Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Boise Idaho
322 am MDT Friday Apr 18 2014
Short term...today through Saturday...surface low and cold front
have moved to southeast Idaho as of 3 am. Showers are shifting east as
well with light rain showers across the Magic Valley at 3 am. No
thunderstorms observed since midnight our County warning forecast area. Dry slot on water
vapor imagery over Washington and west Oregon will over spread SW Idaho and
southeast Oregon later this morning and south central Idaho this
afternoon. One change this cycle is the moisture with the low to
our south. Moisture remains over Nevada then lifts north to the Idaho-Nevada
border Saturday afternoon...where a surface low also forms. Warm
SW flow will bring temperatures back up into the 70s which may
provided enough instability to combine with the moisture for a
slight chance of thunderstorms late Saturday over highest terrain.
Long term...Saturday night through Friday...a dry cold front will
sweep east across eastern Oregon/western Idaho late Saturday night.
Main effect will be gusty winds early Sunday morning and
temperatures 5 to 7 degrees cooler by Sunday afternoon. Weather
pattern will shift on Monday as the upper level ridge rebuilds over
the Continental Divide...leaving Oregon/Idaho under the influence of
southwesterly flow aloft on the backside of the ridge. Middle-level
moisture will be advected northeastward in this set-up...supporting
the development of showers and thunderstorms as early as Monday
afternoon. Significantly cooler Tuesday...Wednesday...and Thursday
as a deep upper level trough moves inland over the western Continental U.S..
expect valleys to peak in the middle to upper 50s. Trough looks to exit
by next weekend...but model agreement wavers significantly by
Aviation...cold front exited toward eastern Idaho approximately 09z
this morning. Scattered MVFR showers and moderate Post-frontal
winds /W-northwest with gusts to 25 kts/ will continue across southwest
Idaho through 15z. Snow levels at or above 6000 feet mean sea level. Across southeast Oregon -
patchy IFR fog and surface winds generally 10 kts or less. Westerly
winds aloft will average 30 knots at 10k feet mean sea level.
Weekend outlook...VFR. A dry cold front will move east across Oregon/Idaho
late Saturday night. Expect gusty winds through 18z Sunday.