Area Forecast Discussion
Issued by NWS Wilmington, OH-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KILN 211636
Area Forecast Discussion
National Weather Service Wilmington OH
1236 PM EDT Fri Apr 21 2017
-- Changed Discussion --Cooler conditions will continue into the weekend, with some
chances for rain, as the front stalls south of the area. Warmer
conditions are expected from Sunday into next week.
-- End Changed Discussion --
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --Some light rain will be possible across southern portions of the
forecast today closer to a frontal boundary. CAA and cloud cover
will keep temperatures cooler today generally in the 50s and
-- End Changed Discussion --
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
Based on theta-e / MSLP analysis, the Friday morning cold front
is expected to stall and pivot just south of the ILN CWA by late
Friday and into Saturday morning. Precipitation chances through
Friday night and Saturday will be tied to mid and upper level
support moving eastward across this front, ultimately ending up
with a surface low passing south of the region at some point on
Saturday. Regarding all of the above features, model
timing/placement agreement is disappointingly and remarkably
poor. If there has been any trend with the 00Z runs, it has been
for a slightly more southerly frontal position. This -- if
nothing else -- will help to limit the potential for instability
or more significant deep-layer moisture, limiting the threat
for heavy rainfall. Models are not unanimous on this, however --
the 00Z ECMWF remains further north with the front and thus with
its axis of greater QPF. The 00Z NAM is at the other end,
keeping the majority of the CWA dry after an initial batch of
rainfall on Friday night. WRF-ARW/WRF-NMM/NSSL Realtime WRF
forecasts are similarly split on details but not as dissimilar
on the overall picture, helping to paint a picture for PoPs
based on a compromise scenario. Based on the majority of the
model guidance, along with relatively unimpressive SPC SREF
probabilities for >1" rainfall, the heavy rain mention will be
removed from the forecast. Thunder was also removed from the
grids, with even elevated instability expected to remain south
of the area -- though, it should be noted, the elevated frontal
boundary will be slightly further north than the surface front.
PoPs were raised slightly with an initial wave of generally
lighter precipitation late Friday evening into the overnight,
with the greater chance for more persistent rainfall across the
southern CWA at some point on Saturday.
On the north side of the surface boundary, and in a regime of NE
flow, Saturday will be a notably cool day -- with max temps at
least 10 degrees below normal, only forecast to reach the lower
to mid 50s. Obviously, the way the precipitation forecast plays
out will have a role in these temperatures, making this a
little lower confidence than normal. A rainier day on Saturday
might keep temps closer to 50, but areas that escape the rain
could get a little warmer.
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Upper level low will continue to dig south into the Tennessee
Valley Saturday night into Sunday. As it does, it will gradually
lose influence on the region. Clouds will decrease from the
north but will remain some in the south with a lingering threat
of showers. Temperatures should rebound into the lower and mid
60s on Sunday with the highest readings expected where more
sunshine will occur.
For Sunday night into Monday, upper level low will rotate
southeast toward the southeast United States coastline. The
threat for precipitation will end in the south with all
locations expected to have sunshine on Monday. With airmass
modification and solar radiation, temperatures will warm into
the upper 60s to the lower 70s.
Weak high pressure ridging at the surface and aloft will
influence the regions weather Monday night into Tuesday. Dry
weather and airmass modification will continue the warming trend
with 70s expected on Tuesday.
For the period Tuesday night into Wednesday night, upper level
flow will allow a frontal system to push into the region from
the northwest where it may briefly stall out by Wednesday
night. This will bring at least a chance of showers to the
northwest zones Tuesday night, and then a chance of showers and
thunderstorms to all locations Wednesday into Wednesday night.
By Thursday, models suggest that the upper level flow may begin
to amplify. If this occurs, frontal boundary will lift north as
a warm front into the Great Lakes on Thursday. This will
eventually take the threat of precipitation with it. Temperatures
will become above normal by this time with upper 70s to lower
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
Showers have ended at the TAF sites, and by 12Z, all of the
airports are expected to be within a clear slot. While the
clearing should be relatively short-lived, the clouds that move
back in will likely be a mix of mid/high clouds (VFR) through
the rest of the day. An MVFR stratocumulus deck is currently
over northwest Ohio, but as of now this is not expected to make
it to DAY/CMH/LCK before lifting. Winds are expected to be out
of the northwest at around 10 knots.
Tonight, clouds will thicken from south to north, as chances
for precipitation gradually begin to increase. Forecast
confidence for tonight into Saturday is low, with regards to
specific precipitation timing, so there may need to be changes
to what is currently in the TAFs as it becomes more clear when
rain ends up forecast to move into the area. It does appear
that rain is more likely to occur at the southern TAF sites
(CVG/LUK) through this time period, especially after midnight,
with slightly greater chances for all TAF sites by Saturday
OUTLOOK...MVFR ceilings and visibilities possible Saturday with