Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/10/22

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
943 PM CST Fri Dec 9 2022 .UPDATE... Issued at 926 PM CST Fri Dec 9 2022 Western edge of the stratus deck is stalled just east of the Missouri. Under the stratus we are seeing light (also patchy dense) fog, along with scattered flurries and patchy freezing drizzle. Evidence of this on web cams and an mping report near Watertown. Added mention of flurries/freezing drizzle to the forecast earlier to account for this. Will monitor for increasing areal coverage of dense fog, which some guidance suggests. May need a headline if that`s the case. Otherwise, visibility at reporting stations remains above 1SM as of 03Z. Should start to see eastward movement of the stratus deck closer to morning as the surface trough/wind shift line continues advancing eastward, bringing with it drier air. Don`t expect much change in temperatures through the night under the stratus deck either. Also issued a Winter Storm Watch for central SD to better match up with surrounding offices. Left it along the Missouri River for now as this is where ensemble means continue to show the highest probs for 6+ inches of snow. Some of these higher probs do show up further northeast to between Aberdeen and Jamestown, but will let later shifts sort through those details. UPDATE Issued at 533 PM CST Fri Dec 9 2022 Aviation discussion updated below for the 00Z TAFs. Also updated the forecast for the overnight hours into Saturday to increase the mention of fog, as most models keep us in lowered visibility into Saturday. Should see the fog/low clouds dissipate from west to east with the passage of the surface trough/wind shift on Saturday. && .SHORT TERM...(This Evening through Saturday Night) Issued at 215 PM CST Fri Dec 9 2022 A persistent stratus layer with some embedded freezing fog will remain a forecast challenge through Saturday morning. Even with high clouds streaming in, the stratus is not eroding but expanding west. The hi-res models all exit it to the east Saturday afternoon as high pressure and northwest flow briefly move in. The NBM (and most of the other models) continue to struggle (a lot) with temperatures, staying too warm in clear areas overnight and too warm over snow covered or cloud covered areas during the day. A mix of HRRR, RAP and HREF proved to be the best contenders today so stuck with that blend for tonight through tomorrow night. Saturday does appear to have the potential to be much warmer with dry mid levels and an upper ridge transitioning in. The ridge will stick around into Saturday night, but high clouds may increase with shortwave flow through the ridge. Southerly winds will increase Saturday night ahead of low pressure along the lee of the Rockies. .LONG TERM...(Sunday through Friday) Issued at 215 PM CST Fri Dec 9 2022 When the period opens on Sunday, conditions are quiet over the CWA. The biggest forecast challenge remains nailing down precipitation timing, type and amounts between Monday night (6PM CST) and Thursday morning (6AM CST), along with what, if any, impacts breezy to windy northerly winds that develop on Wednesday could have on visibility and travel from falling/blowing/drifting snow. By 18Z Tuesday, the whole CWA (except perhaps the I-29 corridor eastward) should be into snow p-type, heavy at times, with the highest amounts likely piling up along and west of a line from Leola to Murdo. That far eastern portion of the CWA may have a hard time switching over to snow prior to 6PM CST Tuesday, and probably end up receiving the least amount of snow from this event (potentially less than 6 inches). It`s likely that precipitation starts off as drizzle by Monday afternoon. Not really seeing data that supports snow p- type until closer to 12Z Tuesday. The drizzle (or freezing drizzle if there is some portion of the CWA at or below freezing on Monday) will likely become heavier heading into Monday night, until saturation aloft catches up to the deep lower stratus deck to produce plain rain or snow, probably by 6AM CST. Still looks like breezy to windy easterly component winds will be setting up as the event unfolds, before gradually switching around to a more northerly direction on Wednesday. NBM4/1 ensemble-based guidance + deterministic poor man`s ensemble of low level wind progs and what`s available in the S.A. Ensemble table suggests that the strongest winds on Wednesday will be developing/spilling over from western SoDak, potentially creating a situation where visibility could be considerably reduced (especially in open/rural areas) in falling/blowing snow, complete with hazardous drifting snow potential. By Thursday afternoon, the system and it`s wintry precipitation/wind should be dwindling/moving away from the region, leaving the remainder of the extended dry and cold, as a rather blocky upper level pattern could be setting up across the central portion of the CONUS. && .AVIATION...(For the 00Z TAFS through 00Z Saturday Evening) Issued at 533 PM CST Fri Dec 9 2022 Terminals KABR,KATY,KPIR,KMBG IFR CIGs/VSBY expected overnight across KABR/KATY. Currently, the fog/low cloud line is just east of the Missouri River. Guidance suggests this line creeps westward to perhaps affect KMBG with lower CIGs, but not KPIR. Will certainly watch this trend and adjust TAFs as needed. Otherwise, anticipate a gradual improvement in conditions from west to east on Saturday as a surface trough moves east across the area and shifts surface winds to a west/northwest direction. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...Winter Storm Watch from late Monday night through late Wednesday night for SDZ003-004-009-015-016-033>035-045-048. MN...None. && $$ UPDATE...TMT SHORT TERM...Wise LONG TERM...Dorn AVIATION...TMT
Area Forecast Discussion
National Weather Service Denver/Boulder CO
806 PM MST Fri Dec 9 2022 .UPDATE... Issued at 758 PM MST Fri Dec 9 2022 Short wave trough is passing across WY this evening, with increasing mid/upper level subsidence developing from west to east across our area. Gusty downslope winds will develop as the airmass be becomes increasingly stable overnight. Berthoud Pass ASOS has been gusting to around 60 mph so far this evening, with gusts of 40-50 mph possible in the foothills. The latest RAP keeps the idea of isolated-scattered snow showers mainly over the higher west facing mountain slope of Jackson and Larimer counties tonight. Most of this is depicted well in the current forecast so only minor adjustments planned at this time. && .SHORT TERM...(This evening through Saturday) Issued at 241 PM MST Fri Dec 9 2022 Winds are starting to blow over the higher foothills as the mid level speed max associated with the passing shortwave approaches. The wave has nosed down into Boulder over the past hour or so. Speeds are mostly 30-40 mph gusts. We expect the downslope winds to become more widespread but mainly stay in the foothills and the spots where it usually leaks out onto the plains...Rocky Flats/Broomfield, Carter Lake, Cheyenne Ridge. Speeds will likely come up a bit more but the 50 mph gusts should be limited to the normally windier areas. There`s still a shallow moisture layer upstream of the Park Range, but it`s pretty limited, so the low PoPs we have over the northernmost mountains through this evening look sufficient. Skies will clear over the plains pretty quickly, allowing for another cool night. That upstream cloud layer will be slower to dissipate, though it should vanish late tonight or Saturday morning. We`re showing warmer lows around zero in the mountain valleys based on the clouds, it could drop much colder if they clear early. A warming and subsident air mass will bring slightly warmer highs tomorrow. Winds drop off pretty quickly, though there will still be some over the ridges. Breezy conditions will also develop over the area south of I-76 in the afternoon, which combined with low humidities will produce elevated fire danger, but we`re not expecting Red Flag conditions. .LONG TERM...(Saturday night through Friday) Issued at 241 PM MST Fri Dec 9 2022 ...Key Messages 1) Large winter storm expected across portions of the region late Monday through late Tuesday 2) Still ample uncertainty in the track of the developing low pressure over the plains - track dictates more/less heavier snows and therefore impacts in tandem with stronger winds 3) Elevated fire danger concerns Sunday across portions of the plains 4) Well below mid-December temperature averages expected through the week... Sunday...Short-wave ridging moves overhead and the upper level jet max pulls farther east across the mid-west allowing surface winds to relax a bit more. Winds veer more towards the south-southwest on bumping up daytime temperatures back to 7-10 degrees above climo averages. With the warmer temperatures and some breezy conditions in place, elevated fire danger conditions will likely be present across the Palmer Divide and eastern plains. Monday...We`ll call this the `Deep Breath Before the Plunge` in a few ways - big pattern swing, potential high impact winter storm, and cold temperatures after Monday. Large scale troughing starts to enter into the Great Basin sending stronger southwest flow aloft into the region. This will help to keep temperatures above average for much of the day, drawing up warmer and somewhat moister air from the south-southeast. The Denver cyclone stands out Monday afternoon which could help to pull down an encroaching cold front later Monday...temperatures start to crash behind the front. Tuesday...The main event. Though modeling has been consistent in the general placement of the surface low pressure on Tuesday, there are still small juxtapositions that will greatly affect the overall impacts from this system. The trends in ensemble guidance have shifted the position of the surface low a few miles farther north meaning, winds are a pretty solid lock, and a little bit less snow outside of the northern mountains and far northeastern plains. We drop the low`s placement a few more miles south, more snow for a lot more places. As of now the positive tilt of the mid-level troughing should transfer the energy from west to east across the state faster on Tuesday morning meaning a more limited shot of snow across the Front Range is expected. If we`re able to slow down the troughs movement a bit more, with stronger downstream blocking, we may be able to have the trough axis go neutral or negative allowing for a slightly longer snowfall event overall. Though details are rather thin at this time we should note that stronger northerly winds will be in place for much of the day Tuesday. The colder nature of the system overall could produce snow ratios into the 12-16:1 ratios, a bit more airy, which would allow for more blowing of the snow to occur. There is still a lot in play with both a snow boom or bust that could occur. Ah, forecasting winter weather with a lee-cyclogenesis in your backyard, it`s rather "fun" at times. Wednesday - Friday...Though there may be some lingering wrap around snow showers on Wednesday as the main trough continues to deepen and pull away to the east-northeast. A much colder airmass then settles in place with highs around 5-10 degrees below climo averages and still rather breezy out east and along the foothills. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 455 PM MST Fri Dec 9 2022 VFR through Saturday. Typical light winds except maybe some brief gusts to 20 kts at KBJC from 03-09z. Not confident enough to put it in the taf at this time however. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Cooper SHORT TERM...Gimmestad LONG TERM...Heavener AVIATION...Cooper
Area Forecast Discussion
National Weather Service State College PA
731 PM EST Fri Dec 9 2022 .SYNOPSIS... 1046 MB high pressure centered just east of James Bay Canada will extend its ridge into Central PA and bring us dry weather into Saturday evening. A shortwave trough will move across the state from the west later in the weekend. A period of light precipitation should result for Saturday night and Sunday, with snow over the north and a mixed bag turning to rain over the south. Upper level ridging is then expected to move in with fair weather for the first half of next week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Lingering low and shallow strato cu based around 1 KFT AGL were noted across the n-central mountains where a light sfc-925 mean NNE flow was transporting moisture off Lake Ontario and the Finger Lakes beneath the strong, 6-7 deg C/kft subsidence inversion. Elsewhere, skies were clear with a very light nerly breeze. Mid and high clouds slide east and overhead late this evening through the overnight, ahead of the weak sfc low over southern Ohio and supporting 500 MB trough near South Bend, Indiana. That wave moves toward us tonight probably makes some very light precip over the southern part of Somerset Co late tonight and very early Sat AM. The big high pressure overhead will continue to suppress the moisture with this system tonight to our S. HRRR and RAP forecasts and HREF precip mean barely makes any precip fall over the Laurels. Thus, the bulk, or even all, of the precip should miss us to the south. There is a better chance for a coating of ZL/ZR over the counties immediately adjacent (S&W) to Somerset Co. This part of the forecast is highly consistent. Whether or not there is an accumulation of any bit is a question which remains slightly below the 50/50 yea/nay line. Without a more-definite threat of a coating of ZL over a majority of Somerset Co, we`ll hold off on issuing a winter wx advy for them at this point. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... Ridging remains overhead Sat with any precip ending by mid morning over the Laurels, followed by another fair day with sun in the AM for much of the area. The return/srly flow over the Ohio Valley will allow clouds to form and ride northeast into the CWA. The clouds should cover about half of the CWA by sunset. Maxes will be cooler than Friday over the Laurels, and maybe just a deg or two lower over the rest of the far wrn tier of counties depending on how fast the clouds encroach/overspread them. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... Upper level ridging should support fair and mild conditions into early Saturday night. Forecast focus then shifts to a potent shortwave approaching from the lower Grt Lks. Strong warm advection at the nose of low level jet, combined with upper level divergence ahead of the shortwave, could support a light to moderate precip event across upstate NY/northern Pa late Sat night into part of Sunday. Borderline model soundings indicate ptype could be either rain or snow, with the best chance of accumulating snow over the northern mountains, where the NBM indicates a 50-60pct chance of at least 1 inch. All medium range guidance supports fair and seasonable conditions for the early and middle part of next week, associated with upper level ridging and strong subsidence between slow moving cutoff upper lows over the central US and the Canadian Maritimes. Guidance has slowed down with the arrival of precip later in the week, now holding off until Wed night or Thu most likely. A surface high and pool of relatively cold air poised north of New England could potentially result in an initial wintry mix before a change to rain. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... A weak wave aloft will cross OH tonight and Sat morning and bring a small amount of very light precip to SWrn PA. Most, if not all, of it will remain to the W and S of JST. Thus, we`ve kept the fcst dry there with only an MVFR deck of clouds developing. Elsewhere, expect VFR conditions with only high/mid clouds overspreading the western half of PA tonight. After the morning clouds slide south, plenty of sunshine can be expected for the Central and Eastern terminals. If there is clearing at JST, clouds (MVFR) should move back in from the SW to JST in late morning, and by late in the day to BFD, AOO, and UNV. The next weather system is a more significant long-wave trough which will deepen some as it moves across the Great Lakes. That will develop light precip over wrn PA and slide it over Central PA Sat night and Sunday. Expect IFR for almost every terminal for 12-24 hrs, and perhaps a period of LIFR, with less impact for MDT and LNS than other terminals. Mainly snow will far N of I-80, and snow/mixed precip may turn to rain before ending in the S. Little or no lake effect is expected after this main batch of precip. Outlook... Mon...MVFR west, VFR east. Tue-Wed...VFR expected. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Lambert/Dangelo NEAR TERM...Lambert/Dangelo SHORT TERM...Dangelo LONG TERM...Lambert/Fitzgerald/Gartner AVIATION...Lambert/Dangelo
National Weather Service Hastings NE
535 PM CST Fri Dec 9 2022 ...AVIATION UPDATE... .DISCUSSION...(This evening through Friday) Issued at 310 PM CST Fri Dec 9 2022 Key Messages: * Fog and Stratus will plague the eastern portions of the forecast area through tonight. * A seasonal weekend with highs back up into the 40s and 50s before the next storm system. * Strong upper low will impact the area next week: Monday night through Wednesday. Stronger winds through much of the work week. Liquid precip expected for the most part with some snow as it exits. * Cold temperatures filter in after the system next week. Below normal temperatures will persist through approximately Christmas. The main forecast concern tonight is Fog and Stratus. The Stratus on the back side of the upper low has been stubborn to erode and model guidance is struggling with it at best. Have trended towards the HRRR with the afternoon and overnight forecast as it seems to have the better handle on the stratus. Have kept Fog in the forecast for much of the area along and east of Hwy 281 where clouds will be the most prevalent. Additionally due to the persistent cloud cover, have increased overnight lows to account for the lack of sufficient radiational cooling. Areas today that have been able to see some sun have warmed nicely...and even those areas with persistent cloud cover have reached to 32 degrees and hopefully this will mitigate the icing on roadways for most areas. This weekend: A disturbance will move overhead tonight, but remain dry. As this system exits Saturday evening, the region will be under southwesterly upper level flow as a deep trough digs into the western CONUS on Sunday. This is the next big weather maker. Ahead of this system, lee troughing will develop and southerly wind will persist. South winds may be breezy during the daytime hours Sunday and even stronger on Monday as the surface low deepens over the High Plains. These winds will help mix the BL causing temps to increase, however, even 50+ degrees won`t feel great with 30+mph winds. Storm system Monday night - Wednesday: The models and ensembles have been in fairly good agreement for quite a few days already about the evolution and track of this system. This system looks to track across Nebraska on its way northeast, which should keep us in the warmer sector for the most part. Rain and thunderstorms look to be the primary threat. As the system moves overhead we could get some snow on the back side, but it doesn`t look to be a large amount. Thursday - Friday and beyond: This system will bring in cold air that will likely persist through the next couple of weeks - until near Christmas. Highs will be below normal which is in the 30s for this time of year. Highs in the 20s and lows in the single digits look to be on tap for the end of the next work week. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Sunday) Issued at 528 PM CST Fri Dec 9 2022 Rather tricky forecast with main concerns being fog and low cigs for KGRI. MVFR conditions at KGRI will deteriorate as we get closer to midnight local time. Cigs are expected to come back down to IFR around 800 ft as the stratus deck back builds to the west. Then the stratus will erode back east slightly and will leave us with clearing and when coupled with lighter winds gives us the potential for fog to develop. Several models show a corridor of fog forming over the eastern half of the area. Closer to morning a trof will be moving in and will gradually switch winds around to the west and then the northwest. This should help clear out the fog and the remaining stratus. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ DISCUSSION...Billings Wright AVIATION...Shawkey
National Weather Service Wilmington OH
901 PM EST Fri Dec 9 2022 .SYNOPSIS... A series of weather disturbances will bring occasional chances for rain through Saturday. Temperatures will remain a few degrees above normal into next week, with the next chance for widespread steady rain arriving by midweek. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... With rain now clear from the area, leaving just some patchy drizzle behind, the main concern going into the rest of the night is the potential for fog. GLAMP data has been more aggressive than HRRR projections in terms of visibility reductions in the southern / southwestern sections of the ILN CWA tonight, but given the very light winds and the visibilities already being observed just outside of the forecast area, the more pessimistic forecast is looking more likely for now. A Special Weather Statement was issued for the fog based on where it is expected to be at its worst, with an eye toward upgrading to a Dense Fog Advisory in the next hour or two as it continues to develop. Temperatures in the far northern CWA have been trending a little cooler than the previous forecast, so some downward adjustments were made there. Previous discussion > An axis of light rain showers, associated with a weakening mid level short wave, will continue to shift east across our area through early evening. On the back side of this, a weakening surface trough and some deeper low moisture could lead to a lingering chance of drizzle as we head into this evening. This could also lead to some areas of fog, especially later tonight, with the most favored area for this appearing to be across Tri- State area. Lows tonight will be in the upper 30s to lower 40s. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... Mid level ridging will shift quickly east across the area through Saturday morning before another weak mid level short wave moves quickly east across the area Saturday afternoon into Saturday night. Deeper moisture is fairly limited with this system though so expect mainly just some lower chances for light showers or sprinkles. Temperatures will remain a few degrees above normal with highs on Saturday in the mid 40s to lower 50s and lows Saturday night in the 35 to 40 degree range. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Surface high pressure builds in from the upper Midwest Sunday as northwest flow aloft persists behind the trough over the northeast United States. The surface high then shifts east across the upper Great Lakes on Monday, then holds across region Tuesday, providing cool dry days over the Ohio Valley. Well-developed troughing moves from the Rockies on Tuesday into the Plains by mid-week. Guidance suggests an amplified low pressure system increases the chance of rain Wednesday into Thursday associated with height falls and a strong cold front ahead of the trough. Likely the best instability (and thunder chances) will be located to the south of the region, with showers occurring across the Ohio Valley. By week`s end, a large upper low will likely cause a few rain/snow showers as weak energy pivots around the low in the cold post- frontal air mass. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... Steady rain will be exiting the Columbus area after 01Z, but some drizzle will be possible for the next few hours at all TAF sites. MVFR visibilities are fairly common around the area right now, but drizzle could briefly drop visibilities to IFR. Ceilings are also generally MVFR, but some IFR ceilings are expected to move into the Cincinnati area in the next few hours. IFR visibilities are also possible later in the overnight hours, mainly at Cincinnati and Wilmington. Tomorrow, visibilities are expected to improve to VFR, but MVFR ceilings are likely through the day. Winds are expected to remain very light through the forecast period. Some light rain could make its way into the Cincinnati area late tomorrow afternoon, but so far the chances appear too low to include in the TAFs. OUTLOOK...Occasional MVFR/IFR conditions are possible through Monday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...JGL NEAR TERM...Hatzos/JGL SHORT TERM...JGL LONG TERM... AVIATION...Hatzos