Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington Ohio
145 PM EDT Sat Aug 23 2014
warm and humid conditions will continue through the weekend into
next week. After a foggy start today...upper level disturbances
will interact with a surface front...providing a chance for
showers and thunderstorms. An upper level ridge will build into
the region Sunday into early next week...providing increasing heat
and a decreased chance of thunderstorm activity.
Near term /until 6 PM this evening/...
still a few lingering areas of dense fog this morning but visibilities
will continue to improve over the next hour or so. Lower clouds
should also mix out through late morning...leaving partly cloudy
skies as we head into this afternoon. With a little better
sunshine than we have seen the past few mornings...expect highs
into the upper 80s across much of the area today. A weak boundary
will remain draped northwest to southeast across the area through
this afternoon with best instabilities generally to the southwest
of the boundary. This will likely serve as a focus for isolated to
scattered thunderstorms development this afternoon so will
continue with highest probability of precipitation across our southwest.
Short term /6 PM this evening through Monday/...
scattered storms expected to be ongoing this evening with the
best coverage over the southwest. These storms will drop southeast
around the periphery of the upper level ridge. Expect this precipitation
to push south of ilns forecast area and weaken tonight tonight. In muggy
airmass low temperatures to range from the middle/upper 60s NE to the
lower 70s SW.
Upper level flow continues to amplify Sunday with the ridge building
northeast into the Great Lakes region. Under the influence of this
ridge do not expect organized convection. Will limit probability of precipitation to over a
slight chance of a thunderstorm...mainly during afternoon/early
Highs to warm up a little and range from the upper 80s to near 90 SW.
Heat indices will top out in the middle and upper 90s in the far SW..so
will continue to mention heat for Sunday afternoon in severe weather potential statement.
Any storm that develop will be diurnally driven and expect to
diminish Sunday evening. Muggy and warm conditions to persist with
Sunday nights lows in the upper 60s and lower 70s.
Instability gradient will exist Monday with low end moderate instability
developing into the south and west during the afternoon. Will limit probability of precipitation to
chance category in the far south but this may need to be expanded
across the west. Very warm highs again in the upper 80s to around 90.
Will continue severe weather potential statement mention of heat indices in the upper 90s across far
Long term /Monday night through Friday/...
an upper level ridge axis will be situated southwest to northeast
across the area early next week. This will help keep temperatures
above normal through at least Tuesday so will nudge temperatures up a bit
warmer than what is suggested by guidance with highs generally in
the upper 80s to near 90 degrees. This will allow for some decent
instabilities to develop Tuesday afternoons. However with the
high overhead and limited forcing...think any thunderstorm
activity will be fairly isolated Tuesday afternoon.
The upper level ridge will begin to weaken through middle to late week
as short wave energy lifts northeast into the Great Lakes region.
This will eventually help push a cold front down into the Ohio
Valley late in the work week but there are model differences as to
exactly how fast this will happen. The 12z GFS remains the most
aggressive with the front...pushing it through faster and farther
south than both the 12z European model (ecmwf) and 12z CMC. Have generally taken a
blend of the models...allowing for increasing probability of precipitation from the
northwest later Wednesday and on into Thursday...then lingering some
lower end probability of precipitation into Friday across the southeast to account for the
slower ECMWF/CMC. Temperatures will of course be dependent on the
frontal timing with cooler temperatures eventually moving in behind
the front late in the period.
Aviation /18z Saturday through Thursday/...
boundary evident on visible satellite imagery stretching from
Northeast Indiana down into south central Ohio. With daytime
heating...the airmass along and to the southeast of this boundary
is becoming increasingly unstable. We have seen a few showers
trying to develop right along the boundary early this afternoon
and expect to see a gradual increase in coverage as we head
through middle to late afternoon. A larger scale complex associated
with a middle level short wave is progressing east across northern
Illinois at this time. Given the northwesterly mean flow...expect this to
begin to work/develop more southeast along the instability
gradient across central Indiana this afternoon into this evening.
Think the best chance for precipitation from this will generally remain to
the west/southwest of our area...so will include just a thunderstorms in the vicinity at
the southwest taf sites from late afternoon into this evening to
cover the threat. Upper level ridge will build a little more east
over our area tonight. Given the light flow regime and high
dewpoints...IFR or lower br development is expected again tonight.
Outlook...no significant weather expected.