Area Forecast Discussion
Issued by NWS Boise, ID
FXUS65 KBOI 071650
Area Forecast Discussion
National Weather Service Boise ID
950 AM MST Wed Dec 7 2016
.DISCUSSION...Clearing skies are expected today, as temperatures
remain cold, with highs in the Snake River Valley climbing only
into the 20s. The next storm system and associated warm front is
still expected to move in tomorrow with advisory level snowfall.
No updates to the forecast are needed this morning.
.AVIATION...Low clouds and IFR conditions will linger through 17-20Z
for Idaho valley sites today. Expect the cloud deck to erode and
become more dispersed thereafter with improving conditions.
Elsewhere, VFR conditions are anticipated today. The next weather
maker will begin approaching the area late today and overnight. At
the surface gusty SE winds between 15 and 20 knots will develop as
the system approaches, affecting Snake Plain sites for much of
Thursday. Precipitation is expected to affect most TAF sites
beginning after 16Z Thursday with IFR conditions becoming likely
through the day.
SHORT TERM...Today through Thursday night...Cold dry weather will
continue today under northwest flow aloft with cold air at the
surface left over from an upper level trough which has move east of
the Rockies. Air of Arctic origin in Montana and Wyoming is being
blocked from moving into Idaho by the central Idaho mountains and
surface high pressure in Oregon, but temperatures are still
averaging around 10 degrees below normal. Westerly flow aloft
currently approaching the west coast will carry a relatively warm
and very moist weather system inland over our area starting late
tonight. As the system rides over the cold air at the surface,
between 1 and 3 inches of snow will fall in the valleys Thursday and
Thursday night, with up to 10 inches in the higher mountains, before
the cold air mixes out and precipitation changes to rain at lower
elevations early Friday. Prior to the transition, there will be a
chance of freezing rain mixed with the snow in the valleys on
LONG TERM...Friday through Tuesday...Period remains active as long
wave trough keeps the storm track centered on the Pac NW. Warm front
moves east of the area Friday with trailing westerly flow focusing
additional light precipitation in the mountains while valleys see
lesser amounts. Have introduced a chance of freezing rain for the
lower Treasure Valley Friday morning as nose of warm air aloft will
change precipitation to rain below 4000 feet, though surface cold
pool likely won`t scour out until the afternoon. Passage of an upper
trough Friday night increases of rain/snow across much of the area.
While northwest flow will keep showers in the east-central Oregon
and the west-central Idaho mountains on Saturday. Some uncertainty
as to how much of a break there is in the precipitation for Sun/Mon
but by Tuesday models are back in agreement on bringing another
round of rain/snow. Temperatures are near normal through the period.
ID...Winter Weather Advisory from 11 AM Thursday to 5 AM MST Saturday
Winter Weather Advisory from 11 AM Thursday to 5 AM MST Friday
Winter Weather Advisory from 11 AM to 10 PM MST Thursday
OR...Winter Weather Advisory from 10 AM Thursday to 4 AM PST Saturday
Winter Weather Advisory from 11 AM MST /10 AM PST/ to 10 PM MST
/9 PM PST/ Thursday ORZ061-063-064.
PREV SHORT TERM...JT
PREV LONG TERM AND AVIATION....DG