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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KILN 192327
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
727 PM EDT Tue Sep 19 2017

.SYNOPSIS...
A weak upper level disturbance will move through the area,
offering a chance of showers and thunderstorms this afternoon
into Wednesday. Drier conditions are expected for the end of the
week into the weekend as upper level ridging builds into the
Ohio Valley. Above normal temperatures will continue into the
upcoming weekend.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Showers continue to weaken across the forecast area today as LLJ
convergence weakens and PVA pulls east. Overall am expecting
showers to continue to weaken with only a slight chance of
showers overnight. High res guidance in general supports this
with the 19.00z WRF DART indicating some potential redevelopment
Wednesday morning. The 12z NSSL WRF and latest runs of the HRRR
and RAP don`t show much. Given the placement of the shortwave
(across our southwestern zones) have left PoPs in for our
southeastern zones. The other concern for Wednesday morning
will be the chance of fog. High res guidance has been fairly
consistent in showing widespread fog development Wednesday
morning as the pressure gradient remains weak allowing winds to
decouple. Dewpoint depressions also approach zero across all
parts of the CWA on the NAM, SREF, GFS, and ECMWF. The main
concern against fog formation will be the possible development
of a low ceiling deck instead. For now have more confidence in
actual fog formation.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
During the day Wednesday have left a slight chance of showers
with isolated thunder across the eastern zones, but taking a
look at the position of the upper level shortwave it appears
that most of the precip will be confined to our far eastern
zones. It should be noted coverage should be sparse across our
area though as the Ohio valley remains in the weak subsidence
zone on the back size of the shortwave. Also on the backside of
the shortwave dry mid and upper level air begins to move in from
the east. During the day Wednesday 850 mb temperatures also
rise to around 17 degrees C and with partly sunny skies highs
will likely reach the mid 80s. Have gone ahead and raised high
temperatures a bit.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Tricky forecast at the beginning of the extended. Leftover moisture
associated with decaying frontal boundary is found over the region.
Even though an upper ridge is trying to dominate the region, there
appears that there will be enough sfc convergence that pop-up
convection can`t be ruled out. Added 20 PoPs for Thursday, but it
might need to be increased to chance PoPs as we get a little closer.

The H5 ridge then builds in and becomes the dominant feature
through the weekend and into early next week.  High temperatures
will be about 10 degrees above normal through the period as they
push into the mid and upper 80s. Morning lows will start out 60-65
degrees, then cool a few degrees to around 60 for the latter part of
the period.

&&

.AVIATION /23Z TUESDAY THROUGH SUNDAY/...
-- Changed Discussion --
Isolated showers are persisting across the region early this
evening. This is associated with an upper level trough axis
pivoting across the Ohio Valley along with some lingering
instabilities. As we continue to lose the daytime heating,
expect to see an overall weakening trend in the pcpn coverage.
However, with some secondary short wave energy working through
overnight and into the day on Wednesday, it will be tough to
rule out a few stray showers through much of the period. The
chances do look low enough though to leave the mention of pcpn
out of the TAFs beyond the first couple hours of the TAF
period. Meanwhile, with a fair amount of low level moisture
present, models are in general agreement developing some IFR
fog later tonight on into Wednesday morning, along with some
possible MVFR to IFR cigs. These conditions will likely linger
through much of the morning before improving as we head into
the afternoon.

OUTLOOK...No significant weather is expected at this time.
-- End Changed Discussion --

&&

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

&&

$$
SYNOPSIS...Haines
NEAR TERM...Haines
SHORT TERM...Haines
LONG TERM...Sites
AVIATION...JGL