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NWS Wilmington, OH Office (ILN)


Area Forecast Discussion/SKEW-T

          FXUS61 KILN 170607
          AFDILN
          
          AREA FORECAST DISCUSSION
          National Weather Service Wilmington OH
          107 AM EST Sun Jan 17 2021
          
          .SYNOPSIS...
          A series of upper level disturbances will bring periods of snow
          to the region tonight through Sunday night. Weak high pressure
          and drier conditions will build into the Ohio Valley for Monday.
          
          &&
          
          .NEAR TERM /THROUGH TODAY/...
          Cyclonic and northwesterly flow exists across the Ohio Valley
          around a deep mid level low centered over NY state. Axis of
          widespread snow pivoting thru the southern 2/3rds of ILN/s is a
          result of isentropic lift ahead of a surface trof. ILN has
          picked up 0.9 inches of snow thus far today, with the higher
          reports for the day around an inch.
          
          Best coverage of snow shifting to the east across the lower
          Scioto Valley. Also, fetch off Lake Michigan has enhanced more
          cellular development over West Central Ohio -- currently moving
          into portions of Central Ohio. Have increased pops and bumped up
          snow a few tenths of an inch across these locations thru about
          midnight. Road sensors indicate temperatures generally in the
          middle 30s, so most of the accumulation has been on grassy
          areas.
          
          Otherwise, overnight expect a transition to flurries or very
          light snow with little to no additional snow accumulation.
          Expect overnight lows in the upper 20s to around 30 overnight.
          
          &&
          
          .SHORT TERM /TONIGHT THROUGH 6 PM MONDAY/...
          Mid level ridging will shift east of our area through Sunday
          morning as a fast moving secondary mid level trough/low
          approaches from the west. This will then progress east across
          our area Sunday afternoon into Sunday night. While low level
          lapse rates and the snow squall parameter do not appear quite as
          favorable as today, the better timing of the upper level energy
          should once again result in fairly widespread snow shower
          activity, especially from late morning through the afternoon.
          Will continue with likely pops for this during the day on Sunday
          and then taper things off through Sunday night as the upper
          level energy moves east. Temperatures will push into the low to
          possibly mid 30s through the day. Expect accumulations to
          generally be less than an inch.
          
          &&
          
          .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
          On Monday morning, a dampening shortwave trough will be moving east
          of the Ohio Valley, as the flow pattern turns more progressive
          heading into Tuesday -- with several quick but largely
          inconsequential changes from warm advection to cold advection. While
          lift will be weakening after the axis of the trough is through the
          area on Monday morning, continuing cold advection may still allow
          for some flurries in central Ohio. A dry forecast is expected for
          the rest of Monday, with a very weak shortwave perhaps bringing some
          light snow to the area late Monday night into Tuesday morning.
          Deterministic models remain very limited in terms of QPF production,
          but the pattern supports light precipitation, so a 20-PoP will be
          maintained across the entirety of the CWA to account for the
          possibility.
          
          A period of warm advection aloft will likely lead to the next chance
          of precipitation on Wednesday night into Thursday morning, ahead of
          yet another frontal boundary. This may also lead to non-diurnal
          warming temperatures going into Thursday morning, with continued
          warming during the day. 12Z models are then fairly aggressive, and in
          fairly good agreement, on a significant system developing in the
          southern stream on Thursday night and Friday -- and largely missing
          the ILN CWA to the south. This is not a certainty, as several GEFS
          members do show precipitation reaching this far north. However, the
          majority of them show little to no precipitation during this time
          frame. PoPs were adjusted downward after the initial shot of warm
          advection precipitation early Thursday, keeping some chance in for
          the southern sections of the ILN CWA through Thursday night to
          account for uncertainty.
          
          High pressure, initially over the northern plains, will then move
          into the Great Lakes on Friday and Saturday. This will likely bring
          dry and cooler conditions to the area.
          
          &&
          
          .AVIATION /06Z SUNDAY THROUGH THURSDAY/...
          Considerable status/stratocumulus clouds remain in the wake of
          departing weather system to our east. Thus, for the overnight
          period, aviators can expect MVFR and IFR ceilings with perhaps a
          few light flurries.
          
          For today, an upper level low over the middle Mississippi River
          Valley will move east into the Ohio Valley. Dynamic lift and
          some weak WAA aloft will first spread snow east/northeast across
          the terminals late this morning into the first part of the
          afternoon. Then, with some diurnal heating, some of the
          precipitation will become showery in nature, especially along
          and south of the Ohio River. During this period, aviators can
          expect MVFR and IFR conditions with snow.
          
          For tonight, the upper level low will begin to move east of the
          region. Scattered snow showers in the evening will diminish from
          west to east overnight. Ceilings will remain in the MVFR and IFR
          category with pockets of MVFR/IFR visibilities possible in snow
          showers.
          
          OUTLOOK...MVFR/IFR ceilings possible into Monday. MVFR ceilings
          may linger into Wednesday. MVFR and IFR ceilings and
          visibilities possible Wednesday night into Thursday.
          
          &&
          
          .ILN WATCHES/WARNINGS/ADVISORIES...
          OH...None.
          KY...None.
          IN...None.
          
          &&
          
          $$
          SYNOPSIS...JGL
          NEAR TERM...AR
          SHORT TERM...JGL
          LONG TERM...Hatzos
          AVIATION...Hickman
          
          
Skew-T

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