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Next 12 Hours

Forecast data from the National Digital Forecast Database.

5 Day Forecast

• Wednesday
• 
• High: 72 °
• Low: 48 °
• Rain Showers

• Thursday
• 
• High: 66 °
• Low: 52 °
• Chance of T-Storms

• Friday
• 
• High: 75 °
• Low: 52 °
• Partly Cloudy

• Saturday
• 
• High: 75 °
• Low: 50 °
• Partly Cloudy

• Sunday
• 
• High: 75 °
• Low: 52 °
• Partly Cloudy

Area forecast discussion 
National Weather Service Spokane Washington 
449 am PDT Wed may 23 2012 


Synopsis... 
unsettled conditions with showers and cooler than normal 
temperatures will remain through Thursday. Friday will bring a dry 
break period except for mountain showers. Unsettled and showery 
conditions will impact the Idaho Panhandle during the weekend, then 
another moist Pacific frontal system transiting the entire region 
early next week. 




&& 


Discussion... 
today and tonight: the inland northwest will remain under weak northwest 
flow aloft and within an upper level cold pool while the jet axis 
lies to the south over Oregon. Minor impulses in the flow will 
help enhance shower activity, as seen by the remnant of one 
exiting eastern Washington and pushing across the Idaho Panhandle. 
The GFS and NAM show weak shortwave ridging developing by 18z 
across the Cascades and into the Columbia Basin, while the west to 
northwest flow from 850mb to 700mb will enhance orographic lift 
over northeast Washington and the Panhandle mountains. The cold 
pool aloft supported by 500mb temps of -24c will keep lapse rates 
and instability high with little if any inhibition to limit 
convection. Would not rule out isolated thunderstorms during the 
late afternoon into the early evening time frame especially east 
of Colville to Spokane to Pullman. Snow levels will be near 5k ft. 
Southwest to west winds which have been occasionally gusty early 
this morning especially lower Columbia Basin and Palouse will 
increase across the region this afternoon with gusts to 25 mph. 
Temperatures will be running similar to yesterday. /Rfox. 


Thursday through Friday...Thursday begins with both the latest NAM 
and GFS models indicating a zonal and somewhat moist flow over 
the forecast area...and a closed upper low near Vancouver Isle. 
Models are in good agreement in dropping this upper low down the 
Washington and Oregon coasts during the day Thursday. Ramifications of 
this transit will include a westerly orographic regime in the 
morning hours...transitioning to an easterly/northeast flow regime 
feeding into this upper low during the afternoon. This suggests 
that all locations in the forecast area will experience at least 
a chance of showers...with the densest concentration over the 
Idaho Panhandle in the morning...and then the Cascades during the 
afternoon. Lifted indices and model soundings from all over the 
forecast area indicate at least marginal instability over the 
entire forecast area...but dynamic forcing will be lacking so the 
chance of thunderstorms will be limited to the higher terrain 
ringing the basin where orographic influence will give the best 
chance for showers to evolve into thunderstorms. 


On Friday all the available model guidance indicates the coastal 
closed low will eject inland into the Great Basin. The dynamic 
trough base region will be far to the south of the forecast 
area...thus once again the only available lifting mechanism over 
the forecast area will be orography. Moisture will become more 
limited as well...with the upper low promoting a strong surface 
low pressure over Utah and an appending inverted surface trough 
stabbing into the Columbia Basin. The gradient provided by this 
inverted trough will suck dry Canadian Continental air through the 
Purcell Trench and into the basin during the day providing breezy 
easterly wind conditions across the forecast area. This dry air 
will stabilize the air mass and allow fairly high confidecne that 
Friday will be a generally dry day over most of the region...with 
the largest shower threat...and only Chancy at that...over the 
southeast zones and mountain zones. 


Saturday through Tuesday...the extended forecast period will 
witness the eastward ejection of the Great Basin closed low 
followed by a return of a more progressive Pacific storm track to 
the region. Models are in general agreement through 
Sunday...with the meandering upper low slowly moving eastward...but 
as it does the threat of a wrap around moisture field cresting the 
northern shoulder of this low will bring a threat of showers 
mainly to the Idaho Panhandle and far eastern Washington Saturday 
through Sunday. Models are also in loose agreement in depicting a 
weak and short lived inter-system ridge over the region Sunday 
night...before a return of more progressive flow possibly 
featuring a shower bearing negatively tilted trough out of the 
North Pacific on Monday and Tuesday. Through the weekend and into 
early next week the unusually col air mass currently in place 
should gradually modify back into the seasonably normal 
temperature range. /Fugazzi 


&& 


Aviation... 
12z tafs: the cool unstable airmass will keep the threat of showers 
across the the eastern taf sites especially this afternoon and 
evening. The numerous showers will continue through much of the 
period over the Idaho Panhandle with mountains obscurred and MVFR 
cigs likely in heavier showers. Surface heating will help lead to 
scattered showers with a slight chance of thunderstorms mainly east 
of Republic to Ritzville to Walla Walla after 20z and through 03z. 
Look for another day of breezy to gusty winds, especially in the 
Wenatchee area where sustained speeds of 15-23kts are anticipated 
along with higher gusts. Showers and winds will dissipate overnight 
as cigs improve to VFR conditions. /Rfox. 


&& 


Preliminary point temps/pops... 
Spokane 60 40 60 43 66 44 / 60 40 30 30 10 10 
Coeur D'Alene 59 40 60 41 64 41 / 70 60 40 30 10 10 
Pullman 56 39 56 41 63 40 / 60 40 40 30 20 20 
Lewiston 63 44 63 46 68 46 / 60 30 40 30 20 20 
Colville 64 41 64 41 70 44 / 70 40 50 50 10 10 
Sandpoint 58 39 57 39 63 38 / 70 60 50 30 10 10 
Kellogg 53 39 55 38 59 38 / 80 60 60 50 20 20 
Moses Lake 66 43 67 46 73 47 / 20 20 30 30 10 10 
Wenatchee 64 46 65 47 72 49 / 20 20 40 40 10 10 
Omak 68 39 64 44 71 45 / 20 20 50 40 10 10 


&& 


Otx watches/warnings/advisories... 
Idaho...none. 
Washington...none. 
&& 


$$