571
FXUS65 KRIW 190730
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
130 AM MDT Tue Aug 19 2025

.KEY MESSAGES...

- Warming trend and dry conditions continue Tuesday and
  Wednesday.

- Afternoon high temperatures Tuesday and Wednesday near record
  highs for some east of the Divide.

- Weather pattern change Thursday and beyond through the weekend
  with more seasonable temperatures and increasing storm
  chances.

&&

.DISCUSSION...
Issued at 130 AM MDT Tue Aug 19 2025

WV imagery continues to show the southwest flow aloft across the
CWA as it continues to weaken and become more broad due to the
building higher heights centered near the Four Corner Region.
Mainly clear on IR with nothing on radar of consequence.

With increasing convergence aloft, the aforementioned ridge
continues to build in across the CWA giving way to hotter than
average temperatures and dry conditions Tuesday afternoon. Near
record temperatures for some parts east of the Divide but better
chances Wednesday afternoon with the strengthening high. Weak
winds and mainly clear skies continue much of these days. Some
weak chances (<15%) across northwest portions of the CWA to
include the Absarokas and Yellowstone for Wednesday afternoon
and early evening with a subtle mid level shortwave around the
aforementioned high. However, confidence low on anything
significant if anything at all at this time. The weak flow
aloft will not see that strong of outflows but some lightning
may be of concern with the ongoing fire weather threat currently
with active fires.

Otherwise, expect a pattern change come Thursday as the high
weakens with decreasing convergence aloft retreating some to the
south allowing for monsoonal moisture to increase into the CWA
from the southwest. Isolated thunderstorms increase in the
afternoon and evening hours with the upper level trough
skirting to the north of the CWA through Montana and southern
Canada. Thunderstorm coverage increases Friday afternoon and
even over the weekend, especially east of the Divide becoming
more widely scattered. As always, frequent lightning and gusty
outflows the main concern this time of year for fire weather.
The aforementioned higher heights near the Four Corner Region
looks to build back up early next week that will give way to a
dryer and warmer than average end to the month of August.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 933 PM MDT Mon Aug 18 2025

VFR conditions are expected to predominate through 06Z
Wednesday. Mainly dry conditions should be present at the TAF
sites with any isolated showers remaining in the mountains. The
one exception may be in vicinity of KWRL, where smoke from the
Red Canyon fire may bring occasional reduced visibility. Wind
should remain at 15 knots or less through the period.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
Air Quality Alert until 1 PM MDT this afternoon for WYZ004>007.

&&

$$

DISCUSSION...Lowe
AVIATION...Hattings