Forecast Discussion 06:23:38.9800

…Updated Aviation Discussion…

.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…(12Z TAF Issuance)
Issued at 622 AM EST Wed Nov 16 2022

A wide area of low-end VFR to MVFR stratus is currently impacting the region and will persist through much of the morning and early afternoon hours. A small area of very light precipitation is currently moving through southern Indiana, and will push into northern Kentucky for the first part of the forecast period. Have included a TEMPO at KSDF for reduced cigs/vis with this precip as it moves through, with VCSH mention at KLEX given uncertainty on how well it will hold together that far east. Current obs are reporting rain with this precipitation, but some snow could mix in later this morning with it.

Some drier low level air will help to lift cigs gradually to VFR levels by the afternoon. Winds will be gusty at times this afternoon and likely exceed 20kts at many locations before subsiding some this evening.




Short Term…DM
Long Term…RAS