Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/10/21

Area Forecast Discussion...Updated
National Weather Service Billings MT
818 PM MST Tue Nov 9 2021 .UPDATE... A fragmented upper trough was working through Washington and northern Idaho this evening. Ascent on the front side of the trough was producing an area of light showers over central zones (away from downslope influences). Generally from Billings west, downslope was ruling over ascent and precipitation was drying out as it moves east. This will turn around later tonight as the main trough axis sweeps across and overpowers the downslope. Main locations for precipitation looks to be over the mountains (in particular the northwest facing slopes) and locations from Treasure to Big Horn counties. This handled pretty well in existing forecast and will let ride. Temperatures were still fairly mild with readings in the 40s and the cold front just west of Billings. Temperatures will fall into the mid to upper 30s as readings will be held up by west to northwest winds. Look for a rain and snow mixture in lower elevations toward morning but believe warm ground and winds will keep accumulations down. Exposed surface, such as bridges and overpasses have the best chance of getting a light accumulation, so keep that in mind for the morning commute. TWH && .DISCUSSION... Tonight through Thursday night... An upper trough will move eastward across southern Canada and the northwestern US tonight and reach the northern Plains Wednesday afternoon. This trough will bring a cold front across the area this evening, with mountain snow showers and lower elevation rain showers that change to snow showers tonight. Mid-level frontogenesis and northwesterly upslope flow look to produce Snow accumulations tonight of generally 1 to 6 inches in the mountains (greatest in Beartooths). Given the northwesterly flow, amounts should be lighter in the foothills due to lack of upsloping from that wind direction, with snow accumulations less than one inch. Downsloping will limit precipitation amounts especially for areas northwest of Billings. The HRRR model is reasonably showing precipitation forming over central areas late this evening and then moving east/southeastward into southeast MT and north central WY early Wednesday morning. Even in these areas that are more favored to receive precipitation tonight, precipitation amounts will be light, generally less than 0.1 inch. There could be a few slick spots, especially on bridges and overpasses, in Sheridan County Wednesday morning as the wet surface from rain and snow could freeze as the air cools. On Wednesday, the upper trough will move eastward into the Dakotas. The precipitation will diminish over southeast MT, but there will still be isolated to scattered rain and snow showers over south central MT and north central WY from instability. This pattern will also cause mid-level wind speeds to increase to about 30-40 kt. Strong low-level lapse rates will facilitate a windy day tomorrow as those mid-level winds mix down to the surface. Winds will gust to 35-50 mph across the area, with the strongest gusts expected in the western foothills, from Nye northward to Big Timber and Harlowton and westward to Livingston. Winds will subside somewhat Wednesday night with the loss of solar heating and associated stabilization of the lower levels, but it will still be breezy over southeast MT with gusts to 30 mph due to a surface pressure gradient there. Thursday, an upper low will deepen as it moves from ND to MN. As this low deepens, winds aloft and the surface pressure gradient will strengthen over southeast MT. This pattern should produce gusts to 50 mph over southeast MT Thursday afternoon. The low will move farther eastward Thursday night which will cause the surface pressure gradient to weaken and thus winds will decrease through the night with gusts to 30 mph possible there late Thursday night. In addition, there will also be snow showers in the mountains as a weak disturbance moves over that area but amounts will be light. Low temperatures tonight will generally be in the 20s and 30s, then 20s Wednesday night and teens and 20s Thursday night. High temperatures will be in the 40s to near 50 degrees Wednesday and 30s and 40s Thursday. RMS Friday through Tuesday... Unsettled weather looks to prevail through the extended forecast with ensembles showing short periods of ridging followed by shortwaves moving through the region in northwest flow. Friday looks to be fairly dry with ridging over the region, before beginning to break down on Saturday as a shortwave drops in from the northwest. The wave will bring some chances for rain and mountain snow, along with cooler temperatures into Sunday. Breezy northwest winds look to spread over the area on Saturday as well. Snow may linger over the mountains on Sunday in unstable northwest flow. Ridging then looks to build in for Monday, before another possible system drops in from the northwest on Tuesday, bringing additional precipitation chances. High temperatures are forecast to range from the 30s over the east, to around 50 degrees over the west on Friday with mainly 50s over the area on Saturday. Temperatures cool into the 40s on Sunday, before warming back into the 50s on Monday and Tuesday. Low temperatures in the 20s and 30s are forecast most nights. STP && .AVIATION... A clipper system dropping through the region will bring increasing clouds and scattered rain and mountain snow showers to portions of the area through tonight, along with a wind shift to the northwest. Localized MVFR to IFR conditions are possible with the shower activity, along with mountain obscurations. Otherwise, VFR will prevail. Breezy northwest winds can be expected across the area on Wednesday behind the clipper. STP && .PRELIMINARY POINT TEMP/POPS... Wed Thu Fri Sat Sun Mon Tue ----------------------------------------------------------- BIL 035/048 029/044 027/048 039/056 036/049 036/057 041/056 52/J 21/N 11/B 23/R 32/R 21/E 24/R LVM 027/043 024/044 029/051 039/054 034/051 037/058 039/053 72/J 12/J 12/O 23/R 33/R 11/N 24/R HDN 033/050 027/044 022/048 035/057 031/049 032/058 036/058 72/W 21/N 11/B 24/R 32/R 21/E 23/R MLS 035/048 028/039 019/040 031/053 029/046 031/052 034/053 42/W 10/N 01/B 33/R 21/E 11/E 12/R 4BQ 037/047 029/039 020/042 033/054 031/046 032/055 036/056 52/W 21/N 01/B 24/R 21/B 11/B 12/R BHK 035/046 026/036 017/035 024/049 026/043 026/050 032/052 51/N 11/N 01/U 33/R 21/B 10/E 12/R SHR 032/046 024/042 022/048 034/057 031/049 030/058 035/058 63/J 22/J 11/B 24/R 32/O 11/B 13/R && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$
Area Forecast Discussion
National Weather Service Grand Rapids MI
708 PM EST Tue Nov 9 2021 LATEST UPDATE... Update .SYNOPSIS... Issued at 257 PM EST Tue Nov 9 2021 - Fall Storm to bring Winds Thursday with Snow Showers over the Weekend - && .UPDATE... Issued at 707 PM EST Tue Nov 9 2021 I have added fog, locally dense ,to our grids/forecast for late tonight into early Wednesday morning in the I-69 area. This is the result of the surface high coming overhead early Wednesday morning, resulting in clear skies and light winds. In the boundary layer we have a weak northeast winds. That is just enough to bring some shallow moisture from Lake Huron into the I-69 area. Since surface temperatures should be near freezing by then, that has the potential of creating several hours of freezing fog. This could be a travel issue if it happens. So for now, I have updated the grids and forecast products to include this. A side note to this, just about all of our that all of our high resolution models are forecasting this fog and in the same area (I-69). I have noted over the past few years ,when the NAM, NAMNEST and RAP model all have dense fog in the same place at the same time, it just about always ends up happening. Tonight that is the case. So I am really concerned about this. Hence the forecast update. && .DISCUSSION...(This evening through next Tuesday) Issued at 257 PM EST Tue Nov 9 2021 Weak f-gen bringing light rain/sprinkles this afternoon with most precip evaporating in dry subcloud layer. This peels off to the east this evening as cold front/sfc trough moves through. Potential remains for a strong Fall storm Thursday with upper low bringing snow showers into Saturday, with an uptick in the snow on Sunday as a clipper/shortwave trough moves through. Upper trough across the northern plains digs southeast on Wednesday with surface cyclogenesis across the central Plains on Thursday before the low occludes and begins to fill on Friday. The deepening low will generate an isallobaric wind component that may result in some strong gusty winds on Thursday. We expect rain showers to break out Wednesday night as warm advection wing arrives. The heavier rain then moves in Thursday morning with the warm conveyer belt as moisture is drawn north into the expanding circulation of the low. There are some fairly strong environmental winds coincident with this feature so any deeper updrafts in embedded convection could bring wind gusts over 40 mph. Fortunately, instability is limited so we are not expecting widespread wind damage, but scattered power outages are possible. The wind threat continues in the cold advection pattern Thursday afternoon, with forecast wind profiles showing 35 to 40 mph in the mixing layer during the afternoon over much of the forecast area and 45 mph gusts possible along Lake Michigan. There looks to be a break in the precip Thursday night as the dry slot is over Lower Michigan, then lake-enhanced snow showers move in on Friday as deeper moisture with the upper low moves in. Southwest flow at this time suggests our northwest zones from Muskegon County to Mason County and inland of there will see the possibility of accumulating snow as strong low level convergence in this area could produce snow rates able to overcome marginal surface temperatures. As the axis of low pressure shifts east Friday night, the flow goes west and the better surface convergence shifts south along the coast. Wet bulb zero heights diminish to near the surface on Friday night and continue there over the weekend, with some areas getting measurable snow sticking to the ground. We expect p-type to be mostly snow except right along Lake Michigan where the residual warmth of the water may be enough to keep a mix with rain and prevent accumulations. An uptick in the snow is expected on Sunday as the core of the cold air moves through with the potential for a clipper type low or sharp upper shortwave trough enhancing the snow. This feature is shearing out as it gets absorbed into the circulation of the big upper low with snow showers diminishing on Monday as it moves east and heights begin to rise. A general 1 to 3 inch snow event could be expected by that time. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 645 PM EST Tue Nov 9 2021 Currently skies are clearing over all of our TAF sites but the I-94 TAF sites still have cigs just above MVFR (3500 ft). There is some drier air moving in so all sites should be clear or nearly so by 03z-05z. Winds will be light and variable. Then we have a fog issue. Seems with winds being calm and skies clear an a northeast wind in the boundary layer this is enough low level moisture from Lake Huron to result in dense fog for our I-69 and I-94 TAF site in the 09z to 12z time frame. I am not 100% on this but since the RAP, HRRR, and NAM are all showing it and typically when they all show this happening it does end up happening I put it in those TAF sites. This fog should be shallow and should mix out quickly after sunrise, even in November. Winds will be more or less east or east northeast at the surface on Wednesday. High and mid clouds will increase during the afternoon as the frontal cloud band gets closer to this area. The system clouds move in late in the day and rain should follow after 04z on Thursday. && .MARINE... Issued at 257 PM EST Tue Nov 9 2021 We will not issue a Gale Watch is it appears winds are marginal and although there could be some gusts to 35 to 40 knots Thursday, the duration is not expected to be more than a few hours. We will assess this again on the midnight shift, but at this point it looks like a long duration Small Craft Advisory from Wednesday night into the weekend will be the way to go. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. LM...None. && $$ UPDATE...WDM SYNOPSIS...Ostuno DISCUSSION...Ostuno AVIATION...WDM MARINE...Ostuno