927
FXUS65 KBOI 070222
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
822 PM MDT Thu Jun 6 2024

.DISCUSSION...Clouds held temps down and limited thunderstorm
development this afternoon, but several strong storms did form
late today along and south of the ID/NV border. At 8 PM MDT KCBX
radar still showed one thunderstorm in southeast Owyhee County,
and scattered light rain showers northward into Elmore County.
The thunderstorm may reach the western Magic Valley between 10
PM and midnight MDT according to hi-res models, but other parts
of our CWA should have only clouds. Hottest days still look like
Friday and especially Saturday before a weak Pacific trough
comes inland with modest cooling Sunday. A 15-30 percent chance
of afternoon and evening thunderstorms is indicated in southern
areas Friday and Saturday, with smaller chances farther north.
Best chance of rain (25-50 percent) for the whole CWA will come
Sunday and Sunday evening when the Pacific trough comes in.
Drier, still warm (but not hot), and breezy weather is indicated
Monday through Thursday under strong westerly flow aloft.
Current forecast covers that well. Possibly more interesting is
a deep upper low in the Gulf of Alaska that longest-range GFS
and ECM bring directly into our CWA next weekend. ECM has been
showing this for several days now and if models verify we would
have showery and much cooler weather, cold enough even for snow
on mountains above 6000 feet. Still too far off to make a firm
prediction. Just letting you know what models see.

&&

.AVIATION...VFR with scattered-broken mid and high level clouds,
decreasing overnight. Scattered showers and isolated thunderstorms
south of a KBNO-KMUO-KJER line, ending by Fri/09Z. MVFR/IFR
conditions within storms. Low confidence (less than 30 percent
chance) of any shower/storm reaching a terminal. Stronger storms
will be capable of producing gusty outflow winds to 35 kt. Surface
winds: variable up to 10 kt, except gusty near storms. Winds at 10k
ft MSL: SW-NW 10-20 kt.

KBOI...VFR. Decreasing mid to high clouds overnight. Variable
surface winds less than 10 kt overnight, becoming NW 8-13 kt
Friday afternoon.

Weekend Outlook...VFR, except MVFR conditions with stronger
thunderstorms. Isolated to scattered afternoon/evening showers
and thunderstorms near the Nevada border on Friday, portions of
SE Oregon and near the ID/NV border Saturday, and all areas on
Sunday. Highest confidence of convection is Sunday. Gusty outflow
winds will be possible from showers and storms. Otherwise, surface
winds generally W-NW 5-15 kt.

&&

.PREV DISCUSSION...
SHORT TERM...Tonight through Saturday night...The short term
will be dominated by an amplifying upper ridge. Highs today
will be about 10 degrees above normal, warming to 15-20 degrees
above normal on Saturday. Clouds/storms today may limit surface
warming in certain areas, but their extent is forecast to be
limited to the ID-NV border on Friday and Saturday so confidence
is higher in hot temps on these days. The rest of today will
continue to be active with showers and a few storms. Outflow
gusts around storms could be up to 40-50 mph, but the current
radar situation seems to favor the lower end of that range if
anything. Precipitation is fairly high-based, limiting
precipitation on the ground and favoring virga. Storms may be
directed into portion of the Snake Plain with the SW flow aloft,
but they will struggle to stay together as they move out of the
SW Highlands. Precipitation cuts off around midnight tonight.
As mentioned previously, unsettled conditions will continue for
the short term, as Friday afternoon/evening storms develop
again. They are much more limited, forming mainly near the ID-NV
border. Precipitation chances increase again Saturday evening
ahead of a quick trough in the long term. There may be some haze
or smoke south of Rome, Oregon due to a fire south of the Owyhees.

LONG TERM...Sunday through Thursday...An upper level low moves
inland on Sunday. With moisture already present, this injection
of energy makes Sunday the most active looking day for this
forecast. The trough also brings PW values in the 90th
percentile, just under 1". Precipitation chances stay elevated
through the day, with a 10-30% chance for lower valleys and
30-50% chance for higher terrain. While temps cool by about 5
degrees from Saturday, there will still be enough instability to
support a 20% chance of afternoon/evening thunderstorms, mainly
over terrain. Drier westerly flow sets in on Monday through the
rest of the long term. The gradient of this flows stays fairly
decent, meaning afternoon winds after Monday will be breezy. The
zonal characteristic will hold our temps mostly steady at about
10 degrees above normal.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...None.

&&

$$

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DISCUSSION...LC
AVIATION.....ST
SHORT TERM...JM
LONG TERM....JM