Area Forecast Discussion
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FXUS61 KILN 252340
Area Forecast Discussion
National Weather Service Wilmington OH
740 PM EDT Sat Mar 25 2017
Southerly flow ahead of low pressure will provide warm
temperatures and mainly dry weather this afternoon. Showers and
a few thunderstorms will develop tonight through Sunday as the
area of low pressure approaches from the west. Another upper
level disturbance will then move across the area Monday
afternoon into Tuesday providing a continued chance of showers
and thunderstorms for the area.
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Temperatures have continued to rise this afternoon thanks to
850mb temperatures of 10 degrees C and 1000/ 850mb thicknesses
of ~1380m. An upper level low over the central United States
will slowly head northeast this afternoon with weak PVA and WAA
moving overhead. Latest forecast soundings on the GFS and NAM
show PWATs approaching 1.00" but a persistent CAP in place
through the afternoon. Even with the elevated PWAT environment
in place and weak lift, the lack of instability will keep the
area dry this afternoon.
This evening a weak band of showers and some embedded thunder
will push into the western zones between 9pm and 12am. Lift for
the precipitation will come from a band of weakening PV rotating
around the upper level low. Omega values on the GFS would
indicate the band breaking apart as it approaches the CWA with
the NAM also hinting at this. Forecast soundings at this time
show only very weak instability with even MUCAPE values of only
100 or 200 J/kg. Have kept thunder only slight chance for now
Sunday morning given the weak instability.
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
Later Sunday morning the upper level low will take on a negative
tilt as it pulls northeast towards the Great Lakes. As this
happens low level temperatures will fall and work together with
daytime heating to steepen low level lapse rates. NAM forecast
soundings are showing MUCAPE values around 1000 J/kg while the GFS
is showing values slightly higher, around 1200 J/kg. At the
same time areas of PV will be rotating around the upper level
low providing a source of lift. In general, global and high res
models are indicating the best lift across our eastern zones
Sunday afternoon with a secondary source of PV in association
with the low moving into the western zones. Forecast soundings
on both the NAM and GFS have k index values in the low 30s
Sunday afternoon with LI values briefly turning negative. PWATs
at this time are also around 1.00". Due to the ample moisture,
sufficient lift, and instability have kept likely PoPs or
greater for Sunday afternoon. It should also be noted that at
this time 0 - 3km bulk shear is around ~30kts. Thanks to the
shear, instability, low level lapse rates SPC has the area in a
marginal risk for isolated small hail and gusty winds.
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Showers and thunderstorms will taper off Sunday night as an
upper level disturbance moves to the east. There will be a lull
in the precipitation for much of the day on Monday before an
upper level disturbance moves through Monday night into Tuesday.
Precipitation will taper off Tuesday night. Moisture will be
trapped across the area for Wednesday therefore increased sky
cover and decreased temperatures some for Wednesday.
The next system will begin to bring rain shower chances to the
region on Thursday. Precipitation is expected to become more
widespread Thursday night into Friday as a low pressure system
nears the region. A cold front will move through Friday night.
Precipitation chances will begin to decrease after the passage
of this feature.
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
The leading line of showers and embedded thunderstorms is
currently stretching from central Indiana down into central
Kentucky. This line has been making a very slow eastward push
and as we start to lose some of the diurnal heating, expect to
see some weakening as it finally pushes into our western areas
later this evening. As a result, will just allow for a vcsh
late this evening and into the early morning hours at the
western taf sites. A stronger mid level vort axis will rotate
up across the area from the southwest late tonight into Sunday
morning, eventually allowing for more widespread showers to
develop from southwest to northeast. This should also allow for
cigs and possibly vsbys to trend down into MVFR as we progress
through Sunday morning. Instability remains fairly limited
through the morning hours so think thunder chances will remain
low enough to leave mention of thunder out of the TAFS through
the morning. As we better destabilize through the afternoon
hours, will go ahead and include a vcts to cover the thunder
OUTLOOK...MVFR ceilings and visibilities will be possible late
Monday into Tuesday morning.