Forecast Discussion 12:25:38.1535

…Updated Aviation Discussion…

.Forecast Update…
Issued at 1000 AM EST Wed Nov 16 2022

Current forecast remains in good shape, with the only changes being to expand PoPs a bit to match current radar trends. Light radar returns continue to shift eastward mainly along the I-64 corridor at this hour, resulting in a very light rain or even some flurries. SDF recently began reporting light rain, though some very light flurries have been observed at the WFO. Temps are generally in the mid to upper 30s, and most of the area should not see a large diurnal range today due to the cloud coverage and steady CAA regime in place. Latest AMDAR soundings out of SDF reveal freezing levels around 1000- 1500 ft, with a healthy inversion around the 750mb level.
Mesoanalysis depicts a tight gradient of increasing DGZ depths over the Ohio River, though the above-freezing layer near the sfc should help keep most precip as drizzle or a very light rain-snow mix. We are beginning to see drier air filter into our southwest CWA, evident by GOES vis channel showing clearing conditions for BWG and nearby locations. Model sounding continue to show increasing lower level dry air as temperatures cool within the PBL later today, with enough moisture possibly tapping into the DGZ to support some snow growth. Majority of model consensus continues to support light precip, though should steepening lapse rates occur, would support some brief snow showers mainly east of I-65 later today. Otherwise, downward momentum transfer will aid in breezy conditions today, with wind gusts in the 20-30 mph range.


.Short Term…(Today and tonight)
Issued at 234 AM EST Wed Nov 16 2022

IR satellite reveals widespread stratus currently across much of the Ohio and Tennessee Valleys this morning. These clouds have helped to keep diurnal swings to a minimum over the last 24 hours, as
temperatures have generally hovered in the mid 30s to low 40s for most spots. Regional radars do show some light echoes where
drizzle/mist may be occurring, though this activity is largely sporadic as of this writing.

Clouds will stick around through much of the day, though there are some signs we could see some clearing out across our
western/southern zones toward the afternoon hours as drier low-level air works in from the west. Ahead of the clearing, we may see a brief uptick in precipitation activity as an elongated vort lobe swings through the region. Forecast soundings show a small, limited in depth area of moisture near the top of the PBL while temperatures in the lower troposphere gradually cool throughout the day due to CAA. There may be enough cooling in the lower troposphere to where icy crystal initiation occurs, switching things over from
mist/drizzle to flurries or even snow showers (given some steeper lapse rates in the low levels). Should snow showers occur, impacts will likely be limited in duration, given surface temps will be above freezing today, but some of the heavier show showers could reduce visibilities briefly and put down a quick dusting (rates overcoming melting). The vast majority of guidance is generally in favor of activity being in the form of sprinkles/flurries today, with only a few solutions (like the HRRR) having any sort of measurable precipitation. So, will keep snow shower mention on the low side (20%) today.

The other story today will be gusty winds. Wind fields gradually increase in strength through the day, and as the lower boundary layer mixes out, we’ll tap into the stronger winds aloft and bring some of them down toward the surface. Expect gusts this afternoon in the 20 to 30 mph range. Taking into account the winds with air temperatures in the 30s, wind chills will likely be in the 20s.

Winds will gradually subside this evening, but still remain steady in the 5-10 mph range overnight. Models are optimistic about clouds clearing across a good portion of the region late tonight, so have trended sky cover forecast in that direction. Will have to watch that closely though as models tend to be a bit too eager to clear stratus out in these types of patterns. Should the forecasted clearing take place, expect lows to fall into the low and mid 20s.

.Long Term…(Thursday through Tuesday)
Issued at 320 AM EST Wed Nov 16 2022

Dry but unseasonably cold weather is expected through the weekend, with a moderating trend beginning Monday.

Broad but deep upper trofiness over the Great Lakes will be the main player through the weekend, but at this latitude the pattern is just flat enough to keep us out of the dynamics needed to squeeze any of the very limited moisture out as precip. One shortwave trof Friday, and another Sat night, will reinforce the cold air in place, but the better forcing remains far enough north that we’ll stay dry. Sunday will likely be the coldest morning as a 1034mb sfc high settles into the Ozarks, but Monday morning could be interesting as the high parks over the Deep South. Any return flow by Monday will be modest, so could be a very sharp inversion with large spreads between ridges and valleys. Bottom line, expect lows in the teens for most
locations outside of the Louisville or Lexington metro areas, which will still be in the lower 20s. The only records even slightly in jeopardy would be Saturday in Bowling Green, where the record low is 17F, set in 1951, and the coldest max was 38F in 1968.

After the cold start Monday, temps finally start to recover with rising heights and southerly low-level flow. By Tue-Wed, we should be back near climo as we start to see southeast CONUS ridging ahead of a deepening Four Corners low.


.Aviation…(18Z TAF Issuance)
Issued at 1223 PM EST Wed Nov 16 2022

Drier air has been filtering into the region, evident by clearing skycover at BWG and HNB. MVFR conditions will continue at LEX for the next few hours. Breezy westerly winds will continue through the remaining afternoon hours. Confidence beyond 00z remains low, with the potential for another round of very light snow showers passing through the region. Was only confident enough to include a TEMPO at LEX for this, but will continue to monitor trends through the day.




Short Term…DM
Long Term…RAS