Area Forecast Discussion
Issued by NWS Riverton, WY

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737
FXUS65 KRIW 270856
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
256 AM MDT Fri Jun 27 2025

.KEY MESSAGES...

- Elevated to critical fire weather is likely across much of the
  area this afternoon and evening.

- Elevated fire weather remains likely on Saturday.

- Showers and thunderstorms are possible each afternoon across
  northern Wyoming, but the chance is generally less than 1 out
  of 5 at any particular location.

&&

.DISCUSSION...
Issued at 250 AM MDT Fri Jun 27 2025

Sometimes as shift workers, we work long stretches of shifts. This
is my seventh in a row. And sometimes, things get a bit redundant. It
turns out that this one of those days. All in all, there is little
change in the reasoning of the forecast this morning when compared
to yesterday.

The main concern of the day is fire weather, both of the elevated
and critical variety. The set up looks the same, with a weak
shortwave moving across the area and a jet streak across Montana,
putting the area in the right front quadrant, enhancing downward
forcing. This will mix some mid level wind to the surface, bring
breezy conditions to much of the area. If this was August, we would
likely have fairly widespread Red Flag warnings. However, most
locations don`t have critical fuels yet. So, these will be limited.
Natrona County still looks good for the Red Flag Warning, so we
continued it pretty much as is. We did given some thought to the
other critical zone, 282, A.K.A. Washakie and Hot Springs
county. However, humidity will be a bit higher here and wind
will be more borderline. A spot or two may get Red Flag
conditions but most shouldn`t so we won`t issue. Critical
conditions are likely in southern Wyoming and portions of
central Wyoming where humidity will fall toward 10 percent as
well. As for convection, a few thunderstorms are possible along
the northern border but the chance is less than 1 out of 5. Any
shower or thunderstorm would be high based though, and with very
high dew point depressions, any shower or thunderstorm could
have a wind gust of 50 mph.

The next question was if we should extend the Red Flag Warnings to
Saturday. For now,we held off. Most guidance is showing dew points
running 5 to 10 degrees above those on Friday. In addition, the jet
will shift a bit further north and wind should be a bit lighter,
making conditions more borderline. If trends favor warnings, we can
issue this afternoon or tomorrow morning. Another shortwave moving
through will bring a somewhat higher chance of showers and storms
across the north. However, the chance will again be less than 1 out
of 4.

A weak cold front then moves across the area Sunday. Moisture is
limited, but it could again bring isolated storms, with the best
chance in eastern portions of the area. It will knock temperatures
down a few degrees East of the Divide and raise dew points a bit
more, so the chance of Fire Weather headlines looks unlikely at this
point (less than a 1 out of 3 chance).

Ridging then builds back northward over the area for early next
week. Monday at this point looks like a nice day with near normal
temperatures and little chance of storms. Chances may increase
Tuesday and especially Wednesday as deeper moisture may try to
return to the area. Details are impossible to hash out this far out,
but POPs have increased on these days.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1035 PM MDT Thu Jun 26 2025

VFR conditions throughout the period for all TAF sites remaining dry
throughout. Light winds and scattered mid to upper level clouds
overnight. Winds will start to increase after 15Z-17Z then pick
up with gusts up to 25 kt at all locations after 18Z-19Z due to
the stronger mixing with peak heating of the afternoon. Winds
will diminish after 01Z-02Z towards sunset becoming around
8-12 kt through the end of the period and overnight into
Saturday morning. Mid to upper level clouds remain scattered to
broken throughout the day Friday remaining above the 10-12kft
mark. No other weather elements are expected at this time.

Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for
the latest information on smoke, icing, and turbulence forecasts.

&&

.FIRE WEATHER...
Issued at 250 AM MDT Fri Jun 27 2025

A weak weather system moving to the north will bring humidity
under 15 percent across much of the area. With a gusty wind
developing this afternoon, elevated to critical fire weather is
likely across much of the area this afternoon and evening, with
the worst conditions across central and southern Wyoming.
Elevated fire weather remains likely on Saturday afternoon
although somewhat less wind and somewhat higher humidity may
improve conditions somewhat.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon today to 9 PM MDT this evening for
WYZ280.

&&

$$

DISCUSSION...Hattings
AVIATION...LaVoie/Lowe
FIRE WEATHER...Hattings