Area Forecast Discussion
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FXUS61 KILN 250857
Area Forecast Discussion
National Weather Service Wilmington OH
357 AM EST Sat Feb 25 2017
A much cooler airmass will continue to settle into the region
today as a weak upper level disturbance brings a few rain and
snow showers. High pressure will build into the Ohio Valley
tonight into Sunday, leading to mainly clear skies. Seasonable
temperatures will remain in place across the area for Sunday.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A dry slot is evident on IR satellite imagery pushing up across
eastern Indiana and far western Ohio early this morning.
However, some lower level moisture is spreading quickly back in
from the west across western and central Indiana. This will
likely pinch off the dry slot across western portions of our fa
as we progress through the next few hours. These lower clouds
are associated with the leading edge of some better low level
CAA and ahead of a mid level trough axis that will push east
across the region through early afternoon. The combination of
this and some weak low level instability will lead to isolated
to scattered shower activity later this morning and into the
early afternoon hours. It looks like any pcpn may start off as
rain but it should transition over to snow from west to east as
the low levels continue to cool off. The low level CAA will keep
temperatures nearly steady or possibly slowly falling through
the day. Winds will also become gusty in the 25 to 35 mph range
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
The trough axis will push off to the east tonight with surface
high pressure building into the region later tonight. This will
lead to decreasing clouds southwest to northeast and overnight
lows in the low to mid 20s. Mostly sunny skies are expected on
Sunday with highs in the low to mid 40s.
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Sunday night surface high pressure will be centered near the
coast of NC with southwest flow across the region. At the same
time an upper level disturbance over AZ will eject east and push
towards the forecast area. Both the GFS and ECMWF have come
into fairly good agreement here with this system ejecting east
and spilling vorticity across the area Monday morning. As this
happens high cloud bases will thicken and slowly lower with
precipitation moving in from the west. Initially Monday morning
a rain/snow mix will be supported with the entire sounding below
freezing except right at the surface. Behind the remnant
shortwave Monday afternoon dry mid and upper level air will work
into the area helping to cut off the precip a bit.
Monday night into Tuesday morning there will be a brief break as the
next upper level disturbance over the Mountain West gets its act
together. Later Tuesday morning into afternoon the upper level
disturbance will push northeast into Minnesota pulling a warm front
north across the area. Widespread overrunning will commence with
PWATs approaching 0.85". Widespread weak lift will also accompany
the WAA which is supported by GFS omega fields. Tuesday afternoon a
surface low will track northeast towards WI allowing temperatures to
rise into the 60s. Shear values Tuesday afternoon will also become
impressive as ILN gets warm sectored with SFC- 3 KM shear 40 + kts
at times. GFS soundings currently show a CAP across the area though
which would limit convection across the region.
Tuesday night into Wednesday morning another upper level disturbance
will swing around the base of the upper level trough axis centered
over the Western United States and push towards the forecast area.
As this happens another surface low will form in the plains and push
northeast along a baroclinic zone. At the same the upper level jet
will begin to strengthen and briefly place ILN in a RRQ. Also a weak
split will occur in the jet. The GFS/ ECMWF/ and CMC all show this
happening. The difference between the three is placement of the
baroclinic zone (e.g., front), and track of eventual surface low as
it heads northeast. The NAEFS shows PWAT anomalies of 2 SD. The GFS
also has a PWAT of 1.35" just south of the region. As mentioned
above though these small differences in track between models has a
big difference on rainfall distribution. The ECMWF is furthest north
with the second surface low and has heavier rainfall totals across
our northwestern zones while the GFS is furthest south with the
track and has the heaviest totals across central KY. The CMC is a
compromise between the two and have trended the forecast this
direction. Given the RRQ, splitting upper level jet, abundant
moisture and lift have raised PoPs for Wednesday.
Wednesday evening into Thursday morning a stronger upper level
disturbance will push east over the area finally pushing the surface
cold front through the area. Thursday afternoon into Friday another
upper level disturbance will head southeast out of southwestern
Canada and bring a chance of snow and rain to the area Friday
morning. GFS soundings completely saturate Friday morning with almost
the entire forecast sounding below freezing. As of now mostly snow
Friday morning would be expected given the thermal profile of the
GFS. Eventual track and strength of this disturbance remains in
question though as the ECMWF is weaker with the disturbance so have
kept PoPs at chance for now. Friday night into Saturday surface high
pressure will dip south into the area from Canada and bring below
normal temperatures to the area. Saturday afternoon the surface high
pressure will already be east of the forecast area as the upper
level trough axis heads east.
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
The cold front is currently pushing through central Ohio and has
moved through both KCMH and KLCK. As a result, the TAF sites
will remain dry through the pre dawn hours. Cigs are mainly VFR,
but we are seeing some spotty MVFR cigs redeveloping across
parts of eastern Indiana and western Ohio so these may affect
primarily KDAY over the next few hours. An upper level trough
axis will swing across the region through early afternoon. This
will be accompanied by some lower level moisture and a few light
rain and snow showers. This will also allow for more widespread
MVFR cigs to overspread the area later this morning and then
linger into early to mid afternoon. Cigs should then lift into
VFR later this afternoon and into this evening as the low level
begin to dry out.
OUTLOOK...MVFR ceilings and visibilities possible Monday,
Tuesday night, and Wednesday.