Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 241558

Area Forecast Discussion
National Weather Service Boise ID
958 AM MDT Mon Apr 24 2017

.DISCUSSION...Upper level trough is moving into the Pacific NW
this morning and widespread precipitation is occurring over
southwest Idaho and southeast Oregon. Expect some partial clearing
this afternoon as a cold front moves through the region. Afternoon
heating will destabilize the atmosphere later today with a slight
chance of thunderstorms, although clouds and precipitation this
morning could keep showers from developing into thunderstorms.
Gusty winds up to 35kt is possible near thunderstorms during the
afternoon. The center of the shortwave is expected to move
southeast across central Oregon this evening northern NV by early
Tuesday morning. Precipitation amounts of 0.75 to 1.25 in of water
equivalent is expected through Tuesday morning in the mountains
with snow levels near 6000ft, lowering to 4500ft this evening.
Lesser precipitation amounts of 0.15 to 0.50 in for the valleys.
Current forecast reflects this well with no updates.


.AVIATION...Widespread rain with areas MVFR ceilings/vis.
Mountains generally obscured. Cold front in eastern OR will move
across western ID 18Z-24Z with increased showers and scattered
thunderstorms along the front. Snow level lowering from near 6000
ft MSL to 4500 feet MSL after 25/03Z with areas of IFR in snow
above 4500 feet MSL. Surface winds: west 5-15 kts, becoming
west/northwest 15-25 kts after 24/20Z. Gusts to 35 kts near
thunderstorms. Winds aloft near 10 KFT MSL: west 25-30 kts.


SHORT TERM...Today through Tuesday...A few showers are lingering
over southwestern Idaho this morning, with most activity moving
quickly northeast. Satellite is indicating cooling cloud tops moving
into eastern Oregon, with the onset of shower activity likely not
far behind. The area of low pressure causing the next round of
shower activity and breezy wind remains off the coast of northwest
Washington, and is expected to move southeast and inland by early
afternoon. Showers will spread quickly through the forecast area
this morning. The best instability looks to be over the ID/OR
border, though increased cloud cover may inhibit convection today.
Regardless, some threat for thunderstorms exists for the majority of
the area. Models are indicating that the area of low pressure will
become an open wave by the late afternoon/early evening hours. The
trough axis will move through the area late tonight. A drier
northwest flow then moves over the area Tuesday morning keeping
showers out of much of Oregon, with lessened coverage in
southwestern Idaho. Cooler temperatures anticipated through the

LONG TERM...Tuesday night through Sunday...Continued unsettled
pattern under a moist northwest flow aloft. Wednesday looks to be
the wettest day in the extended as a cold front passes through the
region in the afternoon bringing a chance of heavy showers and
thunderstorms across the area. An upper level low looks to dip south
and over the region late Thursday into Friday for cooler
temperatures and snow possibly down to valley floors (snow levels
look to reach 3000-3500 ft MSL on Friday). Showers will be lighter
however, as the low continues its journey south and east and a ridge
builds into the region by Saturday. Showers will return to the
region by the end of the weekend. Temperatures will be about 5-10
degrees below normal for the duration of the extended; expecting
temperatures to dip down to 10-15 degrees below normal Thursday and
into Friday.





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