Area Forecast Discussion
Issued by NWS Wilmington, OH

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FXUS61 KILN 190124
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
924 PM EDT Thu Apr 18 2019

.SYNOPSIS...
Showers and a few thunderstorms will overspread the area
tonight into Friday as a cold front pushes slowly east. A cold
upper level low pressure system will then move across the
region Friday night into Saturday, bringing a continued chance
of showers and unseasonably cold temperatures. High pressure
will build back into the area on Sunday, leading to drier and
warmer conditions.

&&

.NEAR TERM /THROUGH FRIDAY/...
A cold front has moved into western Indiana and will continue
to push east tonight. However, a wave of low pressure will ride
north along the front, helping to slow down its eastward
progression. As a result, expect the front to be situated
somewhere across central portions of our fa by daybreak. A
strengthening low level jet ahead of the low pressure system
will lead to increasing low level convergence along and ahead of
the front. This will lead to widespread shower activity
developing/advecting into our area from the west through
tonight. There are some timing differences between the models on
the eastward progression of the pcpn but think by daybreak, the
pcpn should have pretty much overspread our entire area. The
models are also suggesting some weak mucapes across the area
ahead of the front. This could lead to a few embedded
thunderstorms at times and some locally heavy rainfall
overnight, such as the cell that has required an SPS. Models
continue to suggest the highest QPF will be across about the
northwest half of our fa and will keep the mention of possible
localized flooding issues in the HWO.

In continued southerly flow, temperatures will be slow to drop
off overnight, until the front/pcpn start to move into the west
later tonight. This will lead to a non diurnal temperature
trace and an eventual decent temperature gradient across our
area. Will have lows ranging from the mid 40s in the far west to
the lower 60s in the east.

&&

.SHORT TERM /FRIDAY NIGHT/...
Mid level short wave energy rotating through the base of a
seasonably deep trough moving across the central United States
will help develop a closed upper level low over the lower
Mississippi Valley through the day on Friday. The low will
continue to deepen as it lifts northeast into the upper Ohio
Valley through Friday night. This will keep the threat for
showers continuing during the day on Friday and into Friday
night. Expect early highs on Friday with steady or slowly
falling temperatures as the CAA spreads in on the back side of
the cold front. By late afternoon, temperatures should be mainly
in the 40 across the area.

As we head into Friday night, low level thermal fields will
continue to cool off. The NAM and to a lesser extent the ECMWF,
has been consistently indicating a changeover to snow across
our west/southwest as the boundary layer cools off. In fact, the
NAM is trying to indicate several inches of snow across our far
western areas. Even factoring in the warm ground, the 24 hour
snow depth change off of the NAM is indicating an inch or two of
accumulation through Friday night. Meanwhile, the ECMWF has
much less in the way of accumulation, but is still suggesting
some snow possibilities across our southwest, while the GFS
remains warm enough for just some cold rain. Am a little
concerned the NAM/ECMWF may be on to something, as they are
likely picking up on some dynamic cooling with the stronger
lift. Still though, given the time of year, would think it would
be tough to get much in the way of anything sticking to the
ground. Will therefore, just allow for a few wet snow flakes to
mix in across parts of our west/southwest later Friday night.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Mid level low to lift slowly northeast through the region
Saturday. Model solution trends are generally slower/less
progressive with this system. ECMWF track which had been more
east than north is trending more like the GFS/Canadian
solutions. Have trended the fcst toward a blended GFS/Canadian
solution. Under the influence of this system will continue high
pops for showers Saturday. These showers could mix with a few
snow showers west early. Clouds and pcpn to keep temperatures
rather chilly. Forecast highs only expected to reach the upper
40s to 50.

Based on a slower movement will hold onto low pops for a shower in
the far east until early Sunday. Northwest flow with surface ridge
allowing for a decrease in clouds later Sunday. Temperatures to warm
close to normal with Sunday/s highs from the lower 60s northeast to
the upper 60s southwest.

Mid level flow undergoes a transition becoming less amplified with a
band of westerlies working into the Great Lakes early next week.
This will allow a surface front to drop into the southern Great
Lakes Monday. Will limit any pops to low chance category of a shower
across the north. Expect above normal temperatures with highs from
the upper 60s north to the upper 70s south Monday afternoon.

The front looks to sag a little further south on Tuesday with
marginal instability developing. Forcing looks weak, so will limit
pops to very low chance of a shower or thunderstorm. Temperatures to
range from the mid 60s north to the mid/upper 70s south.

Surface wave develops in the Central Plains with model spread
regarding its development and track for the middle of next week.
GFS/Canadian solutions are more progressive with this system - while
the ECMWF closes off a mid level low over the plains. Will follow a
more progressive solution with the sfc wave lifting northeast into
the Great Lakes Wednesday into Thursday. This will place ILN/s FA in
the warm sector Wednesday. Due to the differences in solutions will
limit pops chance/slight chance category. Temperatures will continue
above normal with Wednesday`s highs from the upper 60s northwest to
the upper 70s southeast. As the surface front pushes into the area a
chance of showers/thunderstorms will continue Thursday.

&&

.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Conditions are VFR to start in the increasingly moist
southwesterly flow ahead of a slow moving cold front. Aviation
weather will deteriorate tonight as the front and wave of low
pressure move in, bringing showers, and MVFR ceilings as
humidity increases abruptly along and behind the front. While
showers continue on Friday, ceilings are forecast to drop below
1000 ft to IFR as low levels approach saturation. Improvement to
MVFR may be observed late in the forecast period at some sites.
Winds will stay rather strong, with gusts near 30 knots later
in the forecast in the northerly flow behind this slow to evolve
system.

OUTLOOK...MVFR ceilings and visibilities likely late Friday
night into Saturday night. Wind gusts to around 30 kt possible
late Friday night into Saturday.

&&

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

&&

$$
SYNOPSIS...JGL
NEAR TERM...Coniglio/JGL
SHORT TERM...JGL
LONG TERM...AR
AVIATION...Coniglio


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