000
AXPZ20 KNHC 010917
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SAT DEC 01 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 6N78W 6N87W 5N96W 6N111W 11N129W 9N140. ISOLATED 
MODERATE CONVECTION NEAR 5N78W 9N113W 9N133W AND 9N136W. 

OTHER ISOLATED MODERATE CONVECTION NEAR 13N106W 14N107W 14N108W 
19N108W AND 21N107W.
 
...DISCUSSION...

TWO STRONG FEATURES IN THE MID LEVELS TONIGHT. ONE IS A TROUGH 
DIGGING SE OFF THE CA COAST. THIS TROUGH IS EJECTING THE OLD 
CUTOFF LOW THAT WAS OVER OUR REGION THE PAST FEW DAYS. THIS 
SYSTEM HAS OPENED UP AND IS MOVING NE OVER SRN CA. THE OTHER 
FEATURE IS A TROUGH THAT HAS BECOME NEGATIVELY TILTED ALONG 
150W. THE JET STREAM BEHIND THE TROUGH HAS BECOME MORE WLY WHERE 
LAST NIGHT IT WAS NWLY. IN BETWEEN THE TWO TROUGHS IS A 
WEAKENING MID LEVEL RIDGE ALONG 140W. ON THE SURFACE TONIGHT LOW 
PRES CENTER HAS MOVED INLAND OVER SRN CA BUT WINDS ALONG THE 
BAJA COAST N OF 25N REMAIN W TO NW 20 TO 25 KT ACCORDING TO 
SSMI. THE PACIFIC RIDGE HAS A CENTER 1021 MB NEAR 32N135W BUT 
ONLY A WEAK RIDGE OVER OUR AREA N OF 10N W OF 125W..THUS NE 
TRADES ARE LIGHT. GAP WINDS ARE 20 KT THROUGH TEHUANTEPEC AND 
PAPAGAYO ACCORDING TO SSMI. CROSS EQUATORIAL SLY WINDS S OF 8N 
TO 20 KT NOTED BETWEEN 88W AND 94W AND W OF 115W ACCORDING TO 
SSMI IMAGERY. 

LATER DAY 1 WITH THE MID LEVEL FLOW BECOMING MORE ZONAL OR 
WESTERLY..FEATURES ARE PROGRESSING RAPIDLY EWD. EVEN THE MID 
LEVEL RIDGE ALONG 140W MOVES E TO 135W. SIGNS OF A SRN BRANCH IN 
THE WESTERLIES TAKING SHAPE S OF 20N WITH WEAK SHORTWAVES ALONG 
130W AND 140W. ON THE SURFACE LATER DAY 1 WINDS RELAX ALONG THE 
BAJA COAST AS THE PRES GRADIENT WEAKENS. THE PACIFIC HIGH 1020 
MB MOVES SE TO 29N129W BUT TRADES REMAIN LIGHT. INCREASING SLY 
WINDS N OF 28N W OF 138W AS A FRONT APPROACHES FROM THE W. GAP 
WINDS RELAX THROUGH TEHUANTEPEC BUT REMAIN GUSTY TO 20 KT 
THROUGH PAPAGAYO. CROSS EQUATORIAL SLY WINDS REMAIN ABOUT THE 
SAME.

FOR DAY 2 STRENGTHENING W TO SW MID LEVEL FLOW SETS UP WITH 
STRONG TROUGH MOVING TO 150W. ONE SHORTWAVE IN SRN BRANCH 
WASHING OUT ALONG 120W AS IT MOVES NE OVER A MID LEVEL RIDGE 
ALONG 20N. SECOND SHORTWAVE STUCK NEAR 130W S OF 15N. ON THE 
SURFACE DAY 2 GALE CONDITIONS DEVELOP N OF 27N W OF 132W AS THE 
PRES GRADIENT TIGHTENS. ALSO LOOK FOR INCREASING SW SWELL TO 22 
FT. THE PACIFIC RIDGE MOVES RAPIDLY ENE TO SRN CA BUT MAINTAINS 
A RIDGE AXIS SW TO 20N135W. N AND NE WINDS INCREASE TO 20 KT 
BETWEEN 10N AND 24N FROM 105W TO 130W WITH MOVEMEN TO THE RIDGE. 
GAP WINDS DECREASE THROUGH PAPAGAYO TO 15 TO 20 KT. CROSS 
EQUATORIAL SLY WINDS MOSTLY 10 TO 15 KT S OF 5N.  

$$
RRG