000
AXPZ20 KNHC 160921
TWDEP 

TROPICAL WEATHER DISCUSSION      
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU AUG 16 2007

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0845 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 101W N OF 6N MOVING W 10 KT. SOME 
SCATTERED STRONG CONVECTION NEAR THE MEXICAN COAST OTHERWISE 
CONVECTION IS WIDELY SCATTERED AND NOT ORGANIZED. 

TROPICAL WAVE IS ALONG 121W FROM 5N-16N MOVING W 10 KT. 
SCATTERED MODERATE CONVECTION ALONG THE ITCZ ABOUT 5 DEGREES W 
OF THE WAVE AXIS. THERE IS NO ORGANIZATION TO THE CONVECTION AND 
NO SIGNS OF A CIRCULATION.
 
...ITCZ...
ITCZ AXIS ALONG 7N78W 13N91W 15N105W 12N113W 15N131W 12N140W. 
SCATTERED MODERATE CONVECTION WITHIN 45 NM OF A LINE FROM 5N78W 
TO 6N87W TO 10N96W TO 11N103W TO 14N110W TO 12N116W AND FROM 
12N121W TO 15N130W AND FROM 13N137W TO 12N140W.

SCATTERED MODERATE WITHIN 60 NM OF THE COAST FROM 7N79W TO 7N83W 
TO 11N87W TO 13N91W. SCATTERED STRONG CONVECTION WITHIN 60 NM OF 
THE COAST FROM 16N94W TO 15N99W TO 18N105W TO 21N106W TO 23N107W.

...DISCUSSION...

THE REGION IS MOSTLY DOMINATED BY A LARGE MID LEVEL RIDGE 
CENTERED OVER THE SRN CONUS THAT EXTENDS W AND SW TO 20N130W. 
WATER VAPOR IMAGERY TONIGHT SHOWS A VERY DRY MID AND UPPER 
ATMOSPHERE FROM THE BAJA COAST W AND SW THROUGH THE RIDGE. 
EMBEDDED IN THE RIDGE IS A WEAK INVERTED TROUGH ALONG 118W. 
WATER VAPOR SHOWS A WEAK VORTICITY MAX ASSOCIATED WITH THE 
TROUGH NEAR 27N119W MOVING SSW 15 TO 20 KT. MID LEVEL TROUGHING 
OVER THE NW CORNER OF THE AREA CONINUES WITH A STRONG CYCLONIC 
CIRCULATION WELL N OF THE AREA OFF THE PAC NW COAST. LITTLE IN 
THE WAY OF DISTURBANCES IN THIS CIRCULATION ARE HEADED OUR WAY 
TONIGHT. MOST ARE MOVING E AND NE. ON THE SURFACE TONIGHT A WEAK 
LOW WAS LOCATED NEAR 15N106W WITH LITTLE CONVECTION ASSOCIATED 
WITH IT AT PRESENT. THE PACIFIC RIDGE EXTENDS WEAKLY OVER THE 
REGION TO 15N110W. GFS MODEL FOR 06Z SHOWS NE TRADES OF 20 KT 
FROM 12N TO 22N W OF 130W. LITTLE HELP FROM SSMI AND 
QUIKSCAT..THEY BOTH MISSED THE AREA. WINDS ALONG THE BAJA COAST 
ARE NWLY 10 TO 15 KT ACCORDING TO BOTH MICROWAVE IMAGERY. GAP 
WINDS ARE LIGHT AND CROSS EQUATORIAL SLY WINDS ARE STRONGEST 
BETWEEN 90W AND 100W AND BETWEEN 120W AND 135W ACCORDING TO 
SSMI. SPEEDS ARE 15 TO 20 KT.

LATER DAY 1 LITTLE CHANGE TO THE LARGE SCALE MID LEVEL PATTERN. 
THE INVERTED TROUGH DRIFTS WWD TO 120W STILL STUCK ON THE S SIDE 
OF THE RIDGE THAT EXTENDS FROM THE SRN CONUS SW TO 20N140W. ON 
THE SURFACE LATER DAY 1 SOME INCREASE IN NLY WINDS BETWEEN 120W 
AND 125W DUE TO THE PRES GRADIENT BETWEEN THE PACIFIC RIDGE AND 
LOW PRES OVER THE DESERT NW MEXICO AND SW CONUS DESERT. GFS 
MODEL LIKES THE LOW SW OF THE MEXICAN COAST AND MOVES IT TO NEAR 
13N108W WITH SW WINDS TO 25 KT. ELSEWHERE NO CHANGE. 

FOR DAY 2 THE MID LEVEL RIDGE WILL MAINTAINS IT'S GRIP ON THE SW 
CONUS. A SECONDARY BUBBLE FORMS W OF 130W AND IN BETWEEN THE 
INVERTED TROUGH SITS ALONG 123W. IT IS IN A WEAKNESS IN THE PRES 
FIELD BETWEEN 120W AND 130W AND MAY TRY TO MOVE NWD TOWARD THE 
LARGE TROUGH N OF THE AREA ALONG 130W. ON THE SURFACE DAY 2 THE 
GFS MODEL CONTINUES TO TRY AND DEVELOP THE LOW NEAR 14N108W. THE 
PACIFIC RIDGE STRENGTHENS SOME AND WINDS OF 20 KT ARE PREVALENT 
N OF 14N W OF 120W. WINDS ALONG THE BAJA COAST REMAIN LIGHT AS 
DO GAP WINDS. CROSS EQUATORIAL SLY WINDS WILL INCREASE TO 20 KT 
BETWEEN 100W AND 120W IF THE LOW AT 14N108W STRENGTHENS. 

$$
RRG