Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington Ohio
740 PM EDT Thursday Mar 26 2015
a large scale upper level trough will dig southeast across the
Great Lakes and Ohio Valley through Friday night. Much colder air
will arrive with this system. High pressure will build into the
area on Saturday...moving east of the region Saturday night.
Another weather system will move into the Great Lakes and Ohio
Valley on Sunday.
Near term /until 6 am Friday morning/...
some frontogenetic forcing induced by an upper level jet and middle
level deformation will keep some showers going across our southern and
southeastern County warning forecast area through early evening. As this shifts to the east...so
will the precipitation...and the entire region should remain dry through
the remainder of the night. A large scale upper level trough will
begin to carve itself out over the Great Lakes and the Ohio
Valley region. Post frontal cold air advection will result in lower level clouds
lingering with temperatures dropping into the lower 20s far northwest to
the lower 30s along and south of the Ohio River.
Short term /6 am Friday morning through Saturday night/...
aforementioned large scale upper level trough will continue to dig
over the region on Friday. Clouds will thicken by late morning
into the early afternoon as cold air advection and some warming surface warming result
in steepening low level lapse rates. A somewhat favorable fetch
off of Lake Michigan will bring a slight chance of rain and/or
snow showers near the tri state region during the afternoon. For
the remainder of the area...the afternoon heating/steep low level
lapse rates will bring a threat for a few flurries and/or
sprinkles (depending on near surface thermal fields). Highs will
range from the lower 30s northwest to the lower 40s southeast. These
highs will be some 15 to 20 degrees below normal for late March.
For Friday night...models continue to advertise that a weakening
frontal boundary/low level trough axis will push through our area.
Operational models and some high resolution models indicate that
some snow showers may accompany this low level convergent wind
shift late Friday afternoon into Friday evening over the northern two
thirds of the forecast area. Will bring a low chance of snow
showers to these areas with any sprinkles/flurries dissipating
after peak heating. Clouds will be slow to clear as cold air advection induced
cumulus/stratocumulus take their time to scatter overnight. Lows
ranging from the middle teens north to the lower 20s south will be
quite cold but should stay just above record lows.
On Saturday...large scale upper level trough will begin to slowly
push east. As this occurs...surface high pressure to our northwest
will begin to build into the area. Models indicate some lingering
low level moisture on Saturday...but lapse rates will not be as
robust as Friday...so will keep the forecast dry with partly to
mostly sunny skies. It will be the coldest day with most locations
only reaching the 30s for highs. Looks like low maximum values at the
day and cmh will not be threatened...but cvg has a chance of at
least tying their record low maximum of 37 degrees.
For Saturday night...high pressure will move across the
region...then east of the region late. Skies will become mostly
clear with some middle and high level clouds spilling into the region
from the northwest late. Lows will again be cold...ranging from
the middle teens east of Columbus to the lower 20s elsewhere.
Long term /Sunday through Thursday/...
models are trending slower with the Sunday into Sunday night
system. With a slower system there will be more time for
temperatures to warm ahead of the cold front and therefore expect a
majority of the precipitation to be rain showers. A rain snow mix
will be possible however across northern portions of the forecast area as
colder air works into the region. The system exits Monday morning
and high pressure then works into the area.
After this point models differ and there has been run to run
inconsistencies as well. Tried to focus precipitation chances where
there has been more consistency and model agreement.
A system is expected to move through the area Monday night into
Tuesday. There is some limited instability with this feature and
therefore added in thunder mention during the day on Tuesday. After
this point there are some weak signals in the models for weak
disturbances moving through the region however signal was not strong
enough to include precipitation chances in the forecast at this time.
Aviation /00z Friday through Tuesday/...
MVFR ceilings should lift to VFR early in the taf period and then
scatter. However expect stratocumulus to spread back south across
the region within a couple hours either side of 12z. This deck
should be near the MVFR/VFR threshold initially before lifting to
VFR. VFR ceilings will predominate through the latter part of the
forecast. Northwest winds will increase on Friday with some gusts
between 20 and 25 knots. Cannot rule out some very light precipitation
during the day. At this point if anything does fall then it will
not have an impact on flight category. So opted not to mention in
Outlook...MVFR ceilings and visibilities possible Sunday night.