Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/15/19

Area Forecast Discussion
National Weather Service Billings MT
717 PM MST Thu Nov 14 2019 .UPDATE... Occasional high clouds and dry weather are expected tonight, as we remain under the influence of high pressure aloft. Dew point depressions are 3F and 7F at Baker and Miles City, respectively, and there is a risk of localized valley fog in our east tonight. Latest HRRR continues to keep fog out of southeast MT, but there is no denying the moist boundary layer and another night of relatively light S-SE winds. To the west, we will see winds along the foothills increase through the night, but Livingston has seen W-NW winds linger into the evening. Have made some minor wind, sky and temp adjustments...but overall forecast is in good shape. JKL && .SHORT TERM...valid for tonight and Fri... High pressure building over the region will bring mainly dry conditions to the area through Friday. Tightening pressure gradients and strengthening winds aloft will increase the winds along the western foothills this evening and overnight, but advisory level winds are not expected. Patchy fog is possible from Miles City south to Broadus and areas east tonight. The next system moves into the region Friday night in the form of a shortwave and associated cold front bringing showers to the area. Temperatures look warm enough that any snow will be confined to the mountains. High temperatures on Friday will range from the 40s over far eastern areas to the 50s elsewhere. Low temperatures tonight and Friday night will range from the 20s to 30s. STP .LONG TERM...valid for Sat...Sun...Mon...Tue...Wed...Thu... Saturday still on track for a shortwave drop through the area. Still looks that south and east of Billings will see some rain, with the high elevations see some light snow. Behind the shortwave, the surface pressure gradient will increase Sunday. Guidance, both ensemble guidance and local probabilistic, is showing a fair strong signal for a Wind Advisory around Livingston and Nye. Winds should still decreasing by Monday morning. Tuesday onward the models are still showing significant spread in the ensemble members as a splitting trough moves into the western US. The general tread is for cooling temperatures, and snowfall. Much of the details on this are too uncertain say how cold or how much precip will fall. Reimer && .AVIATION... Localized valley fog is expected from KMLS to K00F eastward late tonight into early Friday. MVFR or lower is possible where fog develops, but it will not be as widespread as Wednesday night. Otherwise, VFR under scattered to broken high clouds will prevail through tomorrow. SW-W winds will become gusty along the western foothills, with gusts to 35 kts at KLVM overnight. JKL && .PRELIMINARY POINT TEMP/POPS... Fri Sat Sun Mon Tue Wed Thu ----------------------------------------------------------- BIL 036/058 039/051 034/058 043/059 035/051 032/041 022/038 00/B 31/B 02/W 11/N 34/R 54/O 31/B LVM 035/060 037/048 034/054 040/055 036/052 031/041 021/040 00/N 51/N 02/W 21/N 35/R 53/O 21/B HDN 028/056 034/050 029/057 039/058 032/051 029/041 018/038 00/B 43/W 02/W 21/U 24/O 44/O 31/B MLS 027/050 033/045 028/053 038/053 030/046 027/038 019/035 00/B 32/W 02/W 21/B 33/O 33/O 21/B 4BQ 027/055 032/046 028/054 038/055 030/049 027/038 018/036 00/B 35/W 02/W 21/B 23/O 43/O 31/B BHK 025/048 030/042 025/047 035/049 027/042 025/036 017/033 00/B 12/W 01/E 21/N 13/O 33/S 21/B SHR 025/056 031/046 024/054 035/056 028/051 027/041 016/038 00/B 46/W 02/W 21/U 23/O 44/O 31/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$
National Weather Service Wilmington OH
902 PM EST Thu Nov 14 2019 .SYNOPSIS... A weak cold front will continue to shift through the Great Lakes while high pressure builds in behind. Temperatures will remain below normal into the weekend as cold air is reinforced a little behind the front, and additional weak backdoor cold front slipping through on Friday night. Dry weather is anticipated through the weekend, although clouds will likely remain plentiful. && .NEAR TERM /THROUGH FRIDAY/... The SCT/BKN 4-5kft clouds that had developed earlier in the evening have since dissipated as expected. However, focus has been on the fairly extensive area of low clouds centered over IL/IN that has been ever-so-slightly shifting southeast through the late afternoon/evening hours. Despite the increasingly deep inversion and relatively weak low level flow, the cloud deck continues to erode somewhat on its southeastern fringe per latest GOES-East imagery. This lends itself to a bit more uncertainty than would ideally be expected for the overnight period in terms of just how much this cloud deck will overspread the area and how it will evolve past daybreak Friday morning. There are several hi-res models that continue to show low level moisture becoming better entrenched across the area past about 2 AM or so through mid-morning. However, the 15.00 KILN RAOB showed quite a bit of dry air in the low levels so the exact evolution of the cloud cover through tonight still remains a bit uncertain. Will maintain a cloudier solution in the official fcst for the late overnight/early morning period than perhaps is being depicted by some of the guidance. This will ultimately have an impact on temp traces as well. Moreover, should expansive cloud cover develop/advect into the ILN CWA, it`ll likely stick around longer than some models have suggested owing to weak low level flow and a fairly deep inversion set to persist through the day. Low temps tonight will bottom out in the low to mid 20s. PREVIOUS DISCUSSION --> Focus on the overnight will be on the cloud/sky trends. Weak/elongated and positively tilted shortwave trough will continue to pull east of the area this evening. While right- entrance region of the upper jet induces a band of dense cirrus across the southern parts of the forecast area through this evening, have a more concerned eye on large area of stratus/stratocumulus over IL/IN/MN/WI in the heart of the low- level thermal trough in the wake of the cold front shifting through. Forecast soundings show the weak low level cold advection as the thermal trough moves into the area tonight, but with the large closed low shifting across Hudson Bay, heights aloft are actually slowly rising overnight with mid/high level warm advection. So - the net effect on soundings is a rapidly strengthening inversion with very dry air aloft - on top of moistening and weak cold advection. This is a recipe for the large area of stratus to our NW to continue to move into and across the area later in the night - and this is corroborated with simulated cloud progs in HREF and experimental RAP sky cover forecasts, as well as the past several NAM runs. These models tend to handle the low stratus better than GFS/CMC, so have definitely shifted to a cloudier forecast especially after midnight as the large area of stratus moves in. There is some concern that some fog may develop on the leading fringe of the low clouds, and while this is not in the forecast right now, it may need to be added by the oncoming shifts if visibility begins to drop in the mid-late evening. Am banking that this will manifest more as a low cloud event - and not any dense fog. This makes low temp forecasts very difficult given inbound stratus. Since much of the evening will be clear or partly cloudy, expect temps to fall off quite rapidly. But there is bust potential on temperatures depending on when exactly the low clouds arrive. Have raised low temps just a smidgen...but this will need to be watched...especially with snow cover still complicating things across the northern portions of the CWA. && .SHORT TERM /FRIDAY NIGHT/... Depending on how expansive the low clouds are on Friday morning, there is concern to how quickly these could erode. Could range from mostly sunny to mostly cloudy depending on where the thickest low clouds form overnight, but have trended the forecast toward more clouds. The low level flow will be weak and turning northerly, and the thermal trough remaining over the area, there is concern that the strong inversion could keep things locked in far longer than what is currently forecast. This is an area of high uncertainty - but did trend things toward more clouds than not especially on Friday morning and especially the west/north parts of the forecast area. A weak backdoor cold front slips into and through the forecast area on Friday night and there will be a reinforcing shot of stratus in the weak cold advection behinds this feature. So will see clouds increasing again on Friday night, and this too is an area of high uncertainty on just how expansive the low clouds will be or if enough holes will be there for a partly cloudy vs. a mostly clouds forecast. && .LONG TERM /SATURDAY THROUGH THURSDAY/... The long term period is characterized by below average temperatures and growing forecast uncertainty beyond Sunday night. There will be chances for light precipitation Tuesday and more widespread precipitation Thursday. An area of high pressure centered in southeastern Canada will lead to tranquil weather to start off the extended period this weekend. Saturday will feature below average temperatures with highs around the middle 30s north and middle 40s south under fair weather skies. Lows Saturday night will be in lower 20s to the north and middle 20s to the south. As the area of high pressure moves east on Sunday, high- and mid- level clouds will build in from the west ahead of an approaching upper-level trough. Forecast confidence starts to diminish Sunday night as details on the phasing and structure of the trough, along with a possible shortwave disturbance rounding the base of trough, are not certain at this time. Currently there is ensemble support for broad troughing over the Ohio Valley Monday through Tuesday night. Under the broad trough highs are expected to remain below average and there are chances for precipitation on Tuesday. Ensemble solutions are widely varied between the European EPS and GEFS in terms of precipitation probabilities. The GEFS offer wetter solutions than the EPS members and cannot be discounted as a shortwave rounding the base of the trough could lead to periods of showers Monday Night through Tuesday night. By Wednesday, ensemble solutions amplify the flow and have some ridging building in before the next chance of widespread precipitation approaches the area toward the end of the next week. The timing of this next cold front is still uncertain, but have included chance for precipitation starting early Thursday morning. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... A somewhat complex fcst is shaping up for the TAF period, particularly as it pertains to the expanse and coverage of a 1200-2000ft cloud deck currently positioned across IL/IN that is slowly shifting southeast toward the local area. Hi-res short-term guidance is not handling these low CIGs well -- especially in comparison to observations which actually show CIGs lowering even in the past several hours upstream of the local TAF sites. Have decided to be a bit more aggressive with the fcst of these low CIGs making into the area past 06z, generally from west to east across the region toward daybreak. There are some select fcst soundings that show a 4-6 hour window of low level moisture thick enough to support IFR CIGs leading up to and through daybreak -- especially for northern sites of KDAY, KCMH, and KLCK. And with this in mind, decided to go prevailing MVFR with TEMPO IFR with the combo of advection of stratus and the development of some stratus immediately overhead past 06z. Did not at this time add any VSBY restrictions as suggested by some data as fcst soundings show a /relatively/ dry layer immediately at/above the sfc to about 1kft. Although guidance is fairly quick at scattering out some CIGs by/past 15z, do think this may be a bit too early especially considering the overall weak flow and deeper inversion in place, essentially creating a setup where the low level moisture does not have anywhere to go. With this in mind, there will be some natural mixing within the BL so did show a scattering/lifting trend by the afternoon but this will be monitored as we progress through the morning hours and may need to be slowed beyond current fcst if data trends suggest so. Additional MVFR/IFR CIGs will be possible past 00z Saturday toward the very end of the period. Light southwesterly winds will go variable/calm tonight before eventually going more northwesterly and northerly by Friday afternoon/evening. Winds will generally stay 8kts or less through the entire period. OUTLOOK...MVFR/IFR CIGs will be possible Friday night. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Binau NEAR TERM...Binau/KC SHORT TERM...Binau/Sites LONG TERM...Campbell/AR AVIATION...KC