Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington Ohio
745 PM EDT Monday may 4 2015
a frontal boundary will push southeast through the Great Lakes
region and stall out in Northern Ohio tonight and then lift
northward on Tuesday. Upper level ridging will limit any shower
activity for the latter part of the week. The next cold front will
cross the region on the weekend.
Near term /until 6 am Tuesday morning/...
evening update generally blended temperatures and dewpoints to observed
values and took into account the lower temperatures along and north of I-70
where showers had just passed through. Upstream convection north
of Indianapolis is weakening and does not appear that it will hold
any chances of severe weather outside of a gusty outflow this
evening. This is primarily due to the 500 mb vorticity that will move
quicker than the storm...the loss of daytime heating...and the
noted outflow pushing S from the system that will inhibit a
continued influx of relatively moist and/or unstable air.
Kept the chances for showers unchanged with a heightened area of
likely probability of precipitation increasing along I-70 from Richmond to cmh and then
concentrating more in the northern Miami Valley by late evening
and subsequently lifting north-northeast overnight.
Short term /6 am Tuesday morning through Wednesday night/...
surface flow from the southwest will resume during the day Tuesday
and the boundary will lift northward with showers and isolated
thunderstorms will primarily be found along and north of I-70. A
larger temperature difference will occur here as rain cooled air
/or at least cloudy skies/ will not permit readings to top out of
the middle 70s while lower 80s are expected along the Ohio River.
Overnight lows will continue to be within a few degrees of 60 and
highs will rise a bit more in the north on Wednesday...possibly
reaching 80 degrees in spots.
While the threat for showers decreases on Wednesday with an upper
ridge building in...they remain nonzero as the surface convergent
boundary and daytime heating could mix to spark some shower
activity. Once the daytime heating is no longer in play...any
precipitation will go the Wayside overnight.
Long term /Thursday through Monday/...
500 mb ridge will be centered over the upper Ohio Valley at the
beginning of the period. Surface high will be off to the east.
GFS continues to be the wettest of the extended
models...developing diurnal convection on Thursday under the
ridge. This could be related to how it is handling the
subtropical system that develops near the Bahamas and the drifts
northwest. The GFS brings in onshore Thursday night...so some of its
upper level moisture could be getting pulled into the region. The
European model (ecmwf) meanwhile keeps the system off the coast. Carried a 20 pop
in southeast Indiana/northern Kentucky per the European model (ecmwf) to cover any rouge convection
that might try and pop.
Any convection that might develop dies down Thursday night. The
GFS redevelops precipitation Friday. It is the farthest west with the
subtropical system...which helps fuel its convection. Prefer the
drier European model (ecmwf).
By the weekend a cold front slow approaches from the west. Locations in
the west/northwest will have the better chance of seeing precipitation on Saturday.
By Sunday the front should be close enough to the entire forecast area to
have a chance of rain. Sunday night the original front stalls out
over the region as 500 mb trough digs out of The Rockies. Surface low
develops in response to the upper level energy. A stronger north-S
oriented cold front will work to towards the Ohio Valley Monday...keeping
scattered convection in the forecast.
With the upper ridge over the region...temperatures will warm to
the lower to middle 80s Thursday into Sunday. With a little better
chance of precipitation on Monday highs should only make the upper 70s to
Aviation /00z Tuesday through Saturday/...
an area of showers is currently situated just west of the taf
sites. Expect these showers to work into kday for a few hours at
the start of the taf period. Area of cumulus southeast of this area of showers
has struggled to develop although cannot rule out an isolated
shower or storm developing during the early afternoon.
Better development looks to be during the early evening hours
across the taf sites along a boundary. Additional development is
expected late this afternoon across western Indiana and is
expected to move southeast into the area during the early to late evening
hours. As the boundary moves north precipitation chances will also
move north. Precipitation will come to an end across the taf sites
from south to north. Best chance for thunderstorm activity looks
to be during the evening hours. Visibilities will be reduced with some of
the heavier shower activity.
Outlook...no significant weather is expected at this time.