…Updated Aviation Discussion…
.Short Term…(Today and tonight)
Issued at 328 AM EST Sun Nov 13 2022
As of 3 AM ET, RAP 500mb analysis and water vapor imagery showed dry subsidence across central KY and south central IN associated with the trough base moving across the region. Light returns on radar and surface observations showed some light flurry activity as the trough base continues to push across the Ohio River valley this morning. Temperatures in the area were all fairly uniform in the lower 30s.
The system that brought rain and wintry weather to the area Saturday will continue to exit today with a shortwave ridge of high pressure building into tonight. Latest model soundings show some lingering lower level moisture under 5K feet, which will keep some lower level clouds possible this morning, but as the day goes on and more dry air moves into position, mostly sunny skies will persist today wit dry weather. Northwest winds throughout the profile will keep temperatures in the lower 40s today and into the low to mid 20s tonight (some spots could radiate out with clear skies and get into the upper teens), which is below normal for mid November.
The next chance for active weather is Monday night into Tuesday, please see Long Term discussion below for more details.
.Long Term…(Monday through Saturday)
Issued at 328 AM EST Sun Nov 13 2022
The large-scale pattern at the beginning of the extended forecast period on Monday will feature broad troughing across much of North America, with multiple shortwave disturbances pivoting around the base of the planetary-scale trough. A particular shortwave of interest for the early week time frame will be pushing from the Four Corners region into the southern Plains Monday morning. Ahead of this disturbance, mid-level heights should build across the Ohio and Tennessee valleys on Monday as low amplitude ridging briefly sets up. Sfc high pressure will gradually exit the Ohio Valley into the NE US Monday, with low-level flow veering from N to E. The abatement of northerly low-level flow, combined with increased 850-mb temps and ample sunshine should help temperatures warm several degrees over Sunday’s highs. Highs Monday afternoon should range between the mid-40s across southern IN up to the low-50s along the Tennessee border.
Monday Night and Tuesday…
By Monday evening, the aforementioned mid-level disturbance will start to enter the Ozarks region, with cloud cover expected to push into central KY and southern IN around sunset. The compactness of the disturbance will allow it to propagate quickly to the NE Monday night, with precipitation expected to enter the western CWA shortly after midnight Tuesday morning. Latest trends in medium-range guidance depict a weaker disturbance by the time the sfc low reaches the area Tuesday morning, with mean ensemble QPF amounts dropping area-wide in the 13/00Z run. Generally less than 0.25″ of QPF is now expected; however, complex precipitation types make this event somewhat more interesting.
Temperatures Monday night are expected to range from the upper 20s and lower 30s across southern IN and the KY Bluegrass up to the mid- to-upper 30s across south central KY. Forecast soundings generally show temperatures steadily decreasing through the column, so most areas should see either rain or snow (or a mix) instead of freezing rain or sleet. The exception to this could be across valleys within the CWA, where a very shallow sub-freezing layer could briefly set up as warm air moves in aloft but is slow to erode the cold air at the surface. However, no impacts from icing would be expected outside of elevated surfaces, as ground temperatures are still fairly warm. As far as snow is concerned, best chances for seeing snow would be across southern IN and the Bluegrass where the coldest column exists at precipitation onset. Across south central KY, the near-sfc above-freezing layer will likely be deep enough that only rain is expected. By late morning, temperatures area-wide will warm enough that all precipitation should transition to rain. Given the meager total precipitation amounts and marginal thermal profiles, little in the way of snow accumulation is expected, with the best chance for a dusting expected the farther north you go. Temperatures by Tuesday afternoon will warm into the 40s for highs. Precipitation will exit the region during the afternoon and evening hours Tuesday.
Tuesday Night through Saturday Night…
Additional vorticity lobes will continue to spin around the large- scale trough during the mid-week time frame, bringing quick-hitting systems to the upper Midwest and Great Lakes regions. With cyclonic mid-level flow pattern and modest low-level moisture in place, can’t rule out an isolated rain/snow shower or two Wednesday or Thursday (particularly across southern IN); however, confidence is low enough at this lead time to withhold mention. Cloud cover could be more stubborn to hang with us, especially north of the Ohio River, and with falling mid-level heights expected, a somewhat persistent cold and dreary pattern looks possible for the mid-to-late week period. By late week and the beginning of next weekend, there is some suggestion that high pressure and drier air aloft will try to work in from the northwest, bringing clear but cold conditions. From Wednesday onwards, most likely forecast would feature dry weather, with highs in the 30s and 40s and lows in the 20s, although
widespread teens are possible Friday and Saturday morning.
.Aviation…(12Z TAF Issuance)
Issued at 620 AM EST Sun Nov 13 2022
Fairly quiet forecast for the area terminals continues with some lingering MVFR ceilings this morning before becoming VFR as high pressure returns to the region. Light wind shifts with speeds under 10kts for the next 24 to 30 hours from NNW to the NNE as high pressure moves into the Ohio valley.