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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KILN 090536
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
1236 AM EST Tue Mar 9 2021

.SYNOPSIS...
Exiting high pressure will give way to southerly flow over the
Ohio Valley through at least Thursday. Dry air will gradually be
worked in with some moisture through this time, then rain
Thursday night and Friday will accompany a cold front as it
crosses south of the Ohio River.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Some mid clouds may pass across the northern part of the
forecast area overnight. Otherwise just more (mostly thin)
cirrus. The center of the high is far enough away that some
southerly winds will persist through the night, except in far
southeast counties. Winds have gone light there which is also
reflected in their temperatures being colder. Given trends,
have dropped lows a bit in that area. Elsewhere, lows look
reasonable.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Weak ridge aloft moves east fairly quickly during the day,
although the tightening of any surface gradient will likely not
be enough to create the potential for winds greater than 10 mph,
and certainly inhibit any gusts. Thicker cirrus will also
inhibit boundary layer warming, but the southwest flow at the
surface will naturally bring in warmer air with readings 2-4
degrees warmer than what is seen over the region today.

Highs will be more uniform around 64-65. Overnight lows will be
even milder as the southwest winds maintain themselves at least
somewhat - looking for 40-45 with the warmest readings in the
northwest as cloud cover increases from w-e overnight, also
aiding the inhibition of temperature drops.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Fairly shallow upper level ridge will slowly sink south as a
broad but slowly deepening trough over the western CONUS
approaches the region and the ridge sinks toward the SE CONUS.
Overall southwest flow and tightening pressure gradient over the
area as the trough amplifies will allow for increasing high
clouds on Wednesday, as well as winds gusting to near 25-30mph
along with much above normal temperatures in the mid to upper
60s.

With lingering dry lower levels of the atmosphere in place, as
well as a slowing of the overall progression of the trough,
onset of precipitation has slowed a bit as deterministic
GFS/ECMWF models struggle to resolve the slow down and both GEFS
and ECME members are slowing the amplification of the trough as
it eventually transitions to a cut off low over the SW CONUS.

For Thursday, a boundary from the upper Mississippi Valley into
the Great Lakes will slowly sink south above the retreating
upper ridge, bringing a chance for showers on Thursday. Still
some uncertainty as to how far south the boundary will advance,
so have only brought in slight chances in the southeast with
drier air to overcome and still closer to the retreating ridge.
High temperatures on Thursday someone uncertain but best chance
for upper 60s in the far south and southeast where precipitation
less likely.

The boundary will sink through the area Thursday night into
Friday, bringing a likelihood of more widespread rain. Still
uncertain as to just how far south the boundary will sink
through the southern forecast area on Friday, as it depends on
the energy ejecting eastward from the cutoff low over the SW
CONUS, and the progression of the more shallow and quickly
moving upper low and shortwave advancing through the Great
Lakes. Still too much uncertainty to hone in on precipitation
chances and timing, so kept with chance for precipitation
focused especially in southern Ohio/SE Indiana/Northern Kentucky
through the weekend. More seasonable temperatures take over for
the weekend and into early next week, with highs in the mid 40s
to mid 50s depending on boundary positioning, with lows in the
lower to mid 30s.

There is some uncertainty with how far south of our area the
front will make it on Friday and then where it will lay out to
our south heading into the weekend. As the the western upper
level low and mid level energy eject eastward across the
southern Plains through the weekend, the boundary may begin to
lift back north toward our area. Given the uncertainty, will
hang on to chance pops through the rest of the long term period,
keeping the highest pops across our south. Will range highs on
Friday from the upper 50s in the northwest to the low/mid 60s in
our south. Cooler temperatures will then settle into the region
through the weekend with highs by Sunday back into the the mid
40s to lower 50s.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
We can be certain that VFR will persist under high pressure and
a very dry airmass. Winds staying from the southwest may gust
close to 20 knots at DAY, with lower velocities at other sites.
Sky cover will continue to consist of altocumulus and cirrus
clouds arriving on a westerly flow aloft.

OUTLOOK...Wind gusts up to 30 kt possible on Wednesday and up to
35 kt on Thursday. MVFR ceilings and visibilities possible from
Thursday afternoon into Friday.

&&

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

&&

$$
SYNOPSIS...Franks
NEAR TERM...
SHORT TERM...Franks
LONG TERM...JDR
AVIATION...Coniglio