FXUS63 KJKL 040557 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 1257 AM EST Wed Dec 4 2024 .KEY MESSAGES... - Despite some ups and downs, temperatures will remain below normal into the weekend. Near to above normal readings should return by early next week. - The greatest potential for precipitation will be with a strong cold front Wednesday night into Thursday morning, and again as low pressure passes to our northwest early next week. - Blustery snow showers and even an isolated snow squall are possible with the cold frontal passage on Wednesday night and Thursday morning. && .UPDATE... Issued at 1155 PM EST TUE DEC 3 2024 The clouds have finally cleared out so nothing is in the way of our very cold low temperatures working out. No significant changes to the forecast with just the inclusion of the latest obs and trends for the T/Td/Sky grids. These minor adjustments have been sent to the NDFD and web servers along with a freshening of the zones and SAFs. UPDATE Issued at 655 PM EST TUE DEC 3 2024 23Z sfc analysis shows high pressure overhead, but that is still struggling to clear out the last of the low clouds plaguing the area. These clouds mightily contributed to a very cold day for eastern Kentucky and as they eventually clear this has set the stage for an even colder night - even as WAA kicks in from the west late. Currently, temperatures are already down in the mid 20s most places while dewpoints are running in the mid to upper teens, amid light and variable winds. Have updated the forecast for the near term mainly by adding in the latest obs and trends for the T/Td grids, lengthening the low cloud residency, and even adding a few flurries under them until they clear out - likely before midnight. These adjustments have been sent to the NDFD and web servers. && .SHORT TERM...(This evening through Wednesday night) Issued at 458 PM EST TUE DEC 3 2024 Low stratus clouds have been slow to clear this afternoon as a wintry brand of chill lingers across eastern Kentucky. Temperatures range from the mid 20s to near 30 below 1,500 feet and in the mid 10s to mid 20s above. The latest analysis shows an ~1035 mb surface high centered over Western Kentucky. Looking aloft, a potent 500H trough stretches from James Bay to the Carolinas. Far to our northwest, a potent vort max/shortwave trough is diving into the trough out of the northwestern Canadian Arctic. An ~1005 mb Alberta Clipper low is situated ahead of this feature over southern Manitoba. The aforementioned surface high will crest over the Southern Appalachians tonight, turning the low-level flow back to the southwest. This will begin advecting a milder air mass back into the area tonight with the strongest surge of warm air advection occurring Wednesday morning. At the same time, the clipper low will deepen to around ~995 mb as it skims the northern shore of Lake Superior. This low will continue progressing to near Ottawa, Canada by 12z Thursday while dragging an arctic cold front through the Ohio Valley. As is often the case with an arctic boundary, there is substantial disparity in the intensity of the arctic air behind the front. The lower end of guidance suggests 850 mb temperatures dropping as low as -13 to -19C around and just beyond the end of the short-term. While we won't be solidly on the cyclonic shear side of the 300 mb jet, the combination of a moderately strong pressure fall-rise couplet, up to a few 10s of J/kg of SBCAPE and around 30 to 40 knots of background 850mb flow will set the stage for rain showers transitioning over to a few gusty snow showers (or perhaps even a squall) late Wednesday night. In sensible terms, look for skies to clear gradually this evening and overnight, allowing temperatures to fall back into the mid 10s coldest hollows to mid 20s on thermal belt ridges. Patchy clouds drift across the area on Wednesday as southwesterly winds increase to between 10 and 20 mph with gusts up to 30 mph and temperatures surge back into the mid 40s to near 50. Shower chances rise from the northwest Wednesday evening and peak overnight with the passage of the arctic cold front. Initially expect the precipitation to mainly be in the form of rain, though a light snow/wintry mix is possible above 3,000 feet. Graupel cannot be ruled out with heavier rain showers. Once the front arrives, expect a quick transition over blustery snow showers and perhaps an isolated squall late Wednesday night. A flash freeze cannot be ruled out in some spots, though strong winds should evaporate much of the moisture before it is able to freeze. Temperatures tumble from the 30s and 40s into the 20s for many locations and into the teens toward the Bluegrass and over the higher mountains near the Virginia border. .LONG TERM...(Thursday through Tuesday) Issued at 411 PM EST TUE DEC 3 2024 Overnight Wednesday into Thursday morning, a really potent upper level low, with abundant cold air will be centered over the Great Lakes. A surface cold front associated with this low will move through portions of eastern Kentucky Thursday morning. A tight pressure gradient will lead to gusty winds through the day Thursday. Model soundings suggest that good momentum transfer will be available early Thursday morning. This will aid in winds being transfered from aloft towards the surface. Winds are anticipated to be strongest early in the morning, with gusts as high as 25-30 mph. Winds have been adjusted towards the 90th percentile of the NBM through the day. Snow showers can be expected with this frontal passage in many areas. Expect moments of significantly reduced visibilities with the this frontal passage. Some snow squall characteristics cant be ruled out. Wind chills could range from 0 to 10 degrees above zero behind this frontal passage, around 7 am or so. Temperatures will rise into the upper 20s to low 30s later in the day, with sustained northwesterly winds remaining 10-15 mph with higher gusts. As the system exits, skies will clear leading to abundant radiational cooling. Nighttime lows will drop into the low teens across much of the area. Friday, winds will be light and out of the west, with dry conditions returning to the state and lasting through Saturday. This is due to a high pressure building into the area. Cooler temperatures will remain across the area Friday with forecasted highs in the low 30s, and lows in the teens throughout eastern Kentucky. Saturday, winds shift out of the southwest leading to warm air advection and temperatures rising into the mid to low to mid 40s. Low temperatures moderate a bit likely being in the low 30s. Overnight Saturday into Sunday, a cutoff low over Mexico begins to progress northeast, bringing with it a surge of Gulf moisture. Cloud cover will increase throughout the day, with rain chances increasing after noon. PWAT will range from 1" to 1.25" Sunday and Monday, as a front associated with the system has the potential to produce steady rain each of these days. Rain tapers off Tuesday, as the low progresses east. Highs Sunday through Tuesday will generally be in the mid to upper 50s, with lows in the 40s. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) ISSUED AT 1257 AM EST WED DEC 4 2024 VFR conditions have returned to the area under clear skies. Ceilings mainly in the 4-6K ft range are forecast to return during the day Wednesday and persist through the end of the period. Winds will pick up out of the southwest during the day Wednesday, with gusts of 20-30 kts by late the day which will last into the night. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...GEERTSON LONG TERM...GINNICK AVIATION...HAL