ILN issues Area Forecast Discussion (AFD) at May 17, 6:23 AM EDT167
FXUS61 KILN 171023
AFDILN
AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
623 AM EDT Fri May 17 2024
.SYNOPSIS...
Scattered to numerous showers and storms will persist through
the daytime today, lingering a bit tonight, with additional
isolated activity possible during the day on Saturday. Drier
conditions are expected to evolve Sunday into early next week,
with much above normal temperatures expected through the first
half of the workweek. The next chance for widespread showers
and storms will arrive midweek.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Scattered to numerous SHRA, with some ISO embedded TSRA, is
overspreading the ILN FA from the W this morning, focusing
initially near/N of the OH Rvr, especially closer to the I-70
corridor. Although some TS will be possible from time-to-time,
this should remain a bit more isolated in nature. The widespread
activity should become a bit more scattered late in the morning
into early afternoon, with additional redevelopment likely to
the N of the steadier/more widespread SHRA activity focused near
the OH Rvr into early afternoon. The activity through the
morning hours will likely inhibit destabilization efforts in the
immediate vicinity of the most widespread early day SHRA, with
the best (albeit still rather meager) instby in an uncapped
environment developing to the N (potentially near the I-70
corridor) by late afternoon once again.
The best LL flow will pull to the E of the local area by late
afternoon into early evening, leaving a rather nebulous LL flow
pattern in its wake across the region by this evening. This
presents an issue in terms of increasingly slow/erratic
storm/cell movements by early evening, especially in comparison
to early day progressive activity. There will likely be one or
more WSW-ENE oriented "clusters" of SHRA/TSRA that redevelop by
late afternoon and persist through early evening, moving
somewhat slowly during this time. This being said, do think that
the overall potential for localized heavy rain to cause flooding
issues is still rather low. Sure, PWATs will be on the order of
125% of seasonal norms, but there is a notable lack of instby,
limiting the more robust updrafts that could be sustained for
any extended period of time. The potential for locally heavy
rain and an isolated instance of flooding would probably be best
described as low, but non-zero, with really no specific
indication for a favored area for such development to occur late
day.
Overall, rainfall today will generally range from about one
quarter of an inch to three quarters of an inch, with locally
heavier amounts in the more persistent late day ISO/SCT
activity.
Temps today will be held in check by the early day widespread
SHRA and ISO TSRA and the persistence of quite a bit of cloud
cover through even late afternoon. Highs should generally top
out in the lower/mid 70s amidst a seasonably humid airmass.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
Some patchy fog development may develop again tonight, although
confidence on this occurring is rather low due to the
expectation for low stratus to disrupt clearing efforts. But...
a /very/ moist LL profile will be maintained through tonight
amidst weakening/stagnant flow, suggesting that fog may be an
issue into Saturday morning, especially for areas that receive
appreciable rainfall today. Some SHRA will linger across the
far SE ILN FA through about midnight as the initial S/W pulls to
the E, with a stray SHRA possible just about anywhere through
the entirety of the nighttime period.
The pattern keeps rolling right along on Saturday as a cutoff
low develops just to the S of the immediate ILN FA, with very
weak LL and deep-layer flow around it continuing in the local
area. There should be better destabilization on Saturday
afternoon than will be the case today, but the shear/wind
profile will be incredibly weak, suggesting some difficulty for
storm organization/maintenance even as we destabilize without
much of a cap in place. This suggests the likelihood of some
"popcorn- like" cells sprouting about by early afternoon
Saturday, continuing in a very disorganized manner until daytime
heating subsides and instby decreases toward sunset once again.
Some spots get a quick/sudden downpour, most stay dry.
Highs on Saturday will be quite a bit warmer than will be the
case today, owing to a bit less cloud cover. This being said,
skies will still be partly sunny through the afternoon hours as
highs top out in the mid (near/S of the OH Rvr) to upper (near/N
of I-70) 70s.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
On Saturday evening, a lumbering upper trough will be moving east
through the southeastern states, with its influence over the Ohio
Valley beginning to wane as it pulls away from the region. At the
surface, there will not be any sort of significant change in air
mass, with somewhat moist and stagnant conditions remaining in place
through Sunday and into the new week. Even as the trough moves away,
to be replaced by narrow ridging by Sunday afternoon, some low-end
chances for showers appear warranted for Sunday with weak
instability building into the area.
Narrow ridging on Sunday will give way to broader ridging in the
southeastern states on Monday, and eventually a more active WSW flow
pattern from the central plains through the Ohio Valley by the
middle of the week. Monday appears likely to be dry, as any forcing
will still be upstream of the area. By Tuesday, quite a bit of
instability will be building into the Ohio Valley, with deep-layer
SSW flow and surface dewpoints getting well into the 60s. However,
forcing will still be mainly upstream of the area, so convection
will be limited -- perhaps more likely to occur in the northern and
northwestern sections of the CWA. The more concerning period of the
forecast will be some time in the Tuesday night through Wednesday
night time frame, as a cold front is expected to overtake this
increasingly unstable air mass. The timing forecast for this front
is far from certain at this distance in the forecast cycle -- and
the juxtaposition of the boundary layer conditions with an expected
fast-moving shortwave will also be key to the forecast. However, at
this point, it is fair to say that there will be some potential for
severe weather in the middle of next week. A drier and cooler air
mass will follow the front to end the week.
The Sun-Mon-Tue period is expected to be rather warm, with highs
well into the 80s each day. Temperatures on Wednesday are a lower
confidence forecast, as this will be dependent on convection and
frontal timing. If the front has not yet moved into the area, then
another day in the 80s is likely.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
Widespread SHRA, with a few embedded TS, have overspread the
local area this morning, initially focusing greatest coverage
for nrn sites of KDAY/KCMH/KLCK. Brief MVFR, or even IFR, VSBYs
will be possible in the heaviest pockets, but prevailing VSBYs
should remain VFR.
MVFR CIGs are likely to develop/expand into nrn parts of the
area, impacting KDAY (and perhaps KCMH/KLCK/KILN) through about
15-16z, with VFR CIGs expected to prevail for srn sites.
Conditions should return to mainly VFR area-wide toward 18z as
CIGs lift. Some SCT/disorganized convective redevelopment is
expected for the afternoon into early evening, likely N of the
steadiest early-day RA (perhaps near the I-70 corridor). It
appears like srn sites of KDAY/KCMH/KLCK/KILN will have the best
chance to see some redevelopment between about 21z-01z, but
really it could occur anywhere at anytime late day into the
evening.
The best coverage of SHRA/TSRA should focus more to the SE of
the local sites late evening, but the nrn fringe of lingering
activity will be very close to KCVG/KLUK/KILN through 06z. CIGs
will go back MVFR, and eventually IFR, toward 06z and beyond
Saturday, with some MVFR/IFR VSBYs also possible as the remnant
LL moisture remains entrenched across the region and some BR
expands.
Winds will generally be light (10kts or less) out of the WSW or
S through the period, going light/VRB at times due to
convective influences. Calm/light/VRB winds will be possible
past 03z, leading to the aforementioned potential for some IFR
CIGs/VSBYs due to the development of BR/FG.
OUTLOOK...IFR CIGs and VSBYs are possible early Saturday
morning.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...KC
NEAR TERM...KC
SHORT TERM...KC
LONG TERM...Hatzos
AVIATION...KC
Source:
ILN issues Area Forecast Discussion (AFD) at May 17, 6:23 AM EDT---------------
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