Area Forecast Discussion
Issued by NWS Wilmington, OH

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FXUS61 KILN 220004
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
804 PM EDT Mon Jun 21 2021

.SYNOPSIS...
A few showers and storms are expected through early evening with
some light rain lingering through early tonight. Much cooler and
drier air moves in early Tuesday, with below normal temperatures
expected for both Tuesday and Wednesday. Dry conditions prevail
midweek before a stormier pattern develops again by Friday into
this upcoming weekend as a more humid and warm airmass once
again settling into the region.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Convection initiated very late morning into early afternoon
initially in central Ohio, with that activity moving east
quickly away from the ILN FA. In the meantime, additional
activity sprouted quickly /just/ to the south of the I-71
corridor being between Wilmington and northern KY along a
prefrontal trof. This storm activity has shown the most
consistently-robust updrafts through the afternoon thus far, but
even this activity will be exiting the ILN FA by 5 PM. Expect
the severe threat should diminish greatly /if not altogether/ by
5 PM for the entire local area, even the lower Scioto Valley
and northeast KY. The ongoing severe thunderstorm watch will
most certainly be cancelled prior to its expiration time of 8
PM.

Will see some overrunning light rain overspread the ILN FA early
this evening, which will expand in coverage and perhaps even
intensity late this evening before the backside works east late
tonight, ending from west to east between midnight and 4 AM or
so. A clearing trend is expected during the predawn hours,
especially for WC OH and EC IN, with that clearing line
advancing to the ESE toward the end of the near term period and
beyond.

Surface obs show the infiltration of drier LL air is already
underway, with DPs already in the upper 50s in WC OH as winds
have shifted around to the northwest. Will see this dry air
advection continue through the evening, even with the fairly
widespread overrunning light rain during this period. In fact,
low temps will bottom out around 50 degrees in WC OH to upper
50s in the lower Scioto Valley/NE KY by sunrise Tuesday.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Abnormally dry air settles into the region for Tuesday with
ample sunshine and highs topping out a degree or two either side
of 70 degrees -- about 15 degrees below seasonal norms. Could
see some SHRA activity to the north of the immediate area
Tuesday afternoon as some S/W energy rounds the base of the
broader-scale trof across parts of MI/extreme northern OH. This
activity should stay to the north of the local area as surface
high pressure builds in from the west.

Will see the sfc high traverse the Ohio Valley Tuesday night
into early Wednesday with some return flow becoming established
Wednesday with some more seasonable /albeit still below normal/
temperatures expected with highs near 80 degrees after morning
lows once again in the lower/mid 50s. Cannot completely rule
out some rural/sheltered spots in central/south-central OH and
NE KY dipping into the upper 40s Wednesday morning before making
a rather large diurnal swing of ~30 degrees.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Large-scale troughing centered over the eastern third of the
CONUS will transition to move solidly NW flow for the OH Vly by
Wednesday as that trof axis continues to pull east toward the
spine of the Appalachians. Meanwhile, a mid/upper level ridge
over the south-central plains will begin to nudge east, with the
digging of S/W energy into the high plains/upper Midwest by
Wednesday night into Thursday.

At the sfc, will see a frontal boundary move east through the
upper Midwest into the western Great Lakes stretching back to
the southwest toward the mid-Mississippi River Valley by
Thursday morning. This front will begin to stall out with the
arrival of the aforementioned system in the western High Plains.

More locally, the subtle midlevel ridging in place during the
daytime Thursday will quickly erode/flatten by Friday as the
front begins to nudge closer to the ILN FA. By this point, a
more seasonable warm/humid airmass will have built north into
the Ohio Valley, setting up a potentially stormy/wet period
Friday through early the following week as the slow-moving
frontal boundary crawls eastward and episodic showers/storms
develop along it for the better part of a 48-hr period beginning
Friday night and lasting into the weekend. This will set up a
persistent SW flow aloft locally as a trof digs into the mid-
Mississippi River Valley by the end of the long term period. Still
quite a bit of model variability at these time ranges regarding
the timing of the front and positioning of it across the Ohio
Valley during this period. However, there is a signal for heavy
rain/storm potential this weekend into early the following week
somewhere within the region, but the details of this threat
will become clearer as we progress through the next several
days.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
The area of persistent -RA has become more scattered over the
last hour or so, leading to some changes in the near term TAFs.
Given the scattered nature, have opted for -SHRA for the
remainder of the evening. Clear skies filter in from the NW
after 12z, with all sites SKC by 15z.

Westerly winds at about 15kts with gusts to 25kts will go more
west-northwesterly very early in the TAF period before subsiding
to closer to 10kts and trending more northwesterly toward 00z
and beyond.

Surface high pressure moves into the region Tuesday morning,
causing winds to shift out of the southeast at around 5 knots.


.OUTLOOK...Thunderstorms are possible on Friday and Saturday.

&&

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

&&

$$
SYNOPSIS...KC
NEAR TERM...KC
SHORT TERM...KC
LONG TERM...KC
AVIATION...McGinnis


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