Area Forecast Discussion
Issued by NWS Wilmington, OH

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437
FXUS61 KILN 051748
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
1248 PM EST Mon Dec 5 2016

.SYNOPSIS...
High pressure will build into the region today. The high will
quickly move off to the northeast tonight and Tuesday as low
pressure moves into the Ohio Valley. A cold front will follow on
the heels of the low Tuesday night, bringing drier and cooler
weather behind it for mid week. Much colder weather is expected
by the end of the week as another cold front pushes across the
region.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Surface high pressure will settle across the middle Ohio Valley
today. Model soundings continue to indicate that low level
moisture in the form of clouds will remain trapped beneath a
subsidence inversion through at least midday. Thereafter, they
suggest that enough dry air aloft will mix with the moisture,
along with some diurnal heating, to allow the clouds to erode.
Current cloud cover is starting to show signs of thinning. If
this process continues, the erosion should work its way north and
east toward sunset. Even so, considerable high level clouds will
already be over the region well ahead of the next weather system.

Have taken the cooler side of guidance for highs in anticipation
of a slow erosion process. Highs will range from the upper 30s
north to the mid 40s far south.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
Operational models remain in great agreement in terms of synoptic
scale systems to affect our region during the short term period.
Have taken a blend of these, along with high resolution models, to
better time the onset and exit of precipitation tonight into
Tuesday.

High pressure will move off to the northeast tonight. Meanwhile,
upper level energy will pivot from the lower Mississippi River
Valley to the Tennessee and Ohio Valleys tonight into Tuesday.
Lows tonight will not drop off too much due to thickening clouds.
Warm, moist ascent in the form of a low level jet, will spread
rain northward into the region after midnight. Temperatures across
the far north will be near freezing toward Tuesday morning. For
now, it looks like precipitation should stay in the form of rain
as it arrives when readings creep above freezing. On Tuesday, the
upper level energy will be associated with a surface low that will
pass northeast through the Ohio Valley. Widespread rain is
expected, with perhaps more showery precipitation in our southeast
near the surface low. This system will be a quick mover, and
associated low over the Ohio Valley will weaken as a coastal low
takes over off the mid Atlantic region by Tuesday evening. Thus,
most precipitation should be out of our region by then. A cold
front will follow on the heels of this system, allowing drier and
cooler air to filter into the region behind it by Wednesday
morning. A consensus blend of raw 2 meter temperatures was
employed tonight into Tuesday night to better capture the non
diurnal fluctuations.

Wednesday will be a quiet, cooler day as high pressure ridging
settles into the Ohio Valley. Models continue to advertise a large
scale upper level trough to dig southeast into the Great Lakes and
Ohio Valley through the end of the week. A cold front is expected
to precede this trough, passing east/southeast through our region
Wednesday night into Thursday. The 00Z ECMWF has backed off on
trying to develop a surface wave along the front. As such, it is
much drier with this system which is similar to the 00Z GFS. Have
reduced the chance of light snow to low chance for late Wednesday
night into Thursday morning due to this trend. Highs on Thursday
will be the beginning of a downward trend in temperatures, ranging
from the upper 20s northwest to the mid 30s southeast.

&&

.LONG TERM /FRIDAY THROUGH SUNDAY/...
This period will be characterized moreso by temperature impacts
rather than precipitation impacts - though the latter will still
need to be watched for next weekend.

Confidence assessment - there`s really pretty decent agreement in
larger scale evolution of the flow into next weekend between higher
resolution deterministic runs and parent ensemble means. There`s
much higher confidence on temperature evolution Fri-Sun vs.
precipitation, with the season`s first /well advertised/ cold
spell centering on Friday with temp departures some 10-20 degrees
below normal. It appears that cold flow across the Great Lakes
Friday will be more zonal in orientation which should keep lake
effect snow showers downwind of the Great Lakes and north of our
region. Some stratocumulus clouds, however, may be capable of a
few flurries given its intersection within the dendritic growth
zone.

For the upcoming weekend, progressive shortwave energy is
advertised to move across the Great Lakes. Very low confidence
with the forecast next Sat/Sunday - as it is noted that ensemble
plumes /GEFS and ECMWF/ get extremely noisy in Days 7-10
suggesting the pattern is of very low confidence with how the
energy next weekend evolves. Both data show the deterministic runs
trending away from their respective ensemble means by Day
8, suggesting caution in next weekend`s forecast.

Per confidence assessment above - not a great deal of confidence how
shortwave energy and associated rain/snow chances look for Sunday
and this lingers beyond Day 7 depending how energy ejects within the
upper trough.  For right now have middle-range snow chances
developing Sunday with transition from south to north given warm
advection.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
With surface high pressure centered along the Ohio River, MVFR
ceilings trapped under a subsidence inversion are eroding from
south to north. All sites may attain VFR within a couple of hours
of issuance, but observations and satellite will be monitored
closely in this low confidence scenario.

Tranquil conditions will persist this evening as the high travels
to Pennsylvania. Weather will change quickly later tonight as low
pressure moves to Kentucky from the southwest. -RA will overspread
TAF sites from south to north early Tuesday. IFR ceilings are
expected to form, once the boundary layer saturates. Winds will
generally be out of the east, with speeds rising to near 10 knots
with -RA.

Only slight improvement is forecast at CVG after 18z, with
ceilings increasing to MVFR, while lingering RA ends and wind
direction shifts to west.

OUTLOOK...MVFR ceilings will persist into Wednesday morning. MVFR
ceilings are possible again on Friday.

&&

.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.

&&

$$
SYNOPSIS...Hickman
NEAR TERM...Coniglio/Hickman
SHORT TERM...Hickman
LONG TERM...Binau/Hickman
AVIATION...Coniglio



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