textproduct: Jackson

KEY MESSAGES

- Gusty southwesterly winds between 30 and 40 mph are likely on Wednesday.

- Snow showers are expected to produce spatially variable accumulations and localized travel impacts on Wednesday night into Thursday morning.

- A clipper system is expected to produce more widespread winter precipitation on Thursday night into Friday morning.

- A much colder than normal airmass is forecast to move into the region late next weekend.

UPDATE

Issued at 1253 PM EST TUE DEC 9 2025

Minor adjustments have bee made to the temperature, dewpoint and wind parameters of the forecast. No major changes to report.

UPDATE Issued at 848 AM EST TUE DEC 9 2025

Updated the forecast by incorporating the latest weather observations from around the area. Hourly temperature and dewpoints had the biggest adjustments this morning. Otherwise no major changes were made to the forecast.

LONG TERM

(After midnight Wednesday night through Monday) Issued at 636 AM EST Tue Dec 9 2025

An active synoptic weather pattern will bring periodic precipitation chances and shots of colder air to the forecast area over the next seven days. The period is defined by broad troughing over much of the eastern CONUS, with embedded shortwave disturbances rotating through the resultant mean northwesterly flow aloft. At the surface, this translates to a series of quick-moving, clipper-type systems approaching the Greater Ohio River Valley. The 00z deterministic forecast guidance suite appears to be coming closer to a consensus regarding the timing and evolution of these systems relative to what was observed at this time yesterday, but there remains a significant deal of model spread later on in the forecast period.

When the period opens on Wednesday night, mid/upper-level troughing will have dug deep into the Eastern CONUS. That trough's axis will be positioned in the vicinity of the forecast area, marking the passage of a cold front at the surface. Thus, a cold air advection regime is likely to set up overnight into Thursday. Models collectively depict the 540 decameter critical thickness line over the Cumberland River Basin on Thursday morning as 850mb temperatures drop to between -5 and -10 degrees Celsius. These values favor a transition over to snow showers overnight, and surface temperatures are forecast to drop below freezing area-wide after midnight. Ensemble probabilities for measurable snowfall (>= 0.01 inches) are above 70% for locations east of the I-75 corridor, and locally higher-accumulations appear possible wherever mesoscale-type precipitation enhancements materialize. The post-frontal west- northwesterly low-level flow regime should lead to some orographic enhancements in the higher terrain locales of Southeastern Kentucky. Likewise, some of the currently-available higher-resolution guidance (the NAM) suggests that a fetch off Lake Michigan could overlap with favorable snow squall parameters to yield locally higher accumulations in narrower precipitation bands. The other CAMs will need to be watched closely as this system enters their temporal range, as these smaller-scale details are smoothed over in the baseline NBM grids used to populate the long-term forecast grids. The showery nature of Thursday night's precipitation will make accumulations more spotty, and it is plausible that there will be high spatial variability in this system's storm totals. If the smaller-scale accumulation enhancements come to fruition, isolated travel issues, including potential visibility reductions, could materialize on Thursday morning. Highs will likely struggle to get much warmer than the mid-30s on Thursday afternoon due to the cold air advection regime and residual cloud cover lingering over the area. Additional light snow showers or flurries cannot be ruled out, but more widespread precipitation chances return on Thursday night as another clipper system approaches.

By Thursday night, the deeper upper level troughing will have lifted northeast, although there is generally good model agreement that another shortwave disturbance will rotate around its backside and into the Ohio River Valley by Friday morning. The cold air in place out ahead of this particular system should allow precipitation to begin as snow, although as its surface low reflection approaches, low level winds will back towards the southwest. This could introduce warm air in the bottom portions of the atmospheric column, which could result in a transition to liquid precipitation types. Once this system enters the temporal range of higher-resolution forecast guidance, soundings and temperature profiles will need to be monitored closely, as these will provide greater insight into the p-type forecast and the timing of any transitions. The cold air should stick around for longer the further north and east one goes into the forecast area, and locations northeast of the Cumberland River basin have the highest ensemble probabilties (>50% chance) of measurable snow with this second system. These probabilities increase towards the I-64 corridor, where there is a >80% chance of measurable snow and a 40-50% chance of seeing an inch. Due to greater precipitation coverage and colder antecedent temperatures, more widespread travel impacts cannot be ruled out on Friday morning, and interests with AM travel plans should monitor future forecast updates closely.

Compared to what was forecast a few days ago, guidance has trended warmer for the Friday afternoon to Saturday morning time frame. Shortwave ridging is expected to build into the Upper Midwest and interrupt the train of clipper systems around then, leading to a brief period of midlevel height rises and quasi-zonal flow aloft. Coupled with the previously-discussed southwesterly return flow, this indicates that low-level temperatures will moderate to above freezing values on Friday afternoon. Saturday's MinT and MaxT grids will likely trend upwards in future NBM runs, but spread begins to increase in the temperature guidance beyond then. This makes the precipitation forecast for a third system on Saturday night more ambiguous, although guidance collectively points towards a much colder than average airmass advecting into the region on Sunday. For now, the precipitation type forecast reflects a changeover from rain to snow as the cold air arrives. The magnitude of this cold is highly uncertain, as demonstrated by the 11 to 12 degrees of standard deviation in the European Ensemble's MOS guidance. It is very difficult to provide specific sensible weather details for Sunday and beyond given the compounding uncertainty, but WPC has maintained a 40-60% chance of below-normal temperatures in Kentucky early next week. Average low temperatures for mid-December in Eastern Kentucky are highs in the mid 40s and lows near 32 degrees. The current 25th and 75th NBM temperature percentile data for Monday are 11-22 degrees for AM lows and 27-44 degrees for PM highs. Therefore, it is likely to be noticeably colder than usual at the end of the long term forecast period, regardless of specific values.

AVIATION

(For the 18Z TAFS through 18Z Wednesday afternoon) ISSUED AT 1253 PM EST TUE DEC 9 2025

Mid and high level clouds are currently being observed across the area. Winds will become southwest through the afternoon and increase to between 5 and 15 kts with gusts of 15 to 25 kts. The strongest winds will occur near/west of I-75 and near/north of I-64. Winds aloft will begin to ramp up tonight ahead of an approaching cold front. There's also a Low Level Jet (LLJ) moving across the area tonight, leading to the threat of LLWS for most of tonight. Around 12Z a cold front is expected to move through producing rain for most TAF sites between 13-18Z Wednesday. Winds will remain out of the SW with gusts 20-25 kts, though the threat of LLWS diminishes with the frontal passage.

JKL WATCHES/WARNINGS/ADVISORIES

None.