Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington Ohio
951 PM EDT sun Oct 19 2014
another trough will approach the area from the northern plains
tonight. Ahead of this trough...overnight lows will be more
seasonable...and then precipitation spreads over the area on
Monday. The front will cross the region Monday night keeping
showers across the region...with a chance of rain lingering into
Near term /until 6 am Monday morning/...
evening forecast updates have centered on massaging of the sky
grids to capture scattered-broken cirrus /more opaque far northern forecast area/
and rapidly falling evening temperatures in areas south of this thicker
cirrus. Kuyf /London Ohio/ is a rather extreme example underneath
the center of thin/translucent cirrus and plummeted from 52f to
36f in 4 hours early this evening...and several sites in cntl Ohio
following suit. This area rather calm with weak southwesterly flow still a
few hours away from developing. Thus...took the 01z analysis temperature
grid...and allowed several more degrees of drop before steadying
out and allowing a better rise in the overnight. This should
coincide with arrival of thicker middle/high level cloud seen
gathering over ill/in at this hour. 20.00z radiosonde observation from Kiln sampled
the very dry troposphere that is supporting the temperature drop...with
precipitable water a measly 0.21" amidst a weak warm air advection flow pattern aloft.
Minor disturbance over Illinois ahead of more significant
northern plains shortwave will move east and strengthen some as
heights fall with overall deepening of trough in eastern US.
Result will be continued growth/expansion of 8-9kft altostratus
deck and eventual generation of some -shra later tonight over southern
ind/northern Kentucky. Very dry sub-cloud layer will need to be overcome and
think radar will have more bark than bite /more reflectivity shown
than what will be hitting the ground/ so keeping southeastern Indiana/southwestern
Ohio/northern Kentucky dry overnight...with increase in a sprinkle/very light
shower threat on Monday morning.
Short term /6 am Monday morning through Tuesday night/...
center of the surface high well off to the middle Atlantic by Monday morning
and the trough on our doorstep by 12z. Am siding with the higher
resolution solutions which dont bring in precipitation until after
12z with some lack of ll moisture. Better isent lift doesnt get
into forecast area until after 12z...with the more numerous showers
expected in the northern forecast area into the day. For Monday evening
into Tuesday...models are in fairly good agreement with the upper
trough cutting off and slowing down over the eastern Great Lakes.
This will linger precipitation in the eastern forecast area through
the period...along with ample clouds. As the precipitation tries
to pull east Monday night...moisture wrapping around the upper low
so am keeping chance of showers through the day Tuesday. A return
of some good fetch off Warm Lake Michigan...so have also allowed for
scattered/isolated light showers in the far western forecast area
during the day on Tuesday before the flow becomes more due
northerly and the chances diminish area wide. Confidence not high
with completely pulling out precipitation in the east...as we will
have to watch the progression (or lack thereof) of the upper low.
Long term /Wednesday through Sunday/...
highly amplified middle/upper level flow with a Sharp Ridge over the
nations middle section and a mean trough over the East Coast to start the
long term period. Numerical model solutions in good agreement showing
upper low cutting off to our east over the Middle Atlantic States
Wednesday. Flow around this low will result in northerly flow over
the Great Lakes/Ohio Valley with surface high pressure building south
into the region. Expect main area of precipitation to be east of
iln/S forecast area with a decrease in clouds from west to east during the day.
Expect Wednesday/S high temperatures to be about 10 degrees below
normal...with highs ranging from the lower 50s north to the middle
Upper low to translate into New England with ridging aloft and at
the surface building into the region through the end of the work week. This
ridge will keep iln/S forecast area dry with embedded short wave to pass south of the
region Friday. Below normal temperatures will continue with some
moderation through the week. Lows in the middle/upper 30s on Wednesday and Thursday
nights may lead to patchy frost formation. Have included a mention
in the grids and severe weather potential statement product.
Expect highs on Thursday in the middle and upper 50s with some
moderation on Friday when highs are expected to range from near 60
north to the lower 60s south.
Northern portion of upper level ridge to flatten with northwest flow
over Ohio Valley next weekend and active weather to stay well to our
northeast. Surface high pressure to re-establish over the Great
Lakes/Ohio Valley offering continued dry weather. Highs near normal
next Saturday/Sunday...ranging from the lower 60s north to the middle
Aviation /02z Monday through Friday/...
going tafs were well trended. Cirrus continues to spread over the
taf sites early this evening. Conditions should remain VFR at
least through 12z to 15z. Toward sunrise some high-based showers
should develop in a scattered fashion over southeastern ind/northern Kentucky/southern Ohio
and spread quickly east. These should mostly fall out of a 8-10kft
altostratus deck...so expect no visibility restrictions or ceiling issues.
Boundary layer flow will steadily increase through the morning and
become gusty out of the SW...with gusts in excess of 20kts likely
at all airfields. By about 16z...more widespread shower activity
should develop near and north of kday and spread quickly toward
kcmh/klck...where prevailing VFR -shra have been added to the tafs
for the afternoon hours. These may also affect iln/cvg/day/luk but
confidence not high enough right now to go beyond VFR cigs/vsby.
Outside chance of some MVFR ceilings in the at kcmh/klck...but will
hold off on that for now. Also outside threat for MVFR ceilings in the
30 hour portion of cvg taf as further moistening occurs ahead of
Outlook...MVFR ceilings are possible from Monday night through