Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington Ohio
1017 am EDT Sat Sep 20 2014
high pressure will move off to the east today as a cold front
approaches from the northwest. The cold front will move across the
area late tonight and Sunday. High pressure will then become
reestablished for much of next week.
Near term /until 6 PM this evening/...
went with a dry forecast for today. Clouds will increase out
ahead of a cold front which is moving toward our region from the
west. Increasing southwest flow with gusts over 20 miles per hour between
the departing high and the front will boost temperatures into the
upper 70s to the lower 80s.
Short term /6 PM this evening through Tuesday night/...
have again used a blend of the ECMWF/GFS...along with convection
allowing models...to hone in on the prospects of precipitation tonight into
A series of S/waves will dig east/southeast through the Great Lakes
tonight into Sunday night...which will eventually establish a long
wave middle level trough over eastern Canada southward into the eastern U.S.
By Monday morning. The first wave...along with prefrontal
convergence...is expected to result in showers/thunderstorms to
our northwest late this afternoon into early this evening. Models
continue to suggest that as this activity propagates southeast into
our area tonight out ahead of a cold front...it will undergo a
weakening trend. Rapidly decreasing instability...weakening low
level forcing...along with weakening upper level support are the
reasons that this is forecast to occur. As a result...have placed
the highest probability of precipitation tonight over the far northwest...decreasing the threat
to just 30 and 40 percent through the remainder of the region
toward Sunday morning.
On Sunday...another embedded shortwave will approach from the northwest
while the cold front pushes east/southeast through the region.
With the faster timing of the GFS/ECMWF...believe any
shower/thunderstorm redevelopment should occur just east/southeast
of the area. In the wake of the front...and before the arrival of
the next shortwave...we should see a pocket of dry weather along with
partly to mostly sunny skies. Highs on Sunday will be tricky as
cold air advection will be ongoing through the day. Will forecast lower 70s
northwest to the upper 70s southern/southeast.
For Sunday night...aforementioned shortwave will pass through the
region along with a surface trough axis. There could be enough
instability with this feature to bring a few spotty showers to the
northern zones Sunday evening. But as time wears on and instability
wanes...the threat should relegate itself to our NE toward
central/Eastern Lake Erie. Partly cloud skies will undergo a
clearing trend...especially west overnight. Lows will drop into
the middle 40s northwest to the lower 50s southeast.
For Monday into Monday night...middle level trough will move east as
a middle level ridge builds northward into the middle and upper MS
River Valley. At the surface...a sprawling area of high pressure
will be found as it settles right over the Ohio Valley by Tuesday
morning. Clouds will continue to decrease through the period with
clear skies expected by Monday night. After cool temperatures
ranging from the lower 60s north to the upper 60s south...overnight
lows will dip into the upper 30s and lower 40s by Tuesday morning.
On Tuesday...with the high remaining in place...skies will be
sunny. Highs will warm into the upper 60s to the lower 70s.
Long term /Wednesday through Friday/...
high pressure will keep dry conditions across the region through
the long term. Temperatures will slowly warm through the long
term with high temperatures by Friday expected to be in the middle to
Aviation /14z Saturday through Wednesday/...
although the majority of the forecast period is expected to be
VFR...there are a few items to discuss. Although any remaining
MVFR visibility restrictions will be short-lived...an increase in
moisture from the south will result in scattered to broken clouds
over the region...generally in the 3500-6000 foot range. Southerly
flow will switch to the southwest...with gusts in the 18-22 knot
range by early afternoon.
A cold front is forecast to approach the region from the northwest
tonight and into Sunday morning. Ahead of this
front...precipitation is forecast to move into the area late this
evening and into the early morning hours. However...the extent of
precipitation with this front is not certain. The precipitation
(which could include thunderstorms) should be on a weakening trend
as it moves through the taf sites. A tempo -shra group was
included at kday...but the other taf sites are not as certain to
receive rain. As the front nears...ceilings are expected to drop
into the MVFR range.
Outlook...a few showers...and possibly a thunderstorm...will be
possible during the first half of Sunday. MVFR ceilings are also
possible on Sunday morning.