Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 251734
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1130 AM MDT Tue Jun 25 2019

.SHORT TERM...(Today through Thursday night)
Issued at 230 AM MDT Tue Jun 25 2019

Forecast challenges today deal with severe thunderstorm chances.
Increasingly warmer temperatures may create elevated fire weather
concerns towards the end of the week.

Currently...Low pressure center located near Riverton this morning
with a frontal boundary draped across our northeast counties.
Dewpoints north of the front in the upper 40s to low 50s. South
and west of the front...dewpoints in the low to mid 30s. This is
the focus area for SPCs Marginal Risk area for this afternoon.

Short term guidance showing MUCAPE this afternoon ranging from
2000 J/KG near Sidney to 1800 J/KG up near Lusk at 00Z this
afternoon. Hires and HRRR simulated radar showing convection
developing along the front around 21Z...moving east and northeast
into this instability late afternoon and early evening. Surface-
6km shear on the order of 40-45kts...so severe storms can not be
ruled out for areas along and east of a Lusk to Torrington to
Sidney line this afternoon. Soundings look to be pretty high
based...so wind will be the primary hazard.

Front moves out eastern Wyoming into central South Dakota and
Nebraska this evening with dry air filtering into all of the CWA
from the west for Wednesday. Looking at temperatures in the 90s
for the Panhandle and 80s out west for Wednesday afternoon. Model
soundings showing possibility of mixing winds down from close to
500mbs...so at least southeast Wyoming likely to see gusty winds
from Wednesday on into the end of the week. Very dry afternoon
humidity down into the single digits near Rawlins by Friday
afternoon could begin to dry out vegetation and creating elevated
fire weather concerns.

.LONG TERM...(Friday through Monday)
Issued at 230 AM MDT Tue Jun 25 2019

Warm weather continues through the period with southwest flow aloft
through Sunday, then becoming west on Monday. Looks like enough low
and mid level moisture for isolated to scattered afternoon and
evening showers and thunderstorms Saturday through Monday. The
warmest day will be Friday, with slowly cooling temperatures each
day thereafter.

&&

.AVIATION...(For the 18Z TAFS through Wednesday morning)
Issued at 1130 AM MDT Tue Jun 25 2019

Main Aviation concern this afternoon and into this evening will be
the timing and coverage of thunderstorm activity expected to develop
by mid-afternoon across southeast Wyoming. Expect VCTS around KLAR
and KCYS as early as 20z, but closer to 22z to 00z across the
western Nebraska terminals. A few thunderstorms may have some hail
and strong gusty winds, but those shouldn`t be too widespread. VFR
conditions will prevail through tonight with maybe brief MVFR VIS
due to heavy rainfall associated with a few thunderstorms into this
evening.

&&

.FIRE WEATHER...
Issued at 230 AM MDT Tue Jun 25 2019

Warm and dry weather along with gusty west to southwest winds
expected over the next week as high pressure over Colorado remains
in place and migratory low pressure systems move through Montana.
Afternoon humidity expected to become critical over Carbon and
Albany Counties west of the Laramie Range Wednesday...becoming
more widespread east of the Laramie Range Thursday and Friday.
Strong winds will mix down from high elevations in the atmosphere
to create gusty winds from mid morning through late afternoon.
Fortunately...fuels are in green stage from recent rains/mountain
snow. But if this dry/warm pattern continues...fuels will become
stressed and dried out. As fuels are still NO on Fuels Page...fire
weather concerns will remain low at this time.

&&

.HYDROLOGY...
Issued at 230 AM MDT Tue Jun 25 2019

Temperatures are expected to continue increasing through the
upcoming week. Increased snowmelt on the Snowy and Sierra Madre
Ranges will keep headwaters elevated on the Upper North Platte and
Laramie Rivers through the next week. Fortunately...not looking at
any rain on snow events over the next several days. Next chance
for widespread rainfall looks to be next Monday into Tuesday next
week. Until then...expect elevated headwaters from increased
snowmelt.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&

$$

SHORT TERM...GCC
LONG TERM...RUBIN
AVIATION...TJT
FIRE WEATHER...GCC
HYDROLOGY...GCC


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