####018005763#### FXUS66 KMFR 091720 AFDMFR Area Forecast Discussion National Weather Service Medford OR 920 AM PST Tue Dec 9 2025 ...New Aviation Section... .AVIATION (18Z TAFs)... Showers will be around the coast and parts of the Umpqua Basin through this cycle. KOTH is likely the main terminal to experience any rainfall, but we cannot completely rule out KRBG as well. Otherwise, a combination of MVFR to IFR/LIFR conditions will persist through most of this cycle with intermittent VFR conditions. Overnight into Wednesday morning we are expecting low clouds/fog to be present, so confidence is high (50%-70%) for at least IFR conditions overnight. -Guerrero && .PREV DISCUSSION... /Issued 323 AM PST Tue Dec 9 2025/ DISCUSSION...Updated Aviation section... AVIATION...09/12Z TAFs...A front remains aimed at the Oregon Coast just north of North Bend. This is bringing gusty winds to the coast and a variety of ceiling conditions across the region. Along the coast and just offshore, IFR and LIFR ceilings are expected to prevail through the TAF period, with visibility also lowering this morning as the front slowly sags south. VFR conditions generally prevail across the region, but LIFR conditions are spotted in the Rogue/Illinois/Applegate Valleys, and these lower conditions will prevail through this morning. In the Umpqua Basin, the proximity of the front could limit fog development there, and VFR conditions are currently present, but have added MVFR ceilings when the sun comes. Meanwhile, strong winds aloft will persist near the Cascades and over the east side in Oregon (north of Highway 140) today where higher terrain could experience gusts in excess of 50 mph. This could lead to some low-level wind shear over there (NE of Klamath Falls) since a low-level inversion probably doesn't allow these winds to mix all the way to the surface in some valleys. Even so, vertical mixing may improve today to allow surface wind gusts to 50 mph from around Summer Lake eastward. PREV DISCUSSION... /Issued 235 AM PST Tue Dec 9 2025/ DISCUSSION...Satellite and observations show that low clouds are developing across some west side valleys, including the Rogue Valley. Heavier cloud cover is preventing fog development in more east side spots, including Klamath Falls for now. Radar has a few showers passing in far northern Coos and Douglas counties as they move east tonight. Through the morning, these showers are forecast to reach ~0.25"- 0.50" near the Douglas/Lane County border. Snow levels in the affected areas are above 8,000 feet tonight. The upper level high to our southwest off of central California is still looking to be enough to keep most of the activity north near Portland and Seattle this week. The main areas to see rainfall for the next few days will be the same locations to see it now. Between this morning and Wednesday morning, very northern Coos and Douglas counties, including parts of the Cascades, can expect 0.30"-0.75", with near 1.25"-1.75" near the northernmost part of Douglas County. Most of the rain will fall between this morning and into the evening. Although most of this will be occurring in a 12 hour period, there is a lower concern for flooding with this compared to areas north of us. East side and Northern California have the lowest chances for rain with less than .15" from Chemult to Fort Rock being the most to expect. Although the area will be dry, east side will have to deal with stronger winds between now and this afternoon. A mid-level jet of 50- 60 kt with similar speeds at 300 mb show that strong winds are forecast to reach the surface during this time with gusts near 50 mph. A Wind Advisory is in effect through this evening, and this includes areas near Silver Lake, Summer Lake, and Paisley. Wind gusts near 45 mph have already been reported at Summer Lake early this morning. Please see the NPWMFR for more information. Getting into the middle of the week, the high pressure to our southwest takes control and brings drier conditions through at least the start of next weekend. Earlier models were showing a continued chance of showers at the coast through the work week, but this has started to back off. The EC has also backed off on weekend rain chances, but it is still coming in earlier than the GFS with a Monday morning vs Monday afternoon timeframe. Either way, there is some more agreement that early next week could have active weather in both Southern Oregon and Northern California. In the meantime, we will be watching for how the system the next few days moves through and watch for how the models handle the next week after. -9 MARINE...Updated 200 AM PST Tuesday, December 9, 2025...Gusty south winds and steep wind waves combined with westerly swell will maintain conditions hazardous to small craft through at least today. Winds subside tonight, but west swell persists into Wednesday, especially north of Cape Blanco. Conditions improve for the latter half of the week as swell dominated seas gradually lower. Expecting showers over the waters through mid-week as well which could further reduce visibilities (fog/low clouds expected as well) over the next couple days. && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Wind Advisory until 10 PM PST this evening for ORZ030-031. CA...None. PACIFIC COASTAL WATERS...Small Craft Advisory until 1 AM PST Wednesday for PZZ356-376. Small Craft Advisory until 10 AM PST Wednesday for PZZ350-370. && $$ ####018013025#### FXUS63 KABR 091720 AFDABR Area Forecast Discussion National Weather Service Aberdeen SD 1120 AM CST Tue Dec 9 2025 .KEY MESSAGES... - Approaching clipper system will (60-95% chance of occurrence) generate a period of light freezing rain today, starting out early this morning across north central South Dakota, before shifting over into northeast South Dakota and west central Minnesota by mid morning through early afternoon. Temperatures warm above freezing from west to east throughout the morning into early afternoon today. A Winter Weather Advisory remains in place this morning for the freezing rain potential. - Northwest winds this afternoon through tonight are expected to gust in excess of 50 to 65 mph across central and north central South Dakota. Gusts in excess of 50 mph are also expected over northeast South Dakota and west central Minnesota by early this evening, persisting into the early morning hours on Wednesday. A High Wind Warning is in effect for these dangerously strong winds. - By the end of the week, colder air is expected to move in. High temperatures will be in the single digits above 0, with overnight lows as low as the teens below zero. Wind chill values Friday and Saturday morning could be as low as -20 to -30 degrees. - Multiple rounds of snow will be possible late this week. Northeastern South Dakota into western Minnesota has a 30-50% chance of 2" of snow Thursday through Friday. A band of snow may impact the area over the weekend, although there is still a lot of uncertainty in the tracks and amounts. && .UPDATE... Issued at 1050 AM CST Tue Dec 9 2025 Much of Faulk county is now well into the mid 30s for the last hour or two, however the rest of the James valley has been a bit more stubborn in regards to warming up. Winds are shifting to southwest so its just a matter of time, with guidance remaining consistent with its slow gradual warmup. May need to extend the advisory up in the far northeast for a little bit longer though since much of the far northeast is still below 0C. The 0.08 of rainfall thus far at KABR has also rendered our snowpack unblowable for the future winds. This rainfall continues to progress east southeast, now into Day, Marshall and Clark counties. Tracking its progression into the afternoon, there may be a northern cutoff where less rainfall falls into the snowpack, for far northern Roberts and parts of Traverse counties, but overall the expectation is with the rain and temperatures, this snowpack will react very little to the incoming winds. In regards to winds speeds, very little has changed with this update. Cold advection is a little convoluted to start with two separate areas of a tight 925mb gradient, one split the CWA north and south at 21Z headed southwards and the second, northwest to southeast coming in closer to 00-03Z (tightest across the northeast CWA). The HREF captures the duality of this surge in winds well, with a surge west river early this afternoon which will leak into our western CWA, and more broadly around 00Z. In- between there is some less efficient mixing but some fraction of that 50-60kts at 850mb will still manage to reach the surface. These most intense wind values start dropping off after 03-04Z as 1/2km winds begin a gradual downward trend. Lastly, many of the CAMS have wrap around snow showers into the northeast of South Dakota and our counties in Minnesota. BUFKIT profiles also support a cooling of profiles but there are issues with ice in the dendritic growth zone until after about 03-05Z. HREF highlights the top of the Coteau for a 1/4 to 1/2 inch per hour snowfall rates from 04 to 09Z, with a mean accum of 2" at its peak. This is just slightly out of phase with the strongest winds, which mentioned above start dropping after 03-04Z. HREF analog for blizzard conditions highlights the whole northeast (northern Coteau through western MN) with just a 20 to as high as 40% probability. && .SHORT TERM /TODAY THROUGH WEDNESDAY AFTERNOON/... Issued at 357 AM CST Tue Dec 9 2025 At 3 AM CST, there was a pocket of freezing fog in the James River valley (mainly Brown County), although, Watertown briefly dropped visibility into some fog as well. It is cloudy over the CWA this morning, with temperatures west of the James River valley predominantly in the mid 20s to upper 30s (warmest out along and west river). Within and east of the James River valley, temperatures were mainly in the teens to mid 20s. Precipitation is overspreading the northern high plains of Montana and far western North Dakota, heading in this direction. Only adjustments to the Winter Weather Advisory for freezing rain was to add a couple more tiers of counties for a few hours for the early part of this morning when WAA-forced precipitation (rain) reaches north central South Dakota (expected prior to 12Z). The MRMS Sfc Probability of subfreezing road temperatures over the next 60 minutes supports this brief expansion of the freezing rain headline over to Corson/Dewey counties from 11Z to 16Z this morning. Did break off a piece of the pre-existing "northeast SoDak" wint wx headline area in order to create a "between the MO and James River valleys" hazard segment to include Campbell, Walworth, Potter and Faulk counties, running from 12Z to 18Z. Otherwise, the rest of the Winter Weather Advisory is basically the same, timing/coverage-wise, and the High Wind Warning remains in place, unchanged from what the Monday day-shift crafted when they issued the High Wind Warning. Should be looking at a corridor of time this morning when freezing rain is happening from west to east across the CWA, predominantly throughout and north of the U.S. Highway 212 corridor. Strong post- cold frontal 0.5km mixing winds on a 16+hpa 6-hourly pressure rise bubble should be able to produce sustained winds at 40 mph for an hour or more, or gusts well in excess of 60mph sometime between late this afternoon and late tonight. Regarding post-clipper system snowfall on the backside of the system late tonight into Wednesday morning, there is now a small section of terrain-influenced "near blizzard"-type blowing snow being produced by the blowing snow model across a portion of Marshall and Roberts counties tonight between roughly 05Z and 10Z when winds and temperatures and upslope on the Prairie Coteau may be able to overcome the general lack of any sort of meaningful snowfall-rates to produce some localized/isolated rather poor visibility in falling/blowing snow. A new wrinkle for the next shift to debate. Despite the warming process coming to an abrupt halt yesterday at the James River valley (temperatures did warm up quite a bit west of the James River valley yesterday), still going with a significant warm-up today, CWA-wide. So, after two days of snowmelt, topped with several hours of rainfall potential, there should be no blowing snow concerns across central/north central South Dakota. Once temperatures fall back below zero this evening, the remaining modified snowfield should transition into blocks/sheets of ice. Similar outcome expected across northeast SoDak and west central Minnesota this afternoon/evening, although CAMS/deterministic GSM's do hint at there being some falling snow (generally less than an inch except up on the far northern portion of the Prairie Coteau) potential later tonight into Wednesday morning across far northeast South Dakota and west central Minnesota. After how warm it will be today, Wednesday will feel like quite a shock to the system, when high temperatures will only be in the upper teens to low 30s over the CWA. && .LONG TERM /WEDNESDAY EVENING THROUGH MONDAY/... Issued at 357 AM CST Tue Dec 9 2025 The pattern of the Northern Plains remaining on the front side of the upper-level ridge over the western CONUS. With this setup, a couple of jet streaks will move over the area, providing enough divergence aloft to support precipitation Thursday through early Friday. Model soundings indicate that snow is the most likely precipitation type through the event, but there will be chances for rain and freezing rain as well. The latter precip types could occur with a de-saturation of the DGZ aloft during the event, which could transition from ice formation to liquid formation aloft depending on how cold temperatures at the top of the saturated layer remain. Latest ensemble medians have broad coverage of 0.10"-0.20" in liquid totals through Friday morning, with the highest totals over north central into northeastern South Dakota. This will translate to around 1"-2" across much of the forecast area, although varying snow to liquid ratios (~10:1 over north central South Dakota ranging to ~15:1 over northeastern South Dakota) may create a disparity between the highest liquid equivalent and highest snowfall locations. Latest probability of at least two inches peaks over northeastern South Dakota, ranging from 30 to 50 percent. With this setup, a strong blast of cold air is expected to move into the region Friday into Saturday. 850mb temperatures by Saturday morning are expected to be in the teens below 0 Celsius, which is below the 10th percentile for this time of year. The presence of this cold air will lead to overnight lows at the surface below zero Fahrenheit Friday and Saturday mornings. At these temperatures, wind chills are expected to reach -20 degrees Fahrenheit in most of north central and northeastern South Dakota, and potentially even approach the Cold Weather Advisory Criteria of the northern counties of -30 degrees Fahrenheit. Friday morning is of particular concern, because while temperatures are slightly warmer than Saturday morning, northwesterly winds of 20-25 miles per hour gusting to 35 overnight will counteract that difference. The latest long-range ensemble guidance put the probability of hitting -30 degrees Fahrenheit for the minimum overnight wind chill in northeastern South Dakota at 20- 40% on Friday morning, easing up to around 10-20% Saturday morning. Yet another round of snow may impact the region this weekend, this time being more banded with a swath of heavier precipitation totals. There is still a lot of uncertainty remaining, but it is worth noting that forecast snow totals have jumped up over the latest forecast cycle. The latest NBM currently puts a band of 50% probability to see 2" of snowfall accumulations, with a band of 20- 30% chance for up to 4". && .AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/... Issued at 531 AM CST Tue Dec 9 2025 Terminals KABR,KATY,KPIR,KMBG Still dealing with a couple of pockets of fog/low clouds at KABR/KATY this morning. IFR fog/stratus should abate by 15Z, just in time to grapple with VFR/MVFR conditions in freezing rain. Temperatures should warm up enough for plain rain to take over at KABR/KATY by early afternoon, just in time to grapple with very strong northwest winds developing. Sustained winds over 30 knots, with gusts over 45 knots are expected. Low level wind shear potential will exist for much of the afternoon into this evening, as well. VFR conditions, to start, at KPIR/KMBG could have brush with MVFR visibility in rain (at KPIR) or freezing rain (at KMBG) this morning. Otherwise, VFR condition are expected at KPIR/KMBG from about 18Z to the end of the TAF valid period. Very strong northwest winds are expected at KPIR/KMBG, as well, by early this afternoon, with sustained winds over 35 knots and gusts over 50 knots. Low level wind shear potential will exist for much of the afternoon into tonight, as well. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...High Wind Warning from 3 PM this afternoon to 6 AM CST Wednesday for SDZ006>008-011-018. High Wind Warning until 2 AM MST Wednesday for SDZ003-015. High Wind Warning from 3 PM CST /2 PM MST/ this afternoon to 3 AM CST /2 AM MST/ Wednesday for SDZ004-005-009-010-016-017- 033>037-045-048-051. Winter Weather Advisory until noon CST today for SDZ005>008-010- 011-018>023. High Wind Warning from 6 PM this evening to 6 AM CST Wednesday for SDZ019>023. MN...Winter Weather Advisory until 3 PM CST this afternoon for MNZ039- 046. High Wind Warning from 3 PM this afternoon to 6 AM CST Wednesday for MNZ039-046. && $$ UPDATE...07 SHORT TERM...10 LONG TERM...BC AVIATION...10 ####018009113#### FXUS61 KPBZ 091724 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 1224 PM EST Tue Dec 9 2025 .SYNOPSIS... Active weather pattern through the weekend will bring rounds of snow, occasionally mixed with rain, as well as fluctuating temperature and gusty winds. Overall, snowfall accumulations favor areas north of Interstate 80 and the ridges of southwest Pennsylvania and northern West Virginia. && .NEAR TERM /THROUGH TONIGHT/... KEY MESSAGES: - Weak, fast moving disturbance brings light snow to northwest PA this afternoon with only light accumulations - A second, fast moving disturbance brings a quick 2 to 4 inches of wet snow to areas along and north of I-80 after Midnight - Seasonably cool temperatures continue --------------------------------------------------------------- A weak shortwave currently crossing the northern Great Lakes is expected to drop through the lower Lakes by this afternoon and evening. As high pressure slides to the Atlantic Coast in response to its approach, weak warm advection will lift area temperatures to the mid 30s. Meager moisture profiles and weak jet-ascent will limit this system's precipitation shield to areas along/north of I-80; timing of the passing wave and weak frontal boundary favors a 2pm onset and 7pm exit. Thermal profiles favor all snow, but the lack of deeper moisture/strong lift and marginal surface temperatures right around or possibly even a degree or two above freezing mean probabilities of exceeding 1 inch of accumulation is low (15-30%). Any lingering precipitation during late evening hours should be even lighter and generally non-accumulating. Rapid transition occurs Tuesday night as a deeper upper trough enters the Great Lakes region hot on the heels of the afternoon wave. A stalled front from the Tuesday afternoon wave lifts northward as a warm front as southwest flow develops ahead of the approaching low. Strengthening jet-aided ascent along with the warm front will aid precipitation development into northwest PA and eastern OH during overnight hours. With deeper moisture and better ascent aligning north of the front, a second, heavier wave of snowfall is expected along and north of the I-80 corridor generally after Midnight through dawn. A Winter Weather Advisory is now in effect for these areas starting at 1 AM EST, with a quick 2 to 4 inches of wet snow possible overnight through dawn Wednesday. Areas between the I-80 corridor and Pittsburgh may see 1 to 2 inches during that time as well, while warming thermal profiles farther south limit accumulations as rain mixes in with snow. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... KEY MESSAGES: - Stronger low Wednesday features a mix of rain and snow that will transition back to all snow Wednesday night ---------------------------------------------------------------- Precipitation spreads areawide on Wednesday as the upper trough continues to dig eastward across the Ohio Valley and large-scale ascent overspreads the region. Precipitation type will be a bit more tricky given the aforementioned warm advection, but overall confidence remains relatively high in any accumulating snowfall remaining north of Pittsburgh and in the ridges during daytime hours while elsewhere all rain or a rain/snow mix will result in little to no accumulation. A transition to rain or a rain/snow mix will be latest for northwest PA and the higher terrain southeast of Pittsburgh, where it may not occur until late afternoon if at all. Until this occurs, accumulating wet snow is likely and favoring these areas. If a transition to rain or rain/snow does occur north of I-80 during the afternoon, it will be rather short lived as winds shift to northwesterly by evening and cooling thermal profiles return snow (possibly with some lake enhancement) through late evening. An additional 1 to 2 inches of localized snowfall will be possible during that time. As such, the Winter Weather Advisory that starts at 1 AM EST Wednesday is not set to expire until 10 PM EST Wednesday, and could be extended a bit further if lake-enhanced snow showers linger into Wednesday night. Meanwhile, in the ridges of SW PA and northern WV, there is some potential for snowfall accumulations to reach 3 to 5 inches, though no headlines have been issued yet as it would be beneficial to wait until additional guidance (especially from higher resolution convective-allowing models) later today allows for those decisions to be made with higher confidence. That said, in the higher ridges of eastern Tucker County (WV), where snow may never change over or mix with rain, latest ensemble guidance suggests at least a 50% chance for total snowfall accumulations to reach or exceed 6 inches, prompting the issuance of a Winter Storm Watch for that area beginning at 7 AM EST Wednesday and lasting until snow is forecast to taper off Thursday afternoon. This Watch may be upgraded to either an advisory or warning in a future forecast package depending on how additional guidance impacts our confidence in accumulations. Beyond the precipitation, tight surface gradients will foster gusty winds between 30-40mph in the afternoon in the lower elevations, with 35-45 mph gusts possible in the ridges and even peak gusts as high as 55 mph possible in the highest ridges of eastern Tucker County, WV. Rapid movement of the surface low and upper trough over the New England region Thursday will bring colder temperatures under northwest flow and a dry day for most. Snow showers may linger north of I-80 where lake-enhancement could allow localized accumulations of up to an inch or so to continue, as well as in the ridges where weak upslope forcing will support additional light accumulations. && .LONG TERM /FRIDAY THROUGH MONDAY/... KEY MESSAGES: - Unsettled pattern continues through the weekend - Lake effect & terrain driven snow Friday with another system over the weekend - Temperatures remain well below average ------------------------------------------------------------------- The unsettled pattern continues to close out the week and into next weekend as mid-level troughing continues to plague the ECONUS. A weak shortwave embedded within the broader trough brings another round of snow to the WV ridges while lake-effect snow showers continue north of I-80. Eventually, the upper low over New England advances eastward over the Atlantic as another upper low dives from northern Canada towards the upper Great Lakes. This allows additional shots of cold air to filter in, albeit with both timing and depth differences evident among global models. Confidence is increasing in a several day period where we have high temperatures some 15-20 degrees below average in the cP airmass through the weekend with highs in the 20s and lows in the teens or single digits. Cold air being entrenched across the region means any additional disturbances are likely to produce snow as the prevailing precip type areawide. While the overall pattern appears messy and ensembles are clearly struggling to agree on timing and intensity of any given wave, confidence is increase in at least one more shot at snowfall over the weekend before long term guidance finally has the eastern Canadian longwave trough breaking down. Stay tuned for more details as we get closer and confidence increases. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... KEY MESSAGES: - Restrictions in snow at FKL and DUJ possible overnight - Increasing S-SW wind into the overnight period. ------------------------------------------------------------------- A crossing warm front will provide sufficient lift areas north of I-80, where FKL and DUJ could see restrictions in snow this evening and overnight. Gusty winds will persist with a tight pressure gradient and a well mixed boundary layer. Snow overnight will transition to a wintry mix early in the morning and eventually rain with IFR or lower cigs likely by late morning. Latest HREF guidance shows increasing IFR cigs over the morning, and eventually a 90-100% chance areawide by early afternoon.; This is also supported by latest analogs. Outlook... Restrictions and scattered snow showers are expected Thursday and Friday with a crossing upper trough, and again Saturday with approaching low pressure. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...Winter Weather Advisory from 1 AM to 10 PM EST Wednesday for PAZ007>009-015-016. OH...None. WV...Winter Storm Watch from Wednesday morning through Thursday afternoon for WVZ514. && $$ SYNOPSIS...Cermak/Frazier NEAR TERM...Cermak/Frazier SHORT TERM...Cermak/Frazier LONG TERM...Cermak/MLB AVIATION...88