ILN issues Area Forecast Discussion (AFD) at Dec 14, 9:52 AM EST
007
FXUS61 KILN 141452
AFDILN
Area Forecast Discussion
National Weather Service Wilmington OH
952 AM EST Sat Dec 14 2024
.SYNOPSIS...
Slightly warmer air will continue to build into the region
through the day today, with widespread rain expected tonight
into Sunday. Above normal temperatures will evolve this weekend
through the first half of the workweek, with several bouts of
widespread rain during this stretch as well. Seasonably cold air
should return to the Ohio Valley by the end of the workweek.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A large area of high pressure centered over the eastern Great
Lakes to continue drifting east of the area today. 12Z ILN
sounding shows a relatively dry environment with PWAT of 0.28
inches. As moisture increases with the approach of the next
system expect to observe an increase in mainly mid and high
level clouds. This will allow for some filtered sunshine.
High temperatures will generally top near 40 north of I-70 to
around 50 degrees south of the Ohio River.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
Robust moisture transport and moisture/mass convergence will be
underway this evening on the nose of a 40-50kt H8 LLJ, allowing
for an expanding shield of RA to overspread the local area this
evening through the overnight hours. Steady rain is expected
for most spots through the majority of the overnight period,
with rainfall amounts generally ranging from 1/2 of an inch to
3/4 of an inch locally by Sunday afternoon.
The one item of interest to keep an eye on will be the potential
for some very brief/patchy -FZRA at the onset across parts of
central OH where sfc temps will be very close to freezing
at/around about 06z. While air temps are expected to get into
the upper 30s in these areas this afternoon (which will help
warm ground temps), residual cold ground in a few spots could
result in isolated instances of icing in central OH, even if
air temps are just above 32F. This remains a low probability
scenario at this juncture, but it is mentioned here for
awareness purposes. Widespread icing on untreated surfaces is
not expected as air temps should generally be in the upper 30s
and lower 40s toward daybreak Sunday.
The solid shield of RA will become more showery/cellular past
mid morning as the deeper moisture begins to erode from SW to
NE. But... sufficient LL moisture amidst subtle lift will keep
SCT to numerous SHRA in the forecast, especially near/S of I-71
even into late afternoon Sunday. This being said, conditions
should trend "drier" from W to E toward the end of the short
term period, with patchy drizzle becoming the main focus later
into Sunday evening.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
The Ohio Valley will be in a brief lull between systems at the start
of the extended period. The first of which, a decaying wave, will be
getting absorbed into strong blocking high pressure off of the
Atlantic coast. Some residual showers will be in the Ohio Valley
region as this feature falls apart.
The next, more potent, system will already be on our doorstep by
Monday morning as a digging wave will be moving into the western
Great Lakes. Strong surging moisture will be pulled north into the
region and PWATS will be ~300% of normals. Additionally, the
environment will already be quite saturated from the previous
disturbance moving through... Vertical profiles are saturated all
the way up to ~200 mb and FZL levels are reasonably high at ~10k ft,
so we'll be expecting some efficient rain rates. Right now, guidance
struggles to resolve any sort of instability, however, with warm and
moist surface conditions, cannot rule out a rumble of thunder. 50th
percentile QPF falling between 0.5"-0.75" but would not be surprised
to see the higher quartiles come into play, bringing QPF closer to
1.0"+ Monday into Tuesday. Daytime temperatures in the upper 50s
along with a warm vertical profile resolve P-type as rain.
This brings total multi day storm total QPF anywhere from 1-3
inches. Again, looking at some NASA SPoRT guidance, we definitely
will see our rivers respond, though no strongly concerning signals at
the moment. It should be noted that anywhere where precip trains
(moves over the same area repeatedly) may result in some isolated
flooding issues.
Precip tapers off early Tuesday morning and temperatures fall into
the mid 30s. Should there be any lingering precip, might see some
brief wintry mix, but with no impacts. Tuesday we dry out and
temperatures are a tad cooler, with highs in the upper 40s.
The mid and end of the working week get a bit more muddled as
guidance lacks consistency both spatially and temporally. There is a
signal for another wave to move up Wednesday into Thursday. The
ECMWF ensemble has been reasonably consistent with keeping highest
QPF footprint in Kentucky/ southeastern Ohio. GFS ensemble hones in
on a more northerly track, bringing another good slug of rainfall
and possibly even some wintery precipitation. Canadian splits the
difference. Definitely will be something to watch, especially if the
GFS members resolve, considering that this would ramp up additional
flooding concerns.
However this system pans out, there does seem to be a good signal
for a return to below normal temperatures by the end of the working
week.
&&
.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
SCT/BKN mid/high clouds will stream through the region from
time-to-time through the afternoon before thicker/lower cloud
cover arrives by/after 00z progressively from SW to NE. Rapid
moistening of the profile will occur after 00z, with widespread
RA overspreading the area between 00z-06z, which will persist
through daybreak Sunday.
As the steady RA moves in, VFR CIGs will transition to MVFR, and
eventually IFR, between 06z-09z Sunday. Prevailing MVFR VSBYs
are expected with the steadiest/heaviest RA, with some brief IFR
VSBYs possible, too.
Easterly flow at 8-12kts will be maintained through 00z before
going more out of the SE by the end of the period.
OUTLOOK...MVFR to IFR conditions are likely Saturday night
into early Tuesday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...KC
NEAR TERM...AR
SHORT TERM...KC
LONG TERM...CA
AVIATION...KC
Source: ILN issues Area Forecast Discussion (AFD) at Dec 14, 9:52 AM EST (https://mesonet.agron.iastate.edu/p.php?pid=202412141452-KILN-FXUS61-AFDILN)
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