Area Forecast Discussion
Issued by NWS Wilmington, OH

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FXUS61 KILN 172340

Area Forecast Discussion
National Weather Service Wilmington OH
740 PM EDT Wed May 17 2017

Gusty south winds have resulted in another very warm day this
afternoon. The chance of showers and thunderstorms will return
to the area Thursday morning as moisture increases. A cold front
will then sag southwards through the area Friday morning
allowing the chance of showers and thunderstorms to continue. The
front will then lift back north on Saturday only to be followed
by a stronger cold front moving in from the west on Sunday.


Temperatures have quickly climbed into the mid to upper 80s this
afternoon thanks to gusty winds and warm 850 mb temperatures.
Winds have also been breezy this afternoon thanks to the tight
low level pressure gradient. This evening the mid-level ridging
will start to push east of the region with an upper level low
ejecting towards Wisconsin. The upper level low will help keep
the pressure gradient tight across the area through tonight.


Thursday morning the mid-level ridge axis will be pushed east
with heights falling across the region. Looking at the Ensemble
Situational Awareness table shows high PWATs and increased
moisture transport around the subtropical ridge and across the
central zones of the CWA. As this happens weak showers and
thunderstorms will move across just north of Interstate 71 in
the morning. Looking at the latest RAP there is a weak
shortwave moving across at this time and with more than
sufficient instability have kept chance PoPs in the forecast.
Later in the morning there should be brief break in
precipitation until the afternoon when high res models show pop
up showers and thunderstorms forming. PWATs on both the NAM and
GFS rise to around 1.50" Thursday with CAPE values increasing
in the afternoon. Both the NAM and GFS have an instability axis
across the central zones with the GFS slightly further north
with the higher instability values. NAM instability values are
much more robust than the GFS but think this is overdone. For
now have kept chance PoPs Thursday afternoon across the area
with higher values near Interstate 71.

Thursday evening a surface cold front will push south into the
area as the upper level low that was over Wisconsin merges into
a much bigger upper level low located over Quebec. The NAM,
GFS, and ECMWF all have the front across the northern zones
around 6z Friday and stalling north of Interstate 70 Friday
morning. Accompanying the cold front will be a weakening line of
thunderstorms. This isn`t surprising as instability will also
be waning during the evening.


Active weather pattern through the long term forecast period.
East-west oriented front will remain stalled near the Ohio River
Friday. Will keep chance pops with best chance across the southern
counties. Highs on Friday will be a little cooler, ranging from the
the lower 70s north to the lower 80s south.

Mid level shortwave and associated surface wave of low pressure to
eject northeast into the Great Lakes Saturday. Associated warm front
to lift north across the region Saturday/Saturday night. This will
keep a continued threat of showers and thunderstorms with the best
chance west. Temperatures will warm with highs from 80 to 85.

As surface wave tracks across the Great Lakes associated cold front
to push east across the region Sunday/Sunday night. This will bring
an enhanced chance for thunderstorms. Have continued likely pops
for this period. With clouds and precipitation, temperatures will be
a little cooler, with Sundays highs ranging from the upper 70s
northwest to the lower 80s southeast.

A lingering chance of precipitation Monday across the east counties.
Cooler temperatures expected Monday with highs a little below
normal, ranging from near 70 northwest to the lower 70s southeast.

Surface high pressure to provide temporary dry period later Monday
and Monday night. Model solutions diverge on timing and amplitude
of developing mid level trof for Tuesday and Wednesday. This results
in placement and timing differences, therefore uncertainty
increases. Have chance pops west developing Tuesday afternoon and
across the region Wednesday. Highs Tuesday will be close to normal
with and generally 70 to 75, and then a little cooler Wednesday
from the upper 60s to lower 70s.


Conditions are likely to remain VFR as a weak cold front
approaches from the northwest. Under a veil of cirrus, surface
winds will decrease to around 10 knots this evening. However,
strong winds just off the surface warrant Wind Shear for the
overnight period.

A few showers may develop in the vicinity of TAF sites Thursday
morning in increasing moisture and convergence well ahead of
the front. Thunderstorms may occur in the vicinity of DAY ILN
LCK and CMH Thursday afternoon as the front moves toward an
unstable regime. Kept ceilings VFR since models suggest isolated

Winds from the southwest will gust over 20 knots Thursday
afternoon in the tight pressure gradient ahead of the front.

OUTLOOK...Thunderstorms possible Friday through Sunday.




NEAR TERM...Haines
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