ILN issues Area Forecast Discussion (AFD) at Dec 19, 12:38 PM EST
837
FXUS61 KILN 191738
AFDILN
Area Forecast Discussion
National Weather Service Wilmington OH
1238 PM EST Thu Dec 19 2024
.SYNOPSIS...
Although surface high pressure will move across the region
today, mainly cloudy skies will persist. The high will shift
east tonight, allowing a clipper system to make inroads into the
region. This system will affect the Great Lakes and Ohio Valley
on Friday, bringing rain and snow. The clipper system will
depart Friday night, bringing an end to the precipitation with
colder air pushing south into the area. High pressure will then
extend across the region this weekend, resulting in below normal
temperatures. Warmer conditions are expected next week, with
precipitation chances returning by Monday night.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
No significant changes to the forecast through this evening. The
area remains under cloudy skies, with a stratocumulus deck at
about 900mb at the top of a mixed layer. Winds remain light and
variable, as an area of high pressure moves east across the
Great Lakes, but winds are expected to settle into a
southeasterly direction by late afternoon.
Previous discussion >
A surface ridge axis will pass across our region today. Despite
the surface high, it appears that stratocumlus clouds will
remain trapped underneath a subsidence inversion, which will
keep skies mainly cloudy. Thus, diurnal heating will be limited.
Highs will range from the mid to the upper 30s.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
The surface ridge will push east tonight, allowing a clipper
system to make inroads into our region. Isentropic lift
associated with the low pressure system will develop/spread
precipitation into the western half of the forecast area
overnight. Most of the precipitation will fall in the form of
snow, although some rain may mix in along and south of the Ohio
River. A few tenths of an inch of snow may accumulate,
especially across west central Ohio and east central Indiana.
Given that most road temperatures will likely be above freezing,
most of the snow should melt. However, a few slick spots could
occur on the typical elevated bridges/overpasses where pavement
temperatures could be around freezing. Lows will fall in the
lower 30s.
On Friday, the surface low is forecast to move east/southeast
across Ohio. Some warming ahead of the low and attendent cold
front will allow some rain to mix in across the eastern half of
the forecast area, while CAA behind the front will allow wrap
around precipitation to remain in the form of snow for the
western half. By late in the day, the eastern half should see
the precipitation transition over to snow as colder air
continues to move in behind the front. Snow accumulations will
be around an inch across the western half with a half inch or
less across the eastern half. Highs will range from the lower
30s west to the mid 30s east.
For Friday night, as the clipper system moves away, colder air
will continue to filter south into the area. Snow will taper off
in the evening, leaving partly to mostly cloudy skies for the
overnight period. Lows will range from the upper teens across
the far northwest to the upper 20s south of the Ohio River.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Deep and cool northwest flow on Saturday will bring a good bit
of cloud cover. With the limited sunshine and cold advection,
highs will be 2-3 degrees on either side of 30. High pressure to
the north makes an eastward progression, which will turn
northerly winds over the Ohio Valley to a more east-northeast
direction overnight. Overnight Sunday will see return flow from
the southeast, along with increasing heights. This will get more
notice on Monday as the flow becomes solidly from the south and
high temperatures rise into the mid 30s north to low 40s south.
Models seem to be a bit quick on the onset of precip late
Monday and into the evening. If the earlier scenario plays out,
there will be a mix of rain and snow to begin the next round of
precipitation to the region. Continuing this early possible
start to precip, any rain/snow mix will be limited to the
eastern CWA overnight Monday.
On Monday night, low pressure in the Upper Midwest will lay out
a cold front through IA and nw MO. Ahead of this front, rain
will overspread the CWA from northwest to southeast as it gets
closer. The general consensus has the leading edge of the rain
near the I-71 corridor at daybreak Tuesday, with rain expected
for most of the CWA through the rest of the day and overnight
hours. Models diverge in mass fields by Wednesday evening but
still keep a solid bit of precip over the CWA that looks to end
Wednesday evening. Overnight, high pressure to the north shunts
any precip to the south and turns winds easterly during the day
Thursday.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
A mix of VFR and MVFR ceilings will continue to affect the
region through the afternoon and evening hours, before ceilings
begin to lower more significantly overnight. MVFR ceilings are
expected to be prevailing everywhere by 04Z-06Z. Winds will be
generally light and out of the south.
Early tomorrow morning, snow will begin to move into the area.
Some of this snow may mix with rain at times, particularly at
the Cincinnati airports. Nonetheless, the snow is expected to
bring a period of prevailing IFR visibilities to all TAF sites,
along with IFR to LIFR ceilings. As this occurs, winds will
eventually shift to the west, with some 10-15 knot wind speeds
in the forecast.
OUTLOOK...IFR/LIFR ceilings and MVFR/IFR visibilities expected
to continue into Friday afternoon and evening. MVFR/IFR ceilings
will continue into Friday night, with MVFR conditions possible
through Saturday. MVFR conditions are possible again on Tuesday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...Hickman
NEAR TERM...Hatzos/Hickman
SHORT TERM...Hickman
LONG TERM...Franks
AVIATION...Hatzos
Source: ILN issues Area Forecast Discussion (AFD) at Dec 19, 12:38 PM EST (https://mesonet.agron.iastate.edu/p.php?pid=202412191738-KILN-FXUS61-AFDILN)
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