117 
fxus66 kmfr 211703 
afdmfr 


Area forecast discussion 
National Weather Service Medford or 
903 am PST Sat Nov 21 2009 


Discussion...current forecast looks good over region with front 
entering the coastal waters tonight...ushering windy conditions 
over the coastal waters and into the Coos and Curry counties. High 
wind watch is accurately portraying conditions for tonight as 
strong winds will impact the coastal counties...and will likely be 
issuing High Wind Warning for that area with the afternoon package. 
Will be looking at the data and progression of upstream developing 
storm further to decide on any possible Wind Advisory for Douglas 
County area with NAM intensifying low a bit on recent model runs. 
Also...will be fine tuning snow forecast for Klamath Falls area 
and looking at Snow Advisory for that area late tonight into 
Sunday morning. Models are still agreeing on dry solution for 
Monday through Wednesday with a weak front entering the area 
Thursday. Current snow level is about 3500 feet per mfr 
sounding...and levels will rise a bit ahead of front and then drop 
behind the front tomorrow morning. 




&& 


Aviation...fog in the Rogue Valley and Umpqua basin...resulting 
in IFR conditions...will lift to VFR by later this morning. VFR 
conditions will be short-lived as another front drops most 
terminals to MVFR in low clouds and showers by this evening. 
Mountains and east side will have snow reducing visibilities 
tonight and Sunday morning. Mountain obscuration will be 
widespread by tonight through Sunday as deep moisture pushes into 
the region. 




&& 


Previous discussion... /issued 405 am PST Sat Nov 21 2009/ 


Discussion...a few showers will linger across the higher terrain 
of the forecast area this morning but the trend is for brief 
drying this afternoon. By early evening another Pacific front will 
move into the coastal waters. First the warm front will bring 
gusty south winds to the coast tonight. Both the NAM and GFS show 
boundary layer winds to be in the 40 to 50 miles per hour range. As a result 
have issued a high wind watch at the coast. The strongest winds 
should occur between 10pm and midnight tonight. Farther east 
southwest winds will also pick up ahead of the front. Part of 
Highway 31 running from Paisley to Summer Lake in Lake County is 
expected to see another round of gusty winds and Wind Advisory may 
be needed later. Guidance also indicates increasing winds in the 
Shasta Valley this evening although wind direction does not appear 
as conducive to the speed reaching warning criteria. 


The cold front will move into southwest Oregon this evening with 
precipitation spreading into the Rogue Valley in the early 
evening. Steady precipitation is expected to be overnight tonight 
and through Sunday morning. Southerly wind ahead of the front 
could delay cold air from filtering into Klamath Falls but by late 
tonight the front is expected to bring cold air into the east 
side. If the current quantitative precipitation forecast forecast holds...we may need a Snow 
Advisory for northern Klamath County from Diamond Lake Junction 
north through Chemult. By Sunday afternoon precipitation should 
taper off to showers and be confined mainly in upslope area and 
higher terrain. 


The latest GFS and European model (ecmwf) continues with the drying trend for most 
of next week as the storm track shifts north. The European model (ecmwf) brings the 
next cold front inland on Thanksgiving but the GFS holds the front 
offshore before bringing the front inland during that night. Have 
introduced a chance probability of precipitation for Thanksgiving day but confidence on 
timing is not very high. 


Aviation...widespread MVFR at the coast this evening through 
tonight in frequent moderate rain. Winds along the coast will also 
be very strong overnight with low level wind shear possible. MVFR ceilings and visible 
spread inland and are more likely after 06z tonight. Higher mountains 
will be obscured overnight. 


&& 


Mfr watches/warnings/advisories... 
or...high wind watch from 4 PM PST this afternoon through late 
tonight for orz021-orz022. 


California...none. 


Pacific coastal waters...Small Craft Advisory for winds until 1 PM 
PST this afternoon for pzz350-pzz356-pzz370-pzz376. 
Gale Warning from 1 PM this afternoon to 4 am PST Sunday for 
pzz356-pzz376. 
Hazardous seas warning until 4 PM PST Sunday for pzz350-pzz356- 
pzz370-pzz376. 
Storm Warning from 4 PM this afternoon to 4 am PST Sunday for 
pzz350-pzz370. 
Gale Warning from 1 PM to 4 PM PST this afternoon for pzz350- 
pzz370. 


$$ 


Nk