Area Forecast Discussion
Issued by NWS Wilmington, OH

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FXUS61 KILN 231448

Area Forecast Discussion
National Weather Service Wilmington OH
1048 AM EDT Mon Apr 23 2018

An upper level low pressure system will push slowly east across
the Tennessee and Ohio Valleys today through Tuesday, bringing
rain showers to the region. High pressure and drier conditions
will return for mid week. Cooler than normal high temperatures
will persist through the end of the week.


Easterly flow at the surface is evaporating the northern edge of
the precipitation shield. Mesoscale models are still indicating
that the rain band will gradually overcome the drier air at low
levels and will reach central Ohio by the end of the afternoon.

Upped PoPs in the sw to 100, and increased Pops across all the
southern half to categorical. Left northern areas as likely.

Coolest highs are still expected in Cinci Tri-State where they
will be around 60. Highs will increase as you head northeast
towards Central Ohio where the highs will be in the mid to
upper 60s.


The upper level low will drift slowly eastward across the
Tennessee Valley tonight through Tuesday and weaken somewhat as
it does. This will keep the chance of showers going into
Tuesday with the highest pops slowly shifting east across our
area tonight into Tuesday. Instability looks to be marginal at
best across our area, generally remaining to our south, so think
thunder chances will be rather low.

Lows tonight will be in the upper 40s to lower 50s with highs
on Tuesday only in the mid to upper 50s.


Tuesday night a vertically stacked upper level low will be located
over the Kentucky/ Tennessee border with another potent upper level
disturbance located over Wisconsin. This secondary wave will dive
southeast helping to eject the upper level low off quickly to the
northeast Wednesday. There are some slight differences in the upper
level flow depicted Wednesday with the ECMWF keeping the upper level
low slightly deeper than the GFS and CMC. This means that for
Wednesday afternoon the GFS, NAM, and CMC all only show exiting
precipitation across the area, while the ECMWF is slightly more
bullish. For now have just trended the precipitation to a slightly
quicker exit for Wednesday.

Wednesday evening an upper level disturbance over Wisconsin will
move east pushing a surface cold front through the area. By this
time enough dry air has moved into the region which will keep the
area dry. There remains a lot of slight model differences beyond
this period that still have to be resolved, but the general idea is
for another upper level disturbance to push through the area Friday
afternoon into evening allowing another cold front to pass through.
For the most part Saturday through Monday looks dry with
temperatures moving closer to normal. Confidence with this remains
low though as multiple model to model and run to run consistencies
are lacking.

The first discrepancy exists Thursday afternoon as the ECMWF deepens
the upper level low over Pennsylvania, while the CMC and GFS are more
progressive. Since the GFS and CMC are more progressive they
actually are stronger with the southern stream of PV keeping
precipitation to the south (ECMWF has precip Thursday across our
northeast). For now the ECMWF appears to be the outlier here, so
have kept the area dry for Friday. For Saturday into Sunday another
upper level trough axis will move across the area with the ECMWF and
GFS now being the progressive models and the CMC wrapping up an
upper level disturbance across Tennessee (544 dam heights). Given
all the above, have kept the forecast dry, but this could easily
change given the complex flow.


An upper level low will push slowly east across the Tennessee
and Ohio Valleys today through Tuesday morning. Precipitation
associated with this has been steadily but slowly spreading
north through the morning hours and this trend should continue
through the rest of the day. The precipitation is moving into a
relatively dry airmass so it will likely take much of the day
for the precipitation to reach all the way to the northern TAF
sites. Cigs will slowly fall through VFR today and eventually
into MVFR as the lower levels begin to saturate later today. The
threat for showers along with some MVFR conditions will then
prevail through the remainder of the TAF period.

OUTLOOK...MVFR ceilings will be possible through Wednesday.




LONG TERM...Haines
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