240
FXUS65 KRIW 161128
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
528 AM MDT Thu May 16 2024

.KEY MESSAGES...

- A nice today today with mild temperatures.

- Elevated fire weather into the weekend, especially on Friday
  afternoon.

- Early next week looks cooler and unsettled.

&&

.DISCUSSION...
Issued at 311 AM MDT Thu May 16 2024

The pattern is looking to remain fairly progressive and active into
next week. The best day of the period may turn out to be today.
Shortwave ridging will be transiting across the area today. And this
should bring a pretty nice Spring day to most of the area with some
sunshine and mild to warm temperatures. There will be a bit of a
breeze in the favored locations, like Rock Springs to Casper, but
nothing unusual for May in Wyoming. As for precipitation, the chance
is very small. A weak shortwave brushing by to the north could bring
an isolated shower or thunderstorm to far northern Wyoming but the
chance is less than 1 in 5. These showers should end this evening.

Things get more active tomorrow. And we have a few hazards to talk
about. The culprit from this will be another shortwave and cold
front that will sweep across the area. As for convection, there is a
better chance than yesterday. However, this system does not have a
ton of moisture to work. Most guidance is showing any showers and
storms remaining largely across northern Wyoming and the highest
chance is only around 2 in 5, with lesser POPs further south. The
concern is the strength of the storms. There will be some upper
level divergence and an 100 knot jet approaching. With dew point
depressions approaching 50 degrees in some locations along with
models soundings with the inverted V signature; many storms
could end up high based. This will lead to possible downburst
winds of 50 mph or more. The Storm Prediction Center has issued
a marginal risk for severe thunderstorms to our east and I could
see this extended further westward if trends continue.

Further south, the hazards remind me of on my favorite 70s bands;
Earth, Wind and Fire. The approaching cold front and the downward
forcing from the left front quadrant of the aforementioned jet will
bring strong wind across much of the southern two thirds of the
area. At this time, the 700 millibar wind does not look quite
sufficient for high wind, but it will be close. The day shift may
want to consider watches if this trends upward. There is over a
4 in 5 chance of wind gusts past 40 mph in the favored area.
And that leads us to the next potential hazard, fire that could
scar the earth. Dew points will be very low across much of this
area, falling into the teens at times, bringing humidity under
15 percent at times. Fuels are in green up, so no fire warnings
are expected. However, elevated fire weather will be a near
certainty (over a 4 in 5 chance) across much of the southern
half of the area. The main threat will be across the south,
which has been dry for a while. In central Wyoming, the area saw
decent rain earlier this week and this could mitigate the
threat somewhat.

Things should quiet down on Saturday, which looks like a somewhat
cooler day with less wind, but still breezy at times. Wind increases
again on Sunday though as another trough and cold front approach
the area. The chance of elevated fire weather looks less though, as
temperatures should be somewhat cooler and dew points a bit higher.
It will still be rather windy though. This system has a bit more
moisture, and will have a better coverage of showers and storms. The
chance is only 1 in 3 at best in most locations with exception of
the mountains though.

The active pattern looks to continue into next week. At this point,
Monday and Wednesday look like the best chance of showers.
Confidence is not high on this as timing shortwaves this far out is
fairly difficult. Temperatures will be cooler behind the front,
averaging below normal, especially Monday depending on sky cover.
this will be followed by gradual moderation later next week.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 524 AM MDT Thu May 16 2024

VFR conditions will prevail at terminals through the period. Wind
will increase by early afternoon for much of the area with gusts of
20 to 25 knots likely. Otherwise, isolated convection is possible
(<20 percent) across the mountains of northern Wyoming but is not
expected to impact terminals. Wind will wane after sunset.

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 311 AM MDT Thu May 16 2024

No real concerns are expected today. On Friday afternoon, an
approaching cold front will bring strong wind to much of the
area, with wind gusts over 50 mph possible in central and
southern Wyoming. With humidity falling into the teens, elevated
fire weather is likely (greater than a 3 in 4 chance). The
highest chance is across southern Wyoming, which has been fairly
dry over the past week or so.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION...Hattings
AVIATION...Myers
FIRE WEATHER...Hattings