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Area forecast discussion 
National Weather Service Boise Idaho
1022 am MDT Tuesday Mar 31 2015

Discussion...windy day on tap for much of the area. A surface
pressure trough has already moved through the County Warning Area this
morning...but the real cold front will move through from late
morning in eastern Oregon through early evening in the western Magic
Valley. This front will have accompanying showers which will aid
in mixing down stronger winds. Therefore we will let the Wind
Advisory stand as is. We suspect it may need to be extended a
little longer into the evening in the far southeast portion of the
County Warning Area...but will make that decision based on timing as the afternoon
unfolds. For now...will extend the area of slight chance thunder
to cover the remainder of the northern portion of the County Warning Area for this
afternoon and evening. Will also raise maximum temperatures for much of
the area. Update out shortly.


Aviation...VFR with increasing clouds...lowering into late
morning. Chance showers begin by 19z in southeast Oregon with an east
moving front along a NE-SW line. Expect brief MVFR across
east-central Oregon and west-central Idaho mountains with showers...and possible
thunder. Could see vcsh in the Magic Valley...but this will be
more of a wind event. Northwest 15-25kt surface winds with gusts up to
40kt in the upper Treasure to Magic Valleys and south after
31/21z...decreasing to 5-10kt overnight. Winds aloft near 10k feet
mean sea level...SW 20-30kt....becoming west-northwest 20-30kt 01/00z...and west-northwest 10-20kt
by 01/18z.


Previous discussion...
short term...Pacific cold front will move across eastern Oregon
this morning and southwestern Idaho midday and early afternoon
followed by gusty west or northwest winds. Front looks stronger
than it did in yesterday/S models and the slightly later timing will
increase the thermal gradient across the front. Strong westerly
winds aloft will contribute to the strength of the front. Strongest
surface winds will hit late today in the snake basin east of
Mountain Home as models show tightest surface pressure gradient in
that area at that time. Maximum temperatures today will be about 20 degrees
lower than yesterday in Oregon zones...but in Idaho the front will
come late enough to allow daytime temperatures to rise into the 60s before
cooling in the afternoon. The full cooling will arrive Wednesday
when maximum temperatures will only be in the 40s in the mountains and lower to
middle 50s in the valleys throughout our County Warning Area. The front will not be
especially moist but numerous light rain and snow showers will fall
in northern zones...little if any precipitation is expected south of the snake
basin. Air mass will be marginally unstable in the central Idaho
mountains where isolated thunderstorms are being forecast. Upper
trough will re-develop light rain and snow showers in our northern zones
Wednesday afternoon.

Long term...Wednesday night through weather pattern
still on track through the extended forecast. First trough will
move over the forecast area Wednesday night and Thursday for a
chance of precipitation over Baker County and the central mountains
of Idaho with slight chance everywhere else. Temperatures on
Thursday will be 5-7 degrees below normal. A low-amplitude ridge
will move over the region Thursday night and Friday with mostly dry
conditions. Models have been fairly consistent with this ridge but
differ from run to run as to how much if any moisture will be moving
through the flow. Forecaster thinking at this time is that any
moisture riding over the top of the ridge will remain to the north
of the forecast area so will keep the dry forecast through Friday.
Temperatures will begin to warm under this weak ridge with high
temperatures on Friday warming back to near normal. From Friday
night through Monday forecaster confidence in the models is low.
Models seem to be having a hard time with next weather system that
is dropping south out of the Gulf of Alaska. There is no run-to-run
consistency so this will also affect the timing and placement of any
precipitation. For now do not want to yo-yo the forecast with the
changing models so will not make any changes to probability of precipitation for the weekend
and into early next week. Even with the uncertainty in the models
.It does look like the region will be in for a cool-down with
temperatures by Sunday falling to around 5 degrees below normal and
snow levels between 4000 and 6000 feet.


Boi watches/warnings/advisories...
Idaho...Wind Advisory from 2 PM this afternoon to 9 PM MDT this evening




Discussion...snow pellets
previous short
previous long term....ja

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