Nyssa, Oregon Weather Forecast Discussion

829
FXUS65 KBOI 071531
AFDBOI
Area Forecast Discussion
National Weather Service Boise ID
931 AM MDT Sun Sep 7 2025
.DISCUSSION...Patchy smoke aloft, but much less than previous
days. Some morning convection has resulted in a few showers in
S-Central ID, with a few lightning flashes detected near the
Magic Valley. These showers are expected to dissipate around
noon, as the environment becomes increasingly unstable. CAPE is
expected to rise to 500-1000 J/kg, with some lingering moisture
even in the dry slot behind yesterday`s wave. While shear is
limited, a few stronger storms could form over Baker county,
central and s-central Idaho this afternoon and evening. Storms
could produce outflows up to 50 mph and small hail. While most
models delay the development of storms until they are well into
the mountains, the southwesterly steering flow will likely allow
convection to kick off on the leading edge of the mountains.
Precipitation chances and thunder chances have been increased to
cover more of the ID mtns then model composite reflectivity may
support, to account for orography. Along the NV border,
conditions will become much drier and a little breezy, leading
to elevated fire concerns. Otherwise no update, Monday will be
more quiet before the unsettled and cooler conditions Tuesday
onwards.
&&
.AVIATION...Mostly VFR, but lingering LIFR in fog in central ID
mtn valleys. Light showers in s-central ID this morning,
becoming scattered this afternoon and expanding into the Boise
and W-central mtns of ID and Baker County. Showers may
strengthen into thunderstorms, producing outflows up to 45 kt
and small hail. Storms clearing by Mon/06Z. Surface winds:
variable 5-10kt becoming SW-NW 5-15kt during the afternoon. Winds
aloft at 10kft MSL: SW 10-20kt.
KBOI...VFR. SE 5-10kt this morning, shifting to NW 5-10kt during
the afternoon.
&&
.PREV DISCUSSION...
SHORT TERM...Today through Tuesday night...An upper level
trough remains off the northern CA coast. Southwest flow has
developed over the area. Drier air will move into the area today
from the southwest. There is enough residual moisture for
showers and thunderstorms to form (20-30 percent chance) over
the central ID mountains, southwest ID highlands south of Twin
Falls and the Blue Mountains this afternoon. Drier air will
suppress shower and thunderstorm development over much of the
eastern OR basins and the Snake Basin this afternoon. The dry
slot continues into Monday with breezy west-southwest winds
during the afternoon. Afternoon low RHs and breezy conditions
will be a fire concern over eastern OR and southwest ID
highlands on Sunday and Monday. The upper level trough slowly
moves inland on Tuesday with a cold front moving through the
area. The cold front will bring a 20-30 percent chance of
precipitation to the area, with the exception of the west
central ID and Baker County mountains where there is a 40-60
percent chance.
LONG TERM...Wednesday through Sunday...The trough will be slow
to move across the area through the long term. The trough brings
cooler conditions and a 20-50 percent chance of showers and a
10-20 percent chance of thunderstorms through Saturday.
Temperatures lower to 5-10 degrees below normal Wednesday
through Saturday before moderating to near normal after the
system moves eastward on Sunday.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...None.
&&
$$
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DISCUSSION...JM
AVIATION.....JM
SHORT TERM...KA
LONG TERM....KA

NWS BOI Office Area Forecast Discussion