Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 161649

Area Forecast Discussion
National Weather Service Boise ID
949 AM MST Tue Jan 16 2018

.DISCUSSION...Precipitation associated with an upper trough in
southeast Oregon, which has been primarily rain south of a Burns
to Ontario line, and snow north of the line, will weaken and move
into southwest Idaho late this morning through mid-afternoon.
Light precipitation is still expected in southwest Idaho, with
rain in the valleys and snow (less than an inch accumulation) in
the mountains. No updates.


.AVIATION...VFR. Showers pushing out of SE Oregon by 19z and out
of SW Idaho by 22z. Patchy fog/stratus early Wednesday in lower
valleys. Surface winds, variable 10-15 kts. Winds aloft to 10k
feet MSL: SE Oregon W 15-25 kts, SW Idaho SW-NW 10-25 kts through
06z then SW 10-30 kts.


SHORT TERM...Short wave trough and surface cold front in central
Oregon will weaken as it moves east today but will still be strong
enough to produce light pcpn in all of eastern Oregon this
morning. System will weaken as it gets into Idaho this afternoon
but will still manage light pcpn except in the Western Magic
Valley. Clearing from west to east tonight, and dry Wednesday,
except a slight chance of rain and snow in the higher terrain of
Baker County Wednesday. Will continue a slight chance of light
freezing rain this morning in central Malheur County, OR, and the
sw corner of Owyhee County, ID. Snow level will range from 4500
feet MSL north to 6500 feet MSL near the Nevada border, so rain
will be the pcpn-type in most populated areas. Gusty east or
northeast winds today from Mountain Home through Jerome. Will
continue patchy valley fog this morning, and again late tonight
and Wednesday morning.

LONG TERM...Wednesday night through Monday...Strong southwest
flow develops on Wednesday night ahead of a deep upper level
trough off the Pacific NW coast. Expect mild and breezy conditions
on Thursday. Temperatures could reach the mid to upper 50s across
portions of the forecast area with strong pre-frontal flow aloft.
850mb temperatures (around 5000ft MSL) reach +12C (54F) along the
Owyhee Mountains on Thursday afternoon. Precipitation will become
widespread on Thursday evening, with moderate liquid amounts on
Thursday night. Snow levels will be quite high (around 6500-8000ft
MSL) with the onset of precipitation, then slowly lower as the
cold front moves through the region. Snow amounts across much of
the mountains will be limited to the second half of the storm, as
temperatures aloft remain warm through early Friday morning. Snow
levels will fall to around 3500-4500ft for the second half of the
storm, as precipitation begins to taper off on Friday afternoon in
the valleys. Snow showers across the mountains will continue
through Friday night and taper off after sunset. Temperatures will
lower to seasonable values for the remainder of the period.
Expect mountain snow showers during the day on Saturday afternoon,
with the cool air aloft helping to create instability showers
over the terrain. The next system moves into the region on Sunday
afternoon, bringing a warm front and subsequent cold front. Snow
levels may rise above the lowest valley floors (3000-3500ft) with
this warm front, although some models keep snow levels at the
valley floors. Stay tuned.





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