Area Forecast Discussion
Issued by NWS Wilmington, OH

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS61 KILN 291838

Area Forecast Discussion
National Weather Service Wilmington OH
238 PM EDT SUN MAY 29 2016

A weak cold front will move through the region tonight, providing
a chance of showers and thunderstorms. High pressure will move in
on Monday, with drier conditions expected through the middle of
the week. Another cold front will approach the region on Thursday,
bringing the next chance for precipitation.


With only some light showers remaining in the eastern sections of
the forecast area, attention will turn to the approaching cold
front just to the west. The front appears roughly coincident with a wide
band of enhanced cumulus on visible satellite imagery. Current
surface observations indicate that the front currently extends
from around Lansing MI to Bloomington IN. There is a very slight
wind shift (210-220 degrees to 240-250 degrees) and a notable
change in dewpoints (upper 60s to lower 60s), but temperatures are
virtually identical on either side of the boundary. With these
parameters in mind, and knowing that the front is not moving
quickly, it is apparent that frontal forcing is not going to be
especially strong. Nonetheless, the first convective cells have
begun to develop, and this activity is expected to grow during the
next few hours.

High-resolution computer model forecasts have, across-the-board,
been too fast in generating convection today. This suggests their
instability forecasts may have been aggressive. A modified 12Z KILN
sounding with current conditions produces MLCAPE of around 1500
J/kg, which is close to current LAPS analysis values (with higher
values approaching 2000 J/Kg just ahead of the front in eastern
Indiana). Surface-based parcels may be able to add another 500
J/kg on top of that, and perhaps more importantly, SPC
mesoanalysis and the aforementioned modified sounding both support
values of DCAPE of 600-1000 J/kg. This means that where convection
does develop and become mature, it will likely be deep, and will
have the potential for strong to possibly severe winds. However,
weak forcing and shear (0-6km bulk shear of only around 20 knots)
will make it very difficult for storms to become organized. Thus,
any severe threat will likely be more pulse-type than based on
updraft longevity, but a marginal risk of severe winds and hail
still appears a possibility.

Storm chances will be highest in the western half of the CWA
between 18Z-21Z, and will then move to the east between 21Z-01Z,
gradually diminishing after peak heating has been passed. Dry and
mostly clear conditions are expected for the entire forecast area
after 03Z, as the slightly drier air mass behind the front advects
into the area. With less moisture in the boundary layer, min temps
will get to around 60 degrees in the northwestern CWA, with lower
60s elsewhere.


Behind the weak front, no huge change in air mass is expected,
though dewpoints will be 5-8 degrees lower than they were over the
weekend. At the surface, high pressure will be centered over the
lower Ohio Valley, providing light northwesterly flow across the
ILN CWA. Drier conditions will allow for mostly sunny skies, and
thus despite the wind shift, temperatures will again be able to
reach the lower 80s across the entire forecast area.

As the surface high spreads northeast across the region and into
southern Michigan, tranquil conditions are expected on Monday
night, with lows in the lower 60s.


High pressure will continue over the region Tuesday into Tuesday
night. Warm temperatures in the lower to mid 80s will
persist with lows in the upper 50s to the lower 60s.

A mid level trough is still advertised to move from the northern and
central Plains to the Great Lakes Region Wednesday into Thursday.
Most of the region will squeeze out one more dry day on Wednesday as
high pressure moves off to the east. There could be enough moisture
and diurnal instability late in the day on Wednesday for a low
chance of showers/storms far west. As the mid level trough moves
through the region on Thursday, an associated cold front at the
surface will move through as well. There are some minor timing
differences, but the region is still expected to see a gradual
increase in showers and storms Wednesday night into Thursday. Warm
highs in the mid to upper 80s on Wednesday will be tempered on
Thursday by clouds and the threat for precipitation.

For Thursday night into Friday, the cold front is forecast to exit
southeast of the region, ushering in cooler and drier air with the
threat for precipitation ending. Highs on Friday will range in the
75 to 80 degree range.

For the upcoming weekend, the upper level pattern will transition to
a broad long wave trough over the Great Lakes and Ohio Valley. High
pressure on Saturday will give way to a weak disturbance Saturday
night into Sunday. Have kept a low chance of showers and storms with
this system at this time. Temperatures will generally range from 75
to 80 degrees for highs with upper 50s to lower 60s for lows.


Shower development is expected to coalesce into a line of
thunderstorms ahead of the passage of a cold front this evening.
H5 trough in the Upper Midwest will pivot northeastward into the
Great Lakes early this afternoon. Showers that develop in the warm
sector ahead of the cold frontal passage will deepen with the
heating of the day, and as the front approaches later today there
may be enough low level shear available for a line of storms to
develop and propagate eastward in the late day and early evening.
skies will be VFR until storms roll through. Gusty winds and mvfr
vsbys are expected in thunderstorms but timing cannot be gleaned
at this moment. Will have to wait until the expected line develops
and extrapolate positioning and timing with any amendments this
afternoon. Sky cover will rapidly improve this evening in favor of
generally clear skies overnight. Some fair wx cu may sprout in the
drier if not cooler air behind the front tomorrow.

OUTLOOK...Showers and thunderstorms are possible Thursday.




NEAR TERM...Hatzos
LONG TERM...Hickman
AVIATION...Franks is the U.S. government's official web portal to all federal, state and local government web resources and services.