ILN issues Area Forecast Discussion (AFD) at Apr 30, 3:41 AM EDT821
FXUS61 KILN 300741
AFDILN
Area Forecast Discussion
National Weather Service Wilmington OH
341 AM EDT Wed Apr 30 2025
.SYNOPSIS...
Frontal boundary stalls out near the Ohio River today. This front
eventually lifts back northward as a warm front, which will result
in periods of showers and thunderstorms through tonight. Thunderstorm
chances increase on Thursday with additional energy moving through.
The pattern looks to remain unsettled through at least the beginning
of the weekend as an upper level trough persists over the Ohio
Valley.
&&
.NEAR TERM /THROUGH TODAY/...
Showers have shifted southeast of the region this morning, but the
progression of the cold front has slowed. This is resulting in some
pooling moisture and thus surface visibility reductions for portions
of southern OH/northern KY and southeast IN. Dense fog is very
patchy, so will just issue an SPS to highlight some of the reduced
visibilities early this morning.
Dry weather conditions will initially return for the beginning of
the day across the CWA. However, this stalled front near the Ohio
River will act as a source of lift, which will interact with a
relatively warm and humid air mass that persists for locations in
southern OH into northern KY. Given this setup, some CAMs try to
initiate isolated shower/storm development near the Ohio River this
afternoon. Any storm that spawns could produce small hail and locally
gusty winds. While severe chances remain low today, it is still a
non-zero threat.
A gradient in highs and especially surface dewpoints will be
expected today. Highs near the I-70 corridor will be in the upper 60s
to lower 70s, with dewpoints being more pleasant in the mid-40s to
near 50. Further south, highs will approach the middle to upper 70s,
but dewpoints will be in the upper 50s to middle 60s, making it feel
a lot muggier.
&&
.SHORT TERM /TONIGHT THROUGH 6 PM THURSDAY/...
The stalled front will actually begin to lift as a warm front late
this evening and continue through the overnight hours. As the front
lifts northward, episodic showers and thunderstorms will be possible
through a good chunk of the night. These storms will be elevated, so
not anticipating a severe threat.
By daybreak Thursday, the front will be located near the I-70
corridor and continue lifting northward. The ILN fa will be firmly
planted in the warm sector of a surface low developing from a robust
shortwave propagating northeastward from the Ark-La-Tex region.
Shower and thunderstorm chances will greatly increase by Thursday
afternoon, with the potential for multiple rounds of storms. It does
appear that a complex of storms will initiate during the afternoon
and quickly develop into a QLCS (which would be the primary severe
threat). SBCAPE values could increase to 1000-1500 J/kg just before
storms build in. Wind shear profiles show sfc-3km values near 30
kts, which would help promote some organize convection. Hodographs
are more straight given the unidirectional flow out of the southwest,
so currently not anticipating a tornadic threat. The primary threat
would be damaging straight-line winds, with hail being a secondary
threat.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Showers and thunderstorms will be ongoing at the beginning of the
period, with some strong storms still possible. The more robust
activity will diminish through the evening as upper support lifts
northeast and instability decreases. However, some showers and
thunderstorms may linger with a weakening surface boundary in the
area.
Northern stream short wave will dig southeast Friday into Friday
night. This, along with diurnal heating, will be sufficient to bring
an increased chance of showers and thunderstorms again during the
day. This will continue into Friday night as weak low pressure and a
cold front finally move through.
At this point, guidance diverges as the flow transitions into a
blocky pattern. The GFS and much of its ensemble system are quite
progressive with the trough, not closing it off until reaching the
Maritimes, allowing high pressure to build into the region and
predominate. Meanwhile, the ECMWF and CMC along with many of their
respective ensemble members close off a low near or west of the
Appalachians which then meanders about the region through the rest
of the period. Needless to say, these two scenarios would result in
a substantial difference in sensible weather. The NBM and the lag
built into that is still pretty optimistic. But with the trends seen
in the ECE and GEPS, have begun to trend the forecast to more clouds
and low PoP chances.
&&
.AVIATION /07Z WEDNESDAY THROUGH SUNDAY/...
*07:30Z UPDATE*
Cold front progressing slower than anticipated. Moisture is pooling
just ahead of the boundary, resulting in notable vsby reductions for
locations closer towards the Ohio River. KCVG/KLUK and KILN may
observe IFR/LIFR vsbys early this morning before the pool of low
level moisture gets shunted southward. Have amended TAFs to account
for this.
Cold front continues to work its way through during beginning of the
taf period. However, the front will be just southeast of all
terminals just an hour or two into the period (if not already
through), resulting in a rapid shift in surface winds to the
northwest. Winds will continue to veer clockwise through the rest of
today, becoming northeasterly by daybreak and eventually out of the
southeast by the afternoon. Surface winds will remain around 5kts
through the period.
The front stalls out south of the Ohio River, which could pose a
concern for additional thunderstorm development late in the day today
and continuing overnight. Models keep any convection pretty isolated,
so have not yet included in the TAFs but may need to at least
include a PROB30 mention in the next forecast.
OUTLOOK...Additional thunderstorms are possible tonight. MVFR/IFR
conditions likely Thursday into Thursday night along with a chance of
thunderstorms. MVFR conditions possible Friday into early Saturday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...Clark
NEAR TERM...Clark
SHORT TERM...Clark
LONG TERM...
AVIATION...Clark
Source:
ILN issues Area Forecast Discussion (AFD) at Apr 30, 3:41 AM EDT---------------
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