Area Forecast Discussion
Issued by NWS Wilmington, OH-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KILN 252007
Area Forecast Discussion
National Weather Service Wilmington OH
407 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/...
-- Changed Discussion --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.
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.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
All TAF sites currently VFR this afternoon as a surface low over
the Midwest slowly pulls northeast. Latest runs of high res
models continue to show precipitation moving in from the west
around 6z Sunday morning. The showers and isolated thunder
Sunday morning will move into the area in the form of a band and
will likely loose cohesion as it progresses eastwards.
Sunday afternoon forecast soundings begin to destabilize with
ceilings lowering towards MVFR as the upper level low moves over
central Indiana. As forecast soundings destabilize showers and
thunderstorms will develop across the forecast area with higher
coverage across our eastern TAF sites. Thunder will be likely in
any storms that develop Sunday afternoon into evening. The
chance of precipitation will continue into Sunday evening as the
upper level low moves overhead.
OUTLOOK...MVFR ceilings and visibilities will be possible late
Monday into Tuesday morning.