Area Forecast Discussion
Issued by NWS Wilmington, OH

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FXUS61 KILN 201507
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
1107 AM EDT Sat May 20 2017

.SYNOPSIS...
A frontal boundary across the region will act as a focus for
scattered showers and thunderstorms again today. A cold front
will move into the region Sunday, providing yet another chance
for storms, before drier and cooler conditions move into the
area on Monday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Main forecast challenge today revolves around chances for
convection and potential for severe weather. Mid/upper level
low to lift northeast thru the central plains today and into the
western Great Lakes tonight. Upstream ridge axis to shift east
with the flow backing in response to this system.

East-west oriented frontal boundary has settled south and is currently
stalled across northern KY. This front will begin to lift north
this afternoon and push across ILN/s fa into southern Lower Mi
overnight. Expect moderate instability to develop over ILN/s
southwest counties invof the warm front this afternoon. 30-40 kt
0-6km bulk shear will support some organization to storms with
damaging wind being the main threat. Added low level shear near
warm front will result in the potential for a few supercells
and therefore an isolated tornado threat will exist.

For the update have adjusted temperatures cooler based on
observations and trends. Also, with showers and thunderstorms
already developing this morning have adjusted pops sooner and
then used a blend of short term CAMs and prev fcst to develop
likely pops into sw counties this afternoon and pivot these pops
north-northeast across CWA.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
Tonight a deep H5 low will lift ne through the northern Great
Plains. As this occurs a sfc low is pushed e ahead of it. While
the models are still showing convection affecting the region
tonight, they are now showing large differences in the
coverage and therefore possibly the severity. There is enough
of a signal to keep the categorical PoPs late tonight into
tomorrow. The following model runs will have to be watched to
see if anything changes.

The cold front will be slow to push through the region Sunday,
as the H5 low spins to the west. Highs on Sunday will be in the
mid 70s with the pcpn keeping temperatures down. The backedge of
the pcpn will reach the wrn counties late Sunday afternoon, but
it will linger in the east for the first part of Sunday night
before ending. Lows Sunday night will range in the 50s.

A weak ridge of high pressure will bring dry weather for Monday,
but also cooler temperatures as highs will be in the upper 60s
to lower 70s.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
The upper level pattern will become highly amplified during the
upcoming week which will eventually lead to a mean mid level
trough setting up residence across the Great Lakes and Ohio
Valley. There continues to be some timing issues with the next
cold front to push through the region Tuesday into Wednesday. A
chance of showers will continue during this period, with thunder
possible during the peak heating of Tuesday into Tuesday
evening.

By Thursday, mid level trough will be slow to progress to the east
which may keep a few lingering showers.

Another quick moving system in the northwest flow aloft may bring
another threat for showers Thursday night into Friday.

Below normal temperatures can be expected by mid to late week with
highs only in the 60s Wednesday and Thursday, then perhaps getting
back into the 70s on Friday.

&&

.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
The low stratus with cigs blo 1kft will lift this morning, with
a rapid improvement of vsbys shortly after daybreak. The weak
front that is south of the CWA in central KY will head north as
a warm front today. Models are limiting any shower activity this
morning and the low stratus could inhibit how warm we do get by
later afternoon. Although confidence remains low, showers could
still pop this morning. Warm sector will be over the region this
afternoon and shower and thunderstorm activity is expected to
initiate. KCMH/KLCK never quite get the warm front through in
time to let the thunderstorms pop - kept vcsh over them for this
afternoon/evening and then let the overnight storms have thunder
towards daybreak Sunday.

Towards the end of the TAF period a line of thunderstorms will
be approaching from the west as a potent upper level low tracks
into Minnesota with a surface low near Lake Superior.

OUTLOOK...Thunderstorms with MVFR conditions are possible
through Sunday.

&&

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

&&

$$
SYNOPSIS...Haines
NEAR TERM...AR
SHORT TERM...Sites
LONG TERM...Hickman
AVIATION...Franks



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