Area Forecast Discussion
Issued by NWS Wilmington, OH

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000
FXUS61 KILN 280134
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
934 PM EDT Wed May 27 2020

.SYNOPSIS...
Warm and humid conditions continue into Thursday. A cold
front will then move through the Ohio Valley on Friday afternoon
bringing showers and thunderstorms. Cooler and drier air returns for
the weekend.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Tropical Depression Bertha is now centered near Charlotte NC,
and will continue on a track almost due north from there
overnight. Moisture associated with Bertha will have its
westward limit, with rainfall amounts of over an inch expected
to remain well outside of the ILN forecast area. With that said,
clouds and some light rain associated with the system may impact
central and south-central Ohio by early tomorrow morning. Some
minor upward adjustments were made to the forecast to adjust
for this possibility.

Otherwise, the forecast has changed little tonight, with
expectations that any precipitation should remain very isolated
across the ILN CWA. The previous forecast included the
possibility of some slightly higher chances for showers and
storms in the far western sections of the CWA near daybreak, and
this still appears to be on track based on latest HRRR runs.

Previous discussion >
Sprawling cumulus fields have developed over the Ohio Valley with
the afternoon heating on the western end of an upper-level ridge. A
few isolated showers have formed over eastern Indiana along with the
cumulus. Showers and storms have been having a hard time forming
early this afternoon since instability is low compared to previous
days and a forcing mechanism is lacking. However, additional
isolated showers and thunderstorms are possible this afternoon
mainly along and west of the I-75 corridor. Any storms are only
expected to pose typical thunderstorm hazards: lightning, gusty
winds, and localized heavy rainfall. With the absence of shear, the
threat for strong thunderstorms is low. Convectively driven showers
and storms are expected to die off in the evening with diurnal
heating.

The chance for showers then increases a bit overnight near and west
of I-75 and along the Scioto River Valley and Columbus metro area.
Areas along and west of I-75 may experience showers as a disturbance
and remnant convection may make it`s way into the Ohio Valley from
the southern US. Across the east (Columbus metro and Scioto River
Valley), the remnants of Tropical Storm Bertha may just clip the
area and bring some showers and cloud cover. The overall forecast
confidence in terms of the precipitation tonight is a bit challenging
due to the convective nature of the showers. Either way,
temperatures will remain warm tonight with lows in the middle
60s.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
Upper-level ridging finally breaks down on Thursday morning as a
cutoff weakens and encroaches the Ohio Valley from the lower
Mississippi River Valley. As the low/opening trough creeps toward
the area, a more potent shortwave along the polar jet absorbs the
weakening cutoff low. As this happens, the Ohio Valley is just east
both systems in a warm and humid air mass. Much like the past few
days, this will allow for afternoon showers and thunderstorms to
develop over the area as highs reach into the low to mid 80s. Some
more shear east of the trough could potentially allow for more
thunderstorm organization than the past few days. Increased cloud
cover just east of the trough is also likely.

The more potent northern shortwave trough will dive out of the
northern Great Plains into the upper-Midwest on Thursday night. As
this happens, the chance for showers and thunderstorms starts to
increase from the northwest late on Thursday night into early Friday
morning. Warm and humid conditions persist with lows in the middle
60s.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Extended period begins with a H5 shortwave swinging through the
Upper Mississippi Valley, with an elongated trof axis extending down
to the Lower Mississippi Valley. Ahead of the s/w, a cold front will
be pushing through Indiana. The system will swing east across the
region on Friday. Ongoing convection in Indiana will push into the
west by mid-morning, then across the rest of the region during the
day.

Latest models runs are consistent with each other and a little
quicker with the system than yesterday`s runs. They now have much of
the area dry by 00Z Saturday, with just some lingering PoPs in the
east during the evening hours. With the widespread convection on
Friday, highs are only forecast to range from the lower 70s in the
Whitewater Valley to around 80 in the far east.

High pressure will drop down out of Canada Friday night into
Saturday. Much cooler and drier air will settle across the region
for the weekend. Highs on Saturday are forecast to range from the
upper 60s to lower 70s. Dewpoints will be in the upper 40s to lower
50s. Cooler air aloft will allow for some fair weather cu to
develop.

The high will drop southeast into the Upper Mississippi Valley by
Sunday morning, before it works east to Ohio by Monday morning.
Lows Sunday morning will once again range from the upper 40s in the
north to the lower 50s in nrn KY. Highs on Sunday will only be in
the mid 60s to lower 70s. Monday morning lows will be a couple of
degrees cooler ranging from 45 to 50 degrees. Temperatures will
start to rebound Monday as the region gets on the backside of the
high. Highs will push back into the lower 70s.

Large H5 ridge, builds over the middle of the country on Tuesday,
with the Great Lakes in northwest flow. Models are developing
convection over the upper Great Lakes and then they drop them
southeast into the area. The ECMWF is furthest south with the pcpn,
while the GFS and CMC are a farther north. Will run a blend to come
up with slight chance PoPs in the Central Ohio for Tuesday and
chance PoPs for much of the area on Wednesday.

&&

.AVIATION /01Z THURSDAY THROUGH MONDAY/...
Generally VFR conditions are expected through the TAF period,
but with occasional chances for showers and storms.

Showers have been very isolated this afternoon, and this will
likely continue to be the case this evening. Over the next few
hours, any showers will be more likely to be near
KCVG/KLUK/KDAY/KILN, but with low coverage not warranting
specific inclusion in the TAFs. This may change late in the
overnight hours into tomorrow morning, with some indications of
a greater chance of precipitation in the 10Z-15Z time frame at
all TAF sites. If confidence in this scenario increases, some
prevailing or TEMPO showers may need to be added later. It is
also during this period, perhaps extending into tomorrow early
afternoon, when some MVFR ceilings may also be possible. This
might need to be added explicitly into later forecasts as well.
Spotty showers will be possible again through the rest of
tomorrow.

Light SE winds are expected overnight, with a switch to
southerly winds of around 10 knots tomorrow.

OUTLOOK...Showers and thunderstorms will be possible at times
through Friday evening.

&&

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

&&

$$
SYNOPSIS...Campbell
NEAR TERM...Campbell/Hatzos
SHORT TERM...Campbell
LONG TERM...Sites
AVIATION...Hatzos


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