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Area Forecast Discussion (AFD)

Issued by Wilmington, OH (ILN)

FXUS61 KILN 220607

National Weather Service Wilmington OH
207 AM EDT Sun Sep 22 2019

Southerly flow over the Ohio Valley will persist through the
weekend, offering increased moisture and continued warm
temperatures. A few showers are expected through this afternoon,
then the chance for showers and thunderstorms will increase 
Sunday night ahead of a cold front that will cross the region 
early Monday. The threat for storms will decrease Monday, as 
surface high pressure begins to build into the region.


Skies have gone mostly clear across the area this evening. In
continued southwesterly flow, we may see some increase in mid 
and high level clouds at times through the night. Lows tonight
will be in the low to mid 60s.


Mid level ridge starts to move away on Sunday as a trough swings
east in the Upper Midwest/Upper Mississippi Valley. Sunday will
be another very warm day with temperatures in the mid 80s.
Gradient tightens up a bit as well, with midday and afternoon
wind gusts possibly 25 to 30 mph. Sunday should be dry, then as
a cold front approaches from the northwest Sunday night, clouds
will increase during the evening and showers and perhaps a few 
thunderstorms are expected to move into western portion of the 
CWA, generally after midnight. Convection will spread through 
much of the CWA through sunrise Monday.


Model consensus remains in good agreement showing a fairly quick 
progression of the much-anticipated cold front southeast through the 
ILN FA Monday morning, yielding progressively drier conditions from 
late morning onward from northwest to southeast. Even with this 
said, do expect a gradual weakening trend of one or more initially 
cohesive bands of showers and isolated thunder as the activity 
pushes further to the south/east -- owing to a gradual loss of 
focused forcing. This will result in mainly dry and clearing 
conditions by mid/late afternoon -- even in the east. And with the 
arrival of the aforementioned drier air will come seasonably cool 
overnight lows Monday night and Tuesday night with highs generally 
in the mid to upper 70s both days.

The cold front will allow for cooler and drier air to infiltrate the 
Ohio Valley from Monday afternoon through at least midweek -- with 
near normal to slightly above normal temperatures during the first 
part of next week. This will occur coincident with surface high 
pressure briefly building into the region followed by a secondary 
weak frontal passage Wednesday night into early Thursday morning. 
While certainly this FROPA could deliver another round of scattered 
showers to the area -- as of right now, it does appear that the 
forcing and moisture availability will be rather meager. This would 
tend to suggest for the front to progress through the area with just 
some chance PoPs at best before drier conditions once again return 
by Thursday afternoon. 

Beyond Thursday, longer range guidance remains in remarkable 
agreement showing potent quasi-zonal mid/upper level flow 
transitioning to anomalously expansive and strong ridging initially 
across the southeastern U.S. late in the workweek before 
overspreading pretty much all of the Tennessee/Ohio Valleys by next 
weekend. While there are some natural discrepancies that exist in 
longer range solutions -- specifically as they relate to exact 
positioning and timing of ridge development -- there remains above 
normal confidence in another period of very warm temperatures 
setting up by the end of the long term period. The persistence of 
several deterministic and ensemble solutions showing this highly-
amplified pattern lends itself to high confidence in above to even 
much-above temperatures to close out the month next weekend into the 
following week. In fact, EPS mean H5 heights approaching 2 standard 
deviations are being advertised across the Tennessee Valley about 7 
days from now, with H8 temps 8C+ above normal. This type of pattern 
-- should it evolve in such a manner -- would suggest the potential
for record or near record temperatures to close out the month.
Of course, the specifics of the pattern which will ultimately 
dictate the sensible weather locally will still be coming into 
better focus in the coming days. So certainly this pattern and 
the eventual evolution will be watched closely in the coming 


Mid level ridge axis to build east thru the region today with 
a southerly low level flow. This low level gradient will 
mitigate the development of widespread fog this morning. The
exception is the protected valley location at KLUK where a 
period of IFR vsby restriction is expected. Any fog that
develops will improve quickly with the gradient tightening up. 
Expect southwest wind gusts up to 25 kts this aftn. 

Dry and VFR conditions expected during the day with only few to
scattered cumulus and some increase in high level clouds. 

Mid level trof moving into the Upper MS Valley by evening and
then east across the Great Lakes tonight/Monday. Airmass is 
capped with marginal instby arriving in a narrow ribbon in the 
frontal zone. Best threat for convection will be between 08Z 
and 12Z. Therefore, have held off any mention of pcpn or this 
TAF issuance. As tail of 50KT H8 pivots thru the area a period
of Low level wind shear will affect the TAF sites. Have this
mention of LLWS at the 30 hour KCVG TAF after 06Z.

OUTLOOK...Thunderstorms possible on tonight into Monday.