Area Forecast Discussion
Issued by NWS Boise, ID
FXUS65 KBOI 192140
Area Forecast Discussion
National Weather Service Boise ID
240 PM MST Thu Jan 19 2017
.SHORT TERM...Tonight through Saturday...Southwest flow aloft
continues throughout almost all of the short term, but heights
fall and cooling aloft will occur. A series of relatively weak
embedded short wave troughs will move through this flow, bringing
scattered snow showers tonight, more widespread snow Friday into
Friday night, and more scattered snow showers Saturday. Snow
amounts are sufficient to warrant a Winter Weather Advisory for
Harney and Malheur counties, along with the Lower Treasure Valley
on the Oregon side, for Friday into Friday night. This storm will
not be nearly as strong as the one we just had, but will bring 2
to 5 inch amounts to mainly the northern halves of the two named
counties, along with 1 to 3 inch amounts in the Lower Treasure
Valley on the Oregon side. Temperatures will be a few degrees
below normal during the day, and near normal at night.
.LONG TERM...Saturday night through Thursday...Active weather
pattern will continue through Tuesday, then upper level ridging
develops with an inversion developing by Thursday into the
weekend. A series of weather systems will move through the region,
with a wave arriving on Sunday, bringing a round of snow to all
locations. As the parent upper level trough digs south along the
coast, a weak shortwave breaks off the parent trough and moves
across southeast Oregon and southwest Idaho. This system on Sunday
through Monday could bring 2-4" of snow in the valleys and 4-8" of
snow in the mountains, although confidence still remains low at
this time. After the system moves through, cold northerly flow
develops and inversion conditions develop in the valleys, with
temperatures well below normal.
.AVIATION...Generally VFR. MVFR-IFR in isolated showers with
mountain obscuration. Snow levels generally around 3-4KFT MSL.
Partial clearing with patchy fog development after sunset in the
valleys. Snow is expected to develop after 12z/Fri in SE Oregon
and spread across the region Friday afternoon. Winds aloft at
10KFT MSL: SW 10-20kt becoming southerly 20-30kt by 18z/Fri.
Surface winds: variable 10kt or less.
WEEKEND OUTLOOK...Unsettled conditions continuing through the
weekend with periods of MVFR-IFR and patchy LIFR fog in mountain
OR...Winter Weather Advisory from 11 AM to 11 PM MST Friday ORZ064.
Winter Weather Advisory from 5 AM MST /4 AM PST/ to 11 PM MST
/10 PM PST/ Friday ORZ061-063.