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Forecast data from the National Digital Forecast Database.

5 Day Forecast

• Tuesday
• 
• High: 70 °
• Low: 50 °
• T-Storms

• Wednesday
• 
• High: 61 °
• Low: 46 °
• Chance of T-Storms

• Thursday
• 
• High: 57 °
• Low: 43 °
• Rain Showers

• Friday
• 
• High: 59 °
• Low: 43 °
• Chance of Rain

• Saturday
• 
• High: 70 °
• Low: 48 °
• Partly Cloudy

Area forecast discussion 
National Weather Service Spokane Washington 
440 PM PDT Tue Jun 18 2013 


Synopsis... 
scattered showers and a few thunderstorms will continue Tuesday 
night. By Wednesday a wet and cool weather pattern will take hold 
of the region. Showery and cool conditions will continue through 
the week, with a drying and warming trend expected this weekend. 
Wetter and cooler weather will return early next week. 


&& 


Discussion... 


Tonight and tomorrow...offshore low pressure pushing up against 
higher pressure inland has a moist and unstable flow in between. 
This is being utilized by smaller mesoscale disturbances and other 
triggers to generate both surface and forced elevated showers and 
thunderstorms through this interval. Hrrr model runs have been 
utilized for the short term hours of tonight to time The Breaks in 
precipitation and allow for the weakening but not really 
dissipating north to south oriented band of showers affecting 
locations in The Lowlands from near Moses Lake and up north to 
Republic. Tonight a disturbances rotating around the periphery of 
the incoming large scale low will fire off more showers and 
thunderstorms and take them in a south to north trajectory with 
storm motion near 30 mph or so through eastern Washington and 
north Idaho overnight and into tomorrow. Number of GFS runs hint 
at some of the later convection being highly organized and thus 
of longer duration late tonight and into tomorrow which means 
there should be a significant amount of rainfall. Thus the 
forecast hints at some locations in the north Idaho Panhandle 
receiving up to one and one half inches of rainfall in 24 
hours...which should increase flow in area rivers and streams. In 
addition to the significant rainfall and as is usually the case 
gusty wind and small hail is possible near any of these 
thunderstorms. /Pelatti 


..persistent band of moderate rain Wednesday into Thursday for 
the Idaho Panhandle may cause localized flooding... 


Wednesday through friday: the biggest concern for the Wednesday 
through Thursday time frame will be the amount of rain that will 
fall over the inland northwest. A slow moving upper level low will 
pivot through northeast Oregon into the Idaho Panhandle and stall 
on Thursday into Friday. Deformation band precip (rain wrapping 
around the low) should bring a prolonged period of moderate rain 
to the Idaho Panhandle, western Montana and southern British 
Columbia. We preferred the 00z/12z European model (ecmwf) blended the 15z sref to 
build our multi-day precipitation totals. The operational runs of 
the NAM and GFS aren't terribly different with their placement of 
the upper low and other mass fields, but these operational models 
do become noisy from time to time with convective feedback. The 
ensemble sref and coarser ec suffer from less feedback which will 
hopefully lead to a better basin average precipitation forecast. 
The highest precipitation totals from early Wednesday morning 
through Friday will likely occur over the Idaho Panhandle, namely 
Bonner, boundary and Shoshone counties where as much as 2 to 2.5 
inches of rain will be possible through Friday. Areas in far 
northeast Washington around Metaline Falls, Newport, and Northport 
could get up to 2 inches as well. Rainfall rates don't appear to 
be particularly heavy, but the European model (ecmwf) and sref (which will be 
conservative) suggest the heaviest rates will occur Wednesday 
morning with as much as a half to three quarters of an inch in 6 
hours within a localized band. Most areas should be able to handle 
these precipitation rates. The 12z-18z NAM has almost double these 
rain rates (up to 1.25 inches per 6 hours) which could cause some 
problems on creeks and small streams. 


Concern area #1: the Idaho Panhandle and southeast British 
Columbia. A Flood Watch may be necessary for Wednesday for 
portions of the Idaho Panhandle for creeks and small streams. 
Another concern will be the large amount of precipitation from 
Wednesday through Friday over the Kootenai basin in southeast BC, 
northwest Montana and far north Idaho. Rises are forecast on the Kootenai 
at Bonners Ferry. The potential for more rain next week is not 
particularly good news, but it is early to say whether rains next 
week will be significant enough to generate run-off. 


Concern area #2: the burn scars in central Washington around 
Wenatchee, Chelan and Entiat. Fortunately, the deformation band 
with the upper low will be well east of the burn scar area on 
Wednesday. There is a small chance on Thursday, that this band 
will pivot into central Washington, but it will not likely 
maintain precipitation intensity into Thursday. There will also 
be a small chance of thunderstorms on Wednesday. The atmosphere 
does not appear to be particularly unstable with a 500mb temp of 
only -18c to -19c. There should also be a good deal of low 
cloudiness Wednesday which should inhibit surface heating 
throughout the day. All-in-all, the threat of flash flood appears 
to be low over the burn scars through Friday. /Gkoch 


Friday night thru Sunday night... lingering showers and cool 
temperatures will continue over eastern sections of the County Warning Area Friday 
night as the persistent upper low slowly moves east from the 
southern part of the Idaho Panhandle. Differences in timing 
between the ec and GFS cast doubt on how fast the system will move 
east on Saturday and while the Cascades and basin will have mostly 
clear skies and warming temperatures, showers may linger over the 
Idaho Panhandle. By Saturday night and early Sunday all models 
agree that the County Warning Area will be in between systems and under a weak 
short wave ridge. The ec then brings in the next system off the 
Pacific by Sunday afternoon with an increasing threat for showers 
over the Cascades. Precip is on the increase Sunday night as the 
ridge moves quickly east and the flows becomes westerly. Jl 


Monday and Tuesday...it looks like another moist storm system will 
be affecting the inland northwest next week, bringing increased 
rain chances to many areas. There is decent model agreement 
regarding this system, with only some slight timing differences. 
We went ahead and bumped up precipitation chances, especially 
along the Cascade crest. With what is going to fall over the next 
couple of days, anything of significance rainfall wise may cause 
some hydrology issues. This is definitely something to watch out 
for. TY 


&& 


Aviation... 
00z tafs: another round of showers and thunderstorms will affect all 
of the taf sites this evening with moderate rain and some MVFR 
cigs. A band of moderate to heavy rain will develop late tonight 
along the Washington/Idaho border, and persist through much of Wednesday. This 
will bring IFR conditions to most of the eastern taf sites all day. 
Kgeg will be on the western edge of this band and conditions may 
improve a bit in the late afternoon. Ksff and certainly kcoe will 
feel the brunt of this event. To the south, kpuw and lws may see 
some improvement in the afternoon but I didn't have enough 
confidence in this. Kmwh and keat should remain out of the action 
for the most part and will actually have better conditions tomorrow 
than today. Rj 


&& 


Preliminary point temps/pops... 
Spokane 52 54 45 55 44 61 / 80 100 80 80 50 60 
Coeur D'Alene 52 54 46 54 42 60 / 90 100 100 90 50 60 
Pullman 49 53 44 56 42 60 / 80 100 70 60 30 60 
Lewiston 54 58 49 64 44 67 / 70 100 70 60 20 50 
Colville 51 63 50 57 48 67 / 90 100 100 100 60 50 
Sandpoint 50 56 46 53 45 60 / 100 100 100 100 60 60 
Kellogg 50 51 44 51 39 57 / 100 100 100 100 50 60 
Moses Lake 55 66 51 65 49 69 / 70 50 50 60 30 30 
Wenatchee 56 66 52 64 51 68 / 40 40 50 60 40 30 
Omak 53 66 51 64 50 69 / 60 80 70 80 60 50 


&& 


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


$$