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Area Forecast Discussion (AFD)

Issued by Wilmington, OH (ILN)

                            
000
FXUS61 KILN 210135
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
935 PM EDT Fri Sep 20 2019

.SYNOPSIS...
Southerly flow over the Ohio Valley will persist through the
weekend, increasing on Sunday ahead of a cold front that will 
cross the region early Monday. Storms will fire along and ahead 
of the front, primarily overnight Sunday with a decrease in 
activity during the day Monday as high pressure builds over 
Illinois. This high will cross the Ohio Valley Tuesday and 
southerly flow will return for the latter part of next week.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
There are still a few lingering showers north and east of
Columbus, but these have been weakening considerably over the
last hour. This trend should continue through the rest of the 
evening. A weak but increasing 925 mb low level jet will shift 
up from the southwest through the overnight hours. This could 
lead to some additional isolated shower development in the 
developing low level convergence out ahead of the jet. As a 
result, will hang on to some lower chance pops for later tonight
and into Saturday morning, with the best chance looking to be 
across our northwestern areas. 

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Saturday will start with showers possible over northern portions
of the CWA then decrease in the late day as the source region
lifts northeast and out of the CWA. Southerly flow will persist
but dry air in place will not necessarily result in this flow
enhancing any storms that may be present with moisture
transport.

Cloud cover in the north will be eroded later in the day and
high temperatures will reach into the mid 80s for yet another
day. Overnight lows will be more uniform in the mid 60s with
a little stronger southerly flow at night.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Warm and breezy conditions on Sunday are expected preceding a cold 
front passage on Sunday night/Monday morning. Showers are possible 
as the cold front moves through the area. Temperatures and humidity 
values drop to near/slightly above normal during the beginning of 
next week before a gradual warm up by the end of the week. 

Highs in the upper 80s along with breezy southwesterly winds around 
15-20 mph with gusts near 30 mph are possible on Sunday as the cold 
front approaches from the northwest. On Sunday night, a narrow band 
of anomalously high PWAT values extends from the Great Plains to the 
Ohio Valley ahead of the cold front, but weak forcing and limited 
instability may limit substantial accumulations. Despite the weak 
forcing, expectations are that a rather widespread area of showers 
with possibly a few thunderstorms advances toward west-central Ohio 
late Sunday evening. These showers continue eastward through the 
overnight with intensity gradually decreasing toward late Monday 
morning hours as the front moves through. The highest accumulations 
(<0.50 inches) are forecast across west-central Ohio before the 
general intensity decreases further east (0.10-0.25 inches). 
Isolated showers are possible during the afternoon on Monday, 
primarily across southeast Ohio before precipitation completely 
clears the area.   

After the cold front moves southeast through the region on Monday, a 
cooler and drier air mass will move in. Cooler temps are felt during 
the morning hours on Tuesday as temperatures drop into the mid 50s 
which is normal for late September. Highs are expected to drop back 
to the mid 70s to near 80 on Tuesday and Wednesday. Widespread 80s 
are likely to return by the end of the week as an anomalous ridge 
for late September builds in. Rain chances are limited through the 
rest of the forecast period if the extended pattern remains as 
expected.

&&

.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
Scattered showers and thunderstorms are continuing to train
slowly east across central Ohio. Expect this to continue over 
the next hour or so with a gradual weakening trend as we lose 
some of the daytime heating. This will likely affect KCMH for 
the first hour or two of the TAF period but should remain 
generally north of KLCK. 

Otherwise, it will be tough to rule out a stray shower overnight
but chance appears to be low enough to leave mention out of the
TAFs. Some patchy valley fog will be possible again later
tonight and this could briefly affect KLUK. During the day on
Saturday, expect mainly some scattered cu with perhaps
some spotty shower development once again heading into the 
afternoon.

OUTLOOK...Thunderstorms possible on Sunday night into Monday.

&&

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

&&

$$
SYNOPSIS...Franks
NEAR TERM...JGL
SHORT TERM...Franks
LONG TERM...Campbell
AVIATION...JGL