249
FXUS65 KRIW 041019
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
419 AM MDT Mon Aug 4 2025

.KEY MESSAGES...

- Red Flag Warning in effect for southwest Wyoming today, with
  very low humidity and gusty southwest winds.

- A pivoting shortwave across northern Idaho and NW Montana may
  bring a few lingering showers this afternoon across far
  northwest Wyoming.

- Very warm, dry and breezy conditions continue through the
  week, with continued fire weather concerns expected.

&&

.DISCUSSION...
Issued at 249 AM MDT Mon Aug 4 2025

A prolonged period of very warm and very dry conditions expected
through the upcoming week as a strong ridge centers on the Four
Corners Region. The ridge has already started bringing much
drier air in from the desert southwest, noted by dewpoint
temperatures in the low to mid 20s across southern WY
currently. The other factor is a shortwave deflecting across
northern Idaho and western Montana. This system may be close
enough to produce a few showers mainly for greater YNP, but the
main concern is the tighter pressure gradient it is producing
across the state. This will bring up the southwest winds this
afternoon, with frequent gusts of 25 to 30 mph. This combined
with the dry air will bring critical fire weather concerns. A
Red Flag Warning remains in effect across southwest WY this
afternoon through 8PM.

The ridge will keep the hot temperatures in place through
Thursday, with highs generally in the upper 80s and 90s each
afternoon. The main question the rest of the week is how strong
winds will be for critical fire weather concerns. Right now
Tuesday winds look more marginal as the passing shortwave
departs. Wednesday looks marginal as well before the next system
approaches starting Thursday. Models have the next wave
squashing down the ridge later Thursday into Friday. As it
approaches, it is becoming more likely that the southwest flow
increases enough to return the fire weather concerns.

The trough will draw far enough south to bring a cold front
well into the state, but with minimal moisture to work with,
shower activity will be limited.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 415 AM MDT Mon Aug 4 2025

VFR conditions are expected a vast majority of the time through
12Z Tuesday. A weak weather system will track across northern
Wyoming and bring isolated showers and thunderstorms to
northwestern Wyoming, The most likely locations to see
convection are in vicinity of KJAC and KCOD, where PROB30 groups
are added for convection. Any shower or thunderstorm could have
wind gusts over 40 mph, mainly between 20Z Monday and 02
Tuesday. A gusty southwesterly breeze will develop this
afternoon across many terminals, largely after 22Z. These winds
should subside after sunset though.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon today to 8 PM MDT this evening for
WYZ277>279-288-289-414-416.

&&

$$

DISCUSSION...Straub
AVIATION...Hattings