109 FXUS65 KCYS 092135 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 335 PM MDT Tue Oct 9 2018 .SHORT TERM...(Tonight - Wednesday) Issued at 304 PM MDT Tue Oct 9 2018 A broad swath of snow has developed across much of western/central Nebraska this afternoon. The western extent of this activity as of 21z was approximately along and south east of a line from Kimball- Alliance. This activity is associated w/ an impressive TROWAL that has taken shape on the back side of a strong upper-level shortwave currently lifting into the Central Plains, along with an excellent fetch of moisture contributing to deep saturated profiles. QPF via several high-resolution models including the HRRR & HREF continues to suggest the potential for snowfall accumulations in excess of 3 inches, potentially as high as 6 inches although snowfall rates do not appear high enough to overcome warm ground temperatures. Rates have been increasing over the last few hours though, w/ visibility finally falling below 1 SM at Sidney recently. We would anticipate seeing some accumulations shortly, especially on grass or elevated surfaces. Winter Wx Advisory looks to be in good shape through the midnight hour, although later shifts may consider extending if any road issues linger into the night. Accumulating snow should end by 06z or so as sounding profiles quickly dry out. A second disturbance was observed over the Intermountain West this afternoon per GOES-16 Water Vapor imagery. This system will follow very quickly in the footsteps of the ongoing weather maker, likely resulting in snow across much of Carbon County by 09-12z. Mountain areas may receive 6 to 12 inches, while lower elevation areas will have a good chance to see a general 2-4 inches of snow through Wed afternoon. The system will be weakening, so just how far east snow accumulations will extend is uncertain at this time. It's possible the I-80 summit may be impacted as well though. The Laramie Valley will likely be shadowed by low-lvl easterly flow regardless, so do not expect to see much in the way of snowfall there. We went ahead and issued a Winter Wx Advisory for far western areas for the time being, and later shifts can expand eastward if necessary. .LONG TERM...(Wednesday Night - Tuesday) Issued at 304 PM MDT Tue Oct 9 2018 Warmer and mostly dry conditions prevail moving into the end of the week as a southerly flow affects the region. However, by Saturday night, the next strong system looks as though it will drop out of the north, bringing the next round of cold temperatures to the region and the next shot at decent precipitation. For now, the remnants of Hurricane Sergio look like they will stay south and east of the region, but should the moisture track change and push further north, this system may spell another story for the region. This will need to be monitored as we move towards the end of the week. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) Issued at 1137 AM MDT Tue Oct 9 2018 IFR to MVFR conditions to persist across the terminal sites this afternoon. Brief periods of heavy snow and reduced visibilities possible across the NE Panhandle through midnight as the trowal region of precipitation moves across. KSNY expected to see worst conditions with some reduction in flight conditions at KAIA as well. Some light snow also expected across KRWL and KLAR ahead of an upcoming shortwave. && .FIRE WEATHER... Issued at 242 AM MDT Tue Oct 9 2018 A cold and active pattern will continue over the next week, significantly limiting fire weather concerns and aiding in fire containment issues. The next best chance of measurable precipitation across the mountains will arrive Wednesday. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Winter Weather Advisory from midnight tonight to 6 PM MDT Wednesday for WYZ109>114. NE...Winter Weather Advisory until midnight MDT tonight for NEZ021- 055. && $$ SHORT TERM...CLH LONG TERM...AB AVIATION...WM FIRE WEATHER...AB