Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 150358

Area Forecast Discussion
National Weather Service Cheyenne WY
958 PM MDT Sat Apr 14 2018

.SHORT TERM...(This evening through Monday night)
Issued at 215 PM MDT Sat Apr 14 2018

Early afternoon water vapor/visible satellite imagery placed the
intense low pressure system over northeast KS. While blizzard
conditions plagued portions of NE, the eastern Dakotas and MN,
strong to severe convection stretched north-south across the
Middle and Lower MS Valley. Skies were mostly sunny, however cool
temperatures prevailed with gusty northwesterly winds 25-45 mph.
Snow ended over western NE earlier this morning, however several
highways, including I-80, remain closed this afternoon. Winds will
gradually diminish through late this afternoon and early evening.

It will be a benign 24 to 48 hour period weather-wise as a large
scale ridge of high pressure dominates the CWA. Southwest winds
will be breezy Sunday afternoon west of the Laramie Range. High
temperatures Sunday will moderate into the 50s for southeast WY,
while much of western NE remains in the 40s. South to southwest
winds increase Monday with a deepening lee side trough over the
eastern plains. Gusts of 40-50 mph will be possible across much
of Carbon County Monday afternoon. High temperatures Monday will
average 10-15 degrees above normal for southeast WY with 60s to
lower 70s. Western NE will be 5-10 degrees cooler though. The
next Pacific upper trough and cold front will approach south
central WY Monday night, with increasing clouds and scattered
rain/snow showers developing after midnight.

.LONG TERM...(Tuesday through Saturday)
Issued at 215 PM MDT Sat Apr 14 2018

Tuesday...Powerhouse shortwave trough aloft and its associated cold
front sweep eastward across our counties, producing scattered to
numerous coverage of rain and snow showers and possible high winds
due to thickness packing and downward vertical motion of the
strongest winds behind the shortwave trough. Cooler day compared
to Monday, with temperatures likely falling in the afternoon
behind the cold front, with strong cold air advection.

Wednesday...Precipitation will end early from west to east as the
flow aloft becomes northwest with drying at low and mid levels.
Based on low and mid level gradients, it looks breezy to windy.
Slightly cooler in the wake of the cold front.

Thursday...Flow aloft turns southwest in advance of the next
approaching shortwave trough aloft, with low level winds turning
southeast upslope, helping to bring increasing low level moisture
westward into our counties. Still looks dry with the atmosphere
slowly moistening. Temperatures still fairly mild before the next
cold front arrives.

Friday...If the GFS and ECMWF are correct, it looks like another
inclement, cold and wet Friday, similar to yesterday. Although the
closed upper low could produce widespread snow, heavy at times,
across much of our counties, the exact track is still quite uncertain
six days away. Will match up with our neighboring offices for rain
and snow chances, anywhere from 40 to 80 percent.

Saturday...If the models are to be believed, the slow moving upper
low will more far enough east of our counties to see some clearing
skies from west to east with a cessation of the rain and snow from
west to east. Still cool in the wake of the cold front and upper
trough, though possibly colder if we get a decent snowpack from the
Friday storm system.


.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 956 PM MDT Sat Apr 14 2018

VFR conditions the next 24 hours and beyond as we are forecasting
westerly winds west of the Laramie Range. Winds turn easterly
across our Panhandle zones later this evening, but low level
moisture is absent, so no impacts are expected.


Issued at 215 PM MDT Sat Apr 14 2018

A northwest flow aloft will promote cool temperatures and breezy
to windy conditions this weekend. Temperatures will moderate Monday
before cooling again for the middle of next week as another low
pressure system moves across the districts.




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