078 
fxus66 kmfr 221020 
afdmfr 


Area forecast discussion 
National Weather Service Medford or 
220 am PST Sat Nov 22 2008 


Short term...today through Monday...the weak front that moved 
onshore last night will continue to weaken and move east of the 
area by tonight. Next...dry conditions under a weak ridge will 
prevail through Monday. Fog should return briefly to the interior 
western valleys. However...the inversion will not be as strong as 
during the first part of the week. 


&& 


Long term...model guidance begins to diverge once again during the 
extended forecast. Therefore...confidence remains low on timing and 
strength details...especially Wednesday night through Friday. 
Nevertheless...given importance of the upcoming Holiday period will 
make some comments to highlight potential winter storm around 
Thanksgiving day. Current consensus forecast follows the following 
scenario. 


Tuesday and Wednesday...European model (ecmwf) and GFS models are now leaning towards 
a closed low moving into central California on Tuesday then 
progressing over the Sierra Nevada's through Wednesday. The NAM 
moves the low inland further northward and with a quicker movement... 
but this scenario is currently regarded as an outlier. 
Therefore...with most of the energy with tuesdays system staying 
south of southwest Oregon and northern California this event 
should have minimal impact over our area other than to draw cool 
air into the valleys and to pull snow levels down to just above 
pass level. 


Thanksgiving day...the 00z GFS run brings a cold short wave 
disturbance down the back end of the trough created by the 
Tuesday-Wednesday system. If this scenario pans out... winter 
weather highlights for passes in southwest Oregon and valley 
locations east of the Cascades would probably be issued. 
However...we will need to monitor how future model runs handle the 
details before advertising a winter storm. 


Friday and Saturday...a broad trough persists over the 
area...though most of the precipitation energy should be south. 
Therefore...a dry but cold forecast given the current guidance. 




&& 


Aviation...scattered showers expected this morning will produce 
areas of MVFR ceilings. Showers will become increasing isolated 
and focused over higher terrain by afternoon. 


&& 


Mfr watches/warnings/advisories... 
or...none. 


California...none. 


Pacific coastal waters...Small Craft Advisory for hazardous seas 
until 9 PM PST this evening for pzz350-pzz356-pzz370-pzz376. 


$$ 


Mwj