ILN issues Area Forecast Discussion (AFD) at Oct 10, 3:55 AM EDT429
FXUS61 KILN 100755
AFDILN
Area Forecast Discussion
National Weather Service Wilmington OH
355 AM EDT Thu Oct 10 2024
.SYNOPSIS...
High pressure will continue to dominate the weather pattern
across the Ohio Valley through the end of the work week with
several more sunny, mild days and clear, crisp nights. A weak
cold front will sag into the Ohio Valley on Saturday morning
where it will stall temporarily, awaiting a ripple of low
pressure to move along it Saturday night into Sunday morning,
and then swinging a cold front across the area as the low
departs. This series of events will allow for a few showers or
thunderstorms across the Ohio Valley later in the weekend as
temperatures remain mild. Behind the cold front, much cooler air
with frost potential will sweep into the Ohio Valley for the
early part of next week, with another week of mainly dry weather
on tap.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Any river valley fog that forms here in the next few hours
before sunrise will mix out and dissipate by mid morning, with
yet another day of blue skies and brilliant sunshine expected as
surface high pressure remains in control of the area. There is a
little more concerted push of low level cooling on northeast
flow today vs. yesterday, with 925mb temperatures dropping by
2-3C from yesterday. That should result in high temperatures
being a few degrees below yesterday's values, and with some
5-7kt easterly winds and plenty of sunshine, have allowed
surface dewpoints to mix out a little more than most model 2m
dewpoint forecasts. All in all, a spectacular autumn afternoon
with the warm sunshine and light winds, that may feel a bit
chilly in the shade given the very dry low level airmass.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
With -1 sigma PWAT anomalies continuing over the ILN CWA
tonight (focus on Scioto Valley), and the surface high pressure
consolidating somewhat and sagging across the heart of the
forecast area around 06Z with light winds, tonight offers a
higher chance of frost where the combination of the coolest low
level temps combines with the deeper dry air and driest soils
(central Ohio). Am right on the fence with issuing a Frost
Advisory for areas north/east of Columbus, and perhaps down the
Scioto Valley into Pike/Ross counties, as this area per HREF
ensemble probabilities has the highest potential to see lows in
the mid 30s. While patchy frost is certainly going to be likely
in sheltered and low lying areas, just am not confident enough
on this forecast cycle for a widespread frost event to hoist an
advisory on this shift, though one may certainly be warranted as
newer data filters in. Valley fog will also likely develop in
the fog prone areas.
Shortwave trough on Friday afternoon will be shifting across
central Canada on fast/progressive northern stream flow. This
system shears/deamplifies as it spreads quickly eastward into
southeast Canada on Friday night, with height falls and any
meaningful kinematic forcing remaining well north of the area,
for the bulk of the night. A low end / outside chance that as
the decaying frontal zone sags toward areas north of I-70 toward
sunrise Saturday, a few showers may approach this area, but
forcing/moisture advection is quite weak, and overall moisture
associated with this feature will be weakening with time, so am
keeping Friday night dry in its entirety.
Low level warm advection ahead of the decaying frontal zone will
focus mainly west/north of the forecast area on Friday, but
there will be enough push to send temperatures well into the 70s
under plentiful sunshine. Minimum humidity will fall back into
the 30-35% range as dewpoints again mix back a little in the
afternoon into the lower 40s, so getting close enough to begin
to have a little concern for elevated fire weather concerns, but
winds should remain < 10kts the bulk of the day which mitigates
a good deal of the concern for a larger scale fire weather
threat.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Frontal zone discussed above will sag into the ILN forecast area
on Saturday and come to a halt on southward progression, in
response to much stronger height falls/shortwave trough/potent
upper jet digging into the Upper Mississippi River Valley. Warm
advection on increasing southwesterly flow into and atop this
frontal zone may promote the development of a few showers on
Saturday morning north of I-70, but with advection magnitudes
and ambient moisture being quite anemic, these chances are quite
low. As the strong shortwave trough digs further into the Great
Lakes, weak low pressure will develop and begin rippling along
the front as the front begins to lift northward as a warm front.
This should continue/increase the chances of showers and a few
thunderstorms on Saturday afternoon across central and northern
Ohio as it will likely take rather dry parcels to be lifted
isentropically atop the front to get something going.
Further deepening of the mid and upper level trough as it
spreads southeast into Michigan on Saturday night will allow the
surface wave to deepen as well, and there is a more notable
925-850mb layered moisture transport axis that develops and
points into the northern 1/2 of the ILN forecast area. Will
likely see a better chance/higher coverage of showers and a few
storms (elevated instability) Saturday night into Sunday
morning as the deepening surface wave runs from Chicago to
Buffalo.
Cold front attendant to this wave will sweep through on Sunday
from west to east, and there may be enough gathering of lower
level instability along/ahead of this front to continue chances
of showers and storms areawide. Given the deepening wave, winds
will respond both ahead and behind the cold front, and some
gusts to 30 mph will be likely making for a breezy / warm
afternoon ahead of the front, and a rapidly cooling/gusty
Sunday night behind the front.
Monday-Wednesday - coldest air of the autumn season sets up shop
as the upper trough continues to mature over the Great Lakes.
Good agreement in ensemble probabilities / anomalies that this
will bring the first areas or widespread frost potential on one
or multiple mornings, depending on coverage of any stratocumulus
clouds that will likely exist in the strong cold advection
regime, and how quickly winds can abate. Probably looking at
Tuesday/Wednesday mornings as providing the highest frost
potential. Once any cold advection sprinkle/shower threat
subsides on Monday, much of next week again looks dry as the dry
October continues.
&&
.AVIATION /07Z THURSDAY THROUGH MONDAY/...
VFR conditions expected across the TAF sites through the next 24
hours, except at KLUK where river valley fog is once again
expected to develop after 07Z or so. There remains above average
uncertainty considering the background setup appears rather
favorable but guidance remains a little conservative on the
formation of valley fog. Based on this, have maintained an MVFR
visibility restriction but could very well see IFR visibility
at LUK at any point the 08Z-13Z time period. A few cumulus may
drift into central Ohio later this morning on light northeast
flow, but overall another day of clear/sunny skies and light
northeast to east winds is expected through the TAF period. Do
expect another round of valley fog after 06Z on Friday morning,
which will be addressed in the next TAF issuance.
OUTLOOK...No significant weather expected.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...Binau
NEAR TERM...Binau
SHORT TERM...Binau
LONG TERM...Binau
AVIATION...Binau
Source:
ILN issues Area Forecast Discussion (AFD) at Oct 10, 3:55 AM EDT---------------
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