Area Forecast Discussion
Issued by NWS Wilmington, OH

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FXUS61 KILN 202349

Area Forecast Discussion
National Weather Service Wilmington OH
749 PM EDT Wed Sep 20 2017

A weak mid level trough will move east of the area today. Over
the next several days, a stagnant weather pattern will set up,
with mid-level ridging and high pressure near the surface.
Temperatures will remain above normal through the weekend.


A stray shower or two may still pop up over the CWA for the
next few hours as a high moisture content airmass continues to
interact with a departing upper level shortwave. Any cells that
might pop will not be deep enough to support thunderstorm
activity and thunder has been removed from the forecast with a
weak 20% coverage added to mainly the southeastern quarter of
the CWA. Did not change the fog forecast tonight given the
unusually moist air over the region.

Fog potential is the greatest concern for tonight, with a
favorable setup in the wind and pressure pattern (overall light
flow with the main axis of the boundary-layer ridging just to
the east). Where skies clear out, conditions will be favorable
for fog to become locally dense, especially in river valleys or
more broadly in the eastern half of the forecast area.


The stagnant weather pattern will essentially remain in place on
Thursday, with broad mid-level ridging extending from the Great
Lakes into the middle Mississippi Valley, and an elongated
surface high centered well northeast of the Ohio Valley region.
Thursday appears to set up as another day with light wind flow
and some chance of afternoon instability, which has resulted in
some inconsistent/weak QPF output across the suite of models.
Looking at soundings, there will be some warming of temperatures
in the 800mb-750mb layer between Wednesday and Thursday, which
will make it less likely for any precipitation to develop. The
chance certainly isn`t zero percent, but appears small or
isolated enough to not include in the main forecast.

Temperatures should be able to rise by a few degrees for both
Thursday and Thursday night.


Strong H5 ridge will be the dominant feature for much of the
forecast period. The ridge will keep Jose off the East Coast and
away from the Ohio Valley, and later on Maria. Meanwhile at the
surface, a surface high centered over the St. Lawrence Valley will
extend southwest into the fa.

The combination of these two features will bring dry condition and
above normal temperatures through the weekend and into early next
week. High temperatures will be about 10 degrees above normal
values through Tuesday as they push into the mid and upper 80s.
Morning lows be around 60.

By Wednesday a cold front will be moving east up the Ohio Valley. It
will bring some scattered convection. The GFS is a little quicker
than the ECMWF and Canadian with the front. Have included 20 PoPs in
the wrn half of the fa for Wednesday. Highs Wednesday will still be
around 80 degrees.


Generally clear skies are expected tonight with some lower
stratocu associated with the showers possible through the
evening, and some higher blowoff cloud cover that will be
thinning through the next several hours. Wind field will be
light and variable, and this will combine with the generally
clear skies and moist lower atmosphere to create another night
of fog development, possibly dense in river valleys. Expect IFR
conditions to be present, with KLUK dropping right to VLIFR in
more dense valley fog.

Moisture will lift to help form some scattered cu in the morning
and early afternoon, which should mix out early in the
afternoon. A brief bkn deck is possible just about anywhere, but
should be the exception and not the rule.

OUTLOOK...No significant weather is expected at this time.




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