Area Forecast Discussion
Issued by NWS Boise, ID
FXUS65 KBOI 240312
Area Forecast Discussion
National Weather Service Boise ID
912 PM MDT Sun Oct 23 2016
.DISCUSSION...High clouds are on the increase this evening with
strengthening southwest flow aloft. Higher elevations of
southeast Oregon and southwest Idaho will see an increase in
southerly winds overnight, with easterly drainage winds in Snake
Plain. Conditions remain dry and mild tonight, which forecast
covers well, so no update.
.AVIATION...VFR. SCT mid and BKN-OVC high-level clouds. Surface
winds generally 12 knots or less, except northeasterly 15-20 knots
with gusts near 25 knots KJER and vicinity after 06Z. Winds aloft 20-
35 knots up through 10K feet MSL. Monday clouds will thicken and
lower with a slight chance of showers at KJER/KTWF and the central
mountains of Idaho after 18Z.
SHORT TERM...Gradually moistening southwest flow aloft will
increase clouds through Monday, especially on the Idaho side.
A chance of showers is forecast for our eastern-most areas
Monday afternoon, with enough instability and shear for a
slight chance of thunderstorms in and near Twin Falls County
Monday afternoon and early evening. More showers will come
into our CWA from the southwest Monday night and Tuesday as
a surface cold front and Pacific upper trough move inland.
Ahead of the front, our CWA will still be warm Monday with
increasing southeast and southerly winds. Harney and Malheur
Counties in Oregon will have southerly winds 20 to 30 mph with
gusts to 40 mph Monday afternoon. The front will pass through
southeastern Oregon Monday night and western Idaho Tuesday
morning. Cooler Tuesday.
LONG TERM...Tuesday night through Friday...As an upper level ridge
builds into the region from the east Tuesday night, shower activity
will become limited to the northern reaches of Harney and Baker
Counties, in addition to the West Central Mountains. Thursday is
looking to be the driest day of the period while under the influence
of the upper level ridge. Temperatures rise to about 7-10 degrees
above normal for both Wednesday and Thursday. Thursday night into
Friday will see an increase in shower activity across the region as
an upper level shortwave enters from the southwest. Timing of this
system`s passage through the region has been a point of contention
between models, however. For now, expecting the temperatures to drop
to 5 degrees of normal as heights lower and cloud coverage increases.
Friday night through Sunday...Timing differences among models makes
confidence in the long term forecast difficult to maintain. Saturday
night, the GFS is a little slower than the ECMWF in pushing a short
wave through the pattern, thus confidence in location of the
precipitation with this short wave is low at this time. By late
Saturday evening into early Sunday morning both models are showing
slight clearing before we are hit with the main upper low. More
widespread precipitation in the forecast starting Sunday night
into Monday as the upper low makes its way down along the coast.
Temperatures are forecast to remain above normal during this time.
PREV SHORT TERM...LC
PREV LONG TERM....AB/JC