Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 202221
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
421 PM MDT MON JUN 20 2016

.SHORT TERM...(This evening through Wednesday Night)
Issued at 421 PM MDT Mon Jun 20 2016

After the stratus dissipated and a few showers developed just
south of the border in Colorado earlier this morning, satellite
and radar imagery have been pretty clear of convection most of
today for our area and vicinity. Cumulus congestus is beginning to
show on vis imagery over the Snowy and Sierra Madre Mountains, so
do still think a shower/storm is possible over the higher terrain.
Not quite sold on the potential further east as a pretty stout
cap is in place across the plains. Will keep Iso-T for southern
zones through 9 pm to account for the llvl jet strengthening and
perhaps initiating some elevated convection. However, do not
anticipate any strong storms. Moist south-southeast sfc flow will
maintain chances for stratus development through the early
overnight period mainly along the Cheyenne Ridge and perhaps the
North Platte River Valley.

A shortwave trough will move quickly across the northern Rockies
and high plains on Tuesday, deepening the leeside pressure trough
and tightening the sfc  pressure gradient. Sfc winds west of the
Laramie Range will increase and shift to the west as the leeside
trough deepens, with winds across the plains following suit as
the trough shifts east through the day. Could see convection fire
along the trough axis in the afternoon, with a focus along the
Laramie Range and locations to the east. Marginal instability and
shear are progged by the models ahead of the trough, particularly
along the Cheyenne Ridge, so may see a stronger storm or two drop
small hail and gusty winds.

The westerly downslope winds combined with rising heights aloft
will lend to very hot, dry, and breezy conditions in the wake of
the trough. High temperature records are in jeopardy as many
lower elevation sites across WY/NE are looking to soar into the
upper 90s with a few spots across the plains exceeding the century
mark. Fire weather concerns will increase with these conditions as
well, with near critical conditions quite possible across the west
and north.

A cool front moving south through the area Tuesday night
and Wednesday will offer some relief to the hot, dry, and
breezy conditions although it`ll still be quite warm. Convection
will once again be confined mainly to the mountains.

.LONG TERM...(Thursday through Monday)
Issued at 421 PM MDT Mon Jun 20 2016

Continued warm for Thursday and Friday with the CWA in the wake of
a flat upper ridge that will be moving over the central part of
the country. A couple weak impulses look to pass across the area
and should interact with some instability to set off some
afternoon and evening convection both days. A stronger upper
shortwave/low will move east along the US/canadian border Friday
through saturday and will push a cold front across the CWA Friday
night. The weekend looks mild and mainly dry with a cool sfc high
settling over Wyoming. Warmer on Monday with an upper high
strengthening some over the desert sw.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday morning)
Issued at 1114 AM MDT Mon Jun 20 2016

Expect VFR to prevail at all terminals through the period.  A few
showers and storms possible this afternoon mainly vcty of the mtns.

&&

.FIRE WEATHER...
Issued at 421 PM MDT Mon Jun 20 2016

Humidities across Carbon County have dropped in the low teens this
afternoon, however winds are relatively light. Further east, moist
southeasterly winds are keeping humidities around 25 percent or
higher. Unfortunately, winds will shift to the west for Tuesday,
ushering in hot, dry, and breezy conditions once again for much of
the district. Near critical conditions are quite possible in the
afternoon for lower elevations of Carbon and Albany Counties, and
also for Converse and Niobrara Counties as well due to expected very
dry humidities and gusty westerly winds. Fuels are still indicated
as being non-critical though, so will hold off on any fire weather
watches. Another cool front will move across the district Wednesday
morning and will offer some relief. However, dry and breezy
conditions will persist west of the Laramie Range.

&&

.CYS Watches/Warnings/Advisories...
WY...None.
NE...None.
&&

$$

SHORT TERM...RJM
LONG TERM...RE
AVIATION...RE
FIRE WEATHER...RJM



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