837 
fxus66 kotx 070558 
afdotx 


Area forecast discussion 
National Weather Service Spokane Washington 
1058 PM PDT Monday Oct 6 2008 


Synopsis... 
a strong Pacific storm system will pass through the region over 
the next 24 hours bringing periods of rain tonight and Tuesday 
morning followed by windy conditions through the remainder of 
Tuesday. Snow levels will decrease tonight with minor 
accumulations of snow expected on the higher peaks by Tuesday 
afternoon. Cool and unsettled conditions will remain through the 
middle of the week. 






&& 


Discussion... 


Warm advection precipitation has moved from eastern Washington 
into the northern Panhandle this evening. As of 1030pm...the bulk 
of the isentropic up-Glide on the 300k Theta surface had moved into 
The Priest lake...Rathdrum...and Saint Maries areas. Periods of 
rain will likely continue along the Canadian border in northeast 
Washington and far northern Idaho through 2-4am. Then the focus 
for precipitation will be the strong cold front. As of 10 
PM...pressure rises had just begun over the olympic penis Ula 
signifying that the cold front was just moving onshore. As the 
cold front crosses the crest of the Cascades between 3-5am...a 
pronounced rain shadow is expected as strong middle-level westerly 
flow accompanies the frontal passage. Precipitation chances have 
been increased in the Spokane area as well as over the Idaho 
Panhandle for early tomorrow morning with the frontal 
passage...but locations prone to the rain shadow like Moses 
Lake and Wenatchee retained low chances for early morning rain. 


The 00z models continue to suggest the potential for a low end 
Wind Advisory across the east slopes...the Upper Basin...into the 
Spokane/Pullman areas. The 850-700mb winds between 18z and 21z are 
forecast to be in the 30-40kt range. It will be interesting to see 
if mixing will occur from as high as 700mb with this storm. Model 
soundings do not suggest that the mixing layer will be that 
high...but water vapor imagery this evening is quite ominous. The 
darkening over Vancouver Island suggests that this storm has a 
strong pv anomaly. I think that the strongest gusts will occur 
early tomorrow afternoon over the Waterville Plateau. A GFS cross 
section perpendicular to the Cascades is forecasting a stable 
layer just above the Mountain Crest...suggesting that there could 
be some mountain wave activity just east of the Cascades. This 
could allow some of the 40-45kt winds around 700mb to mix down to 
the surface...especially over the higher terrain of the Waterville 
Plateau. /Gkoch 


&& 


Aviation... 
ceilings should remain VFR through 12z...but may drop into the 
MVFR or IFR category temporarily with the arrival of heavier 
precipitation between 12z-15z with the passage of the cold front. 
Low level wind shear is in the taf for the Spokane area along and 
just ahead of the vigorous cold front. Behind the front...sustained 
winds of 20-25kts are expected by 18z and will persist until 
around 00z with gusts as high as 35kts. /Gkoch 




&& 


Preliminary point temps/pops... 
Spokane 49 59 36 53 33 48 / 80 40 0 0 10 30 
Coeur D'Alene 47 58 35 53 31 48 / 70 70 10 10 10 30 
Pullman 50 60 36 54 32 49 / 30 30 0 0 10 30 
Lewiston 52 64 40 60 36 53 / 10 20 0 0 10 20 
Colville 46 62 34 54 29 51 / 80 60 10 10 20 40 
Sandpoint 46 56 35 50 28 46 / 80 90 10 10 10 40 
Kellogg 45 54 39 51 32 47 / 60 90 10 10 10 40 
Moses Lake 49 59 35 60 33 56 / 20 10 0 0 10 20 
Wenatchee 47 57 36 58 36 54 / 30 10 10 0 10 20 
Omak 45 59 31 58 30 54 / 70 10 10 0 20 30 


&& 


Otx watches/warnings/advisories... 
Idaho...Wind Advisory from 9 am to 5 PM PDT Tuesday for Coeur D'Alene 
area...Idaho Palouse...Lewiston area. 


Washington...Wind Advisory from 9 am to 5 PM PDT Tuesday for lower Garfield 
and Asotin counties...Moses Lake area...Spokane area... 
upper Columbia Basin...Washington Palouse...Waterville 
Plateau...Wenatchee area. 


&& 


$$