Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/17/22

National Weather Service Albany NY
902 PM EST Fri Dec 16 2022 .SYNOPSIS... The coastal cyclone will move slowly northeast of Cape Cod tonight and head towards Nova Scotia on Saturday. The precipitation will change over to snow across the entire region early this evening with the highest totals across the higher terrain but some accumulating snow in the valley areas. The snow will taper to snow showers north and east of the Capital Region Saturday morning. Cold weather will continue this weekend with lake effect snow impacting the western Adirondacks Saturday night through Sunday night. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Messy upper deformation precipitation still building north into our region and small bands of enhanced precipitation should reorient to more west/east through the night. There are zones of very light precipitation between enhanced small bands and that trend will continue through the night, with varying intensities of precipitation. Snow is now falling in the mid Hudson Valley and southern Taconics but seeing a little mix with rain around Glens Falls and Brattleboro but precipitation should become snow later this evening and stay snow through daybreak in those areas. Higher snow amounts in higher terrain will continue but valley areas will see enough for considerable slushy and wet accumulations. Thanks to everyone for snow reports. Just minor adjustments to temperatures and precipitation trends through tonight PREVIOUS DISCUSSION: Coastal low pressure continues to move slowly northeast towards southeast New England for early this evening. The short-wave has become negatively tilted in the mid and upper level deformation zone. The coastal low producing the heavy wet snow over the higher terrain and north and west of the Hudson River Valley will slowly move northeast towards Cape Cod tonight. The secondary low is connected to the occluded/stacked low over the Upper Midwest and wester Great Lakes Region. The closed/cutoff low at H500 continues to spin centered over northern WI and eastern MN. The low to mid level frontogenesis continues to increase in the northwest quadrant/mid-upper level deformation zone of the cyclone and the snow has been rapidly changing over to heavy wet snow in the Capital District/Upper Hudson River Valley. Some low-level warm air in the boundary layer/down-sloping off the western New England higher terrain/lower snow to liquid ratios held totals down in the valleys areas, especially in the Hudson River Valley, portions of the eastern Mohawk Valley and lower terrain west of the Berkshires, and southern Greens. Also, the Taconics has been warm in the mid 30s to around 40F, but the better dynamics, heavy pcpn and cold conveyor belt will allow all the rain or rain/snow mix to change to snow the next couple hours. We are going to hold onto the headlines through the evening commute and into tonight. Many of the valley areas will be on the lower end of the ranges but light to moderate accumulations are expected tonight. The Capital Region/northern Taconics/central and eastern Mohawk Valley could still get 2-6" additional snow. The southern and central Taconics may only get 1-4". The higher terrain of the eastern Catskills, eastern Adirondacks may receive 5-9", and the southern Greens 6-12". Some storm totals in the southern Greens could exceed 2 feet. Also, some tallies in the eastern Catskills in the southern Adirondacks may reach 18-24". The Lake George northern Saratoga Region may get an additional 3-7". The mid Hudson River Valley an inch or two at most. The Berkshires may receive 3-6" with the higher amounts over the northern Berks up to a foot. The northern Litchfield hills possibly 1-3". The 12Z HREFS continue to indicate high chance or low likely probabilities for an inch an hour snow rates over the higher terrain including the Berkshires/southern Greens/eastern Adirondacks and eastern Catskills. Snowfall rates of an half an inch to an inch and hour will allow be possible in the valleys. A possible pivoting snowband may form associated with the coastal cyclone over western to central New England as the H700 low closes off near eastern New England, which may enhance snow rates to an inch or two an hour for southern VT and the Berkshires. We also have to monitor for some localized Mohawk Hudson Convergence documented by local CSTAR research with the north/northwest winds down the Upper Hudson River into the Capital Region and west/northwest winds down the Mohawk River Valley converging with low-level moisture present and good forcing aloft. If this occurs, it may add to the snow totals a bit over the Capital Region/northern Taconics. The latest 3-km HRRR and NAMnest has the snow taper to snow showers south and west of Capital Region between 05Z-08Z, and then further north towards the Capital Region between 08Z-11Z/SAT. Some west/northwest upslope snow showers may continue along the spine of the southern Greens and western Adirondacks,as well as the northern Taconics after daybreak. Lows tonight will be in the mid 20s to lower 30s. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... Winter Storm Watch issued from 1 am EST Sunday to 7 am Monday for the potential of heavy lake effect snow for northern Herkimer and Hamilton Counties.... Tomorrow...Th upstream upper level low continues to slowly migrate eastward over the Great Lakes Region. The coastal low moves east of the Gulf of Maine. We are expecting residual upslope snow showers to persist over the southern Greens, Berkshires, northern Taconics and the southern Adirondacks. Some of the snow showers and flurries may linger over the Lake George Saratoga Region. In the west/southwest flow cyclone flow aloft clouds will persist from the Capital Region north and east with some clearing possible to the south. Additional snow accumulations will range from a half an inch to a couple inches in the upslope areas. Highs will run a little below normal with upper 20s to lower 30s over the higher terrain and mid and upper 30s in the valleys. Saturday Night into Sunday Night...The mid and upper level closed low moves towards the Northeast Saturday night into Sunday. In the cyclonic flow, lake effect snow is expected to develop down stream of Lake Ontario. A persistent, multi-lake fetch and potential band development with extension into the western Dacks is possible based on the 3-km NAM and Canadian Regional as early as Sunday morning. Favorable delta T temps from the surface to 850/700 hPa and a moderate class of instability is implied base on some of the upstream Bufkit soundings. The inversion height looks to range 8-10 kft with the potential for single band Sunday into Sunday afternoon with a 250-260 degree trajectory. Locations mainly along and north of the Old Forge/Route 28 would have the greatest impact. A Watch was issued for the potential of getting 7" inches of snow Sunday into Sunday evening before the flow veers to the northwest and the band may become transitory moving into the Mohawk Valley Sunday night. Most locations will see some clearing Saturday night outside the potential lake band development with lows falling into the teens and lower 20s. The flow gradually veers to the west/northwest late Sunday pm into Sunday night with some upslope snow showers possible over the southern Greens, Berkshires and the west/southwest Adirondacks on Sunday. The snow shower activity may become more widespread with the winds shifting to the west/northwest and the upper low moving over head Sunday Night. We kept likely/categorical PoPs over the western Adirondacks/western Mohawk Valley Sunday night with slight or low chance PoPs from the Capital Region, Berkshires and eastern Catskills north and east. Some light accums are expected with the lake effect snow band south of the watch area with 1-3" or so in the western Mohawk Valley. Fragments of snow showers associated with the upper low may produce light snow accums in a few locations. Within the lake band some amounts could exceed 7" in a 12-hr period (why the watch was issued). The upper low moves southeast Ontario and northern NY on Sunday with partly to mostly cloudy conditions. Highs will be a tad colder in the 20s over the mtns and lower to mid 30s in the valleys and over the hills. Lows are expected in the 20s Sunday night. && .LONG TERM /MONDAY THROUGH FRIDAY/... The longterm forecast period begins with the core of an upper- level, closed low pressure system exiting the region to the east and sliding off the New England coast. While it takes with it the steep moisture axis that will have brought widespread precipitation to the region by the termination of the weekend, encircling its western periphery is a short wave feature that will enhance moisture advection from Lake Ontario, bringing lake effect snow into the western Adirondacks and northwestern-most portions of the Mohawk Valley. This lake effect snow should carry through early Tuesday morning before high pressure ridging builds in overhead, introducing a drier environment to the forecast area Tuesday night through Thursday morning. While confidence is fairly high in the aforementioned conditions, it decreases significantly when considering the model-illustrated event for late next week. While general consensus suggests the introduction of an arctic airmass to the greater portion of central CONUS by mid-week, models differ greatly with the expectations of the track of this airmass and the impacts it could have for the forecast area. While the CMCNH and ECMWF track the potent low pressure system into the region from the west, the GFS appears to show it digging to the southeast before developing a coastal element and heading north in the form of a nor`easter. Precipitation duration, type, and intensity will be track-dependent. With great uncertainty still present at this time, PoPs have been kept on the low-end of likely with NBM output of precipitation type. This system will continue to be monitored as its window of occurrence draws closer. Temperatures during this period are expected to be seasonably chilly with overall temperatures in the 20s to 30s throughout the forecast area. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... Snow is expected to continue throughout the night at all TAF sites causing IFR-LIFR conditions. Currently, KALB/KPSF/KPOU have both restricted visibilities and ceiling heights within the IFR category while KGFL`s conditions fall within the MVFR category. The MVFR conditions at KGFL are expected to transition to IFR by 02z with the possibility of snow increasing in intensity at times. Snow is expected to persist through tomorrow morning, with locally moderate intensities possible at times. Snow showers at KPOU will be the first to taper off as the moisture-rich system progresses northward. Snow should cease by around 10z here while KALB/KGFL/KPSF could see lingering snow showers until approximately 13-15z. Once precipitation ends, MVFR ceilings will be maintained for the remainder of the morning until improvements to VFR come along in the afternoon. VFR conditions will then be maintained for the remainder of the 00z TAF cycle. Winds throughout this period will be light and northwesterly ranging from 5-10 kt. Outlook... Saturday Night: No Operational Impact. NO SIG WX. Sunday: No Operational Impact. NO SIG WX. Sunday Night: Moderate Operational Impact. Chance of SHSN. Monday: Low Operational Impact. Breezy. NO SIG WX. Monday Night: No Operational Impact. NO SIG WX. Tuesday: No Operational Impact. NO SIG WX. Tuesday Night: No Operational Impact. NO SIG WX. Wednesday: No Operational Impact. NO SIG WX. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...Winter Storm Warning until 10 AM EST Saturday for CTZ001. NY...Winter Storm Warning until 10 AM EST Saturday for NYZ032-033- 038>043-047>052-054-058-061-063-082>084. Winter Storm Watch from late Saturday night through Monday morning for NYZ032-033. Winter Weather Advisory until 7 AM EST Saturday for NYZ053-059- 060-064-066. MA...Winter Storm Warning until 10 AM EST Saturday for MAZ001-025. VT...Winter Storm Warning until 10 AM EST Saturday for VTZ013>015. && $$ SYNOPSIS...Wasula NEAR TERM...NAS/Wasula SHORT TERM...Wasula LONG TERM...Gant AVIATION...Gant
Area Forecast Discussion
National Weather Service La Crosse WI
930 PM CST Fri Dec 16 2022 .DISCUSSION...(This evening through Friday) Issued at 250 PM CST Fri Dec 16 2022 Key Messages: - Nuisance light snow continues tonight into Saturday with minor travel impacts - Chance of additional light snow Monday into Monday night, but a more impactful system lies on the horizon for the second half of the week - Pre-Christmas Arctic blast with temps gradually falling Sunday into the work week - increasing likelihood for bitter cold wind chills Continued Light Snow Tonight Into Saturday: Vertically stacked low pressure system continues to slowly inch eastward across northern Wisconsin. Deep cyclonic flow overhead and saturated low levels have been supportive for widespread light snow across the area since last night, but the good news is we`re finally nearing the end of this nearly week-old system. Accumulations will continue to come in small amounts at a time the rest of this afternoon into tonight, adding up to an additional 1 to 2 inches by this time on Saturday. Small enough to not cause major travel headaches, but enough to cause some lingering nuisance slippery roads and reduced visibility. Brisk southwest to west winds today have been strong enough to cause some minor drifting in open areas given this dry/light snow variety. Not seeing much evidence for blowing snow issues, but can`t rule out some patchy blowing snow in open areas west of the Mississippi River. Heading into tonight and Saturday, the low will slowly migrate into the Upper Great Lakes region. Associated QG forcing will gradually become more focused across our north as the system slowly pulls away. So highest snow chances should eventually become focused mainly near and east of the Mississippi River. Moisture aloft will slowly strip out from the the top of the saturated layer heading into Saturday, but forecast soundings suggest a decent chance for lingering light snow or flurries across most of the area for much of the day. Looking like the snow machine finally should shut down heading into Saturday night and Sunday. Can`t rule out a brief transition to light freezing drizzle in spots the rest of today into Saturday if we`d temporarily lose cloud ice, but HRRR soundings indicate this would be transient so stuck with all snow in the forecast. Next Chance of Light Snow Arrives Monday Into Monday Night: Ensemble guidance indicates an increasing likelihood of another system bringing a round of light snow to the region as the new work week unfolds. An upper low coming onshore southern California on Sunday would spawn this system in the lee of the Rockies Sunday night, which would then impact our region Monday into Monday night. Based on current expected speed and track of this system (certainly subject to change), it looks like main impacts would begin Monday afternoon and continue through the overnight. As of now, QPF amounts look light with 16.00Z GEFS/EPS/CMC ensemble blend indicating only about a 20 to 30 percent probability for greater than 0.10" liquid. Stronger Winter System Later in the Week: Greater winter impacts are anticipated from a more organized, intense system arriving sometime in the second half of the work week. Very low model consensus in storm track, timing, and associated impacts that far out, but there`s at least general agreement for a more potent system in that timeframe. For now will let NBM precip chances suffice, with the expectation that models will continue to waver from run to run. Definitely a system to monitor in the coming days if you have holiday travel plans heading into next weekend. Blast of Arctic Air Heading Into Next Week: Biggest story heading into next week will be a blast of Arctic air, which will begin spilling into the region as early as Sunday behind the departing cyclone. Already seeing signals for anomalous cold showing up in NAEFS percentiles (below 10th percentile) and ECMWF EFI, which will likely strengthen in the coming days as models come into better agreement. Coldest blast looks to come Tuesday and beyond. Bitter cold wind chills are looking like a decent bet within that timeframe with potential for -20 to -30 or colder. Will continue to gradually increase our messaging on these potential impacts as we get closer. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 930 PM CST Fri Dec 16 2022 CIGS: cigs look to hold mostly MVFR through Sat night, with improvement as we move into Sunday and a weak ridge of high pressure starts to influence the region. WX/vsby: main areas of -SN exiting and/or shifting north overnight. Cyclonic flow a loft will continue some flurries through Sat, with some threat for an additional snow shower or two (and related drops in vsby). WINDS: westerly and sustained in the low/mid teens through Sat. Some gusts into the lower 20 kts possible. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ DISCUSSION...Kurz AVIATION.....Rieck
Area Forecast Discussion
National Weather Service Goodland KS
626 PM MST Fri Dec 16 2022 .UPDATE... Issued at 622 PM MST Fri Dec 16 2022 With area obs continuing to show a fairly quick decrease in winds, and with the latest HRRR a showing surface ridge axis pushing slowly east into the western portions of the cwa as the evening progresses, plan on updating forecast to remove mention of blowing snow. Will also see if temps warrant a bump down. Clear skies, leftover snowpack and light winds will be major factors, especially in northeast Colorado. Will await latest obs at 02z Saturday then issue. && .SHORT TERM...(This evening through Monday Morning) Issued at 254 PM MST Fri Dec 16 2022 Strong northwesterly winds continue across the area today behind the departing low pressure system. Wind gusts of 50-55 mph have been coming throughout the late morning and afternoon hours. Surface high pressure over Colorado looks to move slowly to the east overnight tonight which will bring this prolonged period of windy conditions to an end heading into the weekend. A few plumes of blowing dust has developed across southern portions of the area as the 1 hour GFS does support some marginal lapse rates based on local office climatology does support the blowing dust potential. An area of lower ceilings which looks to be related from blowing snow in Nebraska being lofted into the area may lead to some flurries over the eastern portions of the area through sunset. Into tonight, winds will become westerly around 10-15 mph along with clearing skies. Overnight lows are forecast near zero across east Colorado to the mid teens over the eastern CWA. Winds are expected to be lightest over areas due to effects of the surface high and lighter winds where an eye on radiational cooling potential looks to be realized. Some locations west of Highway 385 may approach -15 wind chills along with air temperatures near -5 may occur. Into the weekend, weak ridging develops over the western CONUS along with winds becoming more southerly. This will allow temperatures to become more normal with highs in the in the upper 30s to low 40s across the area, snow packed areas from this weeks blizzard may be a few degrees cooler due to a higher albedo. Perhaps the most welcome news will be the relief from the gusty to strong winds that has impacted the area for the majority of this past week. Winds will be mainly from the WNW at 5-15 mph on Saturday before becoming more variable on Sunday. Into Sunday Night, a developing trough over the SW CONUS will be the next potential weather maker for the Tri-State area. As the trough moves through the area this will allow the first area of cold air to drain into the area with NW portions of the area falling below zero with near 15 below wind chills. I did introduce some silent pops over the eastern portion of the area as some light snow may work its way into the CWA. Guidance differs on how far north moisture is able to advect into the area. .LONG TERM...(Monday through Friday) Issued at 328 PM MST Fri Dec 16 2022 The main story for the long term period continues to be the expected cold as an Arctic airmass is pulled southward into the central CONUS. Monday begins with an upper-level trough with its axis through eastern CO/western KS, allowing southwesterly winds aloft to shift west-northwesterly. At the same time, a low pressure center is located over the Maine/New Brunswick/Nova Scotia region with another positioned in the vicinity of Alberta with ridging between the two systems. As a lee low traverses eastward over the TX/OK Panhandles and southern KS, surface winds will be out of the north-northeast over our area. Lows Monday morning range from just below 0 into the mid-teens. Highs will be a bit cooler than they were over the weekend, in the mid-20s to mid-30s. Overnight lows will range from a couple degrees below zero into the mid to upper-single digits. Tuesday continues cold with afternoon highs in the low-20s to mid- 30s. Heading into Wednesday, an amplified ridge over the central CONUS begins to break down as another upper low, and the source of the very cold temperatures, dives south on the backside of the strong low system over the Great Lakes and another ridge amplifies over the west coast. Wednesday`s temperature forecast is largely dependent on timing of cold front passage. Current forecast has the front moving through Wednesday afternoon/evening, so afternoon high temperatures expected to range from near 30 north to low-40s south. Overnight Wednesday night with gusty winds in the 25-35 knot range accompanying the front and the very cold temperatures plummeting to near 10 below, minimum wind chill values range from 20s below to mid- 30s below zero. Currently only looking at slight PoPs for northern portions of the area. On Thursday, highs will struggle to get out of the teens. Thursday night lows fall into the mid-single digits above and below zero. NBM throws slight PoPs in over northern portions of the area towards the end of the long term period as a shortwave trough develops and moves over. Expect some improvement in high temperatures reaching the mid-20s to mid-30s on Friday. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 355 PM MST Fri Dec 16 2022 For KGLD, mainly VFR conditions through the forecast period. 6sm in blowing snow is possible from 00z-03z Saturday. Winds northwest 25-35kts through 03z Saturday, then west-northwest 10-15kts. LLWS 03z-16z Saturday 330@35 to 45kts. For KMCK, VFR conditions through the forecast period. Winds northwest around 20-30kts through 03z Saturday, then west- northwest 10-15kts. LLWS 03z-12z Saturday 320@40kts. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...JN SHORT TERM...Trigg LONG TERM...CC AVIATION...JN
Area Forecast Discussion
National Weather Service Grand Rapids MI
733 PM EST Fri Dec 16 2022 LATEST UPDATE... Update .UPDATE... Issued at 732 PM EST Fri Dec 16 2022 Our forecast remains on track. A quick look at recent observations at MKG and GRR confirm our 12 hour forecast from this morning is on track. IR satellite image loops show the shortwave enhancing the snowfall this evening will continue to impact this area early this evening and then as the upper low gets closer yet another one moves in after midnight. The depth of the moisture is, as noted be previous discussions unusually deep, in the area of 15000 to 20000 ft. The DGZ gets rather deep, nearly 5000 ft actually and the base of it gets down to near 5000 ft. There is lift, mostly below the DGZ but there is decent lift even so in the DGZ. So, bottom line is it will keep snowing through the night. Another aspect to the snow this evening is we have a mid-level cold front coming through. At 850 mb the temperature drops from -9c to -12c in less than 50 miles. That gradient does move inland of the lake shore. So there is some FGEN to this too. Beyond that surface temperatures are now below freezing south of here. South Bend has fallen to 27 degrees and temperatures over WI and IL are all in the lower to mid 20s now. So the surface cold air is coming in. Of course having road temperatures below freezing helps that cause too. All of our road weather sensors have below freezing temperatures now. This tells me the snow will stick on all surfaces. That being so, I increased the pop to 100% over the Advisory area, after all, it is snowing and will keep snowing. I slightly increased snowfall to 2 to 5 inches overnight too. Beyond that I added patchy blowing snow along the lake shore were winds will have gusts over 30 mph, which is enough to cause drifting snow with air temperatures below freezing. && .DISCUSSION...(This evening through next Friday) Issued at 326 PM EST Fri Dec 16 2022 - Lake Effect Snow Impacting Travel Through Saturday Night Several inches of snow are expected in the Advisory area through Saturday night, leading to travel impacts as temperatures drop below freezing this evening and tonight. We have expanded the Advisory to include Osceola, Mecosta, Montcalm, Ionia, and Barry Counties. Synoptic and mesoscale components will work together this evening to enhance snowfall intensity and coverage. Upper level lift and deep moisture in excess of 10,000 ft this evening will couple with increasing lake-induced instability (50-100+ J/kg) and favorable omegas below and within the DGZ to yield accumulating snowfall. Where all these factors line up, SLR values will probably exceed 15:1 in places. Snowfall rates will be decent but not out of control, with generally a half inch to an inch per hour wherever the bands are steadiest. There will be some waxing/waning to the bands as better synoptic lift moves in and out of the region over the next 24 hours. 1000mb-700mb RH stays high for the duration of this event into late Saturday night, and lift below and within the DGZ (especially off the HRRR guidance) will keep bands going for awhile, though there will be a pivot to the orientation of the bands from SW flow this evening to W flow Saturday. Locations that will be impacted by both flow regimes will see the highest accumulations, especially across Ottawa, Allegan, and western Van Buren. That said, accumulations and impacts will be spread out well inland given cloud layer winds over 30 mph. There is some question about whether a convergent band of snow may develop between I-69 and I-94 later Saturday as flow off the lake goes west but near surface flow inland stays closer to SW. That will be something to watch, which could end up being a short duration but locally impactful situation. Overall, there are no compelling factors to change the Advisory to a Warning anywhere, given accumulations are not likely to reach a higher level of impact to travel/commerce on a larger scale, and winds will likely not be high enough to warrant mention of blowing snow. Still, snow may easily get lofted/blown around on roads as traffic displaces newly fallen snow. - Chance for Light Snow Showers Monday Night/Tuesday There is some model support for snow showers Monday night into Tuesday as either a 500mb shortwave moves through or we get a glancing blow from a deepening upper low to our north. The GFS is more ambitious with this, and is probably too deep with the Tuesday upper low compared to the GEFS mean and ECE mean. As a result, this will probably be a minor event in terms of any light synoptic snow or lake effect / hybrid setup. - Impactful Winter Weather Possible Mid to Late Next Week Ensemble guidance continues to indicate a surge of Arctic air moving into the Great Lakes region later next week. The GEFS is on the early side of the ensemble envelope (Wed.) while the ECE and CMC are later (Thu.). The ensembles are averaging 850mb temperatures of -18C to -20C with this air mass, which is not earth shattering but it is pretty cold nonetheless. Ensemble mean high temperatures yield readings in the teens while this air mass is overhead. There are some deterministic runs that show 850mb temps of -25C or colder, which remains within the realm of possibility, but plenty of time to watch. Cold temperatures in the teens or 20s will persist into Christmas Eve and Christmas Day it appears. As this change in air mass occurs, we will have to watch the longwave pattern evolution and monitor the orientation of upper level heights and possible surface cyclogenesis on the cusp of this Arctic air blast. Medium range guidance such as the ECMWF and GEM are depicting borderline wild cyclogenesis impacting Lower Michigan later next week. These types of solutions are not uncommon at this forecast range and for this time of year. While tempting to discard them as fantasy, a closer look at ensemble guidance from the ECE and CMC reveals that there are some members that support a depending low impacting the Great Lakes. Notably, while the ECE still favors the East Coast to have a more favorable synoptic setup for a deep low / Nor`easter, there was a jump in membership from the 00z suite to the 12z suite that shows a Great Lakes cyclone developing. These forecast details will be difficult to resolve until we get closer to the event. At this point we can say that there is at least a small risk for a winter storm mid to late next week with potential lake effect to follow that. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 641 PM EST Fri Dec 16 2022 Lake effect snow showers will keep the western TAf sites mostly IFR through Saturday night. Ceilings will actually mostly be MVFR but visibilities will frequently fall below 3 miles and occasionally may fall to 1/2SM SHSN or even 1/4SM +SHSN. I did not try to time these much beyond 4 hours. Even so for MKG, GRR and even AZO and BTL (not as much at these sites) you will see that off an on. Winds turn more westerly toward 12z, so I would think the conditions at GRR, AZO, and BTL will be lowest then. Inland of US-131, or the I-69 TAFs, the snow showers will likely not get that far inland after 06z but once the sun comes up and winds are more westerly they should get the snow showers too. It will be breezy through Saturday. Typically winds are not as gusty at night, inland of the lake shore (MKG) but once the sun comes up tomorrow the gusty winds will return to all sites. Bottom line .... MVFR cigs with frequently IFR visibilities in snow showers from now through Saturday night. && .MARINE... Issued at 326 PM EST Fri Dec 16 2022 SCA remains in effect until Sunday evening as winds and waves will continue to be hazardous to small craft. SW winds over the lake will shift westerly on Saturday. Waves of 4 to 8 feet are expected. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Winter Weather Advisory until 1 AM EST Sunday for MIZ037>039- 043>045-050-051-056>058-064-065-071. LM...Small Craft Advisory until 7 PM EST Sunday for LMZ844>849. && $$ UPDATE...WDM DISCUSSION...Hoving AVIATION...WDM MARINE...Hoving
Area Forecast Discussion
National Weather Service Gray ME
1043 PM EST Fri Dec 16 2022 .SYNOPSIS... Low pressure moves into the Gulf of Maine tonight. Widespread snow continues across most areas, with rain at the southern beaches, and a mix of rain and snow near the southern coastal areas and through the necks of the Midcoast. Heaviest snowfall amounts are still expected over the higher terrain with no changes to the current Winter Weather Headlines with this winter storm expected to linger through Saturday. The system will be slow to exit into the North Atlantic with continued chances for snow showers in the mountains through Monday while areas south of the mountains see an end to precipitation Saturday night. Relatively quiet weather is expected through mid week as high pressure builds into New England by Wednesday. Another potential impactful system late next week is increasingly likely. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... 1040 PM...Meso models, particularly the HRRR were spot on this evening in bringing some moderate snow into the ME coastal and adjacent coastal plain, as well timing the drop of temps by a degree or two, just enough to allow for efficient accums. transverse banding is noted in the reflectivity just offshore indicating strong FG along the coastal front. Have mot changes the winter hazards, as we could see enough snow, if banding persists in much of ME to reach warning criteria. The area that seems least likely for this to happen is the interior mid-coast and Capital region, where not much has fallen yet, and models are pushing the best forecast back to the east, toward the best FG forcing around daybreak. 740 PM...The storm is panning about well through much of NH, but this is not the story in ME, where many inland areas of wrn ME, have underperformed in snow fall totals so far. Based on that, I have adjusted snow total for today down close to the obs, and this has lowered snow amounts some. Not enough to change any hazards at this point, but would like to see snow accums start to pick up. Most of the problem in this area was that the snow was melting as it fell, given temps roughly 32-24, and although it snowed steadily all afternoon in some places, actual accums were under 2." It is starting to slowly turn colder in ME, and Meso models continue to show a several burst of moderate to heavy snow moving onshore this evening and overnight, so no changes yet to hazards yet. Winds should peak around or shortly after midnight as well and have been gusting 25-35 mph, highest near the coast. Previously...The season`s first significant winter storm pushes northward across New England today, continuing through tonight as a surface low and associated mid-level circulation track northward through eastern Mass. This has been a well-advertised storm for several days, so I won`t go too-terribly far into the meteorological weeds with this... and will (attempt to) stick to the trends and changes to the forecast for this long-duration event. The primary points of uncertainty remain the location rain-snow line and snow accumulation efficiency in the presence of marginal low and mid- level temperature profiles. Focus with this forecast is on the track of the low/mid-level circulation with greater warm air intrusion with a near-shore track and vice-versa. Generally speaking... the forecast has trended ever- so-slightly cooler... but with some impacts to those right along the razor`s edge of the rain/snow line, but ultimately no change to the hazard map. At this mid-afternoon hour, the rain-snow line sits roughly along the Midcoast`s Route 1 corridor, through the southern side of the 202 corridor of SW ME into NH, and down toward the Manchester area into its western foothills. As the driving circulation pushes north, temperatures aloft are forecast to rise above freezing... which will bring the rain- snow line further inland toward the Monadnocks and Belknaps, although by this time the dry slot also works in and cuts precip rates down regardless. This is a slightly cooler solution over the interior where warnings remain in place, with higher snowfall amounts over the Upper Merrimack and into the Saco River Valley... notably, have increased totals through the 202 corridor by a couple/few inches, given this remains the bullseye for forcing as the low pressure circulation pivots toward the Seacoast. One other area of concern was the rain/snow line along the Midcoast. Given elevated dew points south of the current rain/snow line and a maritime contribution to ENErly flow through the necks and islands, I don`t expect this line to change much due to precipitation processes with the heavier band coming onshore later this evening and overnight. This increase in confidence has sharpened the snowfall gradient through the Midcoast with little or no accumulation south of Rte 1 but up to several inches once you`re in the hills further inland. Finally, in the mountains... totals have come up by a couple inches across the board in the higher terrain, particularly through the higher terrain of New Hampshire where confidence continues to increase in 1.5-2" QPF amounts as forcing and adequate moisture slowly pivots over those areas and squeezes out snow for the next 12+ hours... while areas further east dry slot and rates diminish. The general trend through the overnight will be to bring temperatures back below freezing and transition any rain back over to snow as cool air pours in from the north... except for, perhaps, at the immediate southern coast. This trend happens under a general dearth of forcing however so this should only lead to light snowfall amounts during the morning. Winds continue to be of minimal concern especially given cooler solutions keeping lapse rates unfavorable. Strongest wind gusts are expected where rain occurs; along the immediate coast and inland through Rockingham County, topping out in the 35-40 mph range this evening. One potential impact will be gusts where wet, sticky snow clings heavily to trees... which may lead to a few outages, in addition to those further inland under greater snow load. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... By Saturday morning, low pressure will be sitting in the eastern Gulf of Maine with lift from its circulation strewn mostly across the mountains, wrapping back down through western New Hampshire as northwest winds start to filter through behind the system. These are the areas where snow is likely to persist; with bands of snow sliding east through the day as low pressure departs toward Nova Scotia. These bands have a couple inches of snowfall potential, although northwesterly flow will allow upsloping to pile on several more inches through the mountains. Southern New Hampshire may see some pokes of sunshine just before sunset as the system pulls away, with modest clearing over southern New Hampshire though the overnight. Meanwhile upsloping clouds and showers will continue through the overnight... with a chance that showers linger over central Maine into the morning. For winds... mixing won`t be very good so long as clouds and snow remain in play, so for the most part steady 10-15 kt will continue out of the north, then northwest... with gusts to around 25 kts in the southern interior of New Hampshire diminishing overnight. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Overview... Light snow lingers across northeastern areas Sunday morning from today`s system, with upslope snow showers persisting into the work week across the higher terrain. High pressure gradually builds in on Monday and Tuesday, which then crosses New England on Wednesday. Low pressure approaches from the southwest on Thursday, and likely brings rain or snow, and wind Thursday night and Friday. Details... The long duration storm will likely continues to bring light snow to northeastern zones Sunday morning, with improving conditions south of these areas. The storm is expected to linger across the Canadian Maritimes into Tuesday. With high pressure approaching from the west, northwesterly flow brings an extended period scattered snow showers to the mountains and upslope faces from Sunday through early Tuesday. Elsewhere, breezy conditions are expected with the northwesterly flow direction on Monday and into Tuesday. Despite the persistent northwesterly flow and fresh snowpack across most areas, arctic air modified by marine airmasses being entrained by the blocking across northeastern Canada yields temperatures near normal for the early and middle portions of the workweek. The arrival of the high pressure center on Wednesday brings colder nighttime temperatures Wednesday night. Thursday`s temperatures will likely start to be influenced by the next approaching storm system, with the track of this system determining whether a cooler northerly flow or warming southeasterly flow materialize. Model consistency continues on the development of a coastal storm, with impacts likely sometime during the Thursday night to Friday timeframe. What remains unclear is the track and resultant precipitation types. After a shift toward snowier solutions yesterday afternoon, models overall trended warmer with the solutions overnight and today. With the system still about six days out, there will continue to be some back and forth on the model runs, so we will continue to message that precipitation remains likely, while uncertainty on the precip type continue. One concern with any warmer solutions is that stronger onshore winds would accompany a warmer and wetter solution. With astronomical tides at their monthly peak, coastal flooding remains a concern with this system. Even an offshore track would likely yield at least minor impacts, but the severity of these impacts will ultimately be determined by the track and timing of this system, which we`ll continue to monitor over the coming days. && .AVIATION /04Z SATURDAY THROUGH WEDNESDAY/... Short Term...Widespread IFR and local LIFR continues in SN and southern RA (at KMHT/KPSM) this afternoon and evening, the exception being the usual KHIE, sheltered by the White Mountains. Northeasterly winds around 10-15 kts gust to near 30 kts at the coast through... up to around 35 kts later this evening as a storm system pushes northward into the Gulf of Maine. Significant restrictions will continue overnight with bouts of more intense precipitation rates bringing visibility down to 1/2 SM or less at times. As the storm pulls east and away from the area on Saturday... winds will turn to the north and then northwest with very gradual improvement late in the day as ceilings lift and scatter, with improvements more likely toward the east Saturday night. Snow will be more off- and- on tomorrow... leading to off-and- on visibility restrictions. At KHIE, upsloping flow likely leads to prolonged IFR in low CIGs and SHSN through Saturday night. Long Term...Upslope snow showers and mainly MVFR ceilings are likely at HIE on Sunday and Monday. Elsewhere, VFR conditions become predominant on Sunday and persist through midweek. Northwesterly wind gusts around 25kts are expected on Monday, and then ease Monday night. Rain or snow is then likely Thursday night and Friday. && .MARINE... Short Term...Northeasterly winds increase to a strong gale this evening as low pressure crosses the Cape and enters the Gulf of Maine. As the circulation tracks east through the GoM late tonight and tomorrow, winds will turn to the north and then northwest... gradually diminishing to SCAs on Saturday through the overnight. This may bring the Gale Warning down sooner than currently advertised. Long Term...SCA conditions continue through Monday with northwesterly winds and residual elevated seas, and then gradually lower on Tuesday as northwesterly flow eases. High pressure gradually builds in through midweek. A coastal storm is likely Thursday night and Friday. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Winter Storm Warning until midnight EST Saturday night for MEZ007>009-012>014-018>022-033. Winter Weather Advisory until midnight EST Saturday night for MEZ024>028. NH...Winter Storm Warning until midnight EST Saturday night for NHZ001-002-004. Winter Storm Warning until 7 PM EST Saturday for NHZ003- 005>009-011-015. Winter Weather Advisory until 7 PM EST Saturday for NHZ010-012- 013. MARINE...Gale Warning until 6 PM EST Saturday for ANZ150>154. && $$ SYNOPSIS... NEAR TERM...Casey/Cempa SHORT TERM...Casey LONG TERM...Clair AVIATION... MARINE...
Area Forecast Discussion
National Weather Service Indianapolis IN
926 PM EST Fri Dec 16 2022 .Forecast Update... Issued at 926 PM EST Fri Dec 16 2022 Enough justification per radar and ob trends to continue slight chance of light snow showers over northern sections through the early overnight as the upper low spins over northern Wisconsin. Any sort of other support for snow showers was lacking and moisture was rather shallow confined to 2-5K per BUFKIT and ACARS soundings. Thus, not expecting any accumulation with mostly no more than flurries. Cold advection will allow temperatures to bottom out in the lower 20s despite the solid stratocu. && .Short Term...(This evening through Saturday) Issued at 245 PM EST Fri Dec 16 2022 - Cloudy and cold with Flurries or snow showers this evening and Saturday Afternoon Surface analysis early this afternoon shows deep low pressure in place over MN/WI. This deep low was providing broad cyclonic flow across the region, including Indiana, reaching as far south as the Tennessee River Valley. GOES16 shows extensive cloud coverage across Central Indiana. A weak upper wave was found over IL and was pushing east into Indiana. Radar shows some light snow showers entering NW Indiana associated with this wave. Temps were holding in the mid 30s. Aloft, large and broad cyclonic flow was in place, again centered over WI/MN, impacting much of the midwest and plains. Tonight... Cloudy skies are expected to remain across Central Indiana tonight. Models suggest the upper short wave will depart east early this evening and effectively take the best forcing along with it. Furthermore the loss of any minimal surface instability due to heating also points to a diminishing trend. Forecast soundings show a bit more dry air within the lower levels as the wave departs. Still however soundings suggest a thin area of low level saturation indicative of trapped cold air advection strato-cu beneath an inversion aloft. HRRR also suggests some scattered flurry/snow shower coverage tonight, but again they trend toward dry overnight. Overall any accumulation will be minimal to a dusting. Thus will include some early evening pops for some light snow showers as the forcing departs but trend to just an isolated flurry overnight. Expect cloudy skies given the cold air advection and continued cyclonic flow, with lows in the lower 20s. Saturday... The broad and deep upper low over WI is expected to push across the Great Lakes on Saturday. This will keep cyclonic upper flow in place across Indiana and our region. While the models suggest dry mid levels, a weak short wave within the flow once again is suggested to push across Central Indiana during the afternoon. Once again forecast soundings show steep lapse rates favorable for convective snow shower development. Thus will continue with cloudy skies on Saturday and focus on small pops for these minor snow showers or flurries during the afternoon hours. Again, any accumulation will be minimal to a dusting. Given ongoing cold air advection and expected cloud cover will look for only a minimal rise in temps with highs in the upper 20s to near 30. && .Long Term...(Saturday night through Friday) Issued at 245 PM EST Fri Dec 16 2022 * Continued cold with an Arctic blast arriving late in the period. * Mostly dry late weekend through early next week. * Potential for at least light snowfall mid to late week, possibly impactful. The weekend will come to an end with the large upper low that has brought significant weather impacts to much of the central CONUS and much cooler conditions to central Indiana centered over the eastern Great Lakes and rapidly departing. In its wake, modest ridging at the surface and aloft will bring continued cool and dry weather to the area through the start of the work week. A pair of upper level disturbances, one large upper low well to our north and another weak wave near or just to our south, will pass through the region late Monday into Tuesday. While a few flurries cannot be ruled out with these disturbances, their forcing look to be much too far away for measurable precipitation, and the most likely scenario at this point is an increase in cloud cover as the midlevels moisten up but the lower levels remain quite dry. Will keep flurries out for now given the magnitude of the dry low level air. A strong Arctic high will be poised to push toward the region mid to late week, whether it leads or trails the coming weather maker, with high confidence that significantly below normal temperatures can be expected, including highs in the teens or perhaps lower by week`s end, and lows in the single digits and perhaps sub zero depending on snowfall. Dangerous wind chills well below zero appear likely late in the week as the holiday weekend approaches. Various models are struggling mightily to converge on a coherent solution to the mid to late week pattern. In broader strokes, a significant upper level system looks to drop into the central or eastern CONUS mid to late week and induce strong cyclogenesis somewhere in the eastern half of the country. This will have the potential to produce a snowstorm, perhaps significant, for some part of the country that may include central Indiana - this certainly bears close monitoring given the busy pre-holiday travel timeframe. Blend probabilistic guidance shows a high likelihood of at least minor accumulating snowfalls in the Wednesday to Friday timeframe, with low but still significant probabilities of impactful snow accumulations. This will obviously depend upon which of the numerous and varied model scenarios ends up verifying, but again, this will bear close monitoring and scrutiny over the next several days. Anyone with holiday travel plans should keep a close eye on the forecast in the coming days. && .Aviation...(00Z TAF Issuance) Issued at 613 PM EST Fri Dec 16 2022 Impacts: - Borderline VFR and MVFR ceilings through the TAF period - Flurries or light snow showers mainly before 11z and after 18z - Winds 230-250 degrees with gusts to near 25 knots, especially after 18z Saturday. Discussion: Cyclonic flow with embedded impulses moving around the base of the Great Lakes upper low will bring VFR and MVFR flying conditions with flurries or light snow showers possible tonight and Saturday afternoon. It will also be gusty with southwest winds gusting to near 25 knots. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ Update...MK Short Term...Puma Long Term...Nield Aviation...MK
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1004 PM EST Fri Dec 16 2022 .SYNOPSIS... Dry and cool high pressure will build over the area this weekend through early next week. The next storm system could impact ENC by mid to late next week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... As of 1005 PM Fri...Forecast tracking well. Higher cirrus beginning to build a bit with weak jet divergence in congruence with modest moisture fields per RAP analysis. This will persist through the overnight hours. No changes made this evening. Prev disc...Quiet, dry, and cool conditions on deck for tonight with light CAA persisting and mostly clear skies through at least the first half of the overnight allowing for some modest cooling. Mid-upper clouds put a lid on ideal radiational cooling later this evening, so temps will be relatively mild, in the mid/upper 30s interior to low 40s OBX. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... As of 330 PM Fri...Quick moving low amplitude shortwave will swing through the OH Valley and the Mid Atlantic through the day, with reinforcing modest CAA in wswrly flow. Temps will be near climo generally in the mid 50s for most of ENC. The shortwave will act to inc cloud cover with only partly sunny skies expected for a better part of the day. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... As of 3 AM Fri...Cold high pressure will build over the area over the area this weekend and early next week. Mid to late next week looks more active, with potential for coastal low development and another frontal system approaching from the west. Saturday through Monday...Cyclonic flow continues aloft through the weekend with the upper low remaining centered over the Great Lakes through Saturday before sliding into northern New England and southern Canada Sunday as sfc high builds in from the west. A series of shortwave troughs will transition through the flow aloft bringing reinforcing shots of CAA but with limited moisture expecting little to no precip. Below normal temps through the period. Highs Saturday in the low to upper 50s, 45-50 deg Sunday and Mon. Lows near or below freezing expected across much of the area each night. Tuesday through Friday...Sfc high will continue to build in from the west early next week, grad weakening as low pressure grad strengthens moving through the Gulf of Mexico, possibly lifting along the SE coast mid week. Light rain possible Tue and Wed, best chances along the coast, with weak front and low. Forecast continues to look very interesting Wed night into Fri, with a good amt of uncertainty. Amplifying upper trough is forecast to dig through the central and eastern US Thu and Fri, likely leading to cyclogenesis along/near the coast. Based on thermal profiles, added rain/snow mix to portions of the coastal plain late Wed night/Thu am, then expanded mention eastward Thu night and Fri. Still too early for specifics (exact ptype, potential accumulation, etc). But there is potential for wintry precip late next week. Will continue to cap pops at chance. Below normal temps will continue through the period, with much colder arctic air expected late week and next weekend. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... SHORT TERM /through Sat/... As of 710 PM Fri...High confidence in VFR conditions this evening as high pressure expands eastward from the southern Plains. Only clouds overnight should be cirrus riding a powerful H3 jet, otherwise clear skies are expected. Similar conditions expected tomorrow with a modest increase in 6-7 kft cloud cover as a weak shortwave approaches the region. WSW to W winds may gust to 15 kt at times tomorrow afternoon. LONG TERM /Saturday night through Tuesday/... As of 3 AM Fri...Pred VFR conditions expected this weekend into early next week with high pressure in control. && .MARINE... SHORT TERM /through Sat/... As of 330 PM Fri...General wswrly flow at 10-15 kt persist through early this evening, though large ENE swell cont 6-8 ft @ 15 seconds for nrn and ctrl waters. WSW winds inc again tonight ahead of shortwave, with SCA conditions returning to the srn waters once again. Speeds will generally be 15-20 kt over the sounds, and 15-25 kt over the coastal waters. The breezy conditions perist through Sat, and in fact increase a bit late in the day towards evening, where an SCA may eventually be needed for Pamlico Sound late in the day or early Sat evening. LONG TERM /Saturday night through Tuesday/... As of 3 AM Fri...Gusty W/NW winds 15-25 kt will continue through Sunday night. Conditions will be slow to improve with high pressure building in, weak low development offshore and rounds of strong CAA. SCAs continue for the southern waters into Sunday, and Monday for the northern and central waters. Seas 4-7 ft Sat, 4-6 ft Sun and 3-6 ft Mon. NW winds diminish to 15 kt or less Mon afternoon. Seas expected to finally drop below 6 ft Monday evening for the northern and central waters. N/NE winds 5-15 kt Tue with seas 2-5 ft. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...None. MARINE...Small Craft Advisory until 7 PM EST Monday for AMZ150-152-154. Small Craft Advisory until 4 PM EST Sunday for AMZ156-158. && $$ SYNOPSIS...MHX NEAR TERM...TL/MS SHORT TERM...TL LONG TERM...CQD/CB AVIATION...MS/CEB MARINE...TL/CEB