000
AXPZ20 KNHC 190921
TWDEP 

TROPICAL WEATHER DISCUSSION     
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SUN AUG 19 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 ALONG 90W MOVING W AT 10 TO 15 KT. ISOLATED 
CONVECTION WITH NO ORGANIZATION.

TROPICAL WAVE ALONG 113W MOVING W AT 8 TO 10 KT. ASSOCIATED LOW 
PRES CENTER NEAR 20N113W WITH CLUSTER OF STRONG CONVECTION. 
ACTIVITY HAS INCREASED DURING THE PAST FEW HRS. STRONG HIGH 
LEVEL WINDS OVER THE LOW PROBABLY WILL MAKE IT DIFFICULT TO  
DEVELOP. 

A TROPICAL WAVE ALONG 136W FROM 6N TO 16N MOVING W AT 10 TO 15 
KT. NO EVIDENCE OF WAVE. 

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 9N81W 10N94W 19N105W 17N114W 12N122W 
11N140W. SCATTERED MODERATE CONVECTION WITHIN 30 NM OF 7N82W 
6N93W AND WITHIN 90 NM OF 9N105W. AREA OF SCATTERED MODERATE 
FROM 10N TO 17N BETWEEN 104W AND 118W. 

SCATTERED MODERATE WITHIN 30 NM OF 12N91W. ISOLATED STRONG NEAR 
15N94W. CLUSTER OF STRONG CONVECTION NEAR 20N115W.

...DISCUSSION...

WATER VAPOR SHOWS STRONG MID LEVEL RIDGE OVER SW CONUS TONIGHT 
PRODUCING STRONG NE AND E WINDS ALOFT OVER AREA S OF 25N BETWEEN 
100W AND 120W. ALSO VERY DRY MID AND UPPER ATMOSPHERE W OF 122W. 
PERSISTENT WEAKNESS IN PRES FIELD AT MID LEVELS CONTINUES 
BETWEEN 122W AND 132W..SOMEWHAT DIMINISHED AS UPPER TROUGH N OF 
AREA ALONG 126W RECEDES NWD. MID LEVEL RIDGES HAVE STRENGTHENED 
DURING PAST 24 HRS. THE OTHER IS THE ONE OVER THE WRN PORTION OF 
THE AREA W OF 130W. WEAK IMPULSES CONTINUE TO MOVE NW FROM THE 
TROPICAL AREA S OF 20N AND INTO THE ABOVE WEAKNESS AREA. ON THE 
SURFACE TONIGHT A WEAK LOW PRES CENTER NEAR 20N111W WAS MOVING 
SLOWLY NW. HIGH LEVEL WINDS ARE FORCING CONVECTION W OF THE 
CENTER THEREFORE THIS SYSTEM HAS LITTLE CHANCE OF DEVELOPING. 
THE PACIFIC RIDGE HAS WEAKENED OVER THE AREA AND IS MAINLY W OF 
120W N OF 12N. NE TRADES TO 20 KT ARE CONFINED TO THE AREA FROM 
14N TO 28N W OF 125W. WINDS ALONG THE BAJA COAST ARE LIGHT AS IS 
GAP WINDS..ALTHOUGH SATELLITE IMAGERY SHOWS SCATTERED CONVECTION 
ALONG THE COASTS OF CENTRAL AMERICA AND MEXICO TONIGHT. CROSS 
EQUATORIAL SLY WINDS CONFINED TO AREA BETWEEN 82W AND 95W AND 
BETWEEN 108W AND 135W ACCORDING TO SSMI IMAGERY. SPEEDS MOSTLY 
TO 20 KT AND SEAS TO 8 FT IN SLY SWELL.

LATER DAY 1 GFS MODEL SHOWS THE UPPER TROUGH ALONG 126W 
CONTINUING TO WEAKEN AND MOVE NE THUS MID LEVEL HEIGHTS RISE IN 
THE OLD WEAKNESS AREA AND THE TWO MID LEVEL RIDGE CENTERS MERGE 
ALONG 30N. MID LEVEL IMPULSES SW OF THE RIDGE WILL FIND IT MORE 
DIFFICULT TO MOVE NWD WITH THIS MERGING OF RIDGES TO THE N. ON 
THE SURFACE LATER DAY 1 THE GFS MODEL SHOWS THE WEAK LOW 
WEAKENING FURTHER AS SUPPORT ALOFT DIMINISHES. THE PACIFIC RIDGE 
REMAINS WEAK AND NE TRADES TO 20 KT REMAIN ABOUT THE SAME. WINDS 
ALONG THE LOWER BAJA COAST COULD PICK UP TO 20 KT AS THE WEAK 
LOW MOVES TO THE W OF THE AREA BUT SEAS SHOULD REMAIN LESS THAN 
8 FT. NO CHANGE TO GAP WINDS AND CROSS EQUATORIAL SLY WINDS TO 
20 KT ARE CONFINED BETWEEN 110W AND 125W WITH SLY SWELL TO 8 FT.

FOR DAY 2 MID LEVEL RIDGE OVER SW CONUS STRENGTHENS WITH A 
CENTER FORECAST TO BE NEAR 33N112W AND RIDGING WWD TO 140W. 
IMPULSES AT MID LEVELS SW OF THE RIDGE WILL REMAIN ON A WWD 
TRACK AND CLOSING OFF WITH A CENTER NEAR 15N130W. ON THE SURFACE 
DAY 2 THE WEAK LOW REMAINS IN THE PICTURE DRIFTING NW TO NEAR 
24N118W AND NOT BOTHERING ANYBODY. THE PACIFIC RIDGE WEAKENS 
MORE AND NE TRADES DIMINISH TO MOSTLY 10 TO 15 KT. WINDS ALONG 
THE BAJA COAST SHIFT TO E AND SE BUT REMAIN 10 TO 15 KT. GAP 
WINDS REMAIN LIGHT WHILE CROSS EQUATORIAL SLY WINDS DIMINISH TO 
10 TO 15 KT MOST AREAS EXCEPT FOR S OF 5N E OF 100W WHERE THE 
GFS MODEL SHOWS WINDS INCREASING TO 20 KT WITH SLY SWELL TO 8 
FT. 

$$
RRG