423 FXUS65 KPUB 110538 AFDPUB Area Forecast Discussion National Weather Service Pueblo CO 1138 PM MDT Wed Oct 10 2018 .SHORT TERM...(This evening through Thursday) Issued at 334 PM MDT Wed Oct 10 2018 ...Another round of snow for the central mountains and another night of cold temperatures for the southeast plains... Shortwave continues to move eastward across northern CO this afternoon with rapid drying evident in WV pics across the central mountains. There will be some lingering snow showers through this evening but coverage should decrease rapidly towards 00z and have opted to pull down the current set of advisories. Across the remainder of the area...isolated to scattered higher rain and snow showers will continue to move eastward across the area through early evening though should take a quick downturn this evening as best forcing moves east of the area. High res models keep cold air locked in across the plains tonight with stratus filling back in and lowering again as low level winds remain southeasterly. This makes for another tough call with the Freeze warning tonight as we struggled to hit freezing for many areas across the plains last night. Dew points are still in the lower to mid 30s across much of the plains. There may be some clearing towards morning along the Raton Mesa ridge as low level flow becomes more southerly, so we will stand a chance to see some freezing temperatures down that way towards dawn. Farther north across El Paso, Crowley and Kiowa counties, temperatures should drop below freezing as this area is under the deeper colder air. However its a little more uncertain for the lower Arkansas river valley where Min Temp grids are hovering around 32 to 34 degrees tonight. Have opted to put up the freeze warning for all but Baca county where temperatures will be too warm...but confidence is lower along the Arkansas river where clouds will hang in overnight and freezing conditions may be more spotty. It is not likely that this will be an end of season freeze for much of the area...however northern El Paso county and the northern San Luis valley stand the best chance of a longer duration freeze. Upper trof across the northwest U.S. carves out across UT and NV and CA over the next 24 hours with northern stream portion moving through the northern U.S. Rockies late in the period.Increasing moisture an westerly orographics will bring another uptick in snow to the central mountains late tonight and through the day on Thursday. Have hoisted another round of Winter Weather Advisories staring late tonight and continuing through Thursday evening. With the upper jet over the area and influence from northern stream portion of the trof coming in later in the period, we may see a couple of waves of snow with one during the early morning hours, and another coming in for the afternoon and evening period. Overall, looks like 4-8 inches will be possible through the period for the central mountains. Southwest mountains may pick up another 3-6 inches as flow on Thursday transitions southwesterly for a time on but overall, precipitation amounts look lighter. Will let later shifts assess the need for a highlight for these mountains but for now orographics and forcing looks best to the north. There will also be another round of showers for the southeast mountains and plains with some overrunning developing during the morning across the far eastern plains, and some jet banded showers push off the mountains into the adjacent plains during the afternoon. Any accumulations for these areas will be confined to above 8000 feet with generally 2-4 inches. Difficult high temperature forecast for tomorrow as well and leaned grids below guidance across the plains where cloud cover is most likely to stay in. .LONG TERM...(Thursday night through Wednesday) Issued at 334 PM MDT Wed Oct 10 2018 Thursday night through Saturday... The start of the long-term forecast period begins with the continued progression of a relatively weak shortwave through the northern Rockies into the central plains Thursday night into Friday morning. Much of the ongoing rain and snow showers will end across the mountains early Friday morning, along with rain showers and an isolated weak elevated thunderstorm across the far eastern plains. There are model differences with ending time of precip over the central mountains, with the NAM including higher QPF into the early Friday morning hours while most of the precip concludes by late Thursday night in the GFS and ECMWF. It appears as though precip will gradually taper off during the morning hours with forecast QPF representing something in-between the solutions. Behind the storm system, mid-level flow becomes zonal and relatively undisturbed, leading to dry weather across the forecast area Friday through most of Saturday. Sergio reminents are forecast to progress well to the southeast of Colorado, though there is still a small chance the rain shield clips Baca County. Thursday night and Friday night temperatures will stay a little warmer than previous evenings, with lows in the mid to upper 30s across most of the plains. Temperatures across most of the high valleys will span the low to mid 30s on Thursday night, and mid 20s on Friday night. High temperatures will generally reach the low to mid 60s on Friday and Saturday across the plains and mid 50s in Colorado Springs (slightly warmer Saturday), and near 60 in the high valleys. Lower elevation surface winds should generally be light Friday into Saturday. Low clouds are expected to develop over parts of the plains, especially far eastern, both Thursday night and, to a lesser extent, Saturday morning. Saturday night through Monday morning... Models have come into good agreement on the timing of a shortwave digging south/southeast into northern Colorado by Sunday morning spreading fairly potent QG forcing for ascent over eastern Colorado. The right entrance region of an associated upper level jet will also position itself over Colorado during the day on Sunday contributing to the large scale forcing. At the surface, a cold front will push south down the eastern plains late Saturday night through early Sunday morning and will be accompanied by gusty north winds. Rain will transition to snow showers along and behind the front and will be aided by abundant synoptic scale forcing and winds becoming easterly upslope behind the front. It continues to look probable that most, if not all, locations across the plains will see at least some snow with this system. How much is still in question, but given the warm surface and considering precip will start as liquid for most, don't expect significant accumulations over the plains. The eastern mountains are also expected to experience accumulating snowfall. While the GFS takes the system east out of Colorado quicker and ends precip across the far southern plains late Sunday night, the ECMWF and Canadian are slower on exiting the system, lingering precip over the plains and eastern mountains through Monday morning. Temperatures are likely to be the coldest of the season, thus far, Sunday night behind the front. Current forecast has temperatures in the mid 20s across most of the plains, around 20 in Colorado Springs, and teens in the high valleys. Locations that haven't already had a freeze should freeze that evening, so necessary preparations should be made before then. Monday through Wedensday... Mid/upper level flow becomes northwesterly and undisturbed Monday into Tuesday leading to dry weather. Daytime temperatures should rebound to over 50 degrees across most of the plains and high valleys. A broad upper low centered northern Baja California by Tuesday will dampen as it slowly lifts northeast toward Colorado Tuesday night into Wedensday. Models are in surprisingly good agreement on resolving this feature so far out in time. The main impact with this system currently appears to be a chance of isolated showers over the southwest mountains Tuesday night into at least Wednesday, potentially spreading north into the central mountains thereafter. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 1130 PM MDT Wed Oct 10 2018 At KALS, VFR overnight and through the day on Thu. Low risk of a vcsh for a few hrs Thu afternoon, though won't include in the taf as most -shra should stay closer to the mountains. SW winds will increase after 18z, with a few gusts to 30 kts until 02z. At KCOS, low level s-se winds will continue to keep cigs IFR/LIFR, with occasional periods of LIFR vis in fog and very light flurries. Improvement on Thu will be very slow, with IFR conditions until late afternoon, then MVFR hanging on into Thu night. At KPUB, generally IFR cigs until midday Thu, though still some potential for brief periods of MVFR as cigs bounce up and down around bkn010 for much of the night. Could see a period of br early Thu morning as low levels e-se flow persists. Slow lifting of cigs likely Thu afternoon, though still some occasional MVFR conditions possible into the evening. && .PUB WATCHES/WARNINGS/ADVISORIES... Freeze Warning until 10 AM MDT Thursday for COZ069-083>089- 093>098. Winter Weather Advisory until midnight MDT Thursday night for COZ058-060. && $$ SHORT TERM...KT LONG TERM...LINE AVIATION...PETERSEN