Scientific Forecaster Discussion
fxus61 Kiln 210737
Area forecast discussion
National Weather Service Wilmington Ohio
337 am EDT Mon Oct 21 2019
a cold front approaches the area today, bringing showers and
gusty winds to the Ohio Valley. Cooler air and blustery
conditions arrive behind the front for Tuesday. High pressure
will offer dry conditions and seasonable temperatures Wednesday.
A southerly flow will develop on the back side of this high
Thursday when readings are expected to rise a little above
Near term /through tonight/...
any patchy fog present before sunrise quickly dissipates as
winds gradually increase in response to an intensifying pressure
gradient. Surface low pressure over the norther Great Plains
promotes warm southeasterly flow ahead of an approaching cold
front. Ahead of the front, elevated convection associated with
the warm front may brush western areas of the forecast area late
this morning through noon. A few showers are possible further
east, but most precipitation should be delayed until late
afternoon and evening as the front nears. While much of the area
is dry for most of the day, breezy conditions are forecast with
regular wind gusts to 25-30 mph and isolated gusts to 35 mph.
Widespread rainfall is delayed allowing warm air advection to
push many locations into the mid and upper 70s despite scattered
cloud cover. Rain eventually pushes in during the evening hours
with gusty winds over 40 mph possible with the heaviest showers.
Overall instability is rather lacking so severe threat is
limited to southeast Indiana counties.
Short term /Tuesday through Tuesday night/...
additional lift behind the front allows for a slow decrease in
shower coverage from west to east Tuesday morning. While showers
may be somewhat slow to clear, once they do clear, the dry
conveyor belt supplies dry air, clearing cloud cover by
afternoon. Best chance for cloud cover development during the
afternoon will be across northern areas with cold air advection
resulting in scattered cumulus development. Breezy conditions
continue throughout the day on Tuesday as the surface low slowly
moves eastward into southeast Canada. The tight pressure
gradient allows for regular wind gusts of 20-30 mph. Otherwise,
partly sunny skies with temperatures in the low to mid 60s is
forecast area wide.
Long term /Tuesday night through Sunday night/...
the gusty winds of Tuesday afternoon will subside somewhat Tuesday
night but will likely remain breezy through Wednesday even as
surface high pressure briefly builds into the Tennessee Valley.
However, the pressure gradient will stay up a bit owing to the
quick progression of the next system which will arrive in the
Ohio Valley by Wednesday night into Thursday. Temperatures
Tuesday night through Wednesday night will be very close to
normal (lows in the low/mid 40s and highs in the lower 60s) with
perhaps a brief warmup into the upper 60s on Thursday ahead of
the approaching cold front.
A quick moving and mainly dry cold front is forecast to move through
the region during the day on Thursday before digging short wave energy
across the south-Central Plains supports surface cyclogenesis along
the Gulf Coast -- promoting a transition to over-running flow and an
anafrontal boundary structure stretched SW-NE across the Ohio/Tennessee
valleys late Thursday into Friday. This time period will likely
feature at least chance pops across portions of the iln forecast area -- but
admittedly confidence is lower than is typically the case owing to
diverging longer-range solutions with the handling of this short wave
energy late in the week. The GFS is much more progressive in its
solution -- showing a quick sweep of best precipitation chances
through the region Thursday night into early Friday while the European model (ecmwf)
continues to depict a closed upper low scenario (with delayed
ejection of mid/upper level support east of the Mississippi river),
which would tend to favor a much slower but potentially wetter setup
for this weekend. It is important to note that the European model (ecmwf) /as well as
many eps solutions/ have been persistent in the depiction of the
digging short wave transitioning to a closed low across the southwestern
plains on Friday before arriving in the Ohio Valley by Sunday. Did
not have confidence to go with a dry forecast for this weekend and
handled the uncertainty with chance pops for now. However, should
the longer-range guidance begin to trend toward a closed low
scenario, pops and quantitative precipitation forecast may need to be increased with future fcst
Temperatures will run fairly close to normal through the end of the
long term period -- with perhaps a nudge toward slightly below
normal temperatures Friday through Sunday.
Aviation /07z Monday through Friday/...
areas of fog have moved into kluk and klck overnight, resulting
in variable visibility over the last couple of hours. This will
continue over the next couple of hours before winds slowly
increase and eventually mix out remnant fog.
Breezy southeast winds with regular wind gusts near 25 knots are
expected today. Rain should avoid most taf sites until
afternoon when scattered rain showers should arrive. More
consistent rain and lowering ceilings are forecast during the
evening hours before gradually clearing from west to east
through Tuesday morning.
Winds shift from southeast to southwest to west through the
forecast period as the cold front passes. Breezy conditions are
anticipated through Tuesday as low pressure slowly moves away
from the area.
Outlook...MVFR conditions possible again on Friday with the next