Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 191047

Area Forecast Discussion
National Weather Service Boise ID
345 AM MST Sat Jan 19 2019

.SHORT TERM...Today through Monday...Continued wet through early
Monday.  Very moist Pacific warm front currently passing through
our CWA with widespread rain and snow.  Previous forecast remains
on track except for slightly lower snow levels and slightly cooler
temps per latest obs and model guidance.  The winter wx advisory
will continue over the same area and time frame as before, i.e.,
Baker County and Idaho mountains north of the Snake Basin.  After
the warm front passes the main Pacific moisture fetch will sag
south over our CWA this afternoon and tonight, then arch northward
Sunday morning ahead of Pacific cold front.  The cold front will
pass through our CWA Sunday afternoon.  Main moisture fetch will
then sag south again directly over our CWA until the upper trough
moves through Monday morning.  The cold front looks strong enough
for a slight chance of thunderstorms along the frontal zone.
Behind fropa precipitation will turn showery and snow levels will
lower, with several inches further snow accumulation in the
mountains through Monday.  Total precipitation water content
through Sunday afternoon will be 0.25 to 0.50 inch in southern
Harney and Malheur Counties in Oregon and Owyhee and Twin Falls
Counties in Idaho, to around 1.00 inch in the Treasure Valley and
Baker County, and 1.00 to 2.00 inches in the Idaho mountains north
of the Snake Basin.  Snow levels will be high during most of the
event and excessive amounts of snow are not expected below 5000
feet.  Finally, models indicate gusty northwest winds Monday, and
also 5 to 10 degrees cooler than Sunday.

.LONG TERM...Monday night through Friday...Cool northerly flow will
bring the coolest day of the extended period on Tuesday.
Temperatures will be near normal. Moisture will spill over the ridge
into the region on Wednesday morning as a system tracks across
British Columbia into Wyoming by Wednesday night. Temperatures will
be cold enough to support snow at all locations with this system.
The upper level ridge will amplify on Thursday and Friday with dry
conditions and north-northwesterly flow aloft. Temperatures during
this period will be around 5 degrees above normal from Wednesday
through Friday.


.AVIATION...Widespread precipitation and mountain obscuration with
MVFR to IFR. Snow levels near 4000ft this morning, rising to 6500-
7500ft by 00z/Sun southwest of BNO-ONO-TWF and 5500-6500ft near BKE-
MYL. Conditions may improve to low VFR as snow levels rise and
warmer air moves into region during the day on Saturday.
Precipitation band will move northward after 00z/Sun and taper off
from south to north. Surface winds SW-SE 5-15kt. Winds aloft at
10kft MSL: WSW 30-40kt.

Sunday outlook...Areas of low clouds/fog possible in the morning.
Generally VFR during the day. Mountains obscured. Precipitation
redeveloping along cold front on late Sunday afternoon.
Snow levels 7000ft south, 5500ft near KBKE-KMYL, lowering in the
evening behind cold front to valley floors by Mon morning.
Surface winds SW-SE 10-20kt shifting to NW 10-20kt behind front.


ID...Winter Weather Advisory until 11 AM MST this morning
OR...Winter Weather Advisory until 10 AM PST this morning ORZ062.



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