Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 140506

Area Forecast Discussion
National Weather Service Riverton WY
1106 PM MDT Thu Jul 13 2017

.SHORT TERM...(This evening through Friday)
Issued at 115 PM MDT Thu Jul 13 2017

Upper high starting to expand nwd over Wyoming with warm mid level
temps and limited convection potential. Still some lower level
moisture hanging in the ern zones and we could still see a storm
fire in mainly Johnson County but nothing like yesterday (even
though the nern corner is in marginal). A few storms off the Uintas
will still have the potential to skim the srn Sweetwater County
border. As the upper high shifts ever so slightly off to the east
(more straight to our south), it will allow some limited mainly mid
level moisture to rotate/lift nwd into our wrn zones overnight.
Ahead of this moisture, there is a weak disturbance also moving ne
towards wrn Wyoming and sounding do some some small capes (couple
hundred Joules) so it`s possible we`ll see a few storms form later
this afternoon or evening in the far west. The odds increase on
Friday as disturbance and associated moisture over NV lift nwd then
newd across us later tonight into Friday.  Not a significant deep
layered surge but this time of the year it doesn`t take much to aid
in more convection, especially during max heating time and into the
evening. So idea of wdly sct/sct mtn storms Friday with a few across
the lower elevations, especially in and near the foothills and sern
zones seems good and no changes made there. Moisture hangs around
overnight so there will likely be some showers/slgt chance of
thunder over and near the mountains and probably a few weak showers
even across the lower elevations at times overnight Friday. On
Saturday, another plume skims our nwrn corner while some of the
Friday moisture remains east of the divide. Most of the convection
looks to be in the nrn two-thirds of the area so no changes to going
forecast. Sct higher elevations showers/tstms and isold lower
elevations. On Sunday, approaching shortwave and cold front may act
on another plume in the ssw mid level flow and aid in some stronger
storms in YNP and surrounding area. Added in some hail wording up
there instead of just the gusty wind wording. Otherwise, isold
storms just about anywhere with the far ecntrl zones having the
least chance. Still quite warm to hot through the period though with
only some clouds and outflows helping at times.

.LONG TERM...(Friday night through Thursday)
Issued at 115 PM MDT Thu Jul 13 2017

With the ridge axis moving to the east over the Plains and a
secondary high building slightly over the desert southwest, the
northern Rockies into WY will see more of a SW-NE mid-level flow as
the active storm track drops a bit southward.  The forecast pattern
should also allow some return flow from the Plains into eastern WY
as well as a slight decrease in 700mb temperatures.  Overall, enough
moisture and instability will continue the afternoon and evening
showers and thunderstorms from Monday through Thursday.  Some weak
disturbances may also enhance the storminess on a couple of days,
though details are a bit vague at this time.  The models are
suggesting that late Wednesday could be one of those times. The
northern and eastern areas should see a couple of pushes of cooler
air from Montana. Afternoon high temperatures are expected to drop
slightly to near normal or just above normal, with morning lows
still above normal. Sustained gradient wind is not expected through
the period, though thunderstorm outflows could create gusts of 30-40


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1105 PM MDT Thu Jul 13 2017

VFR conditions will occur through the period. Increasing mid and
high level moisture combined with slight instability will result
in isolated showers and thunderstorms developing over and vicinity
of the mountains primarily from 21z Friday until 03z Saturday.
Weak flow aloft will keep these storms mostly anchored near the
higher terrain. KRIW and KWRL were left with no VCTS, while all
other terminals closer to the mountains have VCTS in the forecast.
The primary hazard will be erratic outflow wind gusts 30-40 knots.
Most of this activity should dissipate shortly after sunset Friday


Issued AT 115 PM MDT Thu Jul 13 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). Through Saturday, fire danger will be low to moderate
for most mountain locations...elevated for all other lower
elevations due to very warm to hot daytime temperatures and low
humidity levels. Winds, however, will continue relatively light
across the entire forecast area today through Saturday. The only
exception will occur near any shower/storm where winds could briefly
gust 35 mph or more. Today, mainly isolated precipitation chances
will be found along/near and south of a Casper Mountain to Evanston,
WY line while Friday and Saturday the emphasis for isolated/widely
scattered showers/storms will mainly occur over/near the area`s
mountains or a weak surface boundary/front stretching through
central Wyoming.




LONG TERM...McDonald
FIRE WEATHER...Skrbac is the U.S. government's official web portal to all federal, state and local government web resources and services.