000
AXPZ20 KNHC 230918
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI NOV 23 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 91W N OF 3N MOVING W 10 KT. THERE IS NO 
SIGNIFICANT CONVECTION WITH THIS WAVE AT THIS TIME.  
 
...ITCZ...
ITCZ AXIS ALONG 8N77W 10N91W 9N97W 9N110W 9N130W 11N140W. 
ISOLATED MODERATE CONVECTION NEAR 6N78W AND 8N84W. SCATTERED 
MODERATE ALONG A LINE FROM 9N94W TO 7N101W. SCATTERED STRONG 
CONVECTION WITHIN 30 NM OF A LINE FROM 9N111W TO 9N118W TO 
10N124W. ISOLATED MODERATE NEAR 9N127W 10N131W 11N133W AND 
10N138W.

...DISCUSSION...

MID LEVEL BLOCKING RIDGE ALONG 130W TONIGHT EXTENDS N OF 40N. 
RIDGE SEPARATES MID LEVEL TROUGH ALONG 145W AND LARGE MID LEVEL 
TROUGH OVER WRN CONUS. WRN TROUGH ENERGY LIFTING NWD TONIGHT BUT 
STRONG ZONAL JET ALONG 40N OVER CENTRAL PACIFIC CONTINUES TO DIG 
SE INTO TROUGH AND MAINTAIN IT. SIGNS OF RIDGE WEAKENING TONIGHT 
WITH WEAK SHORTWAVES MOVING NE FROM 20N150W AND FROM 25N135W. NW 
SURGE OF COLD AIR ALOFT DIVING SE OVER WRN AZ TONIGHT LOWERING 
MID LEVEL HEIGHTS N OF 20N E OF 120W. ON THE SURFACE TONIGHT 
WEAK PACIFIC RIDGE ALONG 132W EXTENDS SE TO 15N105W PRODUCING 
TRADES BETWEEN 12N AND 20N W OF 120W 15 TO 20 KT. PRES GRADIENT 
E OF 120W WEAK AND WINDS ALONG THE BAJA COAST NWLY 10 TO 15 KT 
ACCORDING TO SSMI AND QUIKSCAT IMAGERY. WEAKENING FRONT ALONG 
140W NEARLY STATIONARY. GAP WINDS ALSO LIGHT. CROSS EQUATORIAL 
SLY WINDS TO 20 KT IN SMALL AREA S OF 5N BETWEEN 115W AND 125W 
ACCORDING TO MICROWAVE IMAGERY. WINDS ENHANCED BY ARE OF STRONG 
CONVECTION ALONG ITCZ BETWEEN 112W AND 124W..OTHERWISE SLY WINDS 
TO 20 KT S OF 7N BETWEEN 92W AND 138W AS DEPICTED BY SSMI. 

LATER DAY 1 MID LEVEL RIDGE SHIFTS E TO ALONG 128W AS SERIES OF 
SHORTWAVES BATTER WRN SIDE OF RIDGE. STRONG POOL OF COLD AIR 
SETTLES IN BASE OF MID LEVEL TROUGH OVER SW CONUS WILL KEEP MID 
LEVEL GRADIENT TIGHT N OF 22N E OF 120W. ON THE SURFACE LATER 
DAY 1 1023 MB CENTER ANCHORS PACIFIC RIDGE NEAR 33N132W WITH 
AXIS EXTENDING SE TO 15N105W. RIDGE PRODUCING NE AND E TRADES 
BETWEEN 10N AND 22N W OF 125W TO 20 KT.  WINDS ALONG BAJA COAST 
REMAIN NWLY 10 TO 15 KT. GAP WINDS INCREASE TO 20 KT THROUGH 
TEHUANTEPEC AS HIGH PRES BUILDS OVER SW GULF OF MEXICO. IN 
ADDITION NE WINDS INCREASE TO 20 KT W OF NICARGUA AS PRES 
GRADIENT TIGHTENS SOME OVER WRN CARIB. CROSS EQUATORIAL SLY 
WINDS REMAIN 10 TO 15 KT.   

FOR DAY 2 GFS MODEL SHOWS ZONAL JET ALONG 40N W OF WRN TROUGH 
DIGGING LESS WITH SHORTWAVES MOVING EWD. ONE ALONG 125W AND 
ANOTHER ALONG 140W THUS RIDGE FORCED TO SHIFT EWD TO 122W. LARGE 
POOL OF COLD AIR SETTLING OVER NW MEXICO TIGHTENS MID LEVEL 
GRADIENT N OF 20N E OF 120W. ON THE SURFACE DAY 2 SURFACE LOW 
PRES DEVELOPS OVER NW MEXICO. PRES GRADIENT BETWEEN LOW PRES AND 
WEAK PACIFIC RIDGE ALONG 132W INCREASES NLY WINDS ALONG BAJA 
COAST TO 120W TO 20 KT. FRONTAL TROUGH OVER NW CORNER OF AREA 
GRADUALLY DISSIPATING. GAP WINDS TROUGH TEHUANTEPEC DECREASE AS 
WINDS OVER BAY OF CAMPECHE BECOME SE TO S. GAP WINDS W OF 
NICARAGUA REMAIN ABOUT THE SAME. CROSS EQUATORIAL SLY WINDS TO 
20 KT S OF 7N BETWEEN 90W AND 115W WHERE ITCZ FORECAST TO BECOME 
A LITTLE MORE ACTIVE.

$$
RRG