Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 261930
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
130 PM MDT Wed Jul 26 2017

.SHORT TERM...(This evening through Thursday)
Issued at 130 PM MDT Wed Jul 26 2017

Storms firing over ern ID and starting to move into wrn WY early
this afternoon as instability increases. Surface dew points out west
in the lower to mid 50s in the valleys and well up into the 40s to
around 50 in the mountains. Combine that with a couple mid level
disturbances and we`ll get increasing coverage across the west the
remainder of the afternoon. Jet streak to the north may aid some of
this nocturnally in the north and possibly as far south into Fremont
County well into the night. The rest of the mountains are seeing
building cumulus with a few cbs forming and this trend will continue
with more and more coverage through the afternoon and then quite a
few rolling off the hills late in the afternoon through the evening
hours. The far east where the cloud cover is holding the longest,
especially around Natrona County will likely see the smallest cape
and thus the lowest chance of any heavier storms. Storms of the
Uintas and swrn Sweetwater will rumble across at least the south
half into the evening. With precipitable waters up over an inch in
many areas, the main threat will be heavy rain but there is enough
cape to support some hail too with soundings showing 600-900 J/kg
for much of the central and wrn portions into this evening. Northern
CA upper low opens up and moves towards nwrn WY late Thursday and
then across the north into Friday with another day of active
thunderstorms. PW`s stay up and so more heavy rainers possible with
some hail with even larger capes in the ern zones where more sun and
heating occurs on Thursday. Drier air moves in Friday but we still
have our residual CA upper low moving ever so slowly across the nrn
border area providing some support for storms up there. South looks
mainly dry and warm with a few possible storms off the Uintas into
swrn/srn Sweetwater. Ridge starts to rebuild across the area
Saturday with some moisture starting to work around the monsoonal
high to the south. Right now it looks like mainly isolated to widely
scattered storms in and near the mountains.

.LONG TERM...(Thursday night through Wednesday)
Issued at 130 PM MDT Wed Jul 26 2017

The quietest time of my period looks to be Saturday night as most,
but not all of the monsoonal moisture will still be away from the
area. There will still be some isolated activity, but most areas
will stay largely dry.

The rest of the forecast features the return of the monsoon from
Sunday through at least Tuesday. This means a wash, rinse and repeat
pattern through the period. There will be isolated to scattered
thunderstorms around each day in the afternoon, and as expected with
the monsoon, activity could linger past midnight. The driest time of
each day will likely be the morning and midday hours. As for
temperatures, they will be seasonably warm but really hot
temperatures are not expected due to the cloud cover that will be
around the area.

Some models are indicating a bit of drying trend for Wednesday.
However, the models are not that reliable a weak out with timing any
associated shortwaves or moisture plumes so for now we left
continuity alone.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 130 PM MDT Wed Jul 26 2017

Showers and thunderstorms will continue across the west this
afternoon and spread into northern and central parts of WY after
21Z. Locally heavy rain will occur with stronger storms. This will
produce local MVFR conditions due to reduced visibility. Mountains
will be obscured at times. Showers and storms will be decreasing in
coverage by 06Z with lingering showers over the north through 12Z
Thursday. More showers or thunderstorms will develop on Thursday
after 18Z. Fairly similar coverage is expected with stronger storms
possible over eastern portions of the area, especially in vicinity
of KCPR and KWRL.

&&

.FIRE WEATHER...
Issued AT 130 PM MDT Wed Jul 26 2017

Fuels are now at critical levels for most forecast zones east of the
Divide (Please see the Fire Weather Forecast product for more
information). Fire danger will remain low for most mountain
locations...low to moderate for all other lower elevations as
moisture, clouds and a chance of showers and thunderstorms continue
across the forecast area as monsoonal moisture infiltrates Wyoming
from the south. Winds will continue seasonally light across the
forecast area through Thursday except near stronger showers or
thunderstorms (25 to 35 mph). Expect periods of of localized heavy
rain through Thursday. Drier weather to return Friday.

&&

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

&&

$$

SHORT TERM...Skrbac
LONG TERM...Hattings
AVIATION...Hattings
FIRE WEATHER...Skrbac


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