Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/20/22

National Weather Service Albany NY
1002 PM EST Wed Jan 19 2022 .SYNOPSIS... A strong cold front tonight will usher much colder air into the region, and this bitterly cold air will stick around and last into the weekend. A weak frontal wave may bring some light snow to locations south and east of the Capital Region Thursday morning. Snowfall amounts look light, but even the light amounts could result in a slippery morning commute tomorrow. Afterwards, dry weather dominates through the weekend into at least the beginning of next week. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... Update as of 959 pm EST...A clipper low is moving across southeast Quebec at this time. A band of snow showers is moving across northern NY into the western Adirondacks and fell apart. A short-wave move across w-cntrl PA is helping to increase the low to mid-level FGEN for some light pcpn echoes to form south of the region. The 00Z KALY sounding has a strong inversion at 800 hPA with dry air below it. Temps vary quite a bit as light to calm winds and some holes in the cloud cover has allowed temps in the Lake George Region/Glens Falls area to fall into the 20s. The temps should rise or steady with the approaching front. The latest 01Z HRRR and shows light snow expanding north/northeast into the s-cntrl Taconics/Mid Hudson Valley, Berkshires and Litchfield Hills between 09Z-12Z. Lows will be falling into the teens and 20s from the Capital Region north and west with mid 20s to around 30F south and east. We kept a slight chance of snow showers further north and west into the Capital Region. Some lake effect snow showers and flurries will also increase across the northwest portion of the forecast area. Some accumulations will be a dusting to a tenth or two over the north and west of the Capital District with a few tenths of an inch to an inch or so over the Mid Hudson Valley, southern Taconics and NW CT. Some slick spots are possible in these areas for the morning commute. Some more details are below. Previous near term... Turning our attention to our southeastern zones...Late tonight/early tomorrow morning, the cold front will be located to our southeast near the coastline. AS an upper trough moves in from the west, a southern stream shortwave embedded in southwesterly flow aloft will track northeastward, bringing a "surge" of increased moisture towards the region as a weak wave of low pressure develops along the front. Additionally, we will will be in a the right entrance region of a 300 mb jet streak, and there may even be some jet coupling Thursday morning as another upper- level jet streak moves off the Mid-Atlantic coast to our south (putting our area in the vicinity of the left exit region). Finally, there will be a band of enhanced frontogenesis along the front itself. Combination of increased moisture with mid and upper-level support will lead to a an area of snow or snow showers developing along the front. This will primarily impact our southeastern areas (Dutchess and Litchfield Counties), with the highest amounts expected near the I-84 corridor. Best chance for snow appears to be between 4-10 AM EST, and may initially start as a rain/snow mix (no ice expected, though) before transitioning to all snow as colder air works in. Total snowfall accumulations look to only be an inch or two, but given that this snowfall will coincide with the morning rush hour, the morning commute could be slippery tomorrow across our southeastern zones. Even though slippery travel conditions are expected, forecast snowfall amounts look to fall solidly below advisory criteria. Main challenge at this time is how far north and west the snowfall makes it. Some sources of guidance suggest snowfall could make it into Columbia County and the Berkshires, while other sources of guidance confine snow to Litchfield and Dutchess Counties. Opted to go with the further south solution, but will continue to monitor trends as the event draws near. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... Thursday morning, cold front continues moving to the south and east. With the front departing, snow looks to taper to snow showers by mid morning and should end by late morning. With the cold front to our southeast, our region will experience strong cold advection through the day as the troughing and core of the cold air aloft move towards our region. Despite some partial clearing, highs will only be in the 10s and 20s (except in the Adirondacks where single digits are expected). Highs will occur early in the day, with temperatures continuing to fall through the day as the core of the cold air works towards our region. With a tight pressure gradient between the departing low and a 1045 mb high over the midwest, it will also be breezy through the day. Thursday night will be another bitterly cold night, with lows dropping below 0 outside of the Mid Hudson Valley and Litchfield County, with temperatures in the -10s in the Adirondacks. To make matters worse, it will remain breezy (especially before midnight) as the surface high remains to our west. At this time, wind chill values are expected to drop into the -20s across portions of the Adirondacks, southern Greens, and eastern Catskills, and even northern portions of the Berkshires where wind chill advisories will likely be needed. Friday and Friday night, the surface high finally makes its way into our region. This will allow the pressure gradient and therefore winds to relax. Despite partly to mostly clear skies, it will remain cold as daytime mixing looks limited and we will continue to see cold air advection into the region. Highs will be mainly in the 10s, with single digits in the high terrain. Friday night, we will be under the surface high. Combination of clear skies, light to calm winds, and some snowcover should lead to very favorable radiational cooling conditions. Went below NBM guidance with Friday night lows, but still may not be cold enough. Low temperatures will be similar to or even a couple degrees below Thursday night lows, but wind chills will not be as harsh with much lighter winds. Will also note that guidance over the past few days suggested there may be a coastal storm Friday night. However, with positively tilted trough aloft and and southern stream disturbance lagging behind the norther stream trough, any storm that does develop looks to remain well east of us with no impact on our region except for a few high clouds late Friday night. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... Below normal temperatures will continue through the long term, as upper level troughing dominates northeastern CONUS. Precipitation looks to remain limited primarily to Lake Effect and some northern stream systems, although there is a possibility for some added southern stream moisture/energy influence for Tuesday-Wednesday. For Saturday-Saturday night, current model consensus continues to favor any coastal system tracking too far south/east to have much influence on our region other than some high clouds. It will be quite cold, with highs mainly in the teens to lower 20s. Very cold temperatures possible for Saturday night as high pressure remains nearby. Areas with a deep snowpack may have temps drop off precipitously after sunset, with some mins of zero to 10 below possible across the the southern Adirondacks, and zero to 10 above elsewhere. A northern stream clipper looks to approach Sunday-Sunday night, with along with another arctic cold front. This should bring some snow showers to the region, with best chances along and north of I- 90, initially with some isentropic lift and QG forcing, and then with some Lake Enhancement Sunday night. Highs mainly in the 20s, with lows Sunday night ranging from zero to 10 below across the SW Adirondacks, and generally single digits and teens elsewhere. Some lingering Lake Effect snow showers possible Monday, especially western Mohawk Valley and SW Adirondacks, although may shift into the eastern Catskills/Schoharie County as well. Otherwise remaining cold, with highs in the teens and 20s. Lake Effect snow showers should taper off Monday evening, although some light snow or snow showers may develop across far western areas ahead of next incoming system prior to daybreak Tuesday. Lows zero to 10 below across the southern Adirondacks, and zero to 10 above elsewhere. For Tuesday-Wednesday, a clipper type system looks to approach from the west. However, additional southern stream moisture/energy may also eject from the southwest/southern U.S., with some phasing of upper level features possible. At the very least, even without much phasing, some snow showers or a period of light snow will be possible with the northern stream feature, especially during Tuesday. Should added southern stream moisture/energy occur, a more amplified system could result in slower movement, and greater precipitation amounts for the region. So, chance PoPs are included for Tuesday into Tuesday night, then gradually decreasing from NW to SE Wednesday. It will turn even colder in the wake of this system, with highs Tuesday mainly in the teens and 20s, and lows Tuesday night in the single digits above zero for southern areas, and below zero to the north. Wednesday highs mainly in the teens and 20s, although may be even colder. Wednesday night could be frigid, with widespread lows below zero possible. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... Through 00z Friday....VFR conditions are expected to prevail through the 00z TAF period for KGFL/KALB. Later tonight between 02z-08z, a cold front will pass over the local area. Moisture riding up along the front could trigger a few light snow showers/flurries over KALB/KGFL. Confidence is greater to the south across KPSF/KPOU. That`s where we anticipate, MVFR-IFR conditions developing. As far as timing, for the MVFR-IFR conditions at KPSF/KPOU, we`re expecting between 06z- 09z as the front pushes through and precipitation develops. Light snow is possible for KPSF, but the greatest confidence is over KPOU. For KPOU, lower ceilings coupled with light snow will contribute to the MVFR-IFR conditions. Light snow is expected to come to an end mid to late morning on Thursday with categories improving back to VFR levels across KPOU/KPSF. Winds will continue out of the southwest this evening/tonight 5-10 kts before shifting out of the west-northwest later tonight behind the cold front. Winds could gust as high as 20 kts over KPSF upon the wind shift. Outlook... Thursday Night: No Operational Impact. NO SIG WX. Friday: No Operational Impact. NO SIG WX. Friday Night: No Operational Impact. NO SIG WX. Saturday: No Operational Impact. NO SIG WX. Saturday Night: No Operational Impact. NO SIG WX. Sunday: Low Operational Impact. Slight Chance of SHSN. Sunday Night: Low Operational Impact. Slight Chance of SHSN. Monday: No Operational Impact. NO SIG WX. && .HYDROLOGY... A weak disturbance may bring light snowfall amounts (1-2") to portions of Litchfield and Dutchess Counties Thursday morning. Otherwise, mainly dry weather is expected through at least the beginning of next week. Despite a mild day today with many areas rising above freezing, we do not anticipate much snow melt with temperatures turning cold again tomorrow through the end of the week. This will support thickening and strengthening river and lake ice. For details on specific area rivers and lakes, including observed and forecast river stages and lake elevations, please visit the Advanced Hydrologic Prediction Service /AHPS/ graphs on our website. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...Main/Wasula NEAR TERM...Main/Wasula SHORT TERM...Main LONG TERM...KL AVIATION...Evbuoma HYDROLOGY...Main/Speciale
Area Forecast Discussion
National Weather Service Bismarck ND
927 PM CST Wed Jan 19 2022 .UPDATE... Issued at 925 PM CST Wed Jan 19 2022 There is an emerging signal in both global and high-resolution deterministic guidance that there could be a loss of ice crystal production aloft with the precipitation chances late Thursday night through Friday morning, resulting in freezing drizzle being a feasible type. There are timing differences on synoptic features among guidance, but most model sounding locations show at least a brief period of freezing drizzle potential across multiple model cores. While confidence on the lack of ice aloft is growing, there is lower confidence in the amount of forcing that will be tangent, as the dry layer aloft seems to trail slightly behind the strongest forcing. Nevertheless, there is enough support in the 925 mb frontogenesis field coupled with weak ascent along the 285 K surface to introduce freezing drizzle chances to the forecast with this update. The shorter duration and lighter QPF should limit impacts if this threat materializes. In the nearer-term, forecast low temperatures were trended toward the cooler side of NBM guidance based on current trends. But there will likely be a large degree of variability in overnight temperatures, as is often the case in strong radiational cooling regimes. The HRRR and RAP continue to suggest near-surface saturation sufficient enough for fog formation. At temperatures this cold, the fog would be made up of tiny ice crystals, which may not be as impactful as fog made up of water droplets. Would like to see evidence of this occurring before adding to the forecast, as this is not a commonly observed phenomenon. Surface dewpoint depressions are still in the 5 to 10 degree Fahrenheit range, but saturation with respect to ice does not require values as low. UPDATE Issued at 558 PM CST Wed Jan 19 2022 No major changes are needed for this update. The center of surface high pressure sits near the intersection of the ND/MT and Canadian borders as of this writing. The main forecast problem of the night is how cold temperatures will plummet. The surface high will glide southeastward through the night, exiting the state by early Thursday morning. Overnight lows may occur earlier in the night, concurrent with the calm winds at the center of the high and a prevailing clear sky across the region. && .SHORT TERM...(This evening through Thursday) Issued at 245 PM CST Wed Jan 19 2022 Wind Chill headlines remain through Thursday morning in areas outside of the southwest. A longwave trough continues to impact the Northern Plains with very cold temperatures in the short term period. With the embedded vort max passing through the region this afternoon, surface high pressure will build in behind, becoming centered over the eastern Dakotas by early Thursday morning. Morning temperatures colder than -20 F will become common across central and eastern North Dakota while not as cold in the southwest where winds turn southerly. Wind Chill headlines are in effect for areas outside of the southwest through Thursday morning as wind chills down to -30 F to -45F are expected. Though winds will be lighter than the previous night, the colder air mass associated with the passing surface high will compensate. Some radiation fog will be possible early Thursday morning as light winds and clear skies will be associated with the surface high. High- resolution models are inconsistent about this possibility however, and with the very dry air mass and uncertain snowpack moisture contribution the location and probability is questionable. Will leave fog out of the forecast for now and let future shifts reevaluate. Thursday, the surface pressure gradient tightens between the exiting high and developing low to the northwest. Breezy southerly winds are expected as well as warmer temperatures west and central. Highs in the upper 20s west, 5 to 15 central, and around zero in the James River Valley are forecast. .LONG TERM...(Thursday night through Wednesday) Issued at 245 PM CST Wed Jan 19 2022 The long term forecast period will be highlighted by a transition to northwest flow aloft, with periodic chances for snow as well as warmer temperatures to the west and generally colder to the east. As a temperature gradient hangs around the region through the period, varying amplitude shortwaves will bring temperatures above and below normal day to day. The first relatively deeper shortwave will impact the area Thursday night and Friday, bringing a shot of light snow and then warmer temperatures ahead of a cold front on Friday. For the northwest the warmest temperatures may be earlier in the morning before the cold front arrives. Fairly major differences among guidance exists in how the cold air exits to the east on Saturday, with NBM probabilities showing large spreads in potential highs over the central and east. The spread is much smaller in the southwest where highs in the low 30s are forecast. Sunday should deliver warmer than normal temperatures for the west and central ahead of the next cold front. Light snow is possible on Saturday, but accumulating snow looks more likely Sunday night and Monday over the north and east as a greater amplitude wave arrives. NBM/ECMWF/GEFS ensembles show snow accumulation probabilities topping out below warning criteria, which seems reasonable based on the pattern. The beginning of next week features more of the same temperature uncertainty as 500mb model height clusters show greatest differences in east-west placement of upstream ridging and downstream troughing. The greatest impacts of this associated baroclinic uncertainty are in the central and eastern portions of the state where the difference between the NBM`s 25th and 75th high temperature percentiles span 20 to 30 degrees. In the southwest the spread again is much lower, and thus warmer than normal temperatures have a greater predictability in this area. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 925 PM CST Wed Jan 19 2022 VFR conditions are likely through the forecast. There is a low chance of fog/ice crystals developing across central and northwest North Dakota overnight. Winds will diminish this evening, becoming southerly around 10-15 kts Thursday afternoon. && .BIS WATCHES/WARNINGS/ADVISORIES... Wind Chill Advisory until noon CST /11 AM MST/ Thursday for NDZ017>020-034-042-045. Wind Chill Warning until noon CST Thursday for NDZ001>005- 009>013-021>023-025-035>037-046>048-050-051. && $$ UPDATE...Hollan SHORT TERM...AE LONG TERM...AE AVIATION...Hollan
Area Forecast Discussion
National Weather Service Denver/Boulder CO
813 PM MST Wed Jan 19 2022 .UPDATE... Issued at 756 PM MST Wed Jan 19 2022 Overall, only minor adjustments planned for the grids this evening. Some lingering snow showers/flurries expected to diminish by late evening, with partial clearing from north to south after midnight. Timing of this is all reflected in the current RAP analysis. The Winter Weather Advisory has been allow to expire this evening, however continue to exercise caution tonight as roads will be icy and slick, especially over bridge and overpasses, side roads and sidewalks. && .SHORT TERM...(This evening through Thursday) Issued at 314 PM MST Wed Jan 19 2022 Freezing drizzle has largely transitioned to flurries and light snow across the region, as upper sections of the moist layer cool below -10 C. A few light snow accumulations around an inch have been noted across portions of Larimer and Weld Counties along the I-25 corridor. The freezing drizzle has had no issues accumulating on surfaces, particularly untreated roads and sidewalks, so conditions are quite slick. Cloud cover should remain abundant into this evening, with ground temperatures below freezing, so plan on conditions remaining treacherous in spots even during the evening commute, despite the transition away from freezing drizzle. Snow accumulations this afternoon should be extremely light, remaining under a half inch for almost all areas. A few spots along the foothills and Palmer Divide could see a touch more, but under an inch most likely. Any lingering showers should exit our CWA shortly before midnight. Debated dropping a portion of the current winter headlines, but given the observed icy conditions which are expected to persist into the evening rush hour despite much additional precipitation, will keep them up for now. Moist surface conditions and weak winds may lead to some patchy fog tonight into Thursday morning, mainly for low-lying areas of the plains, with chances dropping closer to the urban corridor. It will be a chilly night with gradual clearing and lows largely in the teens for the flatlands, and locally single digits for the lower river valleys and the high mountain valleys. Slightly milder Thursday with highs in the 30`s and low 40`s east of the mountains. Ample clearing is likely by the afternoon, particularly in the plains, with a few increasing clouds late in the day in the mountains ahead of our next system. .LONG TERM...(Thursday night through Wednesday) Issued at 314 PM MST Wed Jan 19 2022 Warm advection cloudiness will spread back over the mountains Thursday night, early enough to help keep temperatures up, and then off of the Front Range by morning. This will be followed by the shearing trough dropping south Friday, dropping a cold front through in the morning. It still looks like the best lift will be over the mountains and further west, but there will likely be enough for a little snow as the moisture band moves over during the day. The main feature will be the upslope enhancement west and south of Denver in the late afternoon and evening. This could wind up being like the event last week where there wasn`t much elsewhere, but there was a pocket of significant snowfall from the lingering showers in the upslope area southwest of Denver. This could also be poorly timed, around rush hour on a Friday afternoon. We`ll have clearing by Saturday morning as we get drier northwest flow starting. There will be warming aloft with increasing winds, but on Saturday this will likely only surface over the mountain ridges and foothills. By Sunday the warmer air and breezes will be spreading east to at least the I-25 corridor and perhaps all across the plains. There`s still a lot of variety in model solutions for early next week. There will be a couple of shortwaves in northwest flow, and with the stronger flow there`s less chance of the energy shearing out towards the southwest like systems have tended to do this week. But there are big differences in timing and which wave will be stronger. There are lots of solutions showing snow on Tuesday, but for different reasons. The 12z GFS was gung ho with a long period of overrunning precipitation as a strong cold front comes early (Monday), but a shearing trough hold west of us through Tuesday. It would be hard to get that just right so that would happen, but there are similar setups in some model runs. Others have a couple of waves that move through more quickly in the northwest flow, still enough for a more transient threat of snow along with colder temperatures. We`ll stick with our model blend for now, though I was tempted to increase PoPs. Knowing just when is the hard part. For now, we`ll have colder temperatures with the PoPs mainly on Tuesday. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 756 PM MST Wed Jan 19 2022 IFR ceilings 005-010ft AGL will continue this evening, but with vsbys improving 3-6+sm most areas. Areas of light snow/flurries will linger at the terminals through 05z, but no additional accumulation expected. Improving trend overnight but could still experience patchy fog, so will continue with vcfg after 10z. East/southeast winds this evening will transition to a light southerly drainage overnight. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Cooper SHORT TERM...Rodriguez LONG TERM...Gimmestad AVIATION...Rodriquez/Cooper
Area Forecast Discussion
National Weather Service Marquette MI
640 PM EST Wed Jan 19 2022 .SHORT TERM...(This Evening and Tonight) Issued at 249 PM EST WED JAN 19 2022 RAP analysis and GOES imagery shows a shortwave and associated 1000 mb sfc low over western Quebec quickly pulling away to the east. Tight pres gradient behind the sfc low and ahead of the Arctic high of 1044 mb building into the Northern/Western Plains still generating strong NW wind gusts of 30-40 mph over the east half of the cwa and generally 20-30 mph gusts over the west half into this afternoon. Temps falling into the single digits abv zero this afternoon combined with the strong nw winds have also lowered wind chills into the zero to -15F range, coldest west half. The LES and strong winds are still contributing to considerable blowing snow over the east half as noted on area webcams so decided to extend the winter weather advisory through this evening for the eastern counties of the U.P. Winds and light LES also contributing to some blowing snow over the west so extended advisories there until 21Z, although weakening winds have already allowed for some improvement in vsbys this afternoon as BLSN has diminished somewhat. Tonight, winds will start to relax this evening, but blustery conditions are still expected. LES will continue in the NW wind snow belts, but accums will remain modest. With cold, arctic air overhead, DGZ will remain near the sfc across the west, which will keep growth and accum potential low. Across the east, a longer fetch will allow for better modification, so a little better accumulation potential will remain there. Additional snow amounts will remain 1 to 3 inches across the west and 2 to 4 inches across the east into tonight. Temperatures will be cold tonight, falling into the single digits blo zero for most locations. Lake effect clouds and air modification will keep temps in the single digits abv zero across the east. A few locations along Wisconsin stateline could see some clearing, which will allow temps to fall closer to -10 blo zero. Wind chills will generally be in the teens blo zero tonight, though a few locations in Gogebic County could fall closer to -20 to -25 late tonight with expected clearing. Not issuing a Wind Chill Advisory at this time, but it will be something to monitor for the evening and overnight shifts. .LONG TERM...(Thursday through Wednesday) Issued at 218 PM EST WED JAN 19 2022 Upper level troughing over the upper Great Lakes 12z Thu will be replaced by shortwave ridging on Fri with a shortwave trough in the northern plains 00z Sat which moves into the upper Great Lakes Fri night into Sat. Strong 850-500 mb q-vector convergence and deeper moisture move in Fri night and both move out Sat afternoon. In the extended, the GFS and ECMWF show a deep 500 mb trough across the ern U.S. 12z Sun. Numerous shortwaves are embedded in this trough with little change in the upper pattern for this forecast period. This will continue the below normal temperatures for this period along with prolonged lake effect snow showers. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 640 PM EST WED JAN 19 2022 Under a cold airmass and nw flow, lake effect snow showers will continue to stream off of Lake Superior. At IWD, expect -shsn and conditions varying btwn MVFR and IFR, but likely becoming prevailing IFR during the night. As low-level winds begin to back Thu, -shsn will shift n of IWD with improvement to VFR early in the aftn. At CMX, -shsn will continue thru the fcst period with IFR likely to prevail, though frequent LIFR will probably occur for much of tonight. At SAW, there may be some flurries at times thru tonight, but no vis restriction expected. Otherwise, cigs will fluctuate around 3000ft, so expect varying conditions btwn high MVFR and VFR. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 218 PM EST WED JAN 19 2022 Gale event will continue to wind down this afternoon and will end this evening. Next period of strong winds will be southwest winds to 30 knots Thu night into Fri night and there could be some gale force gusts to 35 knots with that. With the wind, freezing spray will continue to be a problem for this forecast period. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Winter Weather Advisory until midnight EST tonight for MIZ006- 007-085. Lake Superior... Heavy Freezing Spray Warning until 1 PM EST Thursday for LSZ243>251-264>267. Heavy Freezing Spray Warning until 7 AM EST /6 AM CST/ Thursday for LSZ162-240>242-263. Lake Michigan... None. && $$ SHORT TERM...Voss LONG TERM...07 AVIATION...Rolfson MARINE...07
Area Forecast Discussion
National Weather Service Pocatello ID
903 PM MST Wed Jan 19 2022 .UPDATE...We did an update to account for the potential of light snow/flurries under the stratus deck tonight and tomorrow morning. We also did expand the freezing fog potential as well into some more sheltered valleys outside of the Snake Plain. We will let the overnight shift do any updates in terms of snowfall tomorrow and tomorrow night. Keyes && .PREV DISCUSSION... /issued 200 PM MST Wed Jan 19 2022/ SHORT TERM...Tonight through Friday night. Weak shortwave dropping along the Divide this afternoon is still proving to be not enough to break up the broad area of stratus embedded in lower elevations of East Idaho. There may be just enough moisture present in the mid-cloud deck working into the southern highlands to produce a trace of snowfall in some areas, but confidence is low for anything other than a flurry or two. Expect one more night of inversions before next system works through the region tomorrow into early Friday. Light snow is expected to begin in the central mountains and along the Divide during the morning hours. Frontal boundary rapidly drops southeast through East Idaho during the afternoon and evening, and the main focus for snowfall occurs along/just ahead of the front. Today is no exception. High-res guidance solutions remain absolutely consistent with timing the strongest band of snowfall: afternoon in the central mountains, evening in the Snake Plain, and evening/overnight for the eastern/southeast highlands. The guidance trend has been to creep the expected QPF amounts upwards very slightly with each run, pushing generally an additional quarter to half-inch of snowfall each time depending on location. This puts the latest storm total accumulations towards Winter Weather Advisory thresholds in some of the higher elevation zones from Island Park to Soda Springs. Totals in the Snake Plain remain below general Advisory thresholds, but if the timing of the band narrows to mainly impact the evening commute, this may be enough to tip the scale toward a headline. Will hold on issuance for now, and maintain awareness via social media and continuation of the Special Weather Statement issued this morning. Winds briefly become breezy behind the front Thursday night, but below widespread concerns for blowing snow. A few lingering snow showers are expected to remain into Friday mainly across the southern and eastern highlands, but otherwise high pressure is forecast to return. Models support low level moisture remaining entrenched in the lower elevations, so there is a high confidence in seeing the return of stratus and maybe fog Friday night. DMH LONG TERM...SATURDAY THROUGH NEXT WEDNESDAY... A nearly stationary ridge of high pressure off the Pacific coast will remain the dominant synoptic wx enforcer across the region this weekend into early next week, supporting dry conditions and light winds with an active storm track well north of SE Idaho, but also a return of temp inversions and a more stagnant airmass with attendant risks for fog/low stratus each overnight into the mornings. The ridge may tend to trend/retrograde a bit further west with time as a shortwave trough rides the flow between the ridge and departing trough (by this time a longwave trough feature blanketing the central/ern US). Confidence remains low on the exact track of the shortwave and how significantly it "cuts" into the ern side of the ridge Mon into Tue...most models continue to keep precip largely east of the CWA while the 12z deterministic GFS now brings snow across all of SE Idaho, illustrating this uncertainty. This type of (at least somewhat) wetter scenario has about 20-30% support in cluster analysis right now, but with none of the clusters really producing any widespread precip in our CWA. For now, we hold with the NBM blend which continues to limit PoPs to the Island Park region and immediate WY border. High temps remain stagnant in the mid-20s to lower 30s each day, generally near or just slightly below climo norms for mid-January. - KSmith AVIATION... IFR cigs are likely to continue to hold on today although improving back toward the MVFR threshold, with all terminals then trending back into lowering cigs/vsbys after sunset as the near-sfc airmass continues to remain quite moist. HRRR/NBM guidance offers a slightly less saturated and more "messy" picture overnight tonight into Thu AM with regard to fog/stratus coverage compared to the past 2 nights, which if anything just lowers our confidence in coverage of potential fog (and last night did not verify as dense as HRRR guidance suggested). For now, trended into a 4-6 SM BR regime with IFR low stratus dominating, and will monitor trends on fog development. Except for KSUN which should continue to follow it`s normal diurnal wind cycle, winds at the rest of the TAF terminals are so light in the guidance that confidence in anything beyond variable is also low, and indeed the guidance is split on whether NE down-valley flow or SW up-valley flow will dominate in the Snake Plain. For now, went with light up-valley flow, but all speeds should remain below 7kts. Snow with our next system arrives Thu afternoon, and we kick this off at 22z for now in the longer KSUN TAF period (pending elsewhere in the next TAF package). We may need to consider at least VCSH in advance of the main show at the rest of the terminals, perhaps as early as 16-17z, as mid-level clouds moving in atop the continued low stratus may support a "seeder- feeder" effect and some light snowfall. - KSmith && .PIH WATCHES/WARNINGS/ADVISORIES... None. && $$