Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 250259
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
859 PM MDT Fri Mar 24 2017

.DISCUSSION...Skies were cloudy across the CWA as of 845 pm MDT,
with showers, some strong, moving east mainly across the Upper
Treasure Valley and West-Central and Boise Mountains. These
showers produced a quick tenth of an inch as they passed over the
Boise airport. Showers are expected to continue through most of
the night to the east of where they are now, exiting the Western
Magic Valley and mountains of southwest Idaho by 6 am MDT. River
flooding continues on the Boise in Ada and Canyon counties, and on
the Snake near Weiser. See the Hydrology section below for more
details.

&&

.AVIATION...Low VFR to MVFR in showers, VFR otherwise. Shower
activity will tapper off in SE Oregon by 06Z, and over SW Idaho
around 12Z. However, light showers will continue into Saturday over
the West Central and Boise Mountains, as well as along the Nevada
border. Mountain obscurations expected with lower ceilings. Surface
winds: generally variable, less than 10 kts. Winds aloft near 10k
ft MSL: westerly 10-20 kts.

Weekend Outlook: Low-VFR expected with shower activity continuing
north of a Burns-Ontario-Stanley line and along the Idaho-Nevada
border through the evening. Areas of mountains obscuration possible.
Valleys will remain VFR. VFR expected Sunday ahead of the next
system. Showers expected in southeastern Oregon after 15Z on Sunday,
with showers moving into southwestern Idaho by Sunday afternoon.
MVFR conditions under low ceilings with next moisture push, as well
as mountain obscuration. Scattered to widespread shower activity
expected to remain through Sunday night and into Monday.

&&

.HYDROLOGY...Most rivers and streams will rise over the weekend in
response to precipitation that occurred earlier today and what
will continue to fall this evening and late tonight, but most
will stay below flood stage. Exceptions are the Snake River near
Weiser and the Boise River in Ada and Canyon counties, which will
remain above flood stage through the coming week. Hydrologic
warnings and advisories remain in effect over northern Harney
County and in/near Camas County. Cooler temperatures and snow
above approximately 6000 feet will limit the snowmelt and amount
of runoff from higher terrain.

&&

.PREV DISCUSSION...
SHORT TERM...Tonight through Sunday...Two Pacific systems will
bring precipitation to our CWA. Showers from the first system will
arrive in the Magic Valley by this evening as precipitation tapers
off in eastern Oregon. Most lower elevation areas will see showers
ending by Saturday morning, but isolated showers are still possible
in the valleys in the moist unstable air. Scattered snow showers
will continue over the mountains above 5000 feet through the day. A
temporary high pressure ridge will provide a brief respite from
precipitation Saturday night and Sunday morning, but more showers
will spread into eastern Oregon and the mountains of southwest Idaho
Sunday afternoon as the next system approaches.

LONG TERM...Sunday night through Wednesday...An unsettled pattern
to continue through the long term. A Pacific trough will bring
widespread shower activity Sunday evening which will continue
through Monday evening. Cooler temperatures anticipated in response
to this system. A break in widespread moisture expected into
Wednesday, though the associated ridge is dirty, and may skirt a few
showers across the northern border of the forecast area.

Wednesday night through Friday...Pretty wet for the CWA for
Wednesday night into Thursday as a Pacific System pushes through the
area. A ridge begins to build over the Pacific Northwest come Friday
morning helping to dry things out for most of the CWA. Snow levels
begin around 6500 feet MSL or higher then drop slightly come
Thursday night as the boundary pushes through. Snow levels bottom
out around 4000 feet MSL Friday morning before climbing back above
5500 feet MSL by Friday night. While the snow levels drop, most of
the precipitation has pushed out of the area so only higher
elevations in the West Central and Boise Mountains as well as the
Owyhee Mountains and southern Twin Falls county will see some snow
showers. Temperatures Thursday will sit right around normal for this
time of year then climb to above normal Friday as the ridge builds
in.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...None.

&&

$$

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DISCUSSION...SP
AVIATION.....AB
HYDROLOGY...SP
PREV SHORT TERM...JT
PREV LONG TERM....KB/JC


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