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fxus61 Kiln 160236 
afdiln

Area forecast discussion
National Weather Service Wilmington Ohio
936 PM EST sun Dec 15 2019

Synopsis...
mixed precipitation will push north into our region tonight well
ahead of developing low pressure over northern Louisiana.
Precipitation will taper off on Monday. Then, as low pressure
moves northeast into the Tennessee Valley Monday night,
precipitation will spread back north into the region. The low
will move off to the northeast on Tuesday, allowing precipitation
to come to an end. A weak, but dry cold front will move south
across the area Tuesday night into Wednesday, bringing colder
air for mid week.

&&

Near term /until 6 am Monday morning/...
enhanced snow band that lifted up through nrn Kentucky and srn Ohio has
become more diffuse, but snow continues to fall across much of
the region.

Still expecting that the pcpn will begin to become a rain/snow
mix across the south before changing over to rain as
temperatures begin to warm aloft. In southern in/Ohio there will
be a transition zone where surface temperatures will be around
freezing so there will a chance of some light freezing rain.
Farther north, kept things more in the way of snow. After
midnight, the pcpn will taper off from west to east as support
shift to the east.

Keeping the advisories as is, along with snow amounts. Heaviest
should be in the Whitewater valley towards Wilmington where 2-4
inches are possible. Surround that area 2-3 inches of snow are
expected.

&&

Short term /6 am Monday morning through Tuesday/...
the first part of the Monday should see a relative lull in pcpn
except for the southeast zones where some rain may occur on the
northern fringe of focused low level lift. Under mostly cloudy
to cloudy skies, highs will warm into the mid 30s north to
around 40 far south. Another S/WV is forecast to lift northeast
from the Southern Plains to the Ohio Valley Monday night into
Tuesday. As this happens, low pressure over northern Louisiana
will also move northeast into the Tennessee Valley, then
eventually northeast of the area by Tuesday. Large scale ascent
and low level convergent forcing on the back side of the surface
low (frontogenetic in nature) will spread pcpn back north into
the entire forecast area late Monday into Monday night. Surface
temperatures and Max wet bulb temperatures aloft will become an
issue once again. Current model sounding keep our far north as
snow with 1 to 2 inches possible by Tuesday morning. Farther
south, roughly along either side of the I-71 corridor, rain
will mix with freezing rain, then change over to snow from
northwest to southeast as surface temperatures slowly drop and
warm air aloft begins to nudge toward the southeast. These areas
may see a half inch to up to 2 inches of snow with a light
glaze of ice possible. For our far southern/southeast counties,
these locations will likely remain all rain before mixing with a
little snow before ending Tuesday morning. As the system moves
away on Tuesday, partial clearing will move in from the west.
Temperatures will not warm much from morning lows with highs
ranging from the lower 30s northwest to the mid/upper 30s
southeast.

&&

Long term /Tuesday night through Sunday/...
on Tuesday evening, the axis of a 500mb trough will be moving
east through the Ohio Valley, with any remaining forcing already
well east of the iln forecast area. A north-to-south elongated
area of high pressure initially located over the plains will
begin a slow motion to the east, but before it arrives, a cold
front is expected to move southward out of the Great Lakes on
Wednesday. While moisture appears far too limited to support
anything more than some flurries / lake effect snow in Northern
Ohio (with nothing in the forecast for central ohio), the front
will help to establish a pattern of cool westerly flow through
the day, before the high gets into the region. Calmer conditions
heading into Wednesday night will support the coolest
temperatures of the period, especially if snow remains on the
ground, and min temps were reduced a few degrees from the model
blend. While some min temps in the mid teens are possible
Tuesday night, values in the lower teens are expected Wednesday
night. On the back side of the high, warming is expected to
begin on Thursday, bringing temperatures near normal by Friday
and into the weekend.

While generally uneventful weather conditions are expected
through this segment of the forecast through Friday, there is at
least some potential for precipitation on Saturday. What
remains a high confidence part of the forecast is that a deep
trough is expected to develop over the middle part of the Continental U.S.
On Friday, perhaps with separate vorticity maxima in the
northern and southern jet streams. As this looks to be a
scenario impacted by potential phasing as the troughs move east,
overall confidence in where/when this occurs is low, with the
usual expected increase in model/ensemble spread by late Friday.
As of now, it should be noted that the deterministic European model (ecmwf)/GFS
runs suggest little precipitation in the Ohio Valley, but a dry
forecast does not seem like the best call with a well-defined
trough moving east across the Continental U.S.. a 20-pop will be used for
now on Saturday, with a dry forecast for Sunday.

&&

Aviation /02z Monday through Friday/...
band of moderate to heavy snow has already lifted through
cvg/luk and is moving in on iln. This is associated with an 500 mb
disturbance moving east couple with a 500 mb jet. IFR conditions are
prevalent in the snow band. It is expected to continue to drift
north and weaken over the next few hours.

Behind the band, additional pcpn will develop. With warmer air
aloft lifting north, any pcpn that starts as snow will change to
rain. This second shot of precipitation shift quickly east of
the region between 09z and 12z. Ceilings will remain IFR.

Monday morning is looking dry, but the low clouds will linger.
Ceilings will could recover to VFR in cmh/lck in the afternoon,
but could linger in IFR in the southern tafs. Low pressure
lifts along the front Monday afternoon pushing another area of
pcpn across the tafs. Thicknesses will be warm enough for it to
fall as rain at all the tafs but day.

Outlook...MVFR to IFR ceilings and visibilities will continue
from Monday night into Tuesday morning.

&&

Iln watches/warnings/advisories...
Ohio...Winter Weather Advisory until 7 am EST Monday for ohz026-034-
035-042>046-051>056-060>065-070>074-077>082-088.
Kentucky...Winter Weather Advisory until 7 am EST Monday for kyz089>093.
In...Winter Weather Advisory until 7 am EST Monday for inz050-058-
059-066-073>075-080.

&&

$$

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