NWS Wilmington, OH Office (ILN)

Area Forecast Discussion/SKEW-T

          FXUS61 KILN 262254
          National Weather Service Wilmington OH
          554 PM EST Mon Feb 26 2024
          An unseasonably warm airmass will remain in place across the
          region through Tuesday. A few showers and storms will be
          possible tonight, with additional showers and storms expected
          Tuesday evening through Tuesday night as a cold front moves
          through the Ohio Valley. Once the front moves through, a drier
          but cooler airmass will settle into the region for Thursday.
          Additional light rain chances will be possible Friday.
          Sunny skies will prevail through the afternoon before some
          cirrus approaches from the W toward the evening and beyond.
          Amidst the bountiful sunshine, temps have soared into the
          mid/upper 60s already, with additional rises on the order of 5
          degrees or so possible. This will generally put temps in the
          upper 60s to lower 70s for most spots by late afternoon -- about
          20 to 25 degrees above seasonal norms.
          The main item of interest tonight will be an increase in the
          deep-layer wind fields, with a seasonably robust SW LLJ nosing
          NE into the OH Vly late tonight. This WAA regime, amidst a
          gradually-saturating LL profile, will promote the development
          of ISO/SCT convection, initially in EC/SE IN around midnight.
          This activity should expand in coverage as it quickly tracks to
          the ENE within the increasing steering-layer flow, eventually
          spreading through the Tri-State/WC OH and into central OH during
          the predawn hours. With relatively cool air aloft and steep
          midlevel lapse rates, robust updrafts should lead to quite a bit
          of lightning and some hail in the strongest cores. While it may
          not be /quite/ enough for severe hail, there should be /some/
          smaller hail within this activity (courtesy of cold air aloft
          and decent midlevel lapse rates) as it quickly expands through
          WC and central OH around 09z. Still a few uncertainties in just
          how widespread the coverage will be and whether it will expand
          to the S closer to the OH Rvr during this time frame. Nevertheless,
          felt confident to go with chance PoPs for areas N of OH Rvr and
          likely PoPs in central OH near/prior to daybreak.
          Temps tonight will be very warm by seasonal standards, dipping
          to the lower 50s in central OH to the upper 50s in the Tri-
          State/N KY.
          Key Messages:
          Morning elevated storm activity should decrease in coverage
          locally by mid morning and beyond, with a relative lull in
          activity late morning through late afternoon. Additional
          redevelopment along a surge of LL moisture is possible toward
          late afternoon and early evening, especially in WC and central
          OH. More robust/intense storm activity will be possible late
          evening, overspreading a greater portion of the local area
          around midnight into the heart of the overnight period. Greatest
          severe threat will exist with this activity late evening into
          the first part of the nighttime, with all hazards possible,
          especially near I-70 corridor. Severe threat should diminish
          with eastward extent late in the night. The cold front, with
          additional storms, moves through in the several hour period
          around sunrise.
          Tue morning/early afternoon: lingering elevated SHRA/TSRA
          activity should gradually decrease in coverage locally, with a
          lull in activity expected during this time frame as LL moisture
          pools across the heart of the ILN FA but a relatively strong
          cap, owing to continued WAA aloft) becomes established.
          Overcast sky conditions should limit destabilization efforts
          through the first part of the afternoon before stronger SW
          flow/diurnal mixing helps erode the cloud cover progressively
          from SW to NE late in the day.
          Tue late afternoon/early evening: Some convective development is
          possible coincident with the better LL moisture profile, which
          will shift to the N to near I-70 by late afternoon. Some sfc
          instby should exist within this northward-moving axis, but
          confidence in where exactly this activity develops remains
          relatively low, owing to questions about how long the cap holds.
          This activity, should it develop, may end up developing /just/
          to the N of the ILN FA and expand in coverage late evening as it
          pushes further N.
          Tue late evening/early overnight: This period presents the most
          concern for us locally, especially if storms are able to develop
          in the pre-frontal environment along the leading edge of the
          pool of best LL moisture across IN in an environment that will
          also become increasingly uncapped with a rapid increase in
          forcing. Incredible moisture and mass response will be ongoing
          across the region by this time period. And this will coincide
          with robust LL and deep-layer shear, with a concern for
          discrete activity to develop near/after 00z before expanding to
          the E rapidly into EC IN and WC OH around 03z. Still some
          uncertainty in storm coverage and initiation in this area, but,
          should all the ingredients come together, this would be the
          primary window for strong/severe storms locally, especially as
          it expands E into a larger portion of the local area
          around/after midnight. Breezy southerly flow will develop during
          this time, too, with sustained winds of 20kts and gusts to
          30-35kts possible overnight with the tightening pressure
          gradient. The greatest coverage of storms, and therefore the
          greatest potential for severe storms as a whole, should evolve
          from EC IN into WC OH and parts of central OH through the middle
          of the night.
          Early Wed morning/afternoon: Convective activity will
          develop/expand along the eastward-advancing front, with
          indications for a slightly faster progression into the wrn
          fringes of the ILN FA as early as 12z before /much/ cooler and
          drier air filters in rapidly mid morning into the afternoon.
          Widespread SHRA, with some embedded TSRA, will be ongoing around
          daybreak Wednesday, with activity shifting E quickly during
          this time frame. Some strong wind gusts will be possible with
          this quasi-linear activity, especially with the LL bulk shear
          vector at about 260 degrees and the source of the lift oriented
          more out of the SSW. Some post-frontal SHRA may linger a few
          hours behind the sfc front itself. Gusty westerly winds to
          30-35kts are expected Wed morning into the afternoon in the
          post-frontal environment as LL mixing increases. A non-diurnal
          temp trace is expected Wednesday as temps fall from morning
          highs in the 60s to afternoon temps in the 30s.
          Surface high pressure builds in from the west Wednesday afternoon
          into Wednesday night. Gusty northwesterly flow slowly relaxes
          through the night as the pressure gradient weakens over the Ohio
          Valley. Any precipitation left over behind the front on Wednesday
          afternoon ends Wednesday night with moisture and forcing pushing
          east. Forecast lows are in the lower to middle 20s.
          Surface high pressure remains overhead on Thursday bringing near
          average conditions to the area for late February. Warmer weather
          returns on Friday and into the weekend when surface high pressure
          shifts east giving way to broad southerly flow and upper level
          ridging across the region. Dry conditions are generally expected for
          the end the week and the weekend except for the chance for some
          showers on Friday afternoon when a shortwave passes through.
          Temperatures should make a run at 70 by Sunday.
          VFR conditions are expected at the start of the TAF period. Mid
          and high clouds will gradually build into the area after 00Z.
          Some showers, and possibly a few thunderstorms, will develop
          after 06Z. A VCSH has been included at all TAF sites, with a
          VCTS at the Columbus sites. Overall confidence is fairly low
          regarding a thunderstorm hitting the TAF sites, but it is a
          little higher at KCMH/KLCK. Some adjustments may need to be made
          to time out any thunderstorms that end up developing. Winds
          through the overnight will remain out of the south, but will
          increase -- some gusts to 20kts are expected by morning.
          Dry conditions are generally expected tomorrow, though a few
          showers could occur -- with little impact to aviation. However,
          MVFR ceilings (likely below 2kft for a period of time) will
          develop, and winds will continue to increase. Some gusts to
          around 25kts are possible by afternoon, and then even to around
          30kts by tomorrow evening.
          OUTLOOK...MVFR/IFR conditions and thunderstorms are possible
          Tuesday night into Wednesday. Wind gusts of 30 knots or above
          are also possible Tuesday night into Wednesday, with the
          gustiest conditions expected from early Wednesday morning
          through Wednesday afternoon. LLWS is likely early Wednesday
          morning. MVFR conditions are possible again Friday into
          NEAR TERM...KC
          SHORT TERM...KC
          LONG TERM...Campbell