Area Forecast Discussion
Issued by NWS Wilmington, OH
FXUS61 KILN 302340
Area Forecast Discussion
National Weather Service Wilmington OH
740 PM EDT SAT JUL 30 2016
The threat for mainly daytime scattered showers and thunderstorms
will continue into Sunday as a warm...muggy airmass remains over
the Great Lakes. There will be some tendency for some drying into
early next week and reduced chances for showers and storms.
Temperatures will remain in the 80s.
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
At 19Z...a broad longwave trough axis remained west of the WFO ILN
forecast area...centered from Ill/Ind on southward. The primary
mid/upper level low was still across Wisc/Lake Michigan and moving
very slowly east. This has allowed a continued modest west-
southwesterly mid/upper level flow across our area with numerous
low/mid level perturbations rotating through the longwave trough.
One such disturbance was approaching the tri-state and was
responsible for a more concentrated area of storms from Carrollton
back to Louisville. A low/mid level convergence zone and
attendant weak surface low over northern Ohio was focusing a
separate area of convection across that area. In between...over
the WFO ILN forecast area...diurnally forced and generally weak
showers/storms continue to flare up and drift slowly east.
For the remainder of the afternoon and tonight...expect the weak
disturbance in the tri state to force the kentucky storm cluster
generally east-southeast which should involve portions of northern
ky. Main impact here will be locally heavy/torrential rain rates
and perhaps a marginal wind threat with effective shears around
25kts and steep low level lapse rates. Otherwise...outflow from
northern Ohio storms will likely propogate south into central
Ohio and and will combine with slightly better low level
convergence there and may fire isold/sct storms through about 02Z
with main impacts similar to the storms across nrn ky. Isolated
showers/storms between these two areas should fade rather quickly
by early this evening.
As with previous nights...fog is likely to form as the boundary
layer remains quite moist. One concern is a pool of lower PWAT air
over Indiana that may drop PW rather decently here later this
evening...but boundary layer will likely be decoupled by then
trapping shallow moisture to allow fog formation esp across cntl
Ohio where the low level convergence axis remains.
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
The longwave trough axis will shift through the area on Sunday
changing the mid/upper flow from west-southwesterly to
northwesterly which should reduce our chances for showers/storms
somewhat. There will still be a window of opportunity in the
afternoon /most favored in central Ohio/ for diurnally forced
showers isold/sct showers and storms before subsidence on the
backside of the longwave trough axis shuts things down by Sunday
A quiet Sunday night is expected across the area -- with
potentially some fog to develop again -- but will defer that to
later forecasts once a better feel for winds/dwpts is had.
.LONG TERM /MONDAY THROUGH SATURDAY/...
Models continue to show a weak H5 trof over the Great Lakes on Monday
In the localized nw flow, the models are dropping weak s/w into the
region. Each model handles these weak disturbances differently
and therefore are producing a variety of solutions. The GEM
hemispheric and the NAM drop a MCS thru IN and srn OH. The GEM is
quicker than the NAM, as it brings the bulk of the pcpn thru
Monday, compared to the NAM`s Monday Night. The GFS and to a lesser
extent the ECMWF pop some scattered QPF. Based on the wide
range of solutions, confidence is low, but added a 20 PoP to the sw
2/3 of the fa, to at least start the transition to a wetter forecast.
It looks like highs will be in the lower and mid 80s.
H5 ridge begins to build in Monday night and Tuesday. Models are
trying to slip some pcpn chances into the western counties Tuesday
afternoon, so upped PoPs to 20 in ern IN/wrn OH. Temps will warm a
couple of degrees with highs on Tuesday into the mid and upper 80s.
12Z ECMWF finally has dropped the MCS that the operational ECMWF
runs have been forecasting for the past several days. The 12Z
still brings a chance of pcpn to nrn sections late Tuesday night into
Wednesday however. Went with chance pops over the fa on Wednesday, as
pop-up storms should be possible. Highs on Wednesday will be similar
to Tuesday, in the mid to upper 80s. The chance of pop-up storms now
spills over to Thursday with chance pops added to the forecast.
12Z model runs are a little slower with a cdfnt working south from
the upper MS valley and wrn Great Lakes. We should still see a
chance of storms on Friday, but the front will still be strung
across the region on Saturday keeping the chance of pcpn in the
forecast. Friday will see highs in the mid to upper 80s, but
Saturday should be slightly cooler with everyone in the mid 80s.
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
Cumulus is expected to dissipate early in the TAF period. Clearing
skies with light winds should be sufficient for visibility
restrictions to develop at all sites overnight. Appears that the
lowest visibility will be at the usually more favorable locations.
However...it also appears that KDAY and points north could be
favorable for IFR fog which will then lift into a stratus deck
after 12Z. Elsewhere current data suggests that the chance for
stratus is low. Eventually will get a scattered to broken cumulus
deck during the day. There could be an isolated shower or
storm...but the chance is well too low to include in the TAFS.
OUTLOOK...MVFR visibilities possible again Sunday night. Chance
of thunderstorms Wednesday.