Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington Ohio
1018 am EDT Friday Aug 29 2014
mainly dry conditions are expected once again today as high
pressure slides off to the east through this afternoon. A series
of upper level disturbances will then move through the region
over the next several days...resulting in a chance of showers and
thunderstorms through much of the Holiday weekend.
Near term /until 6 PM this evening/...
dry conditions will start out the near term. A weak warm front
later today will allow for a few isolated showers and storms
primarily across SW portions of the forecast area. Temperatures will warm
into the 80s today. Went close to guidance for high temperatures.
Short term /6 PM this evening through Sunday/...
the warm front will lift northeast across the area tonight. We
could see a few showers/thunderstorms linger into this evening.
However...these will be primarily diurnally driven so expect any
activity to taper off through the evening hours as we lose daytime
An upper level trough moving out of The Rockies will weaken as it
progresses eastward into the East Coast ridge Saturday into
Sunday. However...increasing southwesterly low level flow ahead of
this will allow for an increase in deeper moisture across the
region into Sunday. As short wave energy moving east across the
western Great Lakes combines with some southern stream energy
lifting up from the southwest...expect shower and thunderstorm
chances to increase Saturday night and continue into Sunday.
In warm air advection pattern on Saturday...expect highs to push into the upper
80s to near 90. Clouds and precipitation on Sunday should help keep highs
generally down in the lower 80s.
Long term /Sunday night through Thursday/...
models are in fairly similarly agreement through Tuesday morning.
Thereafter...there are some big differences. Have taken a blend
of the 12z European model (ecmwf)/GFS through Tuesday...with a heavier weight toward
wpc guidance given the Stark differences in the operational models
by middle to late next week.
For Sunday night into Monday...another shortwave is forecast to skim
by to our southeast while stronger energy and a cold front push
east into the western Great Lakes. Moist south to southwest flow
will continue. We will be in a relative lull...but with
instability and moisture will hold on to a 30 pop region wide.
For Monday night into Tuesday...this is where the models are in
agreement for the last time. Shortwave energy is forecast to push
east/northeast across the northern Great Lakes into southeast
Canada. This should nudge aforementioned cold front into the area on
Tuesday. Will maintain a chance of showers and thunderstorms.
For Tuesday into Thursday...models disagree on the strength and
timing of shortwave coming out of the Pacific northwest into either the northern plains
or south central Canada. The European model (ecmwf) is more north and muted with this
energy. This solution hangs the frontal boundary over the region and
eventually pushes it back northeast as a warm front on Thursday as
middle level ridge to our south tries to establish itself once again.
The GFS is stronger and much farther south with the shortwave energy
which results in a cold frontal push through the region Wednesday
into Thursday followed by high pressure in its wake. Have sided more
with the GFS at this time which is more in line with wpc guidance.
However...given such big differences...adjustments will have to be
made with later forecasts in hopes the models come more into
High temperatures through the period will be close to seasonal
normals with lows averaging near or slightly above normal.
Aviation /14z Friday through Tuesday/...
middle and high clouds will be around the taf sites for the start of
the taf period. Some cumulus will develop during the day. A weak warm
front will lift northward later this afternoon into the evening
hours. This feature will allow for some isolated shower or
thunderstorm activity across primarily kcvg and kluk. Handled this
with a vcsh for now. Expect precipitation to taper off around
sunset. There will be an increase in cloud cover towards the end
of the taf period as an upper level disturbance approaches the
area. This will help limit fog Saturday morning however added in
some MVFR fog for a few hours at kluk. Scattered thunderstorm
activity will be possible by the end of the longer kcvg taf.
Outlook...scattered thunderstorms possible on Saturday through