000
AXPZ20 KNHC 260916
TWDEP 

TROPICAL WEATHER DISCUSSION     
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SUN AUG 26 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 85W N OF 5N MOVING W AT 15 KT. ISOLATED 
MODERATE CONVECTION AT THIS TIME WITH NO ORGANIZATION.

TROPICAL WAVE IS ALONG 98W N OF 5N MOVING W NEAR 5-10 KT. 
SCATTERED STRONG CONVECTION ALONG THE MEXICAN COAST BUT NO 
ORGANIZATION.  

...ITCZ...

ITCZ AXIS ALONG 12N85W 16N99W 13N113W 12N126W 9N135W 10N140W. 
SCATTERED MODERATE CONVECTION FROM 6N78W TO 7N81W. SCATTERED 
STRONG FROM 10N88W TO 12N91W. SCATTERED MODERATE TO STRONG 
WITHIN 20 NM OF A LINE FROM 11N101W TO 14N108W. SCATTERED 
MODERATE WITHIN 30 NM OF 12N112W AND FROM 10N121W TO 11N127W TO 
8N134W. 

SCATTERED STRONG CONVECTION NEAR THE MEXICAN COAST FROM 16N96W 
TO 16N99W TO 17N102W. ISOLATED STRONG NEAR 21N106W.

...DISCUSSION...

LARGE MID LEVEL RIDGE HOLDING FIRM OVER SW CONUS TONIGHT PRETTY 
WELL DOMINATES THE REGION. WATER VAPOR IMAGERY TONIGHT SHOWS A 
MOSTLY ZONAL WLY MID LEVEL FLOW N OF 40N BUT A SHORTWAVE ALONG 
132W IS HELPING TO BUILD THE RIDGE EVEN MORE THUS THE RIDGE IS 
GOING NO WHERE IN THE IMMEDIATE FUTURE. A SECOND MID LEVEL RIDGE 
IS JUST NW OF THE AREA NEAR 35N145W BUT THE ZONAL FLOW TO THE N 
IS KEEPING IT IN CHECK AND IT REMAINS WEAK. IN BETWEEN THERES A 
WEAKNESS IN THE MID LEVEL PRESSURE FIELD BETWEEN 120W AND 135W 
AND WEAK DISTURBANCES IN IN THE MID LEVELS THAT ARE ROTATING 
AROUND THE SRN PORTION OF THE SW CONUS RIDGE FIND THEMSELVES 
MOVING NW TOWARD THIS WEAKNESS. ONE TONIGHT IS LOCATED NEAR 
30N121W MOVING N 10 KT ACCORDING TO THE LATEST WATER VAPOR 
IMAGERY. ON THE SURFACE TONIGHT THE PACIFIC RIDGE REMAINS 
CENTERED NW OF THE AREA AND IS PRODUCING NE WINDS TO 20 KT N OF 
27N W OF 130W. OTHERWISE THE PRES GRADIENT IS WEAK OVER THE 
REGION N OF 15N W OF 110W AND WINDS ARE MOSTLY 10 TO 15 KT 
ACCORDING TO SSMI AND QUIKSCAT IMAGERY. GAP WINDS REMAIN LIGHT 
BUT CROSS EQUATORIAL SLY WINDS ARE 20 TO 25 KT S OF THE ITCZ 
BETWEEN 95W AND 120W WHERE CONVECTION IS ACTIVE ACCORDING TO 
SSMI AND QUIKSCAT. SLY SWELL TO 9 FT CONTINUES TO PROPOGATE NWD 
FROM THE S PACIFIC.

LATER DAY 1 WHILE THE SW CONUS MID LEVEL RIDGE HOLDS FIRM..THE 
SECOND RIDGE NW OF THE AREA SLIDES E ALONG 34N TO 130W CLOSING 
THE WEAKNESS GAP TO BETWEEN 120W AND 130W. ON THE SURFACE LATER 
DAY 1 LITTLE CHANGE TO THE OVERALL PATTERN WITH NO CHANGE TO 
WINDS. TRPL WAVES REMAIN WEAK BUT THE GFS MODEL LIKES A WEAK LOW 
ON THE ITCZ NEAR 10N90W AND TRIES TO DEVELOP IT OVER TIME. 
OTHERWISE THE PACIFIC RIDGE REMAINS WEAK OVER THE REGION AND NE 
TRADES MOSTLY 10 TO 15 KT.

FOR DAY 2 THE SW CONUS MID LEVEL RIDGE SLIDES EWD TO 90W BUT 
MAINTAINS A RIDGE AXIS WWD TO 30N120W. THE OTHER MID LEVEL RIDGE 
HOLDS NEAR 35N140W WITH A WEAKNESS PERSISTING BETWEEN THE 
TWO..120W TO 130W. ON THE SURFACE DAY 2 SOME INCREASE IN NE 
TRADES N OF 27N W OF 130W AS THE PACIFIC RIDGE STRENGTHENS 
SLIGHTLY. OTHERWISE NE TRADES REMAIN 10 TO 15 KT N OF 15N W OF 
110W. GAP WINDS REMAIN LIGHT WHILE CROSS EQUATORIAL SLY WINDS TO 
20 KT WILL CONTINUE S OF 10N BETWEEN 90W AND 125W. GFS MODEL 
STILL LIKES A PAIR OF WEAK LOW CENTERS NEAR 11N92W AND 14N105W 
WHICH IS THE USUAL BREEDING AREA OF TRPL SYSTEMS THIS TIME OF 
YEAR. 

$$
RRG