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Next 12 Hours

Forecast data from the National Digital Forecast Database.

5 Day Forecast

• Thursday
• 
• High: 63 °
• Low: 43 °
• Chance of Rain

• Friday
• 
• High: 66 °
• Low: 45 °
• Chance of T-Storms

• Saturday
• 
• High: 68 °
• Low: 46 °
• Partly Cloudy

• Sunday
• 
• High: 72 °
• Low: 48 °
• Partly Cloudy

• Monday
• 
• High: 77 °
• Low: 54 °
• Partly Cloudy

Area forecast discussion 
National Weather Service Spokane Washington 
457 PM PDT Thu may 23 2013 


Synopsis... 
cool and showery weather will continue through Saturday then a 
subtle warming and drying trend is anticipated by Monday as the 
persistent upper-level low moves out of the area. The break will 
be short-lived as another cool and showery pattern returns around 
the middle of next week. 




&& 


Discussion... 


Tonight and Friday...a large closed low near the central 
Washington coast this afternoon will move southeast towards 
Portland overnight. As it does so most of the rain associated with 
this low will remain south and west of the area. However...a cold 
pool aloft associated with this large low will result in an 
unstable atmosphere through early this evening promoting isolated 
showers except for a bit more coverage near the Cascades given 
closer proximity to low. Laps data this afternoon also shows 
surface based cape values of 200-400 j/kg near the Cascades, and 
over the Blue Mountains where a few lightning strikes are 
possible. Once daytime heating is lost, these showers will fall 
apart with dry conditions expected for the late evening and 
overnight hours. Another cool night is in store with localized 
freezing temperatures possible in the Okanogan Highlands and 
northeast Washington valleys where skies are expected to clear 
more significantly overnight. On Friday the low will move east 
across south central Washington in the morning...and then rotate 
northeast towards the Spokane and Palouse areas in the early 
afternoon...and finally into the central Panhandle mountains mid 
to late afternoon. This is the solution the European model (ecmwf) and NAM models 
show and is preferred...compared to the slightly more southerly 
GFS track. This will promote a cool and showery day over the 
inland northwest with the greatest coverage of showers focused 
along the low track and in the mountains. There will be a slight 
chance of thunderstorms Friday afternoon as well over the area 
with forecast convective available potential energy of 200-500 j/kg over the region. Jw 


Friday night through Sunday night: the upper-level low that 
has been parked over the region the last few days will continue 
to have an influence on the weather but does show signs of 
filling/warming. This will translate into less widespread and 
weaker shower activity each afternoon; especially across the 
Columbia Basin and into the latter half of the Holiday weekend. 
There are a few weak waves embedded within the parent low which 
will keep a slight chance for pops during the overnight periods at 
times...but in general, most shower activity will be middle to 
late afternoon and focused over the northern and eastern 
mountains. The best chance for thunderstorms will be Friday 
evening...with very small chances Saturday...then a slight threat 
near The Blues and Camas Prairie Sunday. Temperatures over the 
period will be slowly climbing back near seasonal readings or 
upper 60's to mid 70's. /Sb 


Monday through Thursday...some significant shortwave features of 
note to lock in on and add more detail courtesy of general 
longwave trof lingering and influencing a good portion of the 
western United States through this time interval. Significant 
features of note include what could be described as a deformation 
zone of sorts sandwiched between the upper right corner of a large 
low embedded in the longwave trof that gets squashed against 
higher pressure influencing central Canada that the GFS in 
particular has lingering on and influencing Wednesday and Thursday 
with continued wet weather. Otherwise Monday into very early 
Tuesday morning appear to be the interval potentially least cluttered 
with shortwave triggers so it remains assigned with the lowest 
pops. Tuesday afternoon/evening are hinted at as having negatively 
tilted trof passing as a kicker thus the pops and precipitation 
amounts show an increase. Due to this longwave trof pattern 
persisting forecast temperatures will generally remain on the cool 
side of what would be considered normal for this time of year 
through this time interval. /Pelatti 




&& 


Aviation... 
00z tafs: afternoon showers are expected until sunset over mainly 
the higher terrain; although, we will see some isolated showers 
develop over the basin as well. The main threat for thunderstorms 
will be over the NE blue mtns through 03z and may hold together long 
enough to impact klws. Skies are expected to clear out over much of 
the northern half of the area tonight and we may see some fog 
develop across these mountain valleys. Fog coverage will likely be 
less compared to early this morning as the boundary layer will be 
slightly drier tonight; however, some fog could form in the vicinity 
of ksff, but confidence is low at this time and was not mentioned in 
the taf. The main low generating these showers will slowly drift 
into eastern Washington by Friday morning with showers expected to develop 
from south to north through Friday over the region. Isolated 
thunderstorms will be possible across the region Friday afternoon, 
but confidence is too low at this time to include mention of 
thunder at any taf site at this time. /Svh 




&& 


Preliminary point temps/pops... 
Spokane 40 56 42 63 44 67 / 20 60 30 20 10 10 
Coeur D'Alene 38 56 41 63 42 67 / 10 60 40 20 20 20 
Pullman 37 55 40 63 41 66 / 20 60 30 20 20 20 
Lewiston 43 61 45 70 48 73 / 20 50 30 20 20 30 
Colville 36 62 42 67 43 73 / 20 50 50 40 30 20 
Sandpoint 36 58 40 62 40 66 / 10 70 50 30 30 30 
Kellogg 39 54 41 60 43 64 / 10 70 60 40 30 20 
Moses Lake 42 64 46 72 47 75 / 20 40 20 10 10 0 
Wenatchee 43 63 48 69 48 72 / 30 40 20 10 10 0 
Omak 36 64 42 68 42 73 / 20 40 30 20 20 10 


&& 


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


$$