Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 261935
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
135 PM MDT SUN JUN 26 2016

.SHORT TERM...Tonight and Monday

Not as cool tonight, but mainly light winds with clear to mostly
clear skies persist. A weak dry cold front moves south/southwest
across much if not all of the forecast area by around 12Z Monday.
This will switch winds to the north/northeast/east, but remain
mainly light in most areas. The exception could be in the Jeffrey
City to Casper...including Hiland area where it could become
breezy, but still relatively light for Wyoming.

The upper ridge over the Four Corners region amplifies Monday
across the Rockies with 30 meter height rises over the forecast
area. The easterly surface flow begins to usher in some low level
moisture over the extreme east. This additional moisture combined
with the easterly upslope flow could be enough for isolated late
day thunderstorms to initiate over the eastern slopes of the
Bighorn Mts or the Laramie Range (e.g., Casper Mountain). Increasing
heights, no discernible wave in the flow, and marginal moisture
will all be limiting factors for convection Monday afternoon. If
isolated convection does develop, it does have the potential be
strong/severe due to the expected wind shear with DCAPE ranging
between 1000 and 1500 j/kg.

.LONG TERM...Monday Night THROUGH Sunday

There could still be a few lingering thunderstorms across far
eastern areas during the evening but these should be exiting stage
east during the evening with a balance of the night mainly dry.

Things should get more active for Tuesday as the ridge gets
suppressed south a bit and allows for some shortwaves to top the
ridge and possibly produce a better chance of storms. The previous
coverage of storms looks fairly reasonable at this point so we left
things alone. We did remove the morning showers though. We can not
rule out a couple, mainly later in the morning but these should be
fairly isolated and since most of the morning should be dry, most
people would interpret the morning as being largely dry. There is
still some model disagreement however with the GFS having the area
largely dry and the European the wettest with the NAM in the middle.
And even in places that get a thunderstorm, most areas will be dry
for a majority of the day. The best energy may shift a bit further
north for Wednesday with the chance of thunderstorms sliding a bit
further north as well. The models have not had much consistency on
this however, so we again left continuity alone as it looks like
the most likely scenario.

Thursday looks like a squeeze play kind of day with a few
thunderstorms in eastern portions of the area. With a surge of
monsoonal moisture there will also be a better chance of storms
across the western mountains. At this point the driest area looks to
be across central areas. Friday looks to be the most active day with
monsoonal moisture moving across the area along with a shortwave
that will enhance lift. All areas look to have a chance of
convection this day. Going into the Fourth of July weekend, ridging
will begin to build across the state once again. This means a rise
in temperatures with 90s returning in some areas. This also means a
decreasing chance of showers and thunderstorms, although a few will
remain possible both Saturday and Sunday.

&&

.AVIATION.../00Z ISSUANCE/

SKC with light winds will continue through this evening. Some cirrus
could overspread the area from the west late tonight...while some
low level clouds could begin spread/develop westward into portions
of Johnson/Natrona Counties. Boundary layer moisture is marginal at
best for low clouds, and will only hint at the lower clouds at the
CPR terminal with a FEW group. On Monday there will be a bit more
moisture for some high based cumulus...with even isolated late
afternoon convection possible across the extreme east. KCPR could be
impacted by this activity, but will not mention TS in the TAF due
the expected limited coverage, and the possibility that the
convection will remain east/southeast of the area.&&

.FIRE WEATHER...

...Elevated fire weather conditions over south and southwest
Tuesday and Wednesday...

Very warm with low to very low afternoon RH Monday. However winds
will be on the light side. There is a remote possibility of a late
day thunderstorm over the Bighorn mountains into Johnson and Natrona
Counties. On Tuesday and Wednesday, the combination of breezy
westerly winds, and afternoon RH between 8 and 12 percent across the
southwest and south will create elevated fire weather conditions in
those areas. Farther north and northeast a disturbance moving across
the area, and moisture pushing westward to the Divide will result in
isolated to locally scattered showers and thunderstorms Tuesday and
Wednesday mainly east of the Divide. Some monsoonal moisture tries
to spread northward across the area Thursday which will result in
higher humidity especially over the south/southwest sections which
remain bone dry Tuesday and Wednesday.

&&

.RIW Watches/Warnings/Advisories...None.

&&

$$

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



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