533
FXUS65 KBOI 032021
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
221 PM MDT Wed Jul 3 2024

.SHORT TERM...Tonight through Friday night...A Red Flag Warning
is still out for parts of Southern Idaho, with at least one RAWS
site reporting critical RH and wind so far. Temperatures
warming through the short term. Near normal on Thursday
increasing to 5 degrees above normal on Friday. Winds after
Wednesday afternoon should become fairly typical. With the
exception that gusts to 20-25 mph are possible Thursday
afternoon between Mtn Home, Twin Falls, and Fairfield. In the
same area, gusts to 25-35 mph are possible Friday afternoon.
This could be a concerning fire weather set up with continued
dry conditions, but not necessarily critical based on the
current forecast.

.LONG TERM...Saturday through Wednesday...Still high confidence
in the development of a heat wave that will commence this
weekend and persist into next week. An intense high pressure
system near the west coast gradually moves eastward and the axis
reaches our area by Monday. This will prolong and intensify our
current very dry conditions, but the main hazard is the heat.
Temperatures warm to near or over 100 degrees on Saturday and
continue to gradually increase through the long term. By
Tuesday our area warms to about 10-15 degrees above normal,
which means highs in the range of 105-110 for our lower Snake
Plain zones. This level of heat is flagged as mostly Major with
some areas of extreme through our Heat-Risk product, meaning
most people should take care to prepare for the heat, especially
those sensitive to heat. The longevity of the heat is another
major factor, with no definite end to heat in the forecast.
Latest forecasts are challenging a few records, one of which is
the most consecutive days of 105 or greater in Boise. The
current record is 4 set in 2002, and the extended NBM indicates
we could begin recording consecutive 105 days after Tuesday
through the rest of next week. There will be some relief
overnight as the lows stay around 70 in the Snake Plain and lows
60s to upper 50s for mountain valleys. Either way, the
afternoon heat will be extreme. As a result, we are issuing an
Excessive Heat Watch for most low elevation zones. The Watch for
SE Oregon and the Lower Treasure Valley go into effect this
Weekend, while the Watch for the rest of the Snake Plain/TV, far
SW Idaho, and the Weiser Basin goes into effect on Monday. High
elevation zones are very close to needing a product, but
confidence isn`t quite high enough and the heat in these zones
is still many days away.

&&

.AVIATION...VFR. High density altitude will become a factor by the
weekend into much of next week. Surface winds: N-NW 5-15 kt with
gusts to 20 kt through this evening. Gusts to 25-35 kt through
04/03Z at KTWF/KJER. Becoming light and variable overnight. Winds
aloft at 10kft MSL: W-NW 15-30 kt.

KBOI...VFR with clear skies. Surface winds: NW 7-11 kt becoming NW
11-13 kt with gusts to 25 kt possible through 04/03Z. Light winds
overnight.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Excessive Heat Watch from Saturday afternoon through Wednesday
     afternoon IDZ012-029.
     Red Flag Warning until 9 PM MDT this evening IDZ424-426.
     Excessive Heat Watch from Monday afternoon through Wednesday
     afternoon IDZ014>016-030-033.
OR...Excessive Heat Watch from Saturday afternoon through Wednesday
     afternoon ORZ061>064.

&&

$$

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SHORT TERM...JM
LONG TERM....JM
AVIATION.....JR