094
FXUS65 KRIW 190743
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
143 AM MDT Wed Jun 19 2024

.KEY MESSAGES...

- A very seasonal day today, with near average temperatures and
  dry conditions.

- Rain shower and thunderstorm chances (25% to 60%) Friday.

- Hot and dry starting this weekend. Current long-range models
  continue this trend through next week.

&&

.DISCUSSION...
Issued at 142 AM MDT Wed Jun 19 2024

Temperatures begin to rebound today, with highs 10 to 15 degrees
warmer than yesterday. These values are slightly below average for
mid-June. Dry southwest flow is also in place, keeping the area dry.
A couple models depict a few convective cells this afternoon over
Johnson and northern Natrona Counties. This would be about a 10% to
15% chance. Casper Mountain also has this chance. Winds are also
less today as the previous weather system moves further away. A
light breeze occurs today for Natrona and Johnson Counties; gusts to
around 30 mph are possible if any convection does occur.

This overall tame weather continues into Thursday. Temperatures
continue to climb, with highs in the upper 70s to middle 80s, or a
little above average. Most places look to remain dry, but a little
afternoon and evening convection is possible along the Continental
Divide due to the enhanced lift, and towards Johnson and Natrona
Counties due to some incoming moisture ahead of the next system.

Precipitation chances increase across the area late Thursday and
especially for Friday. A tropical system moving westward into Mexico
from the Gulf of Mexico brings ample gulf moisture. With the
combination of a high over the eastern U.S. and an incoming trough
over the western U.S., moisture will be funneled northward from
Mexico towards Wyoming. Recent model runs have lessened the moisture
reaching Wyoming compared to yesterday. There are widespread chances
across the area, but are currently looking to be more of the
scattered variety, with chances generally 25% to 60%, higher for the
mountain locations.  In other words, everywhere will have a shot of
rain, but not everywhere will get rain. We are still a couple days
out however, and as mentioned, there are really three synoptic
features in play here, so if any of them change, the forecast can
change.

With the projected weakening of the tropical system, and a
strengthening high over the southern U.S., this moisture will not
remain over the state long. Rain chances come to an end Saturday,
with models actually showing less than 15% chances across the entire
area by Saturday afternoon. As this high pressure builds in, so do
increasing temperatures through the weekend. A hot Sunday and Monday
are on tap, with hot conditions looking to continue through next
week. Highs Sunday and Monday are still forecasted to be in the 90s
for much of the area. Hot places, like Greybull, realistically could
hit 100.

Fire weather-wise, fuels are still indicated to be green. Friday
will be the only real shot for rain in the next week. With the hot
and dry conditions through next week, minimum relative humidities
(RH) each day fall below 15%. As the week continues, nighttime RH
recovery worsens, though remains fair to good depending on location.
Breezy to windy afternoons are possible a few days next week.

The next chance for any rain, past this Friday system, could maybe
be next Friday (6/28). This far out, though, there is very low
confidence. The Climate Prediction Center (CPC) has warmer than
normal and drier than normal conditions favored in the current 6-10
and 8-14 day outlooks.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1003 PM MDT Tue Jun 18 2024

VFR conditions will prevail through the period. Wind will generally
remain light at all terminals. While a stray shower or two may pop
up near KCPR Wednesday afternoon, chances are low (less than 20
percent) and no precipitation impacts are expected.

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

&&

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

&&

$$

DISCUSSION...Wittmann
AVIATION...Myers