNIA/OREGON COAST AND THE SUBTROPICAL JET SCRAPES 
BY THE NW PART OF THE AREA WITH MAXIMUM JET SPEEDS NEAR 65 KT.

$$
COBB