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
