Area Forecast Discussion
Issued by NWS Wilmington, OH-- Highlight Changed Discussion --
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FXUS61 KILN 290235
Area Forecast Discussion
National Weather Service Wilmington OH
1035 PM EDT Wed Sep 28 2016
A large low pressure system over northern Indiana will drift very
slowly south into Kentucky...before reversing course and drifting
back to the northwest toward Chicago...before very slowly
weakening and losing grip over the Ohio Valley by the end of the
weekend. Moist southerly to southeasterly flow around this low
will keep rain and scattered thunderstorms in the picture all way
into Sunday...with the better chances of rain focused on Thursday
and Friday. Temperatures will remain below normal underneath
frequent clouds and showers...before warmer and drier weather
spreads through the Ohio Valley early next week.
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
-- Changed Discussion --Upper level low will continue to meander near the area through the
overnight hours and for the next several days. Precipitation has
decreased in coverage and is primarily confined to extreme
northern and eastern portions of the forecast area. There will
continue to be a decrease in precipitation during the overnight
hours, however some lingering shower activity will remain.
There is a lot of low level moisture with many areas receiving
widespread rainfall today and not breaking out of the clouds or
not seeing breaks in the clouds until late. This combined with the
nearby area of low pressure and light to calm winds, expect fog to
develop overnight. Fog has already developed across some areas and
expect additional fog and stratus development overnight. At this
point have gone with areas of fog in the forecast. Some areas will
likely see dense fog and conditions will continue to be monitored
for the potential for a dense fog advisory across portions of the
Temperatures are not expected to drop off much more overnight with
the cloud cover therefore low temperatures in the upper 40s to low
50s are generally expected across the region.
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.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY NIGHT/...
Pesky closed low...with 500mb standardized anomalies to 2 or 2.5
sigma below climo...will drop south into southern KY by Thursday
evening...before stalling. As it fills...this system will begin
drifting aimlessly back into northern Indian by Saturday morning
and there is strong agreement in the suite of NWP on this
solution. This will guarantee a continued threat of episodic
showers and storms Thursday...Friday...and Saturday...though with
time the large scale forcing and cold-core of the system will
weaken to the point that precipitation will become less
organized and lighter...especially Saturday.
Still-strong flow around this system will advect deep moisture off
the Atlantic and into/across the Appalachian mountains and into
the Ohio Valley through the end of the week. A particular area of
enhanced rain threat will be across the northern/eastern CWA in
closest proximity to deeper moisture and enhanced isentropic
ascent. Given cold pool aloft...and slowly enhanced moisture in
the boundary layer on both days...instability is sufficient enough
that storms are possible...and will be drifting from SE to NW - a
decidedly uncharacteristic storm motion. Both days will have a
threat for an anchored or slowly moving arc of rain/storms...so
the heavy rain/minor flood threat is not completely out of the
question. But as with all precipitation around closed upper
lows...there is a wide disagreement in locations/timing of the
individual vort lobes rotating around the central
circulation...thus rain chances are not yet ramped up as high as
they otherwise will likely be in coming forecasts. 60s by day and
50s by night in this reduced diurnal temperature range thanks to
plenty of clouds.
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
This period will be characterized by a much warmer drier/period vs
the short term. On Sunday morning...the closed low will be
drifting northeast...weakening...and opening up into a more
progressive shortwave trough over New England by Monday.
Thus...there is still a small threat of showers into Sunday but
right now the timing/placement of this threat is very tough but
seems focused north of I-70 closer to mid level cold pool. Large
scale ridging ahead of the next longwave trough over the west will
allow for dry weather Monday thru Wed as high pressure at the
surface moves across the eastern U.S. Temperatures will be warming
steadily and by the middle of next week should be well into 70s if
not the lower 80s with dewpoints hanging tough in the 50s.
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --Shower activity will decrease in coverage for the overnight hours
and then pick up during the daytime hours on Thursday, especially
during the afternoon to early evening hours. A few thunderstorms
will also be possible around KCMH and KLCK later in the day on
Cigs and Vsbys will lower during the overnight hours and slowly
improve during the day on Thursday. IFR to LIFR conditions will
be possible at times overnight especially later in the overnight
time frame Wednesday night into Thursday morning.
OUTLOOK... MVFR ceilings and visibilities possible with showers
Thursday night through Saturday. IFR/LIFR ceilings and
visibilities possible Friday morning, with IFR ceilings and
visibilities again possible on Saturday morning.
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