Riverton, Wyoming 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

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FXUS65 KRIW 271707
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1107 AM MDT Fri Jun 27 2025

.KEY MESSAGES...

- Elevated to critical fire weather is likely across much of the
  area this afternoon and evening. A Red Flag Warning is in
  effect today for portions of Natrona County from Noon to 9PM
  local.

- Elevated fire weather remains likely on Saturday.

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

&&

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

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. Regardless, fire
weather conditions will be elevated to critical across the CWA.
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, aka Washakie and Hot Springs County.
However, humidity will be a bit higher here and wind will not be
as gusty. 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 dewpoint 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
dewpoints 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 dewpoints 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. Exact details are difficult to hash out
this far out, but PoPs have increased on these days.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1107 AM MDT Fri Jun 27 2025

VFR conditions through the next 24 hours, with some passing high
clouds and afternoon cumulus. Southwest winds increase late morning
to early afternoon, continuing through about sunset. Gusts 20 to 30
knots will be common across the area.

Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for
the latest information on 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 until 9 PM MDT this evening for WYZ280.

&&

$$

DISCUSSION...Hattings
AVIATION...Wittmann
FIRE WEATHER...Hattings