000
AXPZ20 KNHC 220929
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU NOV 22 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 86W N OF 6N MOVING W 10 KT. ISOLATED 
MODERATE CONVECTION OVER NRN NICARAGUA OTHERWISE NO OTHER 
CONVECTION NOTED IN LATEST SATELLITE PICTURES.  

...ITCZ...

ITCZ AXIS ALONG 9N77W 9N86W 7N95W 8N113W 8N130W 7N140W. ISOLATED 
MODERATE CONVECTION NEAR 6N78W 7N79W 7N82W 7N97W AND 8N104W. 
SCATTERED MODERATE CONVECTION ALONG A LINE FROM 9N129W TO 
10N134W.

SCATTERED MODERATE CONVECTION ALONG 140W FROM 15N TO 20N. 

...DISCUSSION...

A LARGE BLOCKING RIDGE ALONG 130W TONIGHT IS THE MAIN FEATURE 
OVER THE REGION. THE RIDGE SEPARATES A LARGE TROUGH TO THE NW 
FROM A STRONG TROUGH OVER THE CONUS. A SHORTWAVE TROUGH WAS OVER 
NW BAJA MOVING ESE. A WEAKER SHORTWAVE WAS NEAR 21N138W MOVING 
N. ON THE SURFACE TONIGHT THE PACIFIC RIDGE WAS SITUATED BELOW 
THE MID LEVEL RIDGE WITH IT'S AXIS FROM 30N133W TO 15N110W. NE 
TRADES WERE MOSTLY 15 KT BUT INCREASED ALONG 140W N OF 25N TO 25 
KT ACCORDING TO SSMI IMAGERY. WINDS ALONG THE BAJA COAST WERE 
NWLY 10 TO 15 KT ACCORDING TO SSMI AND IN GOOD AGREEMENT WITH 
THE GFS MODEL FOR 06Z. GAP WINDS WERE MOSTLY LIGHT. CROSS 
EQUATORIAL SLY WINDS WERE 10 TO 15 KT BETWEEN 95W AND 130W 
ACCORDING TO QUIKSCAT. 

LATER DAY 1 LITTLE CHANGE TO THE MID LEVEL RIDGE POSITION WHILE 
MID LEVEL HEIGHTS WILL CONTINUE TO FALL E OF 120W N OF 24N AS 
ADDITIONAL COLD AIR SPILLS SWD OVER THE WRN CONUS. THE STRONG 
TROUGH TO THE NW WILL CONTINUE TO LIFT WEAK SHORTWAVES NWD ALONG 
THE WRN EDGE OF THE BLOCKING RIDGE. ON THE SURFACE LATER DAY 1 
THE PACIFIC RIDGE REMAINS IN PLACE WITH LITTLE CHANGE TO NE 
TRADES. WINDS ALONG THE BAJA COAST REMAIN LIGHT. SOME INCREASE 
IN NE AND E WINDS THROUGH GAPS FROM COSTA RICA NWD TO GUATEMALA. 
CROSS EQUATORIAL SLY WINDS MOSTLY 10 TO 15 KT BETWEEN 100W AND 
125W.

FOR DAY 2 A LARGE POOL OF COLD AIR ALOFT SINKS SWD OVER THE SW 
CONUS LOWERING MID LEVEL HEIGHTS E OF 120W. THE BLOCKING RIDGE 
REMAINS IN PLACE WITH LITTLE ROOM TO MOVE. THE MID LEVEL TROUGH 
NW OF THE AREA BEGINS TO INCREASE SWLY WINDS N OF 20N W OF 130W. 
ON THE SURFACE DAY 2 A COLD FRONT WILL APPROACH THE REGION FROM 
THE NW BUT MAKE SLOW PROGRESS GIVEN THE SWLY FLOW ALOFT. THE 
PACIFIC RIDGE WEAKENS A FEW MILLIBARS AND NE TRADES DECREASE 
SLIGHTLY. WINDS ALONG THE BAJA COAST REMAIN NWLY ABOUT 10 KT. 
GAP WINDS MOSTLY NELY 15 KT..BUT WILL INCREASE THROUGH 
TEHUANTEPEC LATER AS HIGH PRES BUILDS OVER THE WRN GULF OF 
MEXICO. CROSS EQUATORIAL SLY WINDS WEAKEN TO MOSTLY 10 KT MOSTLY 
FROM A LACK OF CONVECTION ALONG THE ITCZ.

$$
RRG