Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 082011
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
211 PM MDT Sat Aug 8 2020

.SHORT TERM...Today through Monday night

Shower activity continues to bubble up this afternoon, with
isolated lightning and gusty winds still a threat, while strongest
thunderstorms focus more toward eastern WY.

Models still picking up on the weak cold front dropping southward
across the state tonight, hanging up on the Divide on Monday. This
will knock a couple degrees off the highs for the northern part of
the state, and will stabilize the atmosphere, keeping rain chances
minimal to nil. Areas south of the front will remain hot and dry,
with brisk westerly winds flowing along the stalled front. This
will lead to a fire weather risk for the southern counties during
the afternoon.

.LONG TERM...(Monday through Saturday)

Zonal flow will be westerly across the area to start the work week
with an upper trough well to the northwest and even west of
British Columbia by 12Z Tuesday. We can expect hot and generally
dry conditions to continue across the forecast area into Wednesday
with only isolated afternoon/early evening thunderstorms possible.
By Wednesday, the previously advertised upper level trough and
upper low is progged by the models to begin to move southeastward
over the British Columbia and Alberta provinces.

This will result in a change in the mid to upper level flow, as it
should shift slowly to the southwest across the forecast area.
Will continue with the consensus that scattered afternoon and
evening showers and thunderstorms will be possible over western
portions of the forecast area on Wednesday. The models still
indicate that a couple of weak shortwaves will move northeast
through the western sections. There should again be scattered
afternoon/early evening showers and storms on Thursday across the
western sections. The flow should finally set up to be slightly
more zonal on Thursday, so coverage of precip may not be as
pronounced as Wednesday across the forecast area. Both models are
still in agreement involving moving a trough southeast toward the
region by Friday. This should result in producing increased
southwest winds and very low RH values developing. Fire weather
conditions could likely reach critical levels with Red Flag
conditions becoming possible across much of the forecast area.

Temperatures will remain in the 80s to the low to mid 90s with
light to moderate winds, through the period. Elevated to near
critical fire weather conditions will be in place as well,
especially east of the Divide and southern portions of the
forecast area.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)

Expect VFR conditions to remain across the area through the TAF
forecast period. Have kept in a mention of VCTS at KLND, KRIW and
KWRL until around 02Z this evening to account for any lingering
isolated/widely scattered storms possible in these areas. Have
kept gusty afternoon winds in the terminals also until around 02Z
this evening and slowly lowered wind speeds by 06Z at most
locations. Have added in winds again picking back up on Sunday
between 17Z to 18Z at most TAF sites. Further increased speeds at
KRKS,KPNA and KBPI after 20Z Sunday to at or slightly above 15
knots in the wake of the passage of a cold front across the area.

&&

.FIRE WEATHER...

Driest air and breeziest conditions have been limited to far
southern WY this afternoon, which will continue for the rest of
the day. A few showers are sweeping across the state currently,
with gusty winds and occasional lightning the main threat.
Tomorrow will be similar, with driest air and highest winds
limited to south WY. Winds are forecast to be higher tomorrow,
nearing critical thresholds. Thus the Fire Weather Watch remains
in effect for zones 277 and 279 Sunday afternoon. Thunderstorm
activity will be much more isolated and weaker, so lightning
threat will be minimized. Another elevated fire weather day on
Monday with gusty winds and low RH.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Sunday afternoon through Sunday evening
for WYZ277-279.

&&

$$

SHORT TERM...Straub
LONG TERM...Troutman
AVIATION...Troutman
FIRE WEATHER...Straub


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