590 FXUS65 KCYS 271153 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 453 AM MST Mon Jan 27 2020 .SHORT TERM...(Today and tonight) Issued at 411 AM MST Mon Jan 27 2020 In the immediate short term, quarter mile visibility conditions have persisted across Box Butte County as shown in the last couple hours of observations from KAIA. A freezing fog advisory has been issued for the county till 10 AM MST today. The narrow region of freezing fog coupled with low ceilings as shown on the latest GOES-E nighttime microphysics plus some of the high-res guidance suggests the spread of fog/freezing fog into more of Dawes and Morrill Counties that may warrant extensions later this morning. Current available webcams in the neighboring counties though still show unhindered visibility conditions though patchy fog may linger in some of the lower areas. Other side of the short term is the passage of a surface front this morning ushering in snowfall across the western areas first with KRWL already measuring snowfall this morning. Continued Winter Weather Advisories across much of Carbon County that we inherited from yesterday's day team. HRRR model seems to be a bit aggressive in terms of convective energy with the snow bands rolling through today. Concern to watch will be the low elevations of Converse County and Niobrara County with the snow later today. Considering ground warmth and snowfall rates across these areas thinking snow will have initial trouble accumulating until the evening hours that have decided to hold off on extending Winter Weather Advisories into these areas though monitoring of conditions will be needed. Given latest GFS height gradients between Craig and ARL and BRX, held off on any specific wind headlines as favorable wind direction for BRX is limited in time frame to only a few hours before becoming unfavorable out of the northwest. ARL window of deep gradient via the GFS is between 18z and 21z peaking at 44 meters, 39 meters via the NAM so very low confidence remains for high winds there though gusty winds under criteria will make a mess of road conditions with the falling/blowing snow. .LONG TERM...(Tuesday through Sunday) Issued at 411 AM MST Mon Jan 27 2020 Active weather stretch as two quick moving shortwaves pass through the region, first over the Tue/Wed period followed again Thu/FRI as a deep upper level trough digs across the NM/TX region. Light snowfall accumulation mainly west of the Laramie Range for the first system with more mountain snow mainly in the second system. Deep ridging pattern sets in the wake into the weekend with a 4 Corners high building with plenty of WAA into the region bringing chance for well-above normal if not teetering around record high temps east of the Laramie Range Saturday and Sunday with highs into the low to mid 60s. Another few rounds of high winds are likely as stacked gradients return across the wind prone areas as early as Friday morning and into as late as Monday morning. Craig to ARL gradients via the GFS reaching into the mid 80 meters while Craig to BRX topping into the low 110s Sunday morning. High Wind headlines will likely be needed should guidance remain consistent through the week. && .AVIATION...(For the 12Z TAFS through 12Z Tuesday morning) Issued at 445 AM MST Mon Jan 27 2020 Periods of IFR/LIFR this morning, under low ceilings and low visibilities this morning. FZFG across Box Butte County will continue through midmorning. Snow and a rain/snow mix will be seen across all TAF sites at some point today - areas to the west this morning through the evening, and areas east, this evening and overnight as a system passed through from west to east. Winds pick up behind the front, with gusts to 30 kts across most sites over the next 24 hours. BLSN expected. MVFR will become more common by this afternoon for the region. Mod ICING and terrain obscuration likely. && .FIRE WEATHER... Issued at 237 AM MST Mon Jan 27 2020 Early week period fire weather concerns remain low with expected light precipitation across much of the forecast area through today and into tonight and again on the WY side Tuesday evening into Wednesday. Raised concern for fire weather conditions peak next Sunday particular across Laramie, Kimball, and Cheyenne Counties with min RH values in the upper teens and winds gusty above 25 knots. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Winter Weather Advisory until 11 PM MST this evening for WYZ104- 105-109>112-114. NE...Freezing Fog Advisory until 10 AM MST this morning for NEZ003. && $$ SHORT TERM...WM LONG TERM...WM AVIATION...AB FIRE WEATHER...WM