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KEY MESSAGES

* Continued warming pattern expected through the middle of the week with highs warming into the 40s and 50s.

* Strong cold front Thursday will produce widespread gusty showers and perhaps a few thunderstorms. Some isolated activity could be strong to severe with strong damaging winds as the main impact.

* Rapid temperature drop behind the front Thursday night into Friday morning with scattered snow showers Friday morning.

* Temperatures will trend warmer through the weekend and into next week.

UPDATE

Issued at 940 PM EST Tue Dec 16 2025

This evening, the Ohio Valley is located in the middle of a return flow regime with low-level SW flow increasing ahead of a pressure trough moving across the Great Lakes. A stratus deck which has persisted over the region for much of the day continues to be spread across the Ohio Valley, though ceilings have lifted to around 5k ft over the past few hours. Additionally, regional CIG obs suggest that the back edge of this stratus deck is beginning to move into west KY and southwest IN at this hour, with erosion of some of the stratus likely to begin over the next few hours.

With that being said, the low clouds and warm SW flow has kept temperatures quite mild since sunset, with many locations having reached their high temperature for the day since 0Z. 25-30 degree dewpoint depressions and sporadic wind gusts suggest that we are still fairly well-mixed in the low-levels. Once the lower clouds begin to clear, we should be able to get somewhat better decoupling, but temps are unlikely to fall much tonight.

The main change to the forecast was to increase temperatures over the next few hours in particular and increase minT for Wednesday morning. Now expecting most locations to only fall into the mid-30s to around 40 tomorrow morning.

SHORT TERM /THROUGH WEDNESDAY/

Issued at 310 PM EST Tue Dec 16 2025

Low stratus continues to dominate the weather this afternoon. This helped to keep temperatures cooler than expected, with upper 30s to low 40s this afternoon, but still warmer than the past couple of days. Visible satellite imagery shows the thin stratus layer thinning/mixing out some upstream across western KY and northwest TN. Could see some partial clearing later this evening, but high clouds start to increase as a weak sfc low over the TX Panhandle moves east and meets up with a weak shortwave mid-level trough moving into the Great Lakes by tomorrow morning. Increased cloud cover and continue southerly flow will keep us mild overnight with lows staying above freezing for most overnight.

Shortwave trough axis will move across the Ohio Valley during the day on Wednesday. While most will be dry, we could see an isolated shower or sprinkle mainly along the KY/TN border during the day. Winds will remain out of the south-southwest with gusts of 10-15mph and temperatures warming into the mid/upper 40s to even low 50s during the afternoon.

LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/

Issued at 310 PM EST Tue Dec 16 2025

Strong upper level trough, associated deepening sfc low along with a strong trailing cold front will work out of the Upper Midwest and Dakotas Thursday morning and into the Great Lakes/Ohio Valley late Thursday into Friday. Sfc low strengthens as it moves over the Great Lakes, as central pressure drops tightening the sfc pressure gradient resulting in strong southerly flow with gusty winds of 30- 35 mph. This will continue to advect in warm, moist, Gulf air into the region ahead of the approaching cold front. Moisture pooling ahead of the boundary increase PWAT values between 1.00" to 1.20" which is nearly 250% above normal for this time of year. Gusty winds and widespread rain showers are expected for most of the day Thursday. With the increased sfc moisture ahead of the boundary, dewpoints around could nose north of the Ohio River by Thursday afternoon/evening. Forcing along the strong cold front along with a robust 60-70kt LLJ should be enough to form a thin line of convection right along the boundary as it works from west to east during the day Thursday. Surface based instability remains marginal at best with maybe a couple hundreds Joules of SBCAPE ahead of the front, but likely enough to give us a couple of thunderstorms. With the very weak instability but strong LLJ, we get one of our typical cold weather season high shear-low CAPE scenarios with this system. Main threat with any storms will be the potential for isolated damaging wind gusts. It will be a warm December day as highs will mainly be in the mid/upper 50s with isolated locations near the KY/TN border hitting 60. Precipitation amounts look to be around an inch for most locations across central KY and southern IN with locally higher amounts from any strong convection that may form.

Front is expected to quickly push eastward Thursday night and be generally clear of the CWA after midnight. Cold air advection behind the front will move in behind the departing boundary with temperatures rapidly falling from near 50/upper 40s near midnight to the mid/upper 20s and low 30s just before sunrise on Monday. As the cold air filters in, it is possible that some of it catches up with lingering, post frontal moisture/precipitation giving us some lingering wintry mix or light snow, mainly over towards the Bluegrass early Friday morning. The other concern with rapidly falling temperatures is moisture associated with the evening showers/storms quickly freezing as the colder air moves in. The one thing that works against this is strong westerly winds behind the front helping to dry surfaces before the subfreezing temperatures arrive.

Friday will be mainly dry but much colder and blustery thanks to brisk west-northwest winds. Other than the aforementioned light snow flurries/showers east of I-75 and generally north of I-64 during the morning Friday looks mainly dry and clouds are expected to clear from the southwest to the northeast as the trough and sfc low work east into the Mid-Atlantic and New England. Highs will be about 25 degrees colder than they were on Thursday and about 10-15 degrees below normal for this time of year in the low/mid 30s Friday afternoon.

The shot of colder weather is brief as the upper pattern becomes more zonal over the region as we go into the weekend. Temperatures rebound into the low/mid 50s on Saturday and slightly cooler with 40s to near 50 on Sunday. A weak shortwave trough and fast moving clipper system will pass over the Great Lakes late Saturday into Sunday. A weak, mostly dry cold front will push into the Ohio Valley Saturday night into Sunday with an increase in rain showers over the area. Current pops are between 20-30 percent.

Moving into next week, ridging is expected to build across the four corners region with a continued northwest flow across the Great Lakes into New England. With high pressure moving off the Mid- Atlantic, we'll get back into a broad southwest flow/warm advective type pattern ahead of a weak frontal system that looks to move through late Mon/Tues. Forcing here is weak, but cloudy skies and some light rain showers are looking more likely in the Mon/Tue time frame. Highs Monday will range from the lower-mid 40s over southern IN/northern KY with low-mid 50s over southern KY. Highs Tuesday look to warm into the low 50s over southern IN/northern KY with mid-upper 50s over southern KY.

Extended Forecast from Previous Discussion...

Since our last extended forecast discussion prior to Thanksgiving, we were quite bullish in a colder pattern setting up after Thanksgiving and leading into December as we expected the MJO to orbit out of phase 6 and into phase 7/8. This did verify quite well and the temp departures for December to date rack up there with December of 1989 and December 2013. We expected this colder pattern to persist into the holidays based on the expected MJO forcing. However, the overall hemispheric pattern broke down a bit in the last few weeks which is going to lead to that cold forecast into the Holidays to bust. So what happened? Well, first we had quite the flare up in Indian Ocean convection last week. This was a result of a westward moving Kelvin wave moving out of the Pacific. This feature essentially muted the MJO phase 7/8 forcing and the MJO RMM plots went into the neutral zone. Teleconnection patterns also didn't verify all that well as we had a +AO/+NAO on the Atlantic side and a bouncy EPO/-PNA on the Pacific side. This has allowed the cold pattern to relax a bit and a milder pattern is expected across much of the CONUS over the next week.

However, this break in the cold is likely not to last as 200mb velocity plots show a decent Rossby/Kelvin wave pushing into the Atlantic next week. The global models are picking up on this showing a stronger jet developing across the Atlantic with stronger Blocking developing over eastern Europe. Model progs show this blocking retrograding westward with time setting up the potential for the NAO to trend more negative as we head into late December. Additionally, the AO, while positive now is expected to grow increasingly negative as we round out the year and we're also seeing growing model consensus on stronger blocking developing into AK. Should this be the case, the general pattern looks to reload and we should see a colder pattern return toward the end of December and into early January.

AVIATION /00Z TAFS THROUGH 06Z THURSDAY/

Issued at 641 PM EST Tue Dec 16 2025

Current satellite imagery continues to show a large area of stratus over the region, though most of the MVFR CIGs appear to have moved off to the northeast at this hour. With cloud bases expected to gradually rise over the next few hours, expecting VFR conditions to continue with ~5k ft stratus continuing through much of the night. Tonight, the primary impact should be LLWS as a 45-50 kt LLJ moves across the region. Surface winds should also remain around 10 kt out of the S/SW overnight. On Wednesday, the low-level stratus should scatter out at all sites except possibly BWG as a mostly dry cold front passes to the northeast. Winds could briefly veer around to the SW, but then should back to the S/SE by the end of the current forecast period.

LMK WATCHES/WARNINGS/ADVISORIES

KY...None. IN...None.