Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 232035
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
235 PM MDT Fri Jun 23 2017

.SHORT TERM...(This evening through Monday)
Issued at 230 PM MDT Fri Jun 23 2017

Northwest flow aloft will keep bringing surges of cold
air south across the area Saturday and Sunday.  Then as
a high pressure ridge builds north up from the Great Basin
on Monday, significant warming is expected with the development
of stronger west to southwest winds. Some showers and thunderstorms
may develop over the northern mountains monday afternoon in
response to the increased surface heating.

.LONG TERM...(Monday night through Friday)
Issued at 230 PM MDT Fri Jun 23 2017

Next weeks weather will be driven largely by the passage of a well
defined shortwave trough. The models are forecasting a lead
shortwave trough to track across the Northern Rockies Tuesday with
the main trough to come through Thursday morning. The GFS has the
most amplified soln for this feature with the Euro the slower model,
and the Canadian sort of a compromise. Will go with the more
detailed GFS for timing and strength. The long wave ridge axis will
remain more or less along the Pacific Coast next week with the long
wave trough axis over the Midwest. This would keep us on the
backside of the long wave trough or front side of the long wave
ridge. This would result in cold fronts having a more robust
influence on the weather east of the divide next week with the most
fluctuation in temperatures during the duration of week. The weather
next week will resemble this past weeks weather in many ways with
Monday and tuesday being the hottest days of the week followed by
gradual cooling for the rest of the week. And, like last week, an
increasing chance of some shower or thunderstorm activity by mid
week with the  troughs/cold fronts. At the lowest
elevations east of the divide the highs will be in the 90s once
again with 70s and 80s west. By weeks end, temps in the 70s east and
60s and 70s west. H7 temps will fall from 17C Tuesday to 4C in NW WY
Thursday. So with the first troughpa/fropa later Tuesday and the
main troughpa/fropa Thursday, expect chc late day showers and
thunderstorms late Tue/Wed in Northern WY, with more numerous
activity Thursday over the whole north half of the CWA. The flow
will become increasingly difluent ahead of each shortwave next week.
With the increasing flow aloft ahead of these troughs along with hot
temperatures, strong gusty winds will likely be the dominant
features with next weeks convection, especially on Tuesday.
Measurable rain appears most likely next week across northern WY
east of the divide based on moisture fields and influence the asct
backdoor cold fronts.

Fire danger will increase Tuesday along with increasing westerly
breezes along a min RH in the teens at the lower elevations east
of the divide.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 230 PM MDT Fri Jun 23 2017

VFR conditions to prevail at all terminals through 00Z/Sun morning.
SKC to localized SCT CIGs 070 ft east of the divide and 090 feet
west throughout the rest of this afternoon. Expect similar cumulus
cloud base heights Saturday except in Sweetwater County/KRKS where
any cumulus that form will have bases as high as 120k.

&&

.FIRE WEATHER...
Issued AT 230 PM MDT Fri Jun 23 2017

Northwest flow aloft will keep bringing surges of cold
air south across the area Saturday and Sunday.  Then as
a high pressure ridge builds north up from the Great Basin
on Monday, significant warming is expected with the development
of stronger west to southwest winds. Some showers and thunderstorms
may develop over the northern mountains monday afternoon in
response to the increased surface heating.  There should be adequate
mixing each afternoon for good to very good smoke dispersal increasing
to excellent on Monday afternoon.

&&

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

$$

SHORT TERM...Baker
LONG TERM...Lipson
AVIATION...Lipson
FIRE WEATHER...Baker


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