Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Boise Idaho
933 PM MDT Monday Aug 3 2015
Discussion...mid-high level cloud shield helped cap convective
activity for today...especially across SW Idaho zones. At this
time expect little if any additional development in SW Idaho
through the night. A circulation center over S-central Oregon has
initiated an area of showers and storms that is tracking through
Harney County at 830 PM PDT. Expect this activity to move into
Malheur County through midnight MDT with thunderstorms producing
wind gusts to 45 miles per hour. Do expect showers and storms to diminish as
they approach the Idaho/or line but could very well push an outflow
boundary through the Treasure valley after midnight tonight. Would
expect speeds of 20-30 miles per hour...much like last night. Have made
updates to the forecast for tonight to decrease probability of precipitation for most
zones /especially after midnight/.
Aviation...VFR. Broken-overcast middle and high clouds. Showers and
thunderstorms mainly in central Oregon this evening...diminishing
overnight. Surface winds generally 10 kts or less...except gusts up
to 45kt near thunderstorms and associated outflows. Winds aloft near
10k feet mean sea level...west-southwest 10-20 knots.
short term...at 2 PM MDT upper low was in southwestern Wyoming and moving north-northeast.
Sprinkles or light rain showers have been noted in our County Warning Area but
the extensive cloud shield has limited thunderstorm development.
Harney County has cleared from the southwest and that area may be
the first to see thunderstorms. Activity should die down by sunset
and skies should partially clear overnight as the upper low/trough
moves away. Fewer clouds will allow better cooling than last night.
Weak upper ridge will come through Tuesday. Greater sunshine will
allow maximum temperatures to be a little higher than today. Instability
for afternoon thunderstorms will be mainly along the Nevada border
and central Idaho mountains. Later Tuesday night and especially
Wednesday moisture from the Pacific off southern calif will advect into
our County Warning Area as an upper trough comes in from the northwest coast.
Showers and thunderstorms will develop mainly on the Idaho side with
more substantial precipitation than from tonight/S weak showers. Wednesday
will also be cooler due to clouds and showers.
Long term...Wednesday night through Monday...upper level shortwave
is expected to quickly move east on Wednesday night with a drying
and clearing trend behind it. Zonal flow will set up for Thursday
and...with another upper level cut-off low off of the California
coast. This next low has been very consistently shown across models
and runs...with its arrival in the southern parts of our County Warning Area on
Friday night/Saturday morning. Showers and thunderstorms will
probably spread north and east through the day Saturday. For
Sunday and Monday...models hint at a general trough pattern off
the Pacific coast...but any placement of shortwaves...precip...or
major impacts is quite blurry right now. Temperatures are expected
to remain at or below normal through the period.
Or...red flag warning until midnight MDT /11 PM PDT/ tonight
previous short term...lc
previous long term....ep/jc