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Area Forecast Discussion (AFD)

Issued by Wilmington, OH (ILN)

                            
000
FXUS61 KILN 180256
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
1056 PM EDT Tue Sep 17 2019

.SYNOPSIS...
High pressure will keep warm and dry conditions with 
comfortable humidity across the area. The next appreciable 
chance for measurable rainfall will come later Sunday and into 
Monday as cold front crosses the Ohio Valley.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Continued subsidence with Great Lakes high pressure settling
into the region, and the lingering inverted trough and washed
out frontal boundary over WV becoming more diffuse/weaker. With
nearly clear skies, but very dry low level conditions per the
00z KILN sounding, fog issues expected only in the river
valleys/usual locations. Generally lows in the upper 50s but
lower 60s in the southwest further away from the center of the
high. 

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
A little more of the same is expected with high pressure,
generally clear skies, and more or less comfortable relative
humidity. Highs will rise to the mid 80s and overnight lows
dropping to similar readings around 60 degrees. East winds will
continue and remain relatively light - 8-10 mph during the day
and 5 mph or less overnight.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
The main weather story for the long term period is the 
anomalous high amplitude ridge centered over the Tennessee and 
Ohio Valleys late this week into the weekend. At the start of 
the period, a deep mid-level trof is forecast to be over the 
northwest US with southwesterly flow riding over the ridge into 
the northern Plains and upper Great Lakes. A surface high 
remains centered in the New England states, bringing warm, dry 
southeasterly flow into the CWA, where mostly sunny skies and 
low humidities will dominate.

Models are in good agreement heading through the end of the 
work week into the start of the weekend, showing the western 
trof ejecting northeast into the northern Plains, flattening the
ridge. This leads to a surface low and accompanying cold front 
developing over the upper Mississippi Valley. Meanwhile, 
temperatures in the Ohio Valley (upper 80s/low 60s) continue 
well above seasonal normals (mid-upper 70s/mid-upper 50s) under 
mostly sunny skies.

By Sunday into Monday, the cold front pushes southeast through 
the region. GFS/Euro show a band of frontal showers/storms 
during the Sunday afternoon through Monday evening timeframe 
before a post- frontal surface high builds in quickly behind the
front Tuesday. Main uncertainty here at day 6-7 is whether this
trof will contain enough moisture and forcing to bring 
temporary relief to the current very dry spell. Both models show
a relatively short window of opportunity for precipitation from
Sunday into Monday. The Euro Ensemble mean shows limited precip
as the higher PWATs stay to the west, while the GEFS brings a 
band of a half inch QPF through the region.

&&

.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
With mostly dry air in place, VFR conditions will continue
for most locations through the bulk of the period. The only
concern again will be valley fog affecting KLUK, which could
potentially go briefly IFR in the 09-11z timeframe. Potential
for MVFR at KILN in that same time. MVFR to spotty IFR
visibilities improve to VFR as fog burns off. Few cumulus in the
4-5k ft range expected as NE winds become east after about 15z. 


OUTLOOK...No significant weather expected.

&&

.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.

&&

$$
SYNOPSIS...Franks
NEAR TERM...JDR
SHORT TERM...Franks
LONG TERM...Hogue
AVIATION...JDR