Scientific Forecaster Discussion
fxus61 Kiln 221800
Area forecast discussion
National Weather Service Wilmington Ohio
200 PM EDT Thu Jun 22 2017
moisture from Cindy will overspread the region today. A cold
front will drop southeast across the area Friday afternoon and
evening, with heavy rainfall possible ahead of this front.
Temperatures will drop below normal through the weekend and into
early next week.
Near term /until 6 PM this evening/...
a widespread cirrus shield has pushed into our central and
southern zones this morning with temperatures being held back
slightly. This afternoon the iln forecast area will be in
between a mid-level ridge across the eastern United States and
an upper level trough axis across southern Canada. At the same
time Tropical Depression Cindy will be approaching from the
south. A broad shield of precipitation is currently located in
Tennessee and will move into the iln forecast area this
evening. The main concern for the forecast package this
afternoon will be early Friday morning with a band of
precipitation forecasted to form out in front of Cindy. Latest
run of the 12z NAM has a band of 1" to 3" forming and running
along a Wayne (in) to Champaign County Ohio line Friday morning
and continuing into Friday afternoon. This will likely require a
Flood Watch. Will wait for 12z cams before making final
decision on watch.
extensive high clouds will be present across the area. Looks
like they should be thin enough in the north for temperatures to
still rise into the upper 80s. Further south expect them to be
thicker and/or thicken earlier. In addition, some showers and
thunderstorms may start spreading in late in the day ahead of
mid level impulse. South winds may become a bit gusty.
Short term /6 PM this evening through 6 PM Friday/...
mid level impulse will move northeast during the evening.
Instability is forecast to be decreasing, but still expect an
area of showers and embedded thunderstorms to track across the
region, especially the southern and eastern counties. This area
of precipitation will also be the leading edge of the tropical
air mass with precipitable water over 2 inches.
Strong, persistent moisture transport into the region combined
with good upper support in the right rear quadrant of an upper
jet will result in abundant vertical motion and widespread
showers with embedded thunderstorms starting late tonight and
continuing through most of the day Friday. There will be a
frontogenetical axis that will maximize vertical motion and
create a band that will likely have heavy rainfall. Still some
disagreement in 00z models where this corridor sets up which
provided enough uncertainty to hold off on a Flash Flood Watch.
At this stage, the best forecast is for the highest rainfall
totals to extend from Ripley County to Fairfield County with the
greatest rainfall occurring between 09z and 18z. The band will
become more progressive in the afternoon as the front pushes
Temperatures will remain warm tonight with lows around 70, but
readings will not rise much during the day except for perhaps in
the far southeast counties where there may be a window in the
morning for temperatures to warm before more widespread
precipitation makes it there.
Long term /Friday night through Thursday/...
plenty of lingering tropical moisture in the way of precipitable water values still
in the 95th percentile in the southern and southeast forecast area
in especially the 00-06z period Friday evening. Still some
distinction between the actual ts remains and the ESE advancing
frontal boundary in terms of 2 areas of greatest ascent/forcing
combining with ample moisture. Continued mention of heavy rain in
the southeast forecast area, where lingering warm cloud depths near
4k ft and se counties on the edge of area of favorable moisture
transport and continued ascent with the continued frontogenetic
forcing until the frontal boundary finally pushes the most efficient
moisture further east of forecast area.
A fairly tight back edge gradient and clearing skies for Saturday
after 12z with slightly below normal temperatures as the broader
upper level trough axis begins to swing through and weak surface
high pressure builds into the central MS valley and lower Ohio
As the mid level trough sharpens up a bit on Sunday, precipitation
potential mainly across northern forecast area where some limited
moisture rides along the northern fringe of the aforementioned
surface high. A slightly more pronounced mid level trough and
associated shortwave passes north of the area again late Monday into
Monday evening, so another period of scattered showers and isolated
thunderstorms. For later in the week, decent agreement between the
GFS/GFS ensemble and European model (ecmwf) of a deepening this mid level trough
positioned over the eastern Great Lakes and keeping the region under
broader northwest flow and therefor below normal temperatures through the
remainder of the period, with daytime highs in the mid 70s
increasing to near 80 by the end of the period.
Aviation /18z Thursday through Tuesday/...
currently all taf sites VFR this afternoon with a shield of
precipitation approaching from the south. This shield of showers
are in association with an upper level disturbance that is
forecasted to push north and then east around a ridge of high
pressure off the coast of Georgia. Latest guidance continues to
show the shield of showers weakening as they move north. Brief
restrictions of MVFR will be possible.
A band of showers and thunderstorms will then form Friday
morning starting around 9z and slowly sag southeast. Inside this
band, restrictions down to LIFR will be possible in the
heaviest cells. The band of precipitation will then slowly sag
southeast during the afternoon keeping most of the taf sites
IFR/ MVFR through the day Friday until the end of the taf
issuance. Not until Saturday morning will taf sites recover.
Outlook...intermittent MVFR ceilings possible Saturday through
Ohio...Flash Flood Watch from late tonight through late Friday night
Kentucky...Flash Flood Watch from late tonight through late Friday night
In...Flash Flood Watch from late tonight through late Friday night