Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/02/20

Area Forecast Discussion
National Weather Service Bismarck ND
948 PM CST Tue Dec 1 2020 .UPDATE... Issued at 945 PM CST Tue Dec 1 2020 The forecast for tonight remains on track. Extensive cloud cover across western and central ND, with increasing low clouds east next few hours. Will keep some low POPs going through the evening southwest and south central, with a few indications of isolated precip west (via web cams and a TRACE reported at KHEI). UPDATE Issued at 653 PM CST Tue Dec 1 2020 Main mid to upper level forcing will occur this evening in conjunction with a saturated boundary layer, so will maintain low POPs through this evening, then go dry after midnight. Other forecast elements on track for tonight. UPDATE Issued at 520 PM CST Tue Dec 1 2020 Quick update to expire the wind advisory southwest. Winds have tapered off and will continue to do so over the next few hours. && .SHORT TERM...(This evening through Wednesday) Issued at 243 PM CST Tue Dec 1 2020 The main concerns for the short term period are strong northwest winds in southwest North Dakota this afternoon, a slight chance of light snow across western North Dakota this afternoon through tonight, and a slight chance of light freezing drizzle across central North Dakota tonight into Wednesday morning. A mid level trough axis lies from Saskatchewan toward the Central Rockies this afternoon, with embedded circulations in the process of closing off over southern Saskatchewan and Colorado. At the surface, a north-south oriented cold front is advancing eastward across North Dakota this afternoon, though at a slower pace than expected. Behind the front, strong boundary layer mixing is supporting 30-40 kt northwest surface wind gusts, strongest in far southwest North Dakota where sustained winds around 30 mph have been observed. The ongoing Wind Advisory looks to be in good shape. Earlier today, the cold front was being followed by a band of light to moderate snow in eastern Montana. However, this precipitation has all but dissipated prior to reaching across the border. It does appear there is currently some remnant light snow along and south of Highway 12 in Bowman County. Meanwhile, as the southern Saskatchewan cut-off low drifts southward, some light rain or snow may develop across western North Dakota later this afternoon and into the evening, with the highest probabilities of this occurring in the northwest. Little to no accumulation is expected. Later tonight, as the closed mid level low is forced to the south- southwest by its neighboring closed southern low and a downstream blocking high, low level saturation is forecast to expand across the region. Several consecutive runs of the HRRR and RAP suggest that the saturated layer may become deep enough and contain enough upward vertical motion to support some light freezing drizzle across central North Dakota. The main forcing mechanisms appear to be deformation zone dynamics and isentropic ascent, with upglide actually occurring from north to south due to the closed mid level low. Other guidance is not as bullish on this potential, with saturation layer depth more shallow, weaker lift, and higher ceilings. Therefore, we are limiting this potential to a slight chance for now. Even if the HRRR and RAP do verify, this does not appear to have the makings of a higher-end freezing drizzle event. We also maintained a slight chance of precipitation across western North Dakota through tonight, but forcing is more questionable there and cooler temperatures aloft increase probabilities for hydrometeors falling as snow. High pressure will begin to build over the region on Wednesday, but expect a cooler day with highs in the lower to mid 30s, still near average for this time of year. Cloud cover is expected to decrease through the day, but models are known to dissipate large expanses of low clouds too quickly during the cold season. .LONG TERM...(Wednesday night through Tuesday) Issued at 243 PM CST Tue Dec 1 2020 Mild and dry weather is expected to dominate the long term period. Western CONUS longwave ridging is forecast to hold through early next week, with its influences reaching as far east as the Northern Plains. There is some evidence that a shortwave or two embedded in northwest flow aloft may pass nearby this weekend into early next week, but they look rather weak and dry, and would likely only cause a slight uptick in winds. In fact, both the GEFS and ECMWF ensemble display a 10 percent or less chance of measurable QPF Thursday through Tuesday. There is also strong ensemble support for above normal temperatures, with mean 850 mb temperatures well above freezing and very few sub-freezing outliers in the GEFS. Whichever days over this time period contain mostly sunny skies and westerly winds, which may be most or all of them, will likely see daytime highs outperform model consensus, which is already in the upper 30s to near 50. Looking ahead, there are hints of a cooling trend and a more active pattern by the end of next week. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 653 PM CST Tue Dec 1 2020 A cold front moving through the region will bring gusty northwest winds, MVFR cigs, and a slight chance of drizzle, freezing drizzle, or light snow across western and central North Dakota this evening. The probability of precipitation remains low so will keep out of the TAFs at this time. MVFR cigs will continue into Wed morning, before clearing from north to south during the day Wednesday. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...NH SHORT TERM...Hollan LONG TERM...Hollan AVIATION...NH
...Updated Aviation Forecast Discussion...

.DISCUSSION... Issued at 241 PM CST Tue Dec 1 2020 Today through Thursday: Uneventful weather still expected for the next 7 days. Biggest forecast concern will be how far east the cold front travels before it loses shape and mixes out. One front has already stalled out over central Nebraska. There isn`t much temperature difference with that front, but there is a noticeable wind difference. As of 2 PM, the front stalled out between O`Neill and Norfolk. A strong cold front is currently located in western South Dakota and will move into eastern Nebraska in the overnight hours. How far east and south it goes will be dependent on the low pressure systems on the leeside of the Rockies. HRRR and RAP 500mb analysis show two separate low pressure minima. These mimima are expected to continue their south-southwest trek along the Rocky Mountains. Model guidance suggest they`ll stall out in northern Texas and northern New Mexico and undergo a bit of the Fujiwara effect (essentially, the low pressure centers will pinwheel around each other). Eventually, the system will move somewhat northeasterly and bring a surge of moisture with it. That precipitation should remain well south of Nebraska and Iowa with snow expected in Kansas and Missouri. Lift and moisture are lacking in the area so precipitation isn`t expected. Depending on your location in eastern Nebraska or western Iowa, Wednesday may be your coolest day of the week or Thursday. Locations to the northwest of the cold front will have their coldest day Wednesday. This is likely to be areas north and west of a line from Columbus to West Point to Monona. Though the differences won`t be huge, probably within 5 degrees or so on each day. Temperatures at the 850mb level will increase from about -3C to 0C which should lead to slight warmup on Thursday. Linger cloud may limit temperatures on Thursday in southeast Nebraska and southwest Iowa. Friday through Monday: The pattern is still somewhat convoluted through the weekend and into Monday. In general, a dry and warm pattern will dominate the mid-range as a ridge of high pressure will build over the West Coast. Northwest flow and increased heights over the area may result in temperatures in the 50s on Monday. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 516 PM CST Tue Dec 1 2020 VFR conditions will prevail through the period. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Fajman AVIATION...DEE
Area Forecast Discussion...CORRECTED
National Weather Service Pueblo CO
345 PM MST Tue Dec 1 2020 .SHORT TERM...(This evening through Wednesday) Issued at 325 PM MST Tue Dec 1 2020 Currently... Cloudy, cold and windy weather prevailed across most of the region at 2 pm this afternoon. The only exception was the San Juan region where it was partly cloudy per sat imagery and winds were relatively light. Some sun was note over the far eastern plains, but it was windy and cold. Along the I2-5 corridor region, and especially along the eastern face of the mtns, it was cloudy, cold windy and was snowing in many locations. As one of my colleagues stated "an overall yucky day". Tonight and Tomorrow... The yucky-ness isn`t going to go away anytime soon. major trough moving over the region will keep it cold and windy through most of this period. High res guidance is still indicating it will get quite windy over parts of El Paso county, especially the northeastern sections of El Paso county late this afternoon and evening. Gusts to 45 to 55 mph will be possible per latest runs of the HRRR guidance. There may be some snow falling when this occurs, but is should not be all that heavy. Nonetheless it will be quite miserable for anyone who has to be out an about in this weather. For the rest of the plains, it will remain on the breezy to windy side throughout the night, although winds should be lessening somewhat as the night progresses. As for snow... the best chance will be this evening along the mtns/plains interface from south of Canon City to the NM state line. Several inches of snow will be possible, and I would not be too surprised if some areas see a half foot of snow. Ambient temps tonight will fall into the upper teens to low 20s, but with the winds, it will feel like it is in the single digits and teens. For tomorrow...It will be colder than today, and its going to continue to be rather windy, with winds in the 25 to 35 mph range over a majority of the plains. Best overall chance of snow showers tomorrow will be along the CO/NM-OK border areas and along the CO/KS border, mainly south of Lamar. This precip will due to a combination of upslope flow over the Raton Mesa and possibly wrap- around precip around the large circulation of the cyclone which will be over the TX Panhandle region. With northerly flow continuing over the Palmer Divide, some light snow will be possible over N El Paso county. Max temps tomorrow will only in in the 20s and 30s plains and valleys and tens in the mtns. The winds will make it feel much colder, especially over the plains. /Hodanish .LONG TERM...(Wednesday night through Tuesday) Issued at 325 PM MST Tue Dec 1 2020 ...Blustery Wednesday and Thursday... Wednesday night-Thursday night...Latest models trending into better agreement of an upper low across the Oklahoma Panhandle Wednesday afternoon slowly lifting northeast Wednesday night and Thursday, as secondary energy digging across the Central Rockies Wednesday continues south across the Southern Rockies through the day Thursday. This will keep moderate east to northeast flow aloft across the region Wednesday night, with flow becoming more northerly through the day Thursday, allowing for slowly warming temperatures through out the day. The passing secondary energy will send a secondary front across eastern Colorado keeping breezy northerly winds across the plains through the overnight hours, and combined with slowly decreasing clouds from west to east, may keep the ambient temperature from dropping too much overnight across the far southeast plains, though the apparent temperature will sure be noticed. At any rate, will likely see overnight lows in the teens across the plains, with single digit readings above and below zero across the higher terrain, coldest at the peaks and high mountain valleys. As for precipitation, could continue to see a few light snow showers/flurries across the Pikes Peak region and across the southeast mountains Wednesday evening, with the potential for some wrap around precipitation across the far southeast plains. For Thursday, drier and warm air continues to filter into the region from the north, leading to expected dry conditions. However, Thursday looks to be a "blustery" day with expected breezy northerly winds and temperatures slowly warming into the 30s to lower 40s across the plains, and mainly in the 20s and 30s across the higher terrain. Thursday night will continue to be dry, with continued warming aloft owning to milder overnight lows in the teens and 20s for areas over and near the higher terrain, save for the normal cool pockets across the San Luis Valley and along the lower Arkansas River Valley. Friday-Sunday...Despite model differences on where secondary energy across the Southern Rockies ends up, the main story will be upper level ridging building across the Great Basin and into the region into the weekend. This will keep moderate northerly flow aloft across the area on Friday, which slowly weakens through the weekend. With that said, expecting dry conditions, with breezy afternoon winds, especially across the plains, where warming temperatures will lead to good mixing and increased fire danger. Highs through the weekend look to warm back to at and above seasonal levels in the 50s across the plains, and mainly 30s and 40s across the higher terrain, with at and above seasonal overnight lows. Monday-Tuesday...Again, longer range models indicating differences on location and strength of energy trying to break down the rex blocky pattern across the Conus. With that said, blended model solution keeps dry weather with at and above seasonal temperatures in place across the region through early next week. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 325 PM MST Tue Dec 1 2020 Breezy to windy conditions will continue at the KCOS and KPUB through tomorrow afternoon. Cant rule out some passing snow showers but do not expect any accumulations. Brief periods of MVFR could occur with the snow showers and lower cigs. KALS...winds will be less over this region but as a trough moves over during the nighttime hours, we could see some periods of lower cigs and snow showers. VFR anticipated tomorrow. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...HODANISH LONG TERM...MW AVIATION...HODANISH
Area Forecast Discussion
National Weather Service Riverton WY
754 PM MST Tue Dec 1 2020 .UPDATE... Issued at 754 PM MST Tue Dec 1 2020 The snowfall over the Wind River Basin, Lander Foothills, and adjacent east slope of the southern Wind River Mountains has taken on an upslope pattern. These conditions will likely continue for at least another hour or two. Increased snowfall in these areas to account for this. It appears that Riverton could end up with 2 inches,, and lander close to three, with the adjacent mountains receiving 4 to 5 inches. With the established snow cover in place, and a positively tilted ridge building in from the west, patchy fog will likely occur in the Wind River Basin and possibly the Lander Foothills late Wednesday night and Thursday morning, so added the fog into the forecast. && .SHORT TERM...(This evening through Wednesday night) Issued at 740 PM MST Tue Dec 1 2020 |The latest storm system has moved through the forecast area early this morning and is now over southeast WY. Slightly unstable north-northwest flow follows the system as surface pressures rise. Strongest wind is east of the divide in the Bighorn Basin and across much of Johnson County where wind gusts were over 50 mph earlier. Light showers continue from northern into central WY late in the morning. The current pattern will continue through the afternoon hours, with some showers moving into Sweetwater County as well as off of South Pass. A secondary mid-level low is expected to follow this system and move from eastern Montana into eastern WY this evening. This low is expected to increase snow showers along and east of the divide by midnight as it increases instability and concentrates available moisture into favored upslope areas such as Lander to Beaver Rim. The HRRR is especially showing some increased showers over Casper to Lander by 8pm, then moving south into Sweetwater County by midnight. Some areas may see up to an inch of snow as a result. So, cool breezy north flow will continue into early Wednesday morning with isolated to scattered snow showers. The mid-level low moves over southeast WY Wednesday morning, dragging the area of isolated showers into southern WY with surface high pressure over the area. Clearing skies will occur from north to south Wednesday afternoon with seasonal temperatures and decreasing wind. Upper-level high pressure over the northwest US will then fold over on Wyoming Wed night into Thu morning, likely strengthening surface inversions in the valleys and basins, keeping some low temperatures in western WY below zero. .LONG TERM...(Thursday through Tuesday) Issued at 740 PM MST Tue Dec 1 2020 The upper high that has been progged for the last several model runs will begin its hold over the PACNW/Northern Rockies Thursday. Below normal temperatures remain in the forecast, due to inversions keeping the cold air trapped in the valleys and basins. Fog will remain a possibility in the western valleys Thursday Morning/Friday night/Saturday morning, but confidence has waned in any fog lasting for more than 2 days at this point (Thursday & Friday mornings). The upper high will keep conditions dry, with light winds and mostly clear skies through the weekend. Models have begun to prog a system weakening, as it runs into the ridge. This system will have no impact to the Cowboy State, but could break down the ridge and be a precursor for a more zonal flow pattern next week. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 740 PM MST Tue Dec 1 2020 West of the Continental Divide...KBPI/KJAC/KPNA/KRKS Terminals Expect VFR conditions across the terminals during the TAF period. Snow showers and associated obscurations will linger in much of the mountains through 03z Wednesday. Gusty winds will continue for all locations except KJAC, with gusts to around 30 knots. These winds should diminish between 02Z-06Z across the terminals. Dry conditions expected on Wednesday with some breezy northeast winds in the afternoon across the south. East of the Continental Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals Expect VFR conditions for all terminals through the period, though brief periods of MVFR could occur under snow showers. Snow showers and the gusty north winds will linger in the north, including KCOD, through 02Z Wednesday. Isolated to widely scattered showers will continue in the KCPR area through tonight and most of Wednesday morning. These showers will exit the area around noon. Wednesday afternoon will be cold and dry, with a breezy northeast wind from Natrona to the Green Mountains. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .FIRE WEATHER... Issued AT 740 PM MST Tue Dec 1 2020 Current storm system has moved to the southeast and brought isolated to scattered showers along with cool north to northwest wind. Showers are expected along and east of the divide through Wednesday morning, with the Lander to Beaver Rim area possibly picking up an inch of snow overnight. Light showers will continue Wednesday morning over central and southern WY, but should diminish by noon. Most of western WY will be dry with only some light showers closer to the divide. Temperatures will near seasonal with warming and clearing from the north during the afternoon. High pressure then sets in from Wednesday night through Friday, with strong surface inversions likely forming to keep colder air in the valleys and basins. && .RIW WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Lipson SHORT TERM...McDonald LONG TERM...Hulme AVIATION...Hulme FIRE WEATHER...McDonald