Area Forecast Discussion
Issued by NWS Wilmington, OH

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FXUS61 KILN 241310
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
910 AM EDT Sun Mar 24 2024

.SYNOPSIS...
High pressure will build across the Great Lakes today and pass
off to the east tonight. This high will offer dry weather with a
warming trend as winds become southerly on its backside. Rain
will return as a large storm system moves in Monday night and
affects the area Tuesday and Tuesday night.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Patches of mid clouds continue to progress eastward across the
area. there are more clouds upstream although they seem to be
thinning. Still should be no worse than partly sunny. Forecast
temperatures look on track at this point.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
Surface high pressure will continue moving off to the east as
a storm system takes shape over the nations mid section Monday.
High and mid level clouds to thicken over the area tonight in
WAA pattern. Expect lows to range from the mid 30s north to the
lower 40s south.

Southeast surface flow increasing Monday which will keep the
low levels dry. Expect mainly high level clouds over the area
with temperatures warming to highs from the lower 60s to near
70. These temperatures combined with the dry lower levels will
result in minimum RH values of 20 to 25 percent over the
southeast Monday afternoon. Not out of the question that min RH
values dip into the upper teens in a few locations over the
southeast. Sustained winds of 10 to 15 mph combined with this
dry airmass may result in an elevated fire danger threat.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Focus in this part of the forecast remains solely on the Monday
night/Tuesday morning rain chances, and then storm redevelopment
potential in the dry slot on Tuesday afternoon/evening and the
potential for these to be strong.

Strong shortwave trough will be ejecting up the eastern side of the
developing closed low over KS/NE on Monday night, and will be moving
toward Lake Michigan by sunrise on Tuesday. Closed H5 low opens up
and begins to trend negatively tilted through the day Tuesday.
Surface low Monday night near the KS/MO/IA border area will move
toward Minneapolis and Lake Superior by Tuesday evening. Arcing cold
front will ride eastward through and be entering the ILN CWA at peak
heating or Tuesday evening depending on the model, and therein lies
the concern/problem.

Monday night - Initial ejection of shortwave energy well to the west
of us will drive a band of rain showers across the forecast area
later Monday night with continued depiction of high coverage and
moderate rain amounts. Low level southeasterly to southerly flow
will be strong off the surface, but near surface stable layer should
keep any strong wind gusts from reaching the ground.

North-sound band of showers should continue to traverse the forecast
area during the morning hours with increasing strong ensemble member
agreement that mid level dry slot will wrap around the ejecting low
in IA/MN/WI and overspread the Ohio Valley.  Simulated/synthetic
satellite imagery from most NWP showing some measure of clearing
working from west to east across the area Tuesday afternoon,
allowing temperatures to warm at least into the lower-mid 60s in
eastern Indiana/western Ohio, and this is an upward adjustment from
previous model runs. Boundary layer dewpoints are meager /at worst/
to modest /at best/ with consensus of lower 50s dewpoints riding
northeast in a narrow corridor ahead of the advancing cold front.
Under cold mid levels with steep low level lapse rates, even these
modest dewpoints may allow 250-500 J/kg of surface based CAPE by 21Z
to be established across the Indiana/Ohio border region if optimal
advancement of the moist axis. It is noted that ECMWF/AIFS model
data is slower/less moist and generates much less buoyancy in
comparison to NCEP models, so this will need to be watched as it is
an important difference in convective potential. That being said,
seems to be a growing consensus among the ensemble members in
general that a scattered-broken band of low topped showers or storms
is likely to develop in Indiana and move into the IN/OH border
region by early evening along and ahead of the cold front, weakening
as it loses instability with the setting sun. Forecast
soundings/hodographs across the western half of the ILN forecast
area late Tuesday afternoon and early Tuesday evening show an
environment that would support a severe threat if storms become
established and a more optimal dry slot/moisture axis juxtaposition
occurs , with decent low level flow/hodograph curvature suggesting >
150 m2/s2 of effective SRH and adequate linear forcing with the
front for convective maintenance amidst the weak instability.
Limits/concerns would be a backing mid/upper level wind profile
above the strong/veering low level flow, and ECMWF/AIFS depictions
of dewpoints really not ascending beyond the upper 40s to around 50
and a slower cold front advancement into the area until well after
sunset. GEFS-based machine learning probs from CSU have lit up the
OH/IN border region with lower-end wind/hail probabilities, but
degree of flow / curvature of wind fields in 0-1km/0-3km hodographs
suggest a stronger storm could produce all hazards if lower-mid 50s
dewpoints become established. We`ll have to watch evolution of dry
slot/low level moisture axis juxtaposition in upcoming data.

After the system clears the area, pretty quiet weather and
seasonable temps until a shortwave rides through the area on Friday
night/Saturday.

&&

.AVIATION /13Z SUNDAY THROUGH THURSDAY/...
VFR conditions through the TAF forecast period. Large area of
high pressure to build across the Great Lakes into southeast
Canada today. Dry airmass in the lower levels with mid and high
level clouds spilling in from the west today. Expect mid level
ceilings between 10k-15k FT this morning which will thin some
later in the day prior to thickening up overnight.

East winds at less than 10 kts will increase to 10 to 12 kts
this afternoon with a gust to 18 kts possible. The east winds
will than become southeast at 10 to 12 kts tonight.

OUTLOOK...MVFR ceilings and visibilities possible late Monday
night into Tuesday evening. Wind gusts up to 30 kt possible
Tuesday afternoon and evening.

&&

.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.

&&

$$
SYNOPSIS...AR
NEAR TERM...
SHORT TERM...AR
LONG TERM...Binau
AVIATION...AR


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