Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington Ohio
1006 PM EDT Friday Aug 1 2014
an area of low pressure will serve as a focus for showers and
thunderstorms through Saturday. High pressure will build in early
next week. A weak boundary will move to the Ohio River late
Tuesday and into Wednesday...bringing the next threat for showers
Near term /until 6 am Saturday morning/...
with the inverted trough over the area through tonight...even with
loss of diurnal influence theres enough moisture and weak/subtle
surface features to continue isolated activity overnight. Very
light steering winds will keep thunderstorms very slow moving or
nearly stationary...so though while isolated...threat for minor
With increasing clouds as the upper trough approaches...mild night
Short term /6 am Saturday morning through Saturday night/...
middle level trough with subtle short waves moving through it will
weaken and shift east during the period. The associated inverted
trough at the surface will persist through Saturday and then move
With heating and destabilization on Saturday showers and storms
will increase again with coverage greater than today. Appears
that activity may pass east across the region Saturday evening.
Guidance was close on temperatures...continued with a blend which
put highs within a few degrees of 80 and lows around 60.
Long term /Sunday through Friday/...
at 12z Sunday morning...pattern is still dominated by oceanic
ridging in the Atlantic and persistent southwestern Continental U.S. Ridge...with
still a modest longwave trough between the two oriented in a
positive tilt fashion from the Ozarks through the middle Ohio Valley
into southeastern Canada. A shortwave trough shifting eastward across the
Ohio Valley will help push the axis of the trough eastward into
PA/WV during the day on Sunday...and it seems recent GFS runs
which were lagging the wave back slower over Ohio have trended
toward recent European model (ecmwf) guidance. Thus...will only carry a small storm
chance in the Scioto valley of central/scntl Ohio Sunday before
drying things out Sunday night for all.
Modest height rises on Monday as the area will be between some
energy moving through the base of longwave trough to our south and
the next short wave approaching through the western Great Lakes. Maintaining a dry
forecast Monday/Monday night as weak high pressure shifts through the
area. This is about the highest confidence dry day in the extended.
Tue/Wed...has been a signal for quite some time of slightly lowering
heights in this timeframe which allows a very weak front to sag into
Ohio/ind particularly Tuesday night in Wednesday. Continue to keep Tuesday dry for
most except for areas north of I-70 which may get an afternoon
storm...but unlikely. Better chances Tuesday night/Wednesday as the front
sags slowly south through the area though again forcing/wind fields
are anemic...and little appreciable precipitable water above normal. Modest at
Building uncertainty later Wednesday into thurs/Fri. New 01.12z
European model (ecmwf) indicates weak ripple along the front and potential mesoscale convective system action
Wednesday night through the County Warning Area while previous solutions were a little
more progressive. With models showing upstream energy digging into
the cntl Continental U.S. Hard to imagine front will make much southward progress
with heights aloft starting to turn around/rise by Thursday so played
for a slower front that never really gets south of the area...thus
rain chances from Wednesday into Friday. Still looks like low-middle 80s by
day...low-mid 60s by night...with dewpoints in the low-middle 60s. Typical
early August weather for the area.
Aviation /02z Saturday through Wednesday/...
inverted trough now positioned over the area and will keep rain showers
and isolated thunderstorms and rain with diurnal enhancement through the period.
Isolated activity through 00-06z is most expected near kday though
cannot be ruled out at other locations. Any activity is highly
dependent on very subtle surface features and old outflow
areas...so vcsh/thunderstorms in the vicinity is still necessary.
With increase ll moisture and nearly calm winds...still some
potential for MVFR br with kluk still having potential to drop to
IFR in the 09-12z timeframe.
For Saturday daytime...as the upper trough pushes through and
combines with daytime heating...have continued some prevailing
-shra over all locations as activity will be more widespread.
Because of slow moving storms and moist environment...and location
to receive an afternoon storm could drop to MVFR or even IFR for
the duration of the storm. Both upper level and sft trough pushes
east by the end of the taf period...bringing VFR Sat night.
Outlook...thunderstorms possible Tuesday and Wednesday.