Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington Ohio
326 am EDT Tuesday Jul 22 2014
very warm and dry weather will continue today as high pressure
moves east. A cold front will push a band of showers and
thunderstorms across the region on Wednesday. Cooler and drier
conditions will accompany high pressure on Thursday.
Near term /until 6 PM this evening/...
high pressure is centered near the middle Atlantic coast. This will
keep the iln area in a dry regime...with weather making systems
far to the northwest and southeast. With models overestimating
cloud cover during this period...skies are starting out mostly
clear. Expect mostly sunny conditions with cumulus increasing this
afternoon below a strong cap around 10 kft.
Warm advection on a southerly flow around the high will cause
temperatures to rise a few degrees compared to Monday. High
temperatures in the low 90s will combine with upper 60s dew points
to produce heat indices as high as the upper 90s by late
afternoon. Will continue to mention sub advisory heat in severe weather potential statement.
Short term /6 PM this evening through Thursday/...
cold front will be approaching from the northwest tonight. The
front is forecast to cross the area on Wednesday and then move
east Wednesday night. Showers and thunderstorm may begin late
tonight in the far northwest. A band of showers and thunderstorms
will likely push through with the front on Wednesday. A few of the
thunderstorms may approach severe limits for damaging winds.
However...widespread severe weather is not expected due to rather
weak deep layer shear.
Models have sped up the departure of the front and the arrival of
high pressure and dry air behind the front...so this forecast
reflects that faster progression of systems. Look for showers and
thunderstorms to end Wednesday night in southeast counties...with
mostly sunny conditions anticipated for Thursday.
Went with a notable temperature gradient on Wednesday because of
the frontal location. Highs may be held back in the 70s in
northwest counties due to clouds and precipitation...while locations
south of the Ohio River may reach 90. For Thursday...cooler
readings mainly in the upper 70s are expected.
Long term /Thursday night through Monday/...
a trough over the eastern states will place the Ohio Valley in a
regime of northwest flow over the weekend...gradually increasing
the chances for showers and storms on the back side of the surface
high. There is evidence of a surface trough on both the GFS/European model (ecmwf)
coming through the area on Saturday night into Sunday
morning...which may act to focus some of the precipitation
chances. These chances may increase further heading into the first
part of the week...as upper-level troughing begins to re-establish
itself with greater amplitude over a larger expanse of the eastern
half of the Continental U.S.. it certainly looks like the timing of all of
these features remains a bit uncertain in the models...with
diurnal convective trends also expected to play a role. Probability of precipitation have
been kept in the 20-30 percent range. With cloudier and more moist
conditions expected from the weekend Onward...temperatures will
likely moderate somewhat after peaking near climatological normal
values on Saturday.
Aviation /07z Tuesday through Saturday/...
light southeast low level flow exists on the back side of retreating surface
high pressure. Skies are mostly clear with the exception of few to
scattered clouds around 6000 which will affect the southern taf sites
early. Low level moisture is a little drier than the past couple
of nights. Therefore...do not anticipate widespread areas of dense
fog. However...clear skies and light winds...will result in
areas of MVFR br later tonight...with IFR visibilities at kluk and
possibly Kiln. The fog will burn off quickly this morning...with
scattered cumulus clouds during the day.
Outlook...thunderstorms possible Wednesday into Wednesday night.