Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/02/22

Area Forecast Discussion
National Weather Service Cheyenne WY
751 PM MST Tue Mar 1 2022 .UPDATE... Forecast looks on track this evening. Continuing to watch wind gusts in the wind prone areas reaching the 40-50 mph range, but this is still expected to come down later tonight. .SHORT TERM...(This evening through Thursday night) Issued at 300 PM MST Tue Mar 1 2022 The main concern with this forecast package is the unseasonably warm temperatures and wind speeds during the next couple of days. Latest water vapor loop was showing the upper level ridge dominating the western half of the U.S. Our forecast area was still on the southern edge of the westerlies and deep mixing which has resulted in gusty winds of 40 to 50 mph in the wind prone areas of Arlington, Bordeaux and the I-80 summit with even a few gusts to 55 mph during the last hour. These winds have shown signs of subsiding during the last couple of hours, but gusty winds may linger through the evening into the overnight. This will result in mild temperatures again tonight across much of the area, especially the downslope areas. We followed closest to the HRRR solutions with these warmer temperatures. Wednesday into Wednesday night: Even warmer temperatures are on tap for the region tomorrow in response to warm temperatures aloft, downsloping winds and deeper mixing. The only fly in the ointment that may prevent temperatures from climbing well above guidance is the potential for mountain wave cloud cover. Not confident about the duration of this cloud cover, so we did bump up temperatures a few degrees compared to the previous forecast which agrees with the blends. Thursday-Thursday night: After another unseasonably mild day on Thursday, there is some question on whether a back door front will be able to creep into the northern Panhandle early Thursday morning in response to a weak shortwave aloft. If this boundary can creep into the Chadron area, they may see some low clouds and patchy morning fog in the Pine Ridge. However, it should be rather shortlived in response to the upper level ridge continuing to build into the area. Temperatures will even be approaching record highs for many locations. .LONG TERM...(Friday through Tuesday) Issued at 300 PM MST Tue Mar 1 2022 Friday will consist of a longwave trough parking itself across the entire west CONUS, with the remnants of an atmospheric river from the Pacific Ocean moving onshore in Southern California. Embedded within this longwave trough will be a shortwave disturbance that will carve its way toward the Four Corners region of the desert southwest by Friday afternoon. While this is happening upstream of our cwa on Friday, we will be enjoying the last day of warm temperatures. 850mb temperatures across the NE Panhandle per the GFS are progged at +12C to +19C by 21Z. 700mb temperatures for SE WY will be in the +1C to +3C by 21Z. The bias corrected grids for the NAM/GFS/EC/Canadian all have high temperatures eclipsing 70 degrees for the NE Panhandle, with highs east of the Laramie Range for SE WY in the middle to upper 60s. Have gone with a slow upward trend for the highs on Friday because of this guidance trend. Temperatures are anticipated to rise into the upper 40s and low 50s west of the Laramie Range in SE WY across the lower terrain, and likely into the 60s for areas east of the Laramie Range by Friday afternoon. Clouds will increase throughout the day, likely limiting afternoon high temperatures for several areas, but the southern NE Panhandle is potentially going to have the latest arrival of cloud cover, thus have gone with the upper 60s there in addition to the North Platte River Valley of the NE Panhandle. Lee-side cyclogenesis is progged to develop by Friday afternoon/evening over northeast CO due to the pressure tendencies from the upper level shortwave. This is a favorable area for the northern stratiform precipitation to impact our cwa. With much above average temperatures being in place across the region, this will likely present a tough setup for the precipitation timeline to switch from rain to snow initially. The GFS is advertising a switchover from rain to snow by daybreak Saturday morning in the 12Z-15Z window, but the EC continues to hold onto a colder solution where snow is progged to develop by 6Z-9Z Saturday for areas along the Laramie Range. Have gone with a blend between the two, which has lowered the official snowfall forecast for now. We will have a cold rain before the switchover to snow. Snow ratios will be low at first...meaning we will likely have a heavy, wet snow to deal with for areas across the cwa before a secondary push of colder air arrives via the next shortwave by Saturday night causing a more fluffy snow transition. The mean GEFS Plumes for the event show an approximate 6 inch total for CYS. Have gone against this mean average for now, with a general 2-6 inch snowfall forecast, with slightly higher totals in the mountain zones. Model variability has continued to keep confidence in the low to medium threshold for now. Cold air will be here to stay by Saturday evening. The base of the longwave trough will sweep through the area by Sunday into Monday. This will bring another round of possible light precipitation. Daytime highs will be in the 20s, to around 30 degrees for Sunday into potentially the remainder of next week. This would put the area in the 15 to 20 degrees below normal category for daytime highs if it does indeed occur. Multiple shortwaves are progged to sweep across the area from the end of the weekend into next week, reinforcing the cold air across the region. This would improve the drought conditions across the region, but also keep the thought of an early springtime at bay. For now, we can look forward to improved chances of precipitation reducing drought concerns for the cwa. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 439 PM MST Tue Mar 1 2022 VFR. Wind gusts to 27 knots at Rawlins, Laramie, Cheyenne, Scottsbluff and Sidney until 03Z, then gusts to 24 knots at all terminals except Chadron after 15Z Wednesday. && .FIRE WEATHER... Issued at 300 PM MST Tue Mar 1 2022 Near critical fire weather conditions will be possible during the next couple days, but fuels are currently not ready. However, very dry conditions will be in place during the next couple of days with minimum relative humidites ranging from 15 to 25 percent. Wind speeds will generally range from 15 to 25 mph with the stronger winds mainly in the wind prone areas. The pattern will be changing as we approach the weekend with much cooler temperatures and more precipitation chances. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ UPDATE...MN SHORT TERM...REC LONG TERM...BW AVIATION...RUBIN FIRE WEATHER...REC
Area Forecast Discussion
National Weather Service Grand Forks ND
928 PM CST Tue Mar 1 2022 .UPDATE... Issued at 918 PM CST Tue Mar 1 2022 Current radar shows the highest reflectivity over south central ND just southwest of the CWA, moving from SE BIS area into ABR area. There have a been a few reports of rain in Bismarck and Aberdeen, but overall amounts have been very light. ND DOT highways are showing green throughout most of the state, and road temps to the west are ranging from the upper 20s in north central ND to around 36 in south central ND. Overall, there have been no impacts so far in the FGF area. Echo intensities upstream in north central ND are increasing, with Minot AFB reporting light snow. I believe we have a better chance of seeing precipitation across our CWA with this second round, and CONSHORT and HRRRTL are both increasing POPs shortly after midnight. A transition from snow to rain and freezing rain is still expected along a corridor roughly from Devils Lake to Detroit Lakes. However, with nothing falling to this point...have removed any mention of ice accumulation from 00Z to 06Z. Will change messaging to a trace to five hundredths of an inch, down from the previous forecast but still has the potential to be quite impactful. Snow further north still looks to be a trace to about half an inch, locally higher up to an inch possible but, overall, forcing is fairly weak and no sig snowfalls expected. UPDATE Issued at 624 PM CST Tue Mar 1 2022 Low clouds are moving into central ND and our far western zones, however have not seen any precip reports. It is a matter of waiting for the column to saturate...and prefer the slightly slower models such as the HRRR over the more aggressive RAP. The inherited POP grids reflect this well, and not planning any changes with the 1900 L update. The 00Z Advisory start time will more likely be in the 03Z to 04Z timeframe for impacts in the western zones, and after 06Z for the southern valley. However, some light DZ could start anytime so will keep hazards as they are, but greatest impacts won`t get going until after midnight. && .SHORT TERM...(This evening through Wednesday night) Issued at 333 PM CST Tue Mar 1 2022 A clipper will bring a widespread dusting of snow to the region tonight into Wednesday morning, with a wintry mix and light icing in our west and south. Main baroclinic zone is just west of our CWA with surface high pressure continuing to transition over our area. The next clipper is moving out of Alberta along into southern Saskatchewan, and we already seeing areas of light returns expanding on regional radars in northeast Montana. This timing is matching up well with a consensus of short range guidance which shows it eventually spreading into our northwest after 6pm and then overspread our CWA through the late evening/overnight. Models indicate the wave will remain open with less obvious/weaker synoptic ascent, while any pockets of frontogenesis are progressive/transient. The signal for light QPF is there, but amounts should be light and this matches ensemble trends/NBM probs showing high probabilities of a dusting but very low probabilities (less than 10%) of 1" or greater. Most precipitation should be ending by midday Wednesday with a dry period then favored through Wednesday night to to a stronger influence of mid/upper ridging to our west/rising heights. A warm nose is shown to build east this afternoon/evening ahead of this wave, and HREF FRAM mean shows light icing potential, while NBM4.1 probs for greater than 0.01" are 30-60% along our western and southern CWA. It is hard to say how far east potential freezing rain/drizzle mix would be, but the signal/potential is there and it only takes a trace of icing to cause dangerous travel conditions. Considering the signal in guidance, we went ahead and issued a Winter Weather Advisory for this evening for areas in our far west and south where up to 0.1" of icing is forecast. .LONG TERM...(Thursday through Tuesday) Issued at 333 PM CST Tue Mar 1 2022 Overview... Periodic chances for light snow will continue through the end of the week. Then, a robust Colorado low is expected to impact the region Saturday into Sunday. This will bring with the potential for accumulating snow, which may be heavy in some areas. Otherwise, temperatures will remain generally below normal in the teens to 20s. Thursday and Friday... Northwesterly flow aloft will begin to shift more zonally as an upper trough digs in over the western CONUS. As this occurs, the next shortwave on Thursday is expected to travel to the south and west of the FA. This will lead to a cooler Thursday with highs in the teens. The next opportunity for light snow then arrives on Friday as a midlevel frontogenetical band, associated with an upper trough moving across the Canadian prairies, sets up over the region. This feature will likely produce winter weather impacts across the area, although the degree of these impacts is still to be determined. Impacts will be tied to the strength of the forcing, as synoptic forcing looks to be minimal, as well as the residence time of snowfall in any one area. Overall, light snow is anticipated with this system, with some potential for heavier pockets if mesoscale banding sets up. Saturday through Monday... There continues to be a persistent signal within ensemble guidance for a Colorado low to impact the region in some capacity Saturday into Sunday. Questions pertaining to the exact track of this system, however, continue to plague ensemble guidance. There seems to be two general solutions with regards to this system; a southern Minnesota track of the surface low and a south-central Iowa track of the surface low. The former solution yielding a higher QPF scenario while the latter solution yields a lower QPF solution. Despite the uncertainty in the forecast positioning of this low, the general consensus is honing in on the solution of at least increasing snow chances for most of the area Saturday into Sunday. The main variations will be in regards to the intensity of snowfall across the southern FA. This is further evidenced by NBM probabilities of 24 hour snowfall exceeding 2" in the 20-40% range across the northern FA to the 40-60% range in the southern FA. There is potential for heavy snow in the southern valley into west central Minnesota as well, as indicated by NBM probabilities of 24 hour snowfall exceeding 6" in the 10-20% range. All this said, there are increasing chances for snow across the region, that may be heavy at times across the southern FA. As the deepening surface low tracks to our south, gusty winds out the north-northeast are anticipated. This, in conjunction with falling or freshly fallen snow, may lead to increased blowing snow potential as well on both Saturday and Sunday. By Sunday evening, the bulk of this system should have transitioned eastward out of the forecast area. This will lead into a quieter period moving into early next week. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 514 PM CST Tue Mar 1 2022 Flying conditions will begin to deteriorate by 06Z tonight, with significant impacts on the GA community. A clipper system will move across central and southeastern ND tonight, lowering cigs to near IFR conds. Worse, however, will be the potential for mixed precipitation especially at FAR. DVL would also have a decent chance of seeing FZDZ mixed with SN, however attm it appears to be north of the transition zone. This will likely occur around or after midnight, however icing conditions may be earlier...see for the latest official icing forecasts. Conditions will gradually improve by late tomorrow morning. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...Winter Weather Advisory until 9 AM CST Wednesday for NDZ014-024- 028-038-039-049-052-053. MN...Winter Weather Advisory until 9 AM CST Wednesday for MNZ003-029. $$ UPDATE...Speicher SHORT TERM...DJR LONG TERM...Rick AVIATION...Speicher