540 
fxus66 kmfr 200410 
afdmfr 


Area forecast discussion 
National Weather Service Medford or 
910 PM PDT Tuesday Aug 19 2008 


Discussion...latest forecast is on track with rain coming into 
mainly the west side tonight through Wednesday. So far tonight 
showers have moved through with a few hundredths being measured 
here and there in the Umpqua. Have bumped up the coastal winds as 
latest observation have shown gusts to 40-50 miles per hour from Gold Beach to Cape 
Arago...and latest nam12 guidance shows a 50kt jet at 850 passing 
through that area through the next several hours. Looks like a 
quarter inch or more will fall in parts of the Coast Range and 
Cascades north of Highway 140 by daybreak. The rain continues 
Wednesday and Wednesday night which will slow down the fires on 
the crest and west side significantly. Mts 


&& 


Previous discussion... /issued 200 PM PDT Tuesday Aug 19 2008/ 


Short term...an unseasonably strong closed 500mb low near 50/140w 
will move east through Wednesday then inland along the U.S. Canadian 
border Thursday. A strong westerly jet with about a 140kt core will 
approach the north Oregon coast tonight then spread inland 
Wednesday. By Friday the upper trough will be moving across the 
northern rockies while 500mb heights begin rising over the region. 


A front is approaching 130w this afternoon. The front will move to 
the north Oregon coast tonight then trail southwest off the coast 
overnight and Wednesday. The models show the surface front moving 
inland by Wednesday evening. Some showers will follow the front 
Wednesday night and Thursday morning. Accumulated precipitation amounts 
will be quite challenging with this system. The GFS is wetter while 
the 12z NAM is a fair amount drier overall. After looking at the 18z 
satellite rainfall estimates offshore...have trended more towards 
the 12z NAM amounts. Either way...expect storm totals to be highest 
along portions of the coast...Coast Range and the Cascades near 
Crater Lake. 


Long term...a low will be over the Gulf of Alaska Saturday and 
Sunday while high pressure remains over the western U.S. High 
pressure will weaken somewhat later Monday and Tuesday as a weak 
system moves inland to the north. 


&& 


Aviation...widespread rain developing tonight across the Cascades 
and west and mainly north of the Siskiyous. Mostly VFR this 
evening but MVFR ceilings and visibility on the coast will prevail soon. 
Ceilings will lower inland to the Cascades in Oregon with areas of 
terrain obscuration above 5000 feet through Wednesday. 


&& 


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


California...none. 


Pacific coastal waters...Gale Warning until 5 am PDT Wednesday for 
pzz350-pzz356-pzz370. 
Hazardous seas warning until 8 am PDT Wednesday for pzz350- 
pzz356-pzz370. 
Small Craft Advisory for winds until 5 am PDT Wednesday for 
pzz376. 
Small Craft Advisory for hazardous seas until 5 am PDT Saturday 
for pzz376. 


$$