ILN issues Area Forecast Discussion (AFD) at May 5, 2:04 PM EDT
964
FXUS61 KILN 051804
AFDILN
Area Forecast Discussion
National Weather Service Wilmington OH
204 PM EDT Mon May 5 2025
.SYNOPSIS...
A cutoff low will move very slowly across region through Tuesday,
providing periods of showers and thunderstorms. This will keep below
normal temperatures entrenched across the Ohio Valley until a warmup
develops toward midweek. Drier conditions are favored for the end of
the workweek into next weekend.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Cutoff mid/upper level low centered over central Kentucky to drift
north-northeast toward the Tri-State region today. Cold pool aloft
with 5H temperatures of -22C to -24C advects into the area today.
ILN/s 12Z sounding shows shows favorable mid level lapse rate of
7.2 C/Km. Marginal instability is expected with MUCAPE values of
500-750 J/KG in the far east this afternoon. The placement of
instability and lift should allow the best coverage of showers and
thunderstorms over the eastern and northern counties. Favorable mid
level lapse rates and instby in the hail growth zone will lead to
the potential for small hail with the better updrafts over the east.
Highs will top out in the upper 50s to lower 60s this afternoon.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
Closed low will continue to slowly move east-northeast tonight and
begin to shift to away to our east on Tuesday. Showers will have
best coverage during the day as instability peaks and will be more
likely across our northern and eastern counties where the best
instability remains. Lows tonight will dip into the middle to upper
40s across the south and near 50 across the north. Highs on Tuesday
will rise into the mid to upper 60s over the Tri-State, but will
remain near 60 across the north where the thickest clouds linger.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
The start of the long term period will bring the departure of the
lumbering cutoff low that will have been entrenched across the
region for 3+ days by Tuesday night. A few showers will linger early
Tuesday night on the backside of the departing/weakening low in the
E, impacting mainly parts of central OH with additional light rain
before drier conditions return into Wednesday morning.
Into midweek, attention will return to another cutoff system
meandering about the Four Corners region before slowly drifting into
the south-central plains. The OH Vly will briefly be caught in
between the departing low into the NE CONUS and this one emerging E
into the plains by Wednesday into Thursday, with a narrow ridge axis
attempting to very briefly build into the OH Vly during this time.
These patterns, ones with multiple cutoff lows with the primary nrn
jet shunted way to the N, offer a variety of complexities from a
fcst standpoint and the evolution of the pattern into late week/next
weekend is no different. Although most areas will remain dry on
Wednesday, a few showers in the far E (associated with the departing
system) as well as in the far S (with the approaching system) cannot
be completely ruled out. PWATs will be near seasonal norms and
although forcing will be weak, any slight deviation in the evolution
of these two lows may allow for slightly higher pcpn chances
Wednesday and again on Thursday across at least parts of the area.
By Thursday into Friday, a digging S/W into the northeast CONUS on
the heels of the departing closed low will move to the SW, with a
recent trend toward a more amplified/digging solution with this
feature, which will be important in terms of determining how the
pattern evolves locally by Friday into Saturday. At the very least,
a weak frontal boundary seems likely to progress to the S through
the local area late Thursday, providing some weak lift and a chance
for more SHRA/TSRA, particularly near/S of I-70 where better daytime
heating will allow for more robust instby. The coverage of pcpn may
end up being higher near/S of I-70 during the daytime Thursday than
the current blend suggests, especially if trends regarding a
solution that digs more into the region comes to fruition.
Ensemble guidance seems to be in fairly good agreement showing an
influx of very dry air from the N into the daytime Friday, even with
the details regarding the digging S/W into the ern Great Lakes and
NE CONUS still somewhat uncertain. Should this feature dig to the SW
a bit more into the ern OH Vly, some of the driest air may be
shunted a bit more to the W of the local area into Saturday, but
latest guidance still maintains a dry fcst locally during this
period. This being said, the ensemble data points toward a cutoff
low that develops further to the W closer to the ILN FA Friday into
Saturday, which would likely mean daytime temps that may be quite a
bit cooler than the blended fcst currently suggests. Certainly the
trends portend that we may have another cutoff low to contend with
immediately to our E into Saturday and the interaction between the
digging S/W NE CONUS trof and the lumbering broad cutoff low in the
S mid MS Rvr Vly will be watched closely for adjustments to the
fcst. The exact evolution of this pattern into next weekend still
has some uncertainties at these time ranges given the weak flow and
interaction between various relatively weak systems. But for now,
near to slightly below normal temperatures and drier conditions are
favored mid to late week before a gradual warming trend evolves by
late next weekend into early next week.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
Slow moving cutoff low centered over central Kentucky to track into
Ohio by Tuesday morning and then into northwest PA by Tuesday
evening. Coverage of showers and thunderstorms increase this
afternoon as energy rotates around the east side of this low. Best
coverage of storms looks to affect the Columbus terminals where the
MUCAPE values of 500-750 J/kg will exist. A few of these storms will
have the potential to produce small hail. Focus for rain pivots
northwest and affects the northern TAFS this evening and then
rotates back southeast and looks to increase in coverage late tonight
into Tuesday. Thunderstorm chances increase again Tuesday afternoon
mainly over KCMH/KLCK.
VFR ceilings will drop to MVFR or even IFR in showers and storms
today with widespread MVFR ceilings developing overnight. A period
of IFR ceilings is likely late tonight into Tuesday morning at KCMH
and KLCK. As the low pulls away expect a slow improvement from the
southwest with KCVG and KLUK improving to VFR Tuesday afternoon. MVFR
ceilings look to persist thru the TAF period at all other TAF sites.
OUTLOOK...MVFR conditions will persist, at times, through Tuesday
night.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...AR
NEAR TERM...AR
SHORT TERM...
LONG TERM...KC
AVIATION...AR
Source: ILN issues Area Forecast Discussion (AFD) at May 5, 2:04 PM EDT (https://mesonet.agron.iastate.edu/p.php?pid=202505051804-KILN-FXUS61-AFDILN)
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