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fxus61 Kiln 232347 
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Area forecast discussion
National Weather Service Wilmington Ohio
647 PM EST Thu Feb 23 2017

Synopsis...
a warm front will lift north into the Great Lakes tonight as low
pressure tracks toward the middle Mississippi River valley.
Low pressure and a strong cold front will bring showers and
thunderstorms late Friday, with severe weather possible. Colder
air and brisk winds will follow the front on Saturday.

&&

Near term /until 6 am Friday morning/...
showers and embedded thunderstorms will pass through
northeastern County Warning Area as the warm front lifts northward this evening.
Western edge of the showers looks to be along Route 68 or at the
least the I-75 corridor, with any instability and thunderstorms
occurring northeast of Madison County. Will have another update
out soon to give more detail in these rain chances this evening.
Any showers should lift north of the County Warning Area before midnight.

Overnight lows will be very warm for late February, only
dropping into the mid and upper 50s.

&&

Short term /6 am Friday morning through Friday night/...
the main focus in the short term continues to be the threat for
severe weather late Friday afternoon into Friday night.

The necessary ingredients for different modes of convection will
come together late Friday afternoon into Friday night as low
pressure tracks northeast toward Lake Huron and its attendant
cold front sweeps east across our region.

First off, unseasonably warm air will be place across the warm
sector for the first part of Friday. It looks like we will see
some sunshine, especially east. On breezy southerly flow, high
temperatures are forecast to in the lower to mid 70s. These will
either threaten or break records. Please see the climate section
below for records at the big three climate sites. Winds will
gust from 25 mph over the southeast to near 35 mph across northwest.

The ingredients are coming together for severe storms across our
area late Friday afternoon into Friday night. As the low tracks
to our northwest and deepens, bulk shear, either 0-3 km or 0-6
km, will be sufficiently strong for organized updrafts/convection.
The key will be how much instability and increasing large scale
ascent will be realized late in the day to break through a weak
capping inversion. Cams suggest that the first threat for
severe weather will be within a prefrontal trough region where
convergent flow, shear, and MLCAPES near 1000 j/kg will develop
thunderstorms across the eastern half of Indiana between 4 PM
and 7 PM EST. Cams also suggest that these storms will likely
contain rotating updrafts and may be supercellular in nature.
Given steep mid level lapse rates between 7.5 c/km and 8.5 c/km,
along with the instability and vertical pressure gradient from
rotation, large hail and damaging winds will be possible from
these storms. Tornado potential will depend on how shallow cin
remains into the early evening from Max heating of the day and
whether parcels remain rooted in the boundary layer. As the
evening wears on, it appears that the convection, either
supercellular or multi cluster/broken lines will try to congeal
more into a qlcs as the cold front/convection along this
boundary tries to catch up to the prefrontal trough convection.
If this occurs, the severe threat will then transition more to
damaging winds for our far eastern zones. However, vigilance
still must be kept on the qlcs for any potential spin up
tornadoes along the shear axis. It appears the convection will
be exiting our eastern zones between 1 am EST and 4 am EST. Cold air advection
and a dry slot will ensue in the wake of the cold front with
lows bottoming out toward sunrise Saturday, which should range
from the mid 30s west to the upper 40s. East.

&&

Long term /Saturday through Thursday/...
region will begin Saturday Post frontal. The convection should have
moved into ern Ohio, leaving the fa dry slotted. Windy conditions
are likely in the cold air advection pattern. Forecast soundings across west
central Ohio indicate wind gusts up to 40 mph will be possible into
Saturday afternoon. As 500 mb trof axis swings through the Ohio Valley
Saturday, a few rain/snow showers will be possible. The best chance
will be north and west of I-71. Highs for the day should be at 12z
with temperatures falling.

Surface high pressure builds in Sunday providing dry weather and
more seasonable temperatures.

Model solutions then diverge on the timing and placement of systems
in quick zonal flow. GFS is spreading pcpn quickly NW into the
region, while the European model (ecmwf) is holds pcpn off until late Monday night.
Ran a blend of the two solutions and brought in only chance pops
because of the uncertainty. If the pcpn makes it in it should be a
rain/snow mix.

Ran chance pops Monday night into Tuesday because of the varying
solutions. Best chance of pcpn appears to be Wednesday when a front
is forecast to push through.

Northwest flow develops for the end of the week, which should bring
more seasonable temperatures.

&&

Aviation /00z Friday through Tuesday/...
northward lifting warm front will see shower activity in central
Ohio along with some embedded thunderstorms clipping kcmh end
relatively quickly this evening. Afterwards, the County Warning Area and taf
sites are firmly in the warm sector and cloud cover will
actually be waning with some scattered stratocu btwn 4 and 8kft
overnight. Winds will pick up before daybreak and start seeing
some gusts from the south as the cold front approaches and
tightens up the gradient.

On Friday, low pressure will move from the mid Mississippi
Valley to near Southern Lake Michigan toward 00z Saturday. An
attendant cold front will be located north/south from the low.
Our region should remain in the warm sector for most of the day.
Then as upper level energy and low level forcing increase,
showers and thunderstorms will form near or just to the west of
the region, moving east through the region Friday night. It will
be breezy ahead of the front with wind gusts in the 25 to 30
knot range possible, especially after 18z.

Outlook...thunderstorms likely Friday night. MVFR ceilings and
visibilities possible Saturday and Monday.

&&

Climate...
record high temperatures
date cvg cmh day
Fri 2/24 72(1930) 72(1961) 67(1930/1961)

February record highs

Cvg 76 set 2/10/1932
cmh 75 set 2/26/2000
day 73 set 2/11/1999 and 2/25/2000

&&

Iln watches/warnings/advisories...
Ohio...none.
Kentucky...none.
In...none.

&&

$$
Synopsis...Hickman
near term...franks

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