Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Boise Idaho
249 PM MDT Tuesday Jul 29 2014
Short term...at 2pm isolated thunderstorms were forming in the
mountains near all our County Warning Area borders...earlier than yesterday. Air
mass was quite moist and unstable this morning but on a gradual
drying and stabilizing trend this afternoon...at least according to
models. Therefore we expect thunderstorms to remain isolated. With
only light winds aloft they will move slowly and may drop heavy
rains. Models suggest highest probability of precipitation in Oregon zones this evening
then low probability of precipitation in all zones later tonight and Wednesday morning.
Highest probability of precipitation Wednesday afternoon will be in eastern-most Idaho zones.
Thursday afternoon will have increasing probability of precipitation in all areas. Models...
especially GFS...tap some high-level tropical moisture from Hernan
off Baja California calif and advect it northeastward into our County Warning Area Thursday. Temperatures a
tad cooler Wednesday and again Thursday.
Long term...Thursday night through Tuesday...the very warm upper
level ridge over western North America shows signs of losing
amplitude this weekend...but only slightly lower temperatures are
expected. Monsoon moisture within the ridge circulation will
maintain favorable conditions for convection. Weak disturbances
embedded in the southwest flow aloft over our area...combined with
daytime heating...will provide support for isolated to scattered
thunderstorms each day. The best chances will be Thursday evening
and Sunday afternoon and evening. Monday and Tuesday the upper level
flow will turn more westerly...bringing drier air and decreasing the
chance of thunderstorms.
Aviation...VFR. Expect widely scattered thunderstorms through this
evening in Oregon over Harney and southern Malheur counties...and
in Idaho south of the Snake River Valley and over the central
mountains. Thunderstorms will become isolated after 06z...then
increase in coverage after 18z Wednesday. Surface winds...variable
5-10 kts except stronger and gusty near thunderstorms. Winds aloft...
northwest 5-10 kts up through 10k feet mean sea level.