Flash Flood and Hail in Idaho, August 4, 2023

Area Forecast Discussion
National Weather Service Boise ID
312 AM MDT Fri Aug 4 2023

.SHORT TERM...Today through Sunday night...Light rain showers
continue this morning across much of the forecast area
associated with an exiting upper level low pressure system.
Showers and clouds will remain from Baker County through the
Western Snake River Plain into the central Idaho mountains
through at least early afternoon. This will limit surface
heating today and thus high temperatures. This will also limit
thunderstorm potential. High- res models have captured this
well, developing thunderstorms across southeast Oregon and along
the Idaho/Nevada border this afternoon as well as the
Boise/Sawtooth Mountains. These storms are aided by a weak low
pressure system moving north-northeast from northern California.
Although more stable conditions are shown from the Snake River
Plain northeast into the central Idaho mountains with best
instability across southeastern Oregon and along the NV/ID
border mountains, outflow flow from thunderstorms could initiate
showers in the valleys with sufficient moisture already in
place. Harney County and the Boise Mountains have the highest
probability for thunderstorms today (50% chance). The low moves
north- northeast reaching northeast Oregon Saturday night. This
will continue the threat for showers and thunderstorms
Saturday. Showers and thunderstorms will diminish Sunday morning
as the low exits the region. Temperatures will be near normal
in the short-term.

.LONG TERM...Monday through Friday...Residual moisture will
remain over the area on Monday, with a 15-30 percent chance of
showers and thunderstorms over the central ID mountains Monday
afternoon. Drier air moves in from the West on Tuesday as a
shortwave ridge transitions over the area. A warming trend is
expected by the end of next week as the ridge reamplifies over
the West. Temperatures will be a few degrees below normal on
Monday, before warming to 5-10 degrees above normal by Friday.

&&

.AVIATION...Mainly VFR. Scattered showers this morning. Isolated
thunderstorms developing during the afternoon. Areas of wildfire
smoke reducing visibility. Surface winds variable 10kt or less,
becoming NW-NE 10-20kt during the afternoon. Thunderstorms capable
of producing gusty erratic outflows up to 45kt and small hail. Winds
aloft at 10kft MSL: E-NE 5-15 kt becoming NW 5-15kt by 00z/Sat.

Weekend Outlook...Mainly VFR. Showers and thunderstorms, mainly in
the afternoon. Thunderstorms will be capable of outflow wind gusts
to 45kt. Areas of smoke reducing visibility. Light surface winds at
night, with generally N-NW 10-20kt during the afternoons.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Red Flag Warning until 11 PM MDT this evening IDZ423.
OR...Red Flag Warning until 11 PM MDT /10 PM PDT/ this evening
     ORZ636-637-646.

&&

www.weather.gov/Boise
www.facebook.com/NWSBoise
www.twitter.com/NWSBoise

SHORT TERM...JDS
LONG TERM....KA
AVIATION.....KA