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FXUS61 KILN 231429

Area Forecast Discussion
National Weather Service Wilmington OH
1029 AM EDT Mon Oct 23 2017

Copious moisture associated with a cold front and wave of low 
pressure will bring showers today and tonight. Showers will linger
Tuesday into Wednesday when the low is forecast to meander across 
the Great Lakes. High pressure and dry weather will return on 


Surface low pressure is currently located near Crawfordsville,
Indiana. Though the overall surface pressure pattern is somewhat
convoluted, an initial boundary is currently moving through the
southern sections of the ILN CWA, while a more well-defined cold
front will lag behind by several hours -- though it will travel
largely along the same trajectory. The initial boundary has a
thin line of enhanced showers along it, and it has been leading
to some temporary SSW wind shifts, along with a drop in
temperatures. Temperatures will drop more sharply behind the
actual cold front in a few hours. Based on current precipitation
patterns and HRRR/RAP temperature projections, some adjustments
were necessary to temperatures, allowing for much more of a
non-diurnal pattern through the day today than had been
previously indicated.

Still not seeing enough instability in model soundings to
include thunder in the forecast, which will keep hazard
potential to close to zero. This is good, since there is 
relatively strong southerly flow ahead of the low.

Previous discussion >
Surface map shows a cold front draped across Western Indiana. A
strong wave of low pressure triggered by a closed upper low is 
centered over Southwest Indiana, with dew points in the mid 60s
advecting northward on the east side of the low. 

Showers have developed along the front as expected, with
rainfall rates enhanced near the wave of low pressure. As
depicted by latest models and supported by radar, the wave of
low pressure is lifting north through Indiana, while the cold 
front pivots into Ohio, bringing showers into the ILN area by 
mid morning, requiring categorical pops. The showers will then 
spread eastward and last through today, with intense rainfall 
rates at times in concentrated lift and moisture convergence 
under a 70 knot 500 mb flow ahead of the wave of low pressure. 
Flooding chances should be limited by lack of rain over the last
10 days leading to rather dry soils. Temperatures will still be
above normal in the breezy southerly flow ahead of the front, 
with highs reaching the upper 60s.


The cold front will move east this evening, while the wave of 
low pressure lifts to Michigan and then meanders over the
Central Great Lakes through Tuesday. Showers will remain likely
in the cool and moist cyclonic circulation behind the front,
particularly in northern locations closer to the low. A slow
diminishing trend in shower coverage and intensity should be 
evident as the low departs and weakens by Tuesday evening. 
Still expect one to two inches of rainfall for this event.

Temperatures will be much cooler in the northwest flow behind
the system. Highs Tuesday in the 50s will be about about 7
degrees below normal.


Highly amplified mid/upr level flow pattern characterized by deep 
trof over the Great Lakes and eastern U.S. and a mean ridge over the 
west to start the long term forecast period. This trof will keep a 
chance of a shower in the forecast until Wednesday afternoon. The 
best chance of a shower will occur across the northern counties. 
Wednesday will be the coldest day of the week, with highs ranging 
from the upper 40s northwest to the lower 50s southeast. These 
values will be close to 15 degrees below normal. 

Trof axis translates east with northwest flow developing and surface 
ridge building across the area Wednesday night. Frost will be 
possible, depending on cloud cover and how fast a southerly wind 
flow develops. Expect lows in the mid and upper 30s. 

Mid level ridging quickly builds across the region with a low level 
southerly flow increasing ahead of a front approaching from the 
west. Dry weather to continue Thursday with highs from the upper 50s 
northeast to the lower 60s southwest.     

Energy drops southeast carving out a mid level low over the upper MS 
Vly by the end of the week. Surface cold front pushes into the 
region but the airmass is initially dry. Will allow a chance of 
shower to develop in the post frontal environment over the west 
Friday afternoon. Expect a range of temperatures Friday with highs 
from the upper 50s northwest to the mid/upper 60s southeast.

Mid level trof to settle into the Great Lakes next weekend. Model 
differences exist regarding how far south the closed low develops.
Can not rule out a shower but with main moisture axis to our east 
and solution differences regarding location of the low, will limit 
pops to chance/slight chc category. Expect cool temperatures with 
highs Saturday in the lower/middle 50s and only in the upper 40s to 
lower 50s Sunday.


Aviation to be impacted by showers, low ceilings and wind shear
ahead of a vigorous cold front.

Conditions VFR to start will deteriorate by late morning as deep 
moisture streaming ahead of the cold front moves to TAF sites.
Current radar indicates that CVG and LUK should see showers by
12z issuance or shortly thereafter. Other sites will have at
least showers in the vicinity within a few hours. Prevailing 
showers will occur at all sites by 17z, accompanied by MVFR 
ceilings. CMH and LCK will experience a period of wind shear 
early this afternoon. After a brief return to VFR late in the 
afternoon, featuring VCSH and wind gusts to 20 knots, prevailing
showers with MVFR are forecast to move back in for the evening 
into the overnight hours.

OUTLOOK...MVFR ceilings and visibilities possible through 





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