Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 241024
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
424 AM MDT Fri Mar 24 2017

.SHORT TERM...(Today - Saturday)
Issued at 317 AM MDT Fri Mar 24 2017

No major impacts from the winter storm this morning. The latest WV
satellite loop shows an impressive upper-level low centered across
southeast Colorado with a distinct TROWAL feature from near Denver
northeastward into central Nebraska. This system developed quite a
bit further south than all available guidance advertised 12-24 hrs
ago, which has been problematic concerning the potential west-ward
extent of the precipitation shield. We did have a push of moisture
earlier which may have interacted w/ some lingering instability in
the mid levels as some fairly intense snow bands quickly developed
over Laramie County at elevations high enough for snow. Snow rates
have come down since then, but IR imagery still shows colder cloud
tops trying to inch further west. Do not expect it to make it much
further, but it should be enough to keep snow going long enough to
justify keeping headlines going. We cancelled the Advisory for LAR
and ARL and downgraded the Warning to an Advisory for the Summit &
adjacent foothills as impacts are virtually nil so far. The latest
HRRR suggests the bulk of precipitation will be done by 15z, so we
brought PoPs to zero earlier as much drier air pushes in. We opted
to nudge high temperatures up a bit this afternoon as well with no
snow pack and clouds rapidly decreasing from W-E. Saturday will be
brief break from the active weather pattern w/ a passing shortwave
ridge.

.LONG TERM...(Saturday Night - Thursday)
Issued at 317 AM MDT Fri Mar 24 2017

Unsettled weather pattern will continue for much of the long term
period as a series of upper troughs progress into the
intermountain west. The next in the series will affect the CWA on
Saturday night into Sunday. This system looks less robust than the
current storm and tracks fairly far south so precip amounts at
this time look light. Precip type at this time expected to be
mainly rain with snow generally confined to locations above 7000
ft. At this point think there should not be too many impacts
outside of the mountains with this one. Another upper trough moves
across the area on Tuesday and then yet another in the
Thursday/Friday timeframe. GFS is a bit cooler with the Tuesday
system so will have to watch for more snow potential Tuesday
especially in Wyoming with some decent upper diffluence overhead.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday afternoon)
Issued at 550 MDT Thu Mar 23 2017

Scattered showers with isolated thunderstorms will continue across
parts of SE Wyoming and western Nebraska late this evening. Cold
front currently along a line from around KAIA to KCYS across the
high plains, and then extending northwest, north of KLAR toward
KRWL west of I-25. Behind the cold front we will see a cold rain
switching to snow overnight in Wyoming. We expect lowering
ceilings/visibilities across the entire area, but more impactful
down to LIFR for Cheyenne and Laramie late tonight.


&&

.FIRE WEATHER...
Issued at 317 AM MDT Fri Mar 24 2017

No fire weather concerns today with cooler temperatures and recent
precipitation. Minimum RH values are expected to be above 20% over
the next several days.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Winter Weather Advisory until 9 AM MDT this morning for
     WYZ116>118.

NE...None.
&&

$$

SHORT TERM...CLH
LONG TERM...DEL
AVIATION...TJT
FIRE WEATHER...CLH



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