Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Boise Idaho
322 am MDT Thursday Oct 30 2014
Short term...today through Friday...upper level ridge building
across the forecast area today for above normal temperatures.
The amplifying ridge is in response to the next upper level trough
expected late Friday/early Saturday. Temperatures expected to hit
the upper 60s/low 70s in the valley today. Clouds will increase
overnight as the upper trough reaches the West Coast on Friday.
Despite the clouds...the forecast area will remain in the warm
sector with breezy southerly winds which will keep temperatures in
the middle to upper 60s on Friday. Rain showers will remain west of
the region through 5 PM MDT on Halloween but there is a chance of
rain in Burns and Baker City thereafter.
Long term...Friday night through Wednesday...energy digging
into the base of an upper level trough along the West Coast will
form a low pressure system which will eventually track right through
our area on Saturday. Before the low moves in...a frontal band of
precipitation will gradually shift eastward...spreading showers in
southeast Oregon Friday night. Showers associated with the low
pressure system will encompass most of southeast Oregon and SW Idaho on
Saturday. Snow levels will start off at around 8000 feet then fall
to around 5000 feet on the western side of the low Saturday
afternoon. Precipitation totals will average 0.10-0.25 inches in the
valleys and 0.50-1.00 inches in the mountains. Several inches of
snow are likely in the mountains. The low will move to the northeast
Saturday night with snow levels lowering further to around 4500
feet. Moisture wrapping around the backside of the low could bring
additional light snow accumulations to the Boise Mountains and west
central mountains...including McCall which could see its first
measurable snowfall of the season. The area will begin to dry out
on Sunday as upper ridging starts to build in from the west.
Temperatures will be cool over the weekend with highs in the 40s
to lower 50s. A tight west-east surface pressure gradient will support
gusty west winds...especially in the western Magic Valley which
could be windy through most of the weekend. For Monday through
Wednesday...a moist Pacific flow will continue to bring a chance
of showers across the northern mountains...while upper level ridging
will keep it dry across the remainder of southeast Oregon and SW Idaho.
Temperatures will warm to near normal by midweek.
Aviation...VFR. Scattered-broken middle-high level clouds. Light surface winds
10 knots or less...except east-southeast winds 10-20 knots at kbke and from
kmuo to kjer. Southwest winds aloft 15-25 knots up through 10k feet
mean sea level.