####018009461#### FXUS63 KJKL 132156 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 456 PM EST Sat Dec 13 2025 .KEY MESSAGES... - Another light, to possibly moderate, snowfall is on its way for this evening into early on Sunday, mainly north and east of a Stanton to Jackson to Whitesburg line. - An arctic airmass moves into our region for late tonight through Sunday night with significantly below normal temperatures and bitterly cold wind chills in store. - Nearer to, if not above normal, temperatures can then be expected from Tuesday through the end of next week. && .SHORT TERM...(This evening through Sunday night) Issued at 450 PM EST SAT DEC 13 2025 Late this afternoon, an upper level low was centered over the northern Great Lakes/Ontario with an upper trough extending south into the MS Valley and eastern Conus. A shortwave trough moving through the upper level trough was nearing the Lower OH valley. At the surface, a frontal zone continues to move further into VA and TN. Cold high pressure was centered in the Dakotas and extended through much of the central and northern Plains. The approach of the shortwave trough as well as some jet dynamics/jet streak north of the OH River is leading to widespread snow mainly near and north of the OH River. A north to south temperature gradient is also in place with low clouds having persisted in the north. This evening and tonight, the upper level low is expected to track to near the Lake Huron vicinity while the shortwave trough will track through the OH Valley this evening and working east of eastern KY late tonight. The 500 mb trough axis will begin to approach late tonight. Ongoing cold advection will increase in earnest this evening with 850 mb temperatures expected to fall to near or below 0C during the evening and then to roughly the -10C to -16C range around dawn on Sunday. Along with the passing shortwave and some favorable jet dynamics/right entrance region in the north this evening, the low level flow between the front to the south and east and the cold high pressure over the Central Conus will become increasingly upslope/northwest and low level lapse rates will steepen. These factors should ultimately determine QPF and ultimately amounts as moisture increases as the shortwave nears and crosses the area. Low level moisture into and above the DGZ should linger behind the shortwave. 850 mb temperatures will cool to -16 to -20C late Sunday morning to early Sunday afternoon as the mid level trough axis passes. Mid level height rises follow. However, the lingering low level moisture, upslope northwest flow, and continued cold advection should support some isolated to scattered flurries at times during much of the day on Sunday. The low level moisture will become increasingly shallower Sunday evening and Sunday night and this combined with warm advection should lead to some of the low clouds decreasing though some could remain through the night as the sfc high builds from the MS Valley into the Lower OH Valley and settles across eastern KY. Lows could near the 0 degree mark possibly to more of an areal extent than currently forecast especially where there is any clearing and snowcover. A period of snow is expected to gradually develop early this evening in the north, with the precipitation more spotty and likely mixed initially with rain in the southwest as the area of precipitation gradually spreads south this evening into the overnight hours. The snow should taper to snow showers from northwest to southeast late tonight to early on Sunday. By late evening into the overnight, the snow should also be more convective in nature through the night and again, precipitation should be more spotty in the southwest where the duration of omega and deeper moisture will be shortest. The convective allowing models, especially the HRRR have generally been more pessimistic with snowfall for this evening into Sunday morning though the most recent 20Z run is a bit higher than several previous run. The recent RAP runs and NAMNEST have generally a bit higher in the advisory area as are the global models including the ECMWF AI. This leads to uncertainty in snowfall totals. However, some snow expected to fall in the advisory area combined with falling temperatures travel impacts are anticipated even if totals end up only marginal for advisory criteria on the southern and western edge of the advisory. Wind chills late tonight into Sunday morning are forecast to near and in some spots, mainly the westernmost tier of counties, reach the lower end of the Cold Weather Advisory criteria. Wind chills and or air temperatures should again near 0 degrees Sunday night. For simplicity and better agreement with surrounding WFOs opted to add Harlan County to the Cold Weather Advisory and also extend the Advisory through Sunday night. .LONG TERM...(Monday through Saturday) Issued at 336 PM EST SAT DEC 13 2025 Monday morning, surface high pressure will be situated right over Eastern Kentucky, which will bring mostly clear skies and light southerly winds to the region. It will also feel like a frozen tundra, as some of the coldest air of the season will remain entrenched across the area from the previous arctic air mass that moved through the Commonwealth over the weekend. Temperatures and wind chills will be in the single digits early Monday morning. With high pressure continuing to build across Kentucky, rising heights will lead to temperatures warming into the low 30s around and north of the Mountain Parkway, and mid to upper 30s along and south of the Hal-Rodgers/KY-80 Highway. Dry conditions should last through the better part of Wednesday, as Eastern Kentucky remains in somewhat zonal flow through then. There is some moisture that may creep into the Lower Mississippi Valley Wednesday, morning, but at current POP chances for the southwestern most counties remain just under 15%. North of the area, an upper level low will be passing through the Upper Great Lakes, which pack isobars through that area. Breezy conditions may translate as far south as Eastern Kentucky. At current, gusts up to 20 mph look possible, but conditions should otherwise remain fairly uneventful. POP chances increase heading into Wednesday evening and Thursday, as and another upper level trough begins to deepen over South-Central Canada. Showers will develop out ahead of the systems warm front early Thursday morning. While these showers are ongoing, a surface cold front will be further west, somewhere through the Upper and Mid- Mississippi valley. This trough looks to progress east and looks to become somewhat negatively tilted by Thursday afternoon and evening. There may be a chance for thunderstorms, however current chances remain under 15%, so mention of thunderstorms have been left out of the forecast at this time. Winds are expected to be out of the south to southwest and could gust as high as 25-30 mph. By Thursday, temperatures across the region could be in the upper 50s, and near 60 in some places. Once the cold front moves through the area Winds become westerly and eventually light an variable later Friday. Temperatures may be 10-15 degrees cooler than Thursday, with high temperatures in the upper 30s to mid 40s. There are some signals of another system approaching for next weekend, which would likely be rain, but model spread is to great at this point to nail down any specifics. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) ISSUED AT 135 PM EST SAT DEC 13 2025 Low clouds have cleared or scattered for the most part near a line from KSME to KLOZ to KCPF to near KPBX and this should creep toward KJKL and KSJS. Thus uncertainty during the first 6 hours of the period for ceilings is greatest at KJKL, KLOZ, and KSJS as MVFR was forecast though there may be several hours of VFR at these locations. Otherwise, low clouds should prevail in the north such as KSYM with MVFR anticipated for the first 6 hours of the period. Some snow from the clipper system incoming could affect KSYM and norther locations as early as 21Z or 22Z with snow steadier snow developing there nearer to 00Z. However, the area of snow should shift southeast across the entire area between 00Z and 12Z, with a 2 to 4 hour of impact on VIS and ceilings down into the MVFR and IFR range. Briefly lower ceilings or vis are possible in any more intense snow showers. Generally, light and variable winds are expected initially before winds become northwest at 5 to 10KT by the 03Z to 06Z timeframe and then maintain that magnitude and direction to end the period. && .JKL WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 10 AM EST Sunday for KYZ044- 050>052-059-060-104. Cold Weather Advisory from 1 AM Sunday to 10 AM EST Monday for KYZ044-050>052-058>060-068-069-079-080-083>088-104-106-108-111. Winter Weather Advisory until 1 PM EST Sunday for KYZ106>110-112- 113-115-118>120. && $$ SHORT TERM...JP LONG TERM...GINNICK AVIATION...JP ####018003508#### FXUS65 KVEF 132159 AFDVEF Area Forecast Discussion National Weather Service Las Vegas NV 159 PM PST Sat Dec 13 2025 .KEY MESSAGES... * Mild conditions with light breezes continue across the region through the upcoming week. * A disturbance will bring a 10-25% chance for precipitation to portions of Inyo County, mainly the Sierra Crest, late week. && .DISCUSSION... The unseasonably mild weather continues across the region the next several days, thanks to persistent ridging over the western CONUS. Latest water vapor imagery and RUC 500 hPa analysis indicates a subtle disturbance near the California/Baja border that will undercut the ridge and translate eastward toward the Four Corners Region through Monday. Locally, the only impacts from this will be an uptick in mid-level and high clouds, with winds expected to generally remain light. Heading into midweek, the first of a series of disturbances will translate across the northern tier of the CONUS, acting to flatten the ridge and produce zonal flow over southeastern California, southern Nevada, and northwestern Arizona. This zonal flow will persist thereafter, having little impact on the persistent mild conditions across the area, with temperatures only expected to cool a few degrees through the end of the week, with the cooldown most pronounced across the southern Great Basin. The aforementioned transition to zonal flow will displace the ridge southward and allow for a subtle uptick in moisture across the Sierra. Precipitation chances begin increasing to the north of the area midweek, with low-order PoPs (10-25%) returning to the Sierra Crest late week into the weekend when another trough pushes into the Pacific Northwest. Currently, QPF remains very low (ranging from a trace to around a quarter of an inch along the crest) with only light snow accumulations expected at this time, mainly above 9000 feet. Elsewhere, dry conditions continue through the forecast period and beyond, with cluster analyses and ensembles indicating a more substantial pattern shift possible in time for the Christmas holiday. Stay tuned. && .AVIATION...For Harry Reid...For the 18Z Forecast Package...Winds will follow typical diurnal directional patterns through the forecast period, remaining light with speeds under 8KT. Increasing mid and high clouds are expected this afternoon onward, but with bases 12-15kft and above, operational impacts are not anticipated. VFR conditions prevail. For the rest of southern Nevada, northwest Arizona and southeast California...For the 18Z Forecast Package...Across the region, winds will generally remain light, following typical terrain- driven and diurnal directional patterns. The exception will be along portions of the Lower Colorado River Valley near IFP, where channeling of winds will result in gusts to 20-30KT through sunset, with speeds remaining elevated around 10-12KT thereafter. VFR conditions otherwise prevail with increasing mid and high clouds this afternoon onward. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ DISCUSSION/AVIATION...Phillipson For more forecast information...see us on our webpage: https://weather.gov/lasvegas or follow us on Facebook and Twitter