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

Area Forecast Discussion
National Weather Service Cheyenne WY
849 PM MST Wed Mar 2 2022 .UPDATE... Issued at 820 PM MST Wed Mar 2 2022 Cold frontal boundary zone has slipped south through Chadron this evening and will continue to slowly ooze southward across the central NE Panhandle and should then orient more NW to SE overnight. Confidence is low the boundary reaches Sidney but could barely reach there by 6am Thursday morning. With the cooler airmass comes greater chances of lower ceilings and patchy fog filtering in across the Nebraska Panhandle late tonight and especially Thursday morning from 5am-10am. Can already see lower ceilings building west behind the cooler airmass per nighttime microphysics satellite imagery. HRRR and NAM suggest this trend to continue west as low-level saturation occurs. Confidence is increasing in patchy to areas of fog for Chadron and Alliance with moderate confidence at Sidney and Scottsbluff Thursday morning. Have expanded on day shifts` fog inclusion of patchy and areas of fog farther south across the NE Panhandle and slightly farther west. No precipitation expected but can`t rule out some brief mist in the most foggy/saturated areas. Temperatures will fall near freezing most locations overnight but not too cold with values in the 30s/20s. Another warm day tomorrow with solid rebound into the 50s and 60s. 70s may also be possible in a few select spots in NE Panhandle but clouds could hamper that possibility. Still, an above normal temperature day expected. Updated zone forecast has been sent. && .SHORT TERM...(This evening through Saturday) Issued at 115 PM MST Wed Mar 2 2022 Forecast concerns deal with snow and amounts Friday night into Saturday in the Short Term. Nice warm temperatures the rest of the week...before the bottom drops out Friday night. Currently...Frontal boundary lays across northeastern Nebraska into western South Dakota into southern Montana this afternoon. 1026mb surface high over western Wyoming into northwestern Colorado. Leeside surface trough lays along the east slopes of the Laramie Range with some mid and high clouds over the south Laramie Range. Current 700mb temperatures right around +4C over the Laramie Range...yielding 1PM temperatures in the 50s west of the Laramie Range and near or above 60 east. Very nice day ongoing. Did add some patchy fog across the northern Nebraska Panhandle as we see a slight surge in the northern front into maybe Lusk to Alliance. Surface winds shift to the northeast which is an upslope flow for that area up against the Pine Ridge. GFS showing favorable fog profiles at Chadron and Alliance tonight from rough 08Z to 14Z Thursday. Similar temperatures for Thursday...though more widespread cloudiness may damper afternoon highs some. Most of Friday looks to be warm and dry as well as a low pressure system tracks into the 4 Corners area and moisture begins to increase from southwest to northeast Friday evening. At the same time...the front to our north continues to drop south into the northern Panhandle and Converse/Niobrara Counties in east central Wyoming. May be a brief time Friday evening that precip falls as rain...but my thinking is that we should quickly wet bulb down as forecast dewpoints are in the 20s and low by midnight...precip should be all snow. Definitely all snow by 07 or 08Z Saturday as northern front gets pulled south to near Laramie. Looking like we will need some winter storm watches in the next 24 hours for the mountains out west...maybe the northern Panhandle into Niobrara County as well as the south Laramie Range as current snow totals well above warning levels, Did tweak the qpf amounts over the Pine Ridge in the northern Nebraska Panhandle as guidance usually does not handle the Pine Ridge very well. Will give the night crew a chance to look at another model run before issuing any winter headlines. .LONG TERM...(Saturday night through Wednesday) Issued at 115 PM MST Wed Mar 2 2022 Latter half of the weekend will continue to see light to moderate snowfall across the region with colder temperatures Sunday. Wide upper level troughing across the western CONUS will continue as the leading closed low with the initial round of snowfall Saturday will continue to push off to the northeast while a second closed low will drop into the four corners region. Latest ensemble cluster analysis for Sunday shows little variation in the 500mb pattern all suggesting anomalously low heights. This will result in cold air sitting over the region as 700mb temps drop around -15C through much of the extended. Nudged temperatures slightly below NBM guidance with high temperatures in the low 20s Sunday. Snowfall will mainly continue along and west of the Laramie Range Sunday as a secondary front passes south aiding in additional upslope flow. However, additional accumulations should be light as the better dynamics with this second low appear to remain farther south as the shortwave looks to progress more eastward from the four corners. This upper level troughing over the western CONUS looks to breakdown late Monday with northwesterly low returning to the area with multiple passing progressive shortwaves. This could lead to a brief period of elevated to high winds across southeast Wyoming Monday night into Tuesday and again later in the week. However, parameters do not look all to impressive outside of the wind-prone areas. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 843 PM MST Wed Mar 2 2022 Wyoming TAFS...VFR. Wind gusts to 23 knots from 15Z to 01Z. Nebraska TAFS...VFR at Chadron and Alliance until 07Z, then MVFR until 09Z, then IFR until 14Z, then MVFR until 17Z, then VFR. Wind gusts to 22 knots until 08Z. VFR at Scottsbluff until 09Z, then IFR until 15Z, then VFR. Wind gusts to 22 knots from 09Z to 15Z. VFR at Sidney until 10Z, then MVFR until 15Z, then VFR. Wind gusts to 23 knots from 09Z to 10Z. && .FIRE WEATHER... Issued at 200 AM MST Wed Mar 2 2022 A upper level ridge of high pressure will dominate the districts through Friday. A backdoor cold front will briefly slip southward into far northwest Nebraska Thursday morning, then lift northward Thursday night. Unseasonably mild temperatures will continue for the next few days. Minimum relative humidities of 15 to 25 percent and gusty winds will result in elevated fire weather conditions, however ground fuels are not susceptible for rapid fire growth. A return to colder temperatures, higher humidities and chances for measurable precipitation in the form of rain and snow is expected late Friday through the weekend. Significant snow accumulations are possible, especially for the higher terrain. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ UPDATE...JSA SHORT TERM...GCC LONG TERM...MB AVIATION...RUBIN FIRE WEATHER...MJ
Area Forecast Discussion
National Weather Service Goodland KS
544 PM MST Wed Mar 2 2022 .SHORT TERM...(This evening through Friday) Issued at 145 PM MST Wed Mar 2 2022 Upper ridge remains in control through Friday. The ridge axis will move across the area tomorrow and transition to a southwest flow aloft on Friday ahead of the next system digging into the Four Corners. Main concerns in the short term will be elevated fire weather conditions and a back door cold front which will approach the area Thursday morning with low clouds and areas of fog. The aforementioned front will enter the McCook area around 12z Thursday morning and then stall out near the Colorado/Kansas border area around 18z. HRRR and RAP suggest that there will be a narrow corridor about a county wide of fog immediately on the cool side of the front and low clouds extending well behind the front. RAP is slightly further west with the fog, straddling the Colorado and Kansas border, and more widespread. So, will have areas of fog in that area for Thursday morning. Saturated layer appears very shallow, so will not mention drizzle at this time. Morning lows will be in the lower 30s, so cannot totally discount freezing fog, but clouds may keep temperatures slightly above freezing. Those clouds will gradually burn off by 18z, but more clouds will be moving in from the west in the afternoon. Therefore expecting temperatures to be cooler compared today, with coolest temperatures in southwest Nebraska behind the front where may only see upper 50s. Elevated fire weather threat for Thursday will be confined to southwest part of the area, generally south of Interstate 70, where relative humidity will fall below 20 percent for a few hours. Front will lift out as a warm front on Friday with the warmer temperatures returning. Surface flow will parallel upper winds, and with the added downslope component temperatures should have no problem reaching the upper 70s to lower 80s. Afternoon humidity will fall below 20 percent everywhere and below 15 percent in western areas, resulting in elevated fire weather conditions, but wind speeds for now remain a tad below critical threshold. .LONG TERM...(Friday night through Wednesday) Issued at 202 PM MST Wed Mar 2 2022 For this long-term forecast period, the weather pattern becomes active with several disturbances expected to move through the region. Overall though, confidence is low regarding the threat of high-impact weather from the lead system, mainly because the track is not climatologically favored for a significant winter weather event. The following systems are lower in magnitude and currently do not appear to bring a threat for significant weather. Beginning with the lead system, changes to the overall weather should begin to be observed early Saturday morning as a surface low pressure deepens over the High Plains. In fact, the low should be centered more or less directly over the region. With that in mind, it is currently hard to see the previous day`s weather set up, particularly in the form of placement of the fronts, changing too much until later in the day Saturday as the low moves northeast and swings the cold front southeast. So, on Saturday, it is possible there is a brief period of low relative humidity and gusty southwest winds during the late morning hours. Then, the cold front should move through and cause a shift in the wind direction, which would be problematic for any fires that are able to begin. That being said, this fire weather threat on Saturday is quite conditions as it depends on the exact positioning and timing of the low pressure and front movements. The other weather threat that may come out of this initial system is the chance for wintry precipitation. On the backside of this system, there will be an opportunity for a band of precipitation to develop. Temperature profiles from forecast soundings indicate that behind the cold front, atmospheric profiles are cold enough for snow to be the main precipitation type. That being said, other portions of forecast guidance indicate that the column may not be saturated in the snow growth zone, which could lead to precipitation type in precipitation may fall in the form of freezing drizzle or freezing rain. Again, the wintry threat depends on the movement and exact locations of both the low pressure and surface cold front, as well as any lingering warm layer aloft. This is quite the complicated forecast, but given an evaluation of the overall weather pattern and movement of the upper level low, this system does not currently have the potential to be a significant wintry weather event for the High Plains. Any potential significant snowfall would be well to the north, removed from our forecast area. In addition, forecast probabilities also highlight the same message...there is only a 15 percent chance for QPF to be over 0.25", so the likelihood of significant precipitation in general is quite low. Finally, the temperature forecast is in doubt, mainly as a result of the timing. Once precipitation changes to the wintry variety behind the cold front, I don`t see it changing back due to a warming from daytime heating. Cold air advection should dictate that once the cold front comes through, temperatures drop through the rest of the day. Attention then turns to the next weather system, this one in rapid succession and moving through the region Sunday into Sunday night. However, with this system moving well behind the initial cold front, cold air should prevail and precipitation type issues, or mixed signals on what type of precipitation will fall, are not expected. Therefore, any precipitation with this system should fall in the form of snow due to cold temperatures throughout the atmospheric profile. For this event, there are also no strong signals for substantial lift that would produce any substantial snow bands as we`ve seen. Therefore, am anticipating a broad precipitation field consisting of light snow. Snow amounts should be quite light, only amounting to a dusting for most locations. Finally, another disturbance could move over the Plains on Wednesday. However, model guidance is not in strong agreement, differing drastically on the timing of and somewhat the strength of this system. Therefore, it`s difficult to confidently predict what will happen with this one. A cold front does look to appear to move through, so a return of colder air can be expected. Any precipitation has the possibility of falling as snow, especially if strong cold air advection occurs behind the front. For now, will not highlight this system in any product as uncertainty is quite high at this juncture. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 500 PM MST Wed Mar 2 2022 GLD: VFR conditions will prevail this evening and overnight. A period of IFR stratus and/or fog may develop around, or shortly after, sunrise (12-15Z) -- as a cooler airmass /effective cold front/ progresses southwestward from Nebraska into northwest Kansas. With the GLD terminal situated on, or very near, the western-most periphery of the frontal zone.. considerable uncertainty exists with regard to whether or not low ceilings and/or fog will develop.. and, if so.. the extent/duration thereof. Light and variable winds will prevail this evening through late Thu morning.. shifting to the S and increasing to 10-20 knots by early afternoon. MCK: VFR conditions will prevail through the evening and most of tonight. MVFR-IFR ceilings are anticipated to develop around sunrise (11-14Z).. as a cooler airmass /effective cold front/ progresses southwestward from Nebraska into northwest Kansas. Low ceilings may persist for several hours thereafter. Conditions are anticipated to improve during the late morning and early afternoon. Light/variable or light ENE winds will prevail this evening.. veering to the E and increasing to 12-17 knots shortly before sunrise (10-12Z). Winds will veer to the ESE-SE and decrease to 8-13 knots during the late morning and afternoon. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...024 LONG TERM...RRH AVIATION...VINCENT