Area Forecast Discussion
Issued by NWS Wilmington, OH-- Highlight Changed Discussion --
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FXUS61 KILN 231752
Area Forecast Discussion
National Weather Service Wilmington OH
152 PM EDT Thu Mar 23 2017
Return southeast flow will allow temperatures to modify today.
A warm front will push northeast through the region tonight,
bringing a few showers to the area. Temperatures will continue
to warm on Friday as southerly flow increases. A low pressure
system over the central Plains will slowly move into the Great
Lakes and Ohio Valley this weekend. Warm temperatures will
continue along with an increasing threat of showers and
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --Initial band of mid clouds has moved into the northwest
counties. It appears that these may decrease in coverage as they
continue east. Additional mid clouds will start to move in from
the west late in the day. Little to no change to forecast highs.
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.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
Models are in fairly decent agreement in terms of positions and
of subsequent forecasts of synoptic scale systems.
For tonight, a mid level ridge will build northward and eastward
into the Ohio Valley. As this occurs, a warm front will push
northeast through our area. Clouds will thicken this evening
with a few showers possible for locations north of the Ohio
River overnight as this area will be on the southern fringe
of better moist/isentropic lift farther to the north. Lows will
bottom out early, then steady out or slowly rise toward morning
as southerly flow increases. Temperatures will range from the
lower 40s northeast to the upper 40s southwest.
On Friday, the Ohio Valley will be warm sectored in the wake of
the warm front while a mid level ridge axis shifts east. Models
are indicating quite a bit of low level moisture in the return
low level southerly flow. This will likely result in stratus
clouds early on which will likely convert over to low level
cumuliform clouds during the afternoon. As a result, have kept
skies mostly cloudy. Despite cloud cover, stiff southerly winds
with gusts in the 20 to 30 mph range will boost highs into the
mid and upper 60s.
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
An unsettled pattern will be setting up over the Ohio Valley through
the weekend, turning more progressive but continuing to be active
going into the early part of next week.
On Friday night, the ILN CWA will be within a regime of generally
low pressure, stuck between highs off the southeast coast and over
northern Ontario. The 500mb pattern will be amplifying in the
vicinity of the Ohio Valley, even as relatively tranquil conditions
are expected at the start of the long term forecast period on Friday
night and Saturday morning. Well within the warm sector, heights
will be rising as ridging builds into the Mississippi Valley, with a
frontal boundary remaining nearly stationary across Michigan and New
York. To the west, a complex stacked low pressure system will begin
to take shape over the plains, moving slowly east -- near St Louis
by Sunday morning, then finally clearing the Ohio Valley by Monday
Confidence continues to increase in the overall timing and placement
with this system, though the 00Z ECMWF solution remains slightly
slower than the 00Z GFS. The first part of Saturday is generally
expected to be dry, outside of a few showers developing in the
continued isentropic ascent. It is expected that there will be
several rounds of showers (and potentially thunderstorms) along with
this system, running primarily from Saturday evening through Sunday
afternoon. Though the overall motion of the low will be slow, the
juxtaposition of upper support, low level moisture transport, and
500mb vorticity advection will result in the possibility of multiple
time periods in which showers and possibly thunderstorms will be
able to develop. There continues to be strong agreement in a well-
defined wave moving through the region late Saturday evening through
Sunday morning, and this period has been timed out with categorical
PoPs. On either side of this (Saturday afternoon and Sunday
afternoon) the forcing is not as well defined, but showers and
storms will be possible -- without seeing the mesoscale details,
getting more specific on timing is not yet possible. Thunder has
been included as a possibility on both days as well. This system
will have a respectable feed of theta-e and a tight/compact 850mb-
700mb low, so forcing and moisture should be sufficient for
widespread precipitation. In general, the modeling of instability
has been very fickle -- changing slightly from run to run, never
higher-end, and largely limited by the moist profile and poor mid-
level lapse rates. Building off of that analysis, with questionable
instability, the possibility for heavier rainfall or strong storms
is less certain -- also owing to differences in model specifics and
a pattern that is not necessarily a classic setup for either threat.
Nonetheless, with decent moisture and some turning in the wind field
near the low, there is at least a low-end potential to watch and
refine the forecast for in the next few days.
As the low weakens and moves away from the area late Sunday into
Monday, the weather pattern over the Ohio Valley will become very
wavy -- characterized with short wavelengths and progressive
motions. A narrow ridge behind the stacked low will provide a
reasonable chance for dry conditions for early Monday, but the busy
500mb pattern will mean that this dry period will not stick around
for long. Though there are some timing and amplitude differences
(even within the GEFS member spread) the next wave is expected to
move through Monday night into early Tuesday, producing widespread
precipitation across the area. However, until timing is better
handled, PoPs will be kept at 50 percent for this feature.
Subsidence behind the wave will likely lead to drier conditions
Tuesday night into Wednesday.
The continued warming trend into Saturday is likely to bring
temperatures into the upper 60s to lower 70s, with warmest
conditions in the southeastern CWA, where precipitation is more
likely to hold off until later. Precipitation will keep the
temperature forecast a little lower for Sunday, before warming again
slightly on Monday -- with the air mass changing very little in
general, as the main boundary will remain well north of the area.
This will change after Tuesday, as the Monday night / Tuesday wave
will bring a cold front into the region, beginning a slight cooling
trend going into the middle of the week. Nonetheless, temperatures
should still remain above normal, even on Wednesday.
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
-- Changed Discussion --Mid clouds will spread across the region early in the TAF
period. A warm front will lift across the area after 00Z. There
could be a few light showers with this, particularly from KDAY
to KCMH/KLCK. However, the probability is low and even if they
do occur, there would be no impact on flight category. So that
potential has not been included in the TAFs. Southeast winds
will veer to the south once this front moves through. In
addition, low level winds will increase in speed leading to low
level wind shear until around 13Z. Lower clouds will spread into
the area on Friday morning. Confidence is low concerning what
level these clouds will be. At this point have only lowered KDAY
to MVFR, but it is certainly possible that MVFR ceilings could
affect more areas.
OUTLOOK...MVFR ceilings possible Friday afternoon and evening.
MVFR ceilings and visibilities likely Saturday night into Sunday
along with a chance of thunderstorms. MVFR ceilings and
visibilities will be possible again Monday night into Tuesday.
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