000
AXPZ20 KNHC 120921
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC MON NOV 12 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.

...ITCZ...
ITCZ AXIS ALONG 9N82W 6N89W 11N122W 8N140W. ISOLATED MODERATE 
CONVECTION NEAR 9N84W 8N107W 9N114W AND 10N120W. ISOLATED STRONG 
NEAR 9N118W. SCATTERED MODERATE WITHIN 20 NM OF A LINE FROM 
9N126W TO 8N131W.

...DISCUSSION...

A LARGE BULGING MID LEVEL RIDGE OVER THE NW CORNER OF THE REGION 
TONIGHT EXTENDS NE INTO SW CANADA. THE RIDGE IS HELPING PUSH A 
STUBBORN MID LEVEL SHORTWAVE THAT EXTENDS FROM SRN CA S AND SW 
TO 20N120W AND 10N130W. A MODERATELY STRONG MID LEVEL FLOW IS 
GRADUALLY SAPPING ENERGY OUT OF THE TROUGH IN THE FORM OF WEAK 
SMALLER SCALE SHORTWAVES..ONE OF WHICH IS OVER SW TX MOVING ENE. 
ON THE SURFACE TONIGHT THE PACIFIC RIDGE CENTER 1023 MB IS NEAR 
30N130W AND PRODUCING NE TRADES W OF 120W OF 20 TO 25 KT 
ACCORDING TO SSMI. NO PASS FROM QUIKSCAT. WINDS ALONG THE BAJA 
COAST ARE NWLY 10 TO 15 KT BUT A NEW SURGE IS HEADING SE BEHIND 
A WEAKENING COLD FRONT OFF THE NW COAST OF THE BAJA. GAP WINDS 
ARE MOSTLY LIGHT. TEHUANTEPEC WINDS ONLY 10 TO 15 KT AT 0600 
UTC. CROSS EQUATORIAL SLY WINDS MOSTLY 10 TO 15 KT ACCORDING TO 
SSMI IMAGERY. 

LATER DAY 1 THE GFS MODEL FORECAST THE MAIN ENERGY CENTER IN THE 
SHORTWAVE TROUGH TO CLOSE OFF NEAR 27N115W. THIS SYSTEM WILL 
MOVE LITTLE DUE TO A BLOCKING RIDGE OVER MEXICO AND THE LARGE 
RIDGE CENTERED NEAR 25N135W. ON THE SURFACE LATER DAY 1 THE 
PACIFIC RIDGE WILL GET A BOOST FROM THE MID LEVEL RIDGE AND 
STRENGTHEN SOME TO 1025 MB THUS MAINTAINING NE TRADES OF 20 TO 
25 KT BETWEEN 10N AND 22N W OF 125W. WINDS ALONG THE BAJA COAST 
MOSTLY NWLY 10 TO 15 KT BUT FURTHER OFFSHORE W OF 118W NLY WINDS 
INCREASE TO 20 KT WITH NLY SWELL TO 8 FT. GAP WINDS MOSTLY LIGHT 
EXCEPT TEHUANTEPEC WINDS TO 20 KT. CROSS EQUATORIAL SLY WINDS 
REMAIN LIGHT.

FOR DAY 2 AS EXPECTED THE MID LEVEL CLOSED OFF LOW REMAINS 
STATIONARY NEAR 26N118W STUCK BETWEEN THE TWO LARGE RIDGE 
CENTERS. THE TWO RIDGES WILL KEEP THE WESTERLIES N OF THE LOW 
CENTER THUS NO HELP IN EJECTING THE CIRCULATION FOR ANOTHER TWO 
DAYS WHEN THE WRN RIDGE CENTER IS FORECAST TO BREAKDOWN AND 
ALLOW THE WESTERLIES TO EJECT THE SYSTEM ENE. ON THE SURFACE DAY 
2 A 1025 MB HIGH CENTER WILL ANCHOR THE PACIFIC RIDGE AND 
MAINTAIN NE TRADES 20 TO 25 KT W OF 125W. WINDS ALONG THE BAJA 
COAST WILL REMAIN LIGHT. TEHUANTEPEC WINDS REMAIN 20 TO 25 KT 
WITH HIGH PRES PERSISTING OVER THE NRN GULF OF MEXICO. CROSS 
EQUATORIAL SLY WINDS REMAIN 10 TO 15 KT S OF THE ITCZ.

$$
RRG