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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KILN 190047
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
847 PM EDT Fri May 18 2018

.SYNOPSIS...
A broad area of low pressure will migrate northward into the
area tonight through Saturday, providing widespread showers and
thunderstorms. Another system will move into the region Sunday
into Monday, keeping precipitation chances in the forecast
through early next week and a continued warm and humid airmass.
Drier weather may return by midweek next week.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
-- Changed Discussion --
Went ahead and issued a short flash flood watch for portions of
the tristate area given additional heavy rain moving into the
region.

Updated the forecast to add heavy rain mention in across
southwestern portions of the forecast area across the tri-state
especially. Over 4 inches of rain has already occurred in some
locations. Thunder will be primarily limited to the south this
evening where there is the better instability. Rain showers
will overspread the rest of the region and remain in place this
evening and into tonight. Rain activity will gradually decrease
in coverage late in the overnight hours. Updated the HWO to
include flood threats across primarily the western half of the
forecast area for this evening and into the overnight hours.
Only minor changes to the rest of the forecast at this time.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
A weakly-defined surface low will be tracking west and northwest
of the local area at the beginning of the short term period,
with the front expected to be oriented approximately west to
east just north of the FA. Although cloud cover will be a bit
thicker and more widespread for western parts of the area,
breaks in clouds in the eastern half or so of the region will
allow for spotty shower and thunderstorm development fairly
quickly/early during the day on Saturday. With diurnal heating,
activity will increase in coverage as it moves northeast from
the late morning through early evening hours.

Even though the individual weather features involved in
tomorrows environment are relatively weak and ill-defined on
their own, any surface low moving through the Ohio Valley in
mid-May certainly deserves a second look from a severe risk
perspective. Do think that the MRGL risk per SPC in the east is
well justified as low level destabilization will be more robust
and widespread than is being experienced today (Friday). With
this being said, the wind fields aloft are fairly weak and will
likely limit organization of storms to a degree. With sufficient
instability and lack of any notable shear and/or focused forcing
mechanism aloft, the environment and evolution will bear
watching, but the overall threat will likely remain closer to
the low end of the scale. Certainly cannot rule out some small
hail or gusty winds in the strongest cells that develop
Saturday.

Highs will top out in the mid 70s to around 80 degrees on
Saturday.

By Saturday evening, the surface low will be pulling away from
the local area and with the loss of daytime heating, expect a
fairly rapid downtick in convective coverage towards sunset.
Nevertheless, as the surface low pulls away, the trailing cold front
will once again begin to stall over the local area Saturday
night into Sunday, with lows ranging from the upper 50s in the
north to the mid 60s in the south. With the frontal boundary
continuing to linger in the area, the threat for daily scattered
showers and storms will continue Sunday into the first part of
the long term period.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Wavy quasi-stationary front will extend across the region at the
beginning of the period. The front may briefly lift north of the
area as low pressure tracks across the lower Great Lakes on Tuesday.
But as the low heads east, a trailing front will slide across the
area. Unsettled conditions will persist through this time period
with sporadic showers and thunderstorms.

Center of high pressure will track from the Great Lakes to off the
New England coast from Wednesday through Friday. The influence of
this high will bring dry conditions to the forecast area for the
latter part of the week.

Temperatures will be above normal through the period with lows
having a greater departure from normal than highs.

&&

.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
Showers will move across the TAF sites at the start of the TAF
period and into the overnight hours. There will be thunderstorms
also around the KCVG and KLUK TAFs at the start of the TAF
period. Vsbys will be reduced with some of the precipitation
activity. Cigs will lower overnight into the IFR and MVFR
categories and then rise to MVFR during the day on Saturday.
Additional showers and thunderstorms will be possible on
Saturday in addition to some wind gusts around 20 knots.

OUTLOOK...Chances for thunderstorms will exist at times through
Tuesday.

&&

.ILN WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
OH...Flash Flood Watch until 1 AM EDT Saturday for OHZ077-078.
KY...Flash Flood Watch until 1 AM EDT Saturday for KYZ090>098.
IN...Flash Flood Watch until 1 AM EDT Saturday for INZ074-075-080.
-- End Changed Discussion --

&&

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