Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/15/17

Area Forecast Discussion
National Weather Service Cheyenne WY
820 PM MST Thu Dec 14 2017 .UPDATE... Issued at 820 PM MST Thu Dec 14 2017 Quick update here this evening to upgrade southwest Platte County (ie. Bordeaux area) to a High Wind Warning. Latest HRRR output sends ribbon of low-level subsidence into this area overnight and Friday. Was concerned earlier with winds from 300 degrees (less favorable), but these have since backed to 280 (more favorable). This in combination with 750mb flow of 45-50 knots were sufficient indicators for confidence to be enough to issue the warning. Otherwise, inherited forecast on track this evening. && .SHORT TERM...(This evening through Saturday Night) Issued at 232 PM MST Thu Dec 14 2017 Latest water vapor loop was showing drier air starting to filter into southeast Wyoming behind a departing mid level shortwave. This will continue to allow the snow showers to dissipate through the remainder of the afternoon. Meanwhile, a band of stronger mid level winds are expected to push through Montana late tonight into tomorrow. As this band of stronger wind speeds move through this region, it will cause the low level height/and pressure gradients to tighten along the Laramie Range and Arlington late tonight into Friday. As a result, we went ahead and upgraded the High Wind Watches to Warnings across Arlington and the Laramie Range late tonight into Friday. Hung on to a High Wind Watch for Bordeaux since it appears the subsidence will be less favorable in that region, and the surface trof tends to hang on in that region. Later shifts will need to keep an eye on this potential. Temperatures will be much warmer than today, due to good downslope affects. The next concern will be the shortwave now approaching the Pacific northwest. This feature is expected to dive south during the next couple of days. If this trend continues it will keep the bulk of the snow across western Wyoming. We will have to watch Carbon county especially Saturday and Saturday night especially if that area ends up having a longer period of upper level diffluence. The other concern will be the potential for deep low level moisture developing behind the cold front. This will result in lesser snow amounts mainly east of the Laramie Range. However, it could be in the form or light snow/freezing drizzle which may still cause some impacts Saturday night into Sunday morning especially in the southern Nebraska Panhandle. .LONG TERM...(Sunday through Thursday) Issued at 232 PM MST Thu Dec 14 2017 Things should begin to clear out on Sunday with some upper level ridging developing over the region early next week. This will allow for a gradual warmup early next week, before another strong cold front plows through the region Wednesday night into Thursday. This front may bring some more snow along with it, but it does not look like a significant snow maker. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 525 PM MST Thu Dec 14 2017 VFR conditions to prevail at area terminals through the period as few-sct upper level clouds stream thru the area. More importantly to airfield operations will be developing gusty winds after 07z at RWL, after 10z at CYS/LAR, and after 17z at western Nebraska sites. West wind gusts of 25-35 knots will be standard after these times. Winds will persist thru the end of this TAF cycle before decreasing Friday evening. && .FIRE WEATHER... Issued at 232 PM MST Thu Dec 14 2017 Elevated fire weather concerns are possible tomorrow due to strong west winds developing. However, minimum humidites will most likely range from 15 to 20 percent which will limit any red flag potential. Beyond that timeframe we are looking a period of colder conditions will some potential for snowfall this weekend. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...High Wind Warning from midnight tonight to 9 PM MST Friday for WYZ106-110-116-117. NE...None. && $$ UPDATE...CAH SHORT TERM...REC LONG TERM...TJT AVIATION...CAH FIRE WEATHER...REC
Area Forecast Discussion
National Weather Service Grand Forks ND
955 PM CST Thu Dec 14 2017 .UPDATE... Issued at 955 PM CST Thu Dec 14 2017 Most sites across the region have been seeing at least flurries with -SN, and there have been reports in the Fargo/Moorhead area of around a half an inch. This corresponds well with SPC meso page placement of 925mb frontogenesis, which the RAP has hanging around the area for a few hours longer. Bumped up POPs in this band, and it should slide off to the southeast later tonight. More snow will move in from the northwest by midday tomorrow. Flurries elsewhere for much of the region. Accumulations could be up to a few tenths of an inch. Continued to keep a FZDZ mention for brief periods across eastern ND, as we could see some drying out in the ice producing layer at times. && .SHORT TERM...(This evening through Friday) Issued at 320 PM CST Thu Dec 14 2017 Expecting it to remain cloudy through the entire short term period. Along with that, flurries or very light snow remain possible throughout as well. Currently think more flurries will be around early this evening. Then models indicate a little better chances for light snow will develop by mid evening, mainly over the Devils Lake region and northern Red River Valley. This activity may expand further south and east after midnight. However, really only talking about a dusting of snow with this. Next system still on track for Friday into Friday night. This next system brings most of the area some light snow, but the main band looks to be from the northern Red River Valley over toward Bemidji, where up to 2 to 3 inches of snow are possible. Lesser amounts are expected to the west. Wind speeds do not look very strong, which should lessen the impacts. .LONG TERM...(Friday night through Thursday) Issued at 320 PM CST Thu Dec 14 2017 Friday night and Saturday...Our northerly upper flow will transition to zonal heading into the weekend. As this occurs deep warm air advection snowfall should set up along a northwest- southeast oriented baroclinic zone. The swath should cover a tract from Devils Lake through the north and central valley to west central Minnesota with little or nothing over SE ND. Upper level support is lacking and there is the though that vigorous WAA will trim some of the available ice to the point of a possible mix of pcpn types, first over Devils Lake before propagating toward the valley later Fri night. Nevertheless, still favoring SN as main pcpn and sticking with the inherited 1 to 3 inch amounts. Impacts should be diminished by the lack of wind during this event. Forcing should be over by Saturday afternoon. Sunday through Thursday...Zonal flow will likely persist much of the week, with a stronger system likely affecting the region later Mon and Mon night. The cyclone will likely move across Central Canada while the surface and upper trough swings through the forecast area dropping small snowfall amounts. But here the wind will be stronger behind the front, possibly creating blowing snow impacts. It appears that we`ll go more NW flow midweek as temps drop to near and then below average values. Then a phasing trough could make things more interesting later in the week, with the early money on a more southern track, but we`ll have to keep an eye on it with time. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 644 PM CST Thu Dec 14 2017 Most areas are MVFR although a few have scattered out to VFR. Think this will be short lived and all locations will be MVFR or IFR by morning. Scattered snow showers moving through have brought -SN to the central and eastern TAF sites at various times this evening, with the snow coming in an out but remaining above 6SM for the most part. A stronger band of snow will begin to move into the area tomorrow morning, spreading from northwest to southeast across the forecast area. Think the better chances for significant snow will be at the northern TAF sites. Visibilities in the snow band will be in the 3-5SM range early on with some sites seeing 1-2SM late in the period. Light and variable winds will steady out of the southeast, but remain below 12 kts. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ UPDATE...JR SHORT TERM...Godon LONG TERM...WJB AVIATION...JR
Area Forecast Discussion
National Weather Service Omaha/Valley NE
515 PM CST Thu Dec 14 2017 .SHORT TERM...(Tonight through Sunday) Issued at 300 PM CST Thu Dec 14 2017 Models suggest that isolated snow and rain showers will move through the area this evening, then push south of the area by midnight. These are tied to an upper trough and reinforcing surface trough across eastern SD that will settle southward tonight. No significant accumulation expected although HRRR and Highres ARW/NMM suggest a tenth of an inch if you happen to be underneath one of the showers. Much above normal temperatures return Friday into Saturday ahead of the next cold front which arrives Saturday afternoon. Highs in the 40s tomorrow, and in the mid 40s to upper 50s on Saturday, depending on which side of the front. Models do suggest that the trough currently across northwest Mexico eventually gets shunted north Saturday night into Sunday. the northern edge of this moisture could bring a wintry mix to extreme southeast NE and southwest IA Sunday morning. Meanwhile, an elongated area of Pacific moisture to our north never gets a strong enough push into the area so no precip expected from that feature. .LONG TERM...(Sunday night through Thursday) Issued at 300 PM CST Thu Dec 14 2017 Significant warming takes place Monday through Wednesday of next week ahead of a major pattern shift that hits our area on Thursday. Temps in the 40s Monday and Tuesday, but likely into the lower 50s for Wednesday. That`s the last warm day though, as an arctic front arrives on Thursday. This also could signal a shift to a wetter pattern into the Christmas Holiday period, but then again, that`s still 10 days away, and a lot can change. Fairly high confidence on the colder pattern, but lower confidence on any precip/snowfall patterns at this time. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 512 PM CST Thu Dec 14 2017 MVFR conditions at KOFK will trend toward improvement over the next few hours, with potential for very light rain/snow in or near the site. Kept ceilings at VFR levels at KLNK, with a scattered MVFR mention, and also mentioned vicinity showers there for a few more hours. At KOMA, think conditions will remain just above VFR thresholds, and while I can`t rule out a stray sprinkle or flurry, coverage (and chances) seemed too low to mention it. At all sites, conditions will improve after midnight to VFR, with clouds dissipating. Light northwest winds this evening and tonight will become southwesterly on Friday but will remain 10kt or less. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ SHORT TERM...DeWald LONG TERM...DeWald AVIATION...Mayes
...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Friday) Issued at 304 PM CST Thu Dec 14 2017 A weak disturbance will continue to bring light precip to the region this afternoon and evening before exiting overnight. Afternoon water vapor imagery showed a compact H500 wave/PV lobe tracking southeastward through Nebraska. Enough attendant lift and moisture was present with this feature to generate a broad but rather patchy region of light rain and snow, though accumulations were very light. An overall drying trend has been noted in MRMS data over the last few hours and most model guidance support this evolution. Did keep the mention of light sprinkles/flurries east of Manhattan through midnight given upstream echos extending as far as the Black Hills and recent runs of the HRRR generating light POPs through that same time range. Broad upper level ridging builds in the wake of this system for Friday with increasing H850 WAA aloft setting the stage for a warm start to the weekend. .LONG TERM...(Friday night through Thursday) Issued at 304 PM CST Thu Dec 14 2017 The long-term remains mostly quiet with the best chance of precipitation coming on Sunday morning. The aforementioned upper level ridge will give way to a sharp longwave trough digging southeastward along the West Coast Saturday morning, placing Kansas in broad WSW flow. Saturday will feature yet another round of unseasonably warm weather with H850 temps soaring to +11 to +13 C. The NAM is a surprisingly cool solution and places the stationary surface boundary further southeast than the other solutions, so leaned toward the EC/GFS/GEM consensus for highs on Saturday. Gusty southwest winds of 15 to 25 kts combined with afternoon RH values around 25 to 30 percent will present a very high fire danger throughout northeast Kansas given the dry state of fuels. A sharp, negatively-tilted H300 wave lifts through Kansas between 06 and 18Z on Sunday morning with a weak 1005 mb surface cyclone pulling off the Front Range after 06Z Sunday. The evolution of the surface trough/low as the upper level wave outruns it during the day on Sunday is somewhat uncertain. In either case, most guidance have backed off on the coverage of precip Sunday morning and the thermal profiles would support mostly rain with maybe a wintry mix in the early morning along the NE border. The NAM is, once again, the outlier in holding the surface trough further south and advecting cool/moist near-surface air along the KS/NE border. Should this solution pan out, there may be a brief window of freezing drizzle near the NE border Sunday. However, given the NAM`s high moisture bias and the lack of support from other solutions with warmer and drier profiles, did not include any mention of freezing precip in the updated forecast. A second lobe of energy follows on the heels of this system late Sunday night, but the sensible weather effects look to be minimal. Broad quasi-zonal upper ridging then prevails for Tuesday and Wednesday and will bring above average temperatures and dry conditions. A pattern change does shape up for the end of the week. Upper level ridging builds along the west coast with a potent trough digging southward along the downstream flank of the ridge for Thursday and Friday. The 12Z GFS/EC/GEM vary greatly in the evolution of this wave and this evolution will play directly into the region`s weather around the Christmas holiday. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 520 PM CST Thu Dec 14 2017 VCSH possible at terminals through 04Z though precipitation has to overcome dry air in the lower levels. May see a brief period of MVFR cigs at MHK and have less confidence of a a cig at TOP and FOE. VFR conditions expected after 05Z through the end of the period. Winds increase from the west southwest to around 10 kts after 18Z. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Skow LONG TERM...Skow AVIATION...53