Area Forecast Discussion
Issued by NWS Wilmington, OH-- Highlight Changed Discussion --
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FXUS61 KILN 200604
Area Forecast Discussion
National Weather Service Wilmington OH
204 AM EDT Mon Mar 20 2017
Surface high pressure will move east of our area tonight. A
surface low will track from the Middle Mississippi Valley,
across the Ohio Valley Monday night, bringing showers and a few
embedded thunderstorms. Precipitation may linger into Tuesday
as a disturbance moves across the region.
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
-- Changed Discussion --Lingering clouds over the northeast will exit the area as
surface high pressure shifts east of the area and flat mid level
ridging builds in. This ridge will provide a mainly clear
temporary period for most of the remainder of the night.
Focus shifts to convection that develops over the mid MS Vly
due to low level jet and elevated instability. Expect these
storms to develop over nrn IL and track/develop to the southeast
overnight pushing into ILN/s western counties toward 12Z. These
initial storms will be in a weakening stage and therefore expect
mainly showers with some embedded thunder.
Temperatures to drop to lows from 30 to 35 will some minor
increase late as clouds increase and winds become southeast.
Surface high pressure overhead this afternoon will slowly push
east tonight with clouds also slowly eroding this evening. High
temperatures will also average in the mid 40s across the region
as clouds have helped to keep temperatures down a bit. Tonight
low temperatures will be in the mid 30s with weak southerly flow
returning Monday morning. Cirrus will also start to move into
the area Monday morning as the next upper level disturbance
approaches from the west.
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.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/...
Monday morning surface high pressure will be east of the region
with pressure falls occurring over the midwestern United
States. Also at this time weak pockets of PVA in the mid-levels
will be traversing the region. Adding to the lift will be weak
widespread WAA ahead of a low level trough axis. The GFS is
fairly weak with the PVA but still has enough of a disturbance
for weak lift (via Omega) to occur over the area. The NAM is
slightly stronger with the disturbance and has correspondingly
higher Omega values. Not surprisingly the ARW, NMM, NCEP WRF,
WRF Dart, and NSSL WRF all show a decaying system of weak storms
Monday morning in some form or fashion. Forecast soundings at
this time don`t look all that impressive on the GFS (not fully
saturated) but there is a stout inversion in place at 900 mb.
The NAM forecast soundings look similar to the GFS but show
better saturation. Both soundings show the inversion at 900 mb
which support the development of elevated thunderstorms. 850 to
500 mb lapse rates on the NAM also approach 7 degrees C/ km.
Monday afternoon into evening another weak upper level
disturbance will approach from the west with a disorganized
surface low. The NAM tries to pull the surface low further east
than the GFS which allows for slightly higher MU CAPE values. A
surface cold front will also be pushing through at this time.
Again high res models show a line of showers and embedded
thunderstorms forming along the front. Given the lapse rates
some small hail will be possible in any stronger storms that
form. Monday night the cold front will push south of the
forecast area with high pressure building in from the north.
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Frontal boundary will be south of the Ohio River on Tuesday. With
models trending toward a drier solution showing the front farther
south, kept a chance of showers mainly in southern locations. As the
upper flow turns northwest, surface high pressure is forecast to
provide dry weather on Wednesday.
Unsettled conditions are expected to return Thursday and Friday when
a warm front develops near the Southern Great Lakes, resulting in a
chance of showers mainly in northern counties. A cold front swinging
through on Saturday will bring the likelihood for showers and a few
thunderstorms. A few showers may linger Sunday in residual moisture
and forcing behind the slow moving front.
Temperatures will exhibit variations typical of early spring. Highs
in the 50s Tuesday will be followed by readings around 40 Wednesday
under cold advection on a northerly flow. Highs will rise to the 60s
by Friday with the area in the warm sector. Highs are forecast to
settle back into the 50s Sunday due to weaker cold advection.
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --Surface high pressure ridge will continue to move off to the
east for the remainder of the overnight hours. Our focus then
shifts toward the northern Illinois/northern Indiana region
where models continue to advertise a developing low level jet
focused into this region. Majority of high resolution/convective
allowing models develop showers and thunderstorms in this
region, and then dive the cluster southward into our western
forecast area by 12Z. Thus, have introduced predominate showers
at the western terminals this morning. Given the very elevated
nature of the convection, conditions should remain VFR for the
most part. However, some pockets of MVFR conditions can not be
ruled out, especially near KDAY. VCTS has been employed for now,
and will monitor trends to see if any airport becomes threatened
by predominate or brief thunder.
By late this morning, convection will continue south and
eventually dissipate as it moves into retreating dry air. For
the remainder of the afternoon, focus once again turns toward
our northwest. An area of low pressure and a cold front will be
moving east/southeast to our region. Again, most models concur
that showers and embedded thunderstorms will get going across
northern Indiana and northwest Ohio. This precipitation will be
fed by another developing low level jet and low level convergent
flow. For now, the best chance for rain showers/embedded
thunder is poised for the northern terminals. KCVG/KLUK will be
on the edge of the likelihood of precipitation, so only a VCSH
is being used as of now. MVFR conditions will develop in the
precipitation. As the front slips by to the south, cooler air
and an increasing subsidence inversion will lower ceilings into
the IFR category. Most precipitation should end after 06Z across
our south as the front continues to move away.
OUTLOOK...MVFR/IFR ceilings expected Tuesday morning. MVFR
ceilings and visibility`s possible Friday.
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