Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 160430
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
1030 PM MDT Sun Oct 15 2017

.SHORT TERM...This evening through Wednesday
Issued at 120 PM MDT Sun Oct 15 2017

Dry and warm conditions will be the rule of thumb through the
forecast period, as a zonal flow pattern (with a flat ridge) sets
up. Although downsloping winds will not be very strong, 700mb
WNW winds of 20 to 40kt will be commonplace. Thus, models continue
to trend 700mb temps +6 to +9C east of the Divide. These trends
look to continue into the next period as well. As a result, fire
conditions will be elevated, especially Monday and Tuesday, as Min
RH values drop below 15 percent from southern Lincoln to Natrona
County. Gusty SW winds with gusts up to 30 mph will also be
possible from Rock Springs to Casper. These conditions look to be
marginal by Wednesday.

Gusty winds could return Monday and Tuesday night to the Cody
Foothills, as the temperature gradient tightens and a couple of
mid level waves pass through the area. At this time, the signature
does not look as strong as the event Saturday night and looks to
be more localized to the Clark area.


.LONG TERM...Wednesday night through Sunday night
Issued at 120 PM MDT Sun Oct 15 2017

Forecast looks just like it did yesterday. One system to deal with
Friday into early Saturday otherwise, mild and dry. Ridge aloft
passes overhead Wednesday night with thermal ridge passing by on
Thursday with H7 temps forecast to be between +7 and +9C. It will
likely lead to most areas east of the divide getting into the 70s.
It is late October but we`ll also see some increase in the H7
wind and some weak lee side troughing which may help to mix us
out. If we fully mix, we`ll be well into the 70s. Will continue
yesterday`s idea of nudging temps above the procedure numbers. On
Friday, we may still see a weak disturbance ride up ahead of our
Friday night/Saturday trough on a little jet streak helping to get
a few showers going in the far west. The main front doesn`t
arrive until late in the day Friday and then it sweeps east across
the area Friday night. There will be one more mild day east on
Friday but with increasing southwest wind, especially in the wind
corridor where winds could be quite strong. A quick shot of rain
changing to snow will hit the west and south. A chance of showers
will also move east of the divide Friday night moving out of the
ern zones by Saturday morning. Temperatures are milder than our
last system so at the current time, most precipitation east of the
divide will be in the liquid form except for the mountains. The
one thing to watch with this is the potential for another mid
level circulation developing east of the divide early Saturday.
Right now the GFS shows it in ern Fremont county at 12z Saturday
with a swath of cold rain or possibly a rain/snow mixture for a
couple hours. Either way, it`ll be short lived. We recover quickly
next Sunday not unlike this Sunday and that leads into another
very mild period early next week as the mean ridge starts to build
over the western U.S.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday)
Issued at 1030 PM MDT Sun Oct 15 2017

VFR conds will prevail across the area through Monday evening.
It will be windy from near KRKS to KCPR again on Monday with the
wind decreasing after 00Z Tue. The KCOD area will also see a gusty
west wind through the night, then decreasing by late morning Monday.

&&

.FIRE WEATHER...
Issued AT 120 PM MDT Sun Oct 15 2017

Dry and warm weather conditions will occur through much of the
week. Elevated fire conditions will be possible Monday and
Tuesday, as Min RH values drop to critical values and gusty SW
winds increase during the afternoon. These winds will mainly
impact the Wind Corridor, from Rock Springs to Casper. These
conditions could return Wednesday, but are not expected to be as
critical at this time.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...LaVoie
LONG TERM...Skrbac
AVIATION...Skrbac/AR
FIRE WEATHER...LaVoie



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