Area forecast discussion
National Weather Service Pocatello Idaho
259 am MDT Monday may 20 2013
Short term...today through Wednesday. Showers and afternoon
thunderstorms will continue with a cold core aloft generating
enough instability with plenty of available moisture for scattered
showers and isolated thunderstorms. Upper level closed low is slow to
move...but by Tuesday morning should have most of the precipitation
end with only a slight chance of showers and thunderstorms along
the Idaho-Wyoming border by Tuesday afternoon and evening. The kicker for this
first low then moves onshore by Tuesday night.This is an intense low
that will bring precipitation as early as Tuesday night in the
Sawtooths and Tetons. Guidance continues to indicate that the
precipitation will mainly be in Montana...with only the Montana
border region of the forecast area having significant probability of precipitation on Tuesday
night/Wed. Strong upper level winds could possibly affect eastern
Idaho with moderate to strong wind by Wednesday afternoon...but until
then wind should continue light to moderate. With the clearer
skies Tuesday...this should be the warmest day of the near term.
Temperatures have a chance to get above normal after the previous
three days of clouds and rain...but will be cool again Wednesday.
Overnight lows with with the closed low could mean snow above 8500
feet elevation...but should not accumulate to any significant
amount. Messick
Long term...Wednesday night through Sun night. The intense Pacific
northwest upper level low will slowly spin in place through Thursday
night. Expect continued showery weather...mainly for the northern
half of the forecast area...with afternoon thunderstorms possible
in the unstable air. Thursday has the most significant shortwave enter
the base of the trough and eject northeastward across the Gem
state. This shortwave is enough to lift the entire upper level low
to the north-northeast for the second half of this extended
period. This will mean clearer skies once again with a lowered
threat of showers and thunderstorms after Thursday night. The next
upstream low could arrive as early as Sun afternoon...so it is
mainly a threat in the central Idaho mountains. Messick
&&
Aviation...remnants of departing upper low will linger across
eastern Idaho today. Showers continue this morning under VFR
conditions but expect afternoon instability to produce a few
thunderstorms as well. Conditions will remain mainly VFR with
occasional MVFR in slightly lower ceilings and visibilities under
the stronger cells. Dmh
&&
Fire weather...showers and isolated thunderstorms will remain
across eastern Idaho through this evening as an upper low continues
to shift east. An upper ridge will be in place for Tuesday...but
lingering moisture may allow showers to develop over higher terrain
areas. The central mountains...closest to next upper low deepening
over the Pacific northwest coast...may be most vulnerable to afternoon
convection Tuesday. The Pacific northwest low remains in place through Friday
with the threat of unsettled conditions...then the center fills and
lifts northeast on Saturday. Eastern Idaho remains under southwest
flow with continued trough conditions over the western states. Dmh
&&
Pih watches/warnings/advisories...
none.
&&
$$
