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Area Forecast Discussion (AFD)

Issued by Wilmington, OH (ILN)

FXUS61 KILN 230550

National Weather Service Wilmington OH
150 AM EDT Mon Sep 23 2019

A cold front will push east through the area today, offering 
showers and embedded thunderstorms. High pressure will build in 
later Monday through the Tuesday providing cooler and dry 
weather. Heat will build back into the region at the end of the 


Showers have been lifting quickly northeast across Indiana this
evening with a gradual eastward push in the axis of pcpn. This 
is associated with a cold front that will approach our area 
from the west overnight. This shower activity should slowly 
overspread our area as we head through the overnight hours, 
arriving in our northwest through late evening and possibly 
reaching our far southeast toward daybreak. Instability is very 
marginal and mainly limited to our northwest counties through 
the early morning hours. As a result, will continue with mainly 
showers across all but our northwest, where will hang on to a 
slight chance of thunder.


Prefrontal showers will diminish as they continue east across
the forecast area early in the day. Another band of showers and
possibly a storm may accompany the actual cold front which will
move through the area between 12Z and 18z. Clouds will decrease
in the afternoon and early evening but there will be some gusty
post frontal winds for a period of time. High pressure will
build in late in the period. 

There will be a limited rise in temperatures where the front
moves through early in the day with some heating still possible
ahead of the front in southeast counties. So highs will range
from the mid 70s to around 80. Lows will be able to drop off to
closer to normal Monday night.


The FROPA through the region on Monday will allow for drier air to 
infiltrate the Ohio Valley for the start of the long term period -- 
with near normal to slightly above normal temperatures from Tuesday 
through Thursday. 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 secondary/midweek FROPA could deliver another 
round of isolated to scattered showers to the area -- as of right 
now, it does appear that the forcing and moisture availability will 
be rather meager. Only right along/ahead of the front is the 
moisture return likely to be sufficient enough to support a few 
showers -- but this corridor/stripe of better moisture will be 
rather narrow and transient. 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. The front will be accompanied by a more noticeable return 
of dry air opposed to inherently cooler air. In fact, dewpoints will 
fall again into the lower/mid 50s by late Thursday with clearing 
conditions through the day.

By the end of the workweek into the upcoming weekend, longer range 
guidance remains in very good agreement showing fairly strong quasi-
zonal mid/upper level flow transitioning to anomalously expansive 
ridging initially across the southeastern U.S./Carolinas late in the 
workweek before overspreading pretty much all of the Tennessee/Ohio 
Valleys by next weekend. This will occur coincident with digging S/W 
energy into the Pac NW and an ejecting system from the desert 
southwestern U.S. -- both of which will act to amplify the overall 
flow pattern across the rest of the U.S. The increasing meridional 
pattern /aided in part by the rapid deepening of the upper low along 
the west coast/ will induce tremendous height rises along/east of 
the Mississippi River Valley by this upcoming weekend with 
corresponding troughing across much of the west. While there are 
some natural discrepancies that exist in longer range solutions -- 
specifically as they relate to exact positioning of the center of 
the ridge -- there remains above normal confidence in another period 
of very warm temperatures setting up by the end of the long term 
period and even into the first part of the next week. The 
persistence of several/many deterministic and ensemble solutions 
showing this highly-amplified pattern lends itself to high 
confidence in above to even much-above normal temperatures to close 
out the month next weekend into the following week. In fact, EPS 
mean H5 heights approaching 2 standard deviations continue to be 
advertised across the Tennessee Valley about 7 days from now, with 
H8 temps 8C to even 10 C+ above normal. Many solutions show some of 
the most robust/anomalous heights/temps setting up squarely 
over the OH/TN Valleys. And it should be mentioned that 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. However, 
confidence is increasing in the potential for several days with 
daily temperatures 15+ degrees above normal for the final part 
of September -- with even some more 90- degree days not out of 
the realm of possibilities.


Mid level trof will pivot through the Great Lakes with an 
associated sfc cold front pushing into Northwest Ohio by 12Z
and across the area by early afternoon. H8 50 KT southwesterly 
jet tail with pivot across the area between 06Z and 12Z 
offering a period of LLWS across the northern TAF sites. 

Showers and a few isolated thunderstorms ahead of this front 
will overspread the region from the west through the pre dawn 
hours. Have a period of showers and then bring in some thunder
with a thin ribbon of instby invof the front. Some wind gusts 
of 25 to 30 kts will be possible early with this activity.  

Ceilings will drop into a lower VFR deck as the pcpn moves in 
and then down into MVFR category toward sunrise with the 
approach of the front. Drier air will filter in through the 
afternoon, allowing for cigs to scatter out from the west.
Surface high pressure will build into the Ohio Valley tonight 
offering clear skies.

OUTLOOK...No significant weather expected.