Area forecast discussion
National Weather Service Wilmington Ohio
948 PM EDT Tuesday may 21 2013
Synopsis...
with an unstable airmass in place showers and thunderstorms will
be possible across the region this evening. Thunderstorms will be
present across the area on Wednesday in advance of a cold front.
The cold front will move through the area late Wednesday night
into Thursday.
&&
Near term /until 6 am Wednesday morning/...
northern fringe of linear convective complex which affected the southeast one
third of ilns forecast area is exiting the region. 00z iln sounding showed
cape of less than 500 j/kg with warm temperatures aloft. This lack of
good instability combined with a cap in low level inhibited the
development of deep convection across the northwest two thirds of the forecast area.
Ilns forecast area will be in a minor convective lull through remainder of this
evening into the overnight with weak short wave ridging over the area.
Focus shifts to thunderstorm complex which developed in the lower
MS valley and was moving into the lower Ohio Valley. Short wave in southwesterly flow
expected to pivot NE into the Great Lakes overnight. This complex
was being driven by low level jet. 40 knots low level jet expected to
pivot into western Ohio toward sunrise. At this time...elevated
instability will be marginal. So expect remnants of convective complex
to provide an increase clouds but only a chance of a shower/thunderstorm
with this feature in a weakening stage. Have limited probability of precipitation to chance
west and only slight chance east late.
Given increase in cloud cover and srly gradient...temperatures will be mild
overnight. Expect lows in the middle and upper 60s.
&&
Short term /6 am Wednesday morning through Wednesday night/...
showers and thunderstorms will continue to overspread the forecast area
during the daytime hours on Wednesday. There is still some
question as to the severe potential for Wednesday. There is better
instability across eastern portions of the forecast area for Wednesday. In
addition storms will hold off a little longer across eastern
portions of the forecast area which will allow for some more heating. Due to
this believe that the better severe threat will be across eastern
portions of the forecast area for Wednesday with the main threats being
damaging winds and large hail. Precipitation coverage across the area
will diminish during the late evening hours however some isolated
activity will still remain possible. Additional showers and
thunderstorms will begin to move into western portions of the forecast area
late in the overnight hours Wednesday night as the cold front
approaches the area.
&&
Long term /Thursday through Tuesday/...
showers are likely to develop mainly over northern locations on
Thursday as a sharp upper trough and cool airmass push through the
Great Lakes and Ohio Valley. Friday will be dry and cool with high
pressure crossing the area. Dry weather should continue on Saturday
for most of the area except for far southeast counties where a
developing frontal boundary may cause a few showers.
For Sunday through Tuesday...that frontal boundary is forecast to
linger across Kentucky. This pattern will provide a chance of
showers each day to the southern part of the forecast area...with
northern locations enjoying a period of dry weather.
Slightly below normal highs averaging in the lower 70s on Thursday
will be followed by below normal 60s on Friday under clouds and
showers. Temperatures will then gradually rebound from Saturday
Onward...with highs reaching the middle and upper 70s by Tuesday.
&&
Aviation /01z Wednesday through Sunday/...
possibility of thunderstorms will continue to be the main concern
through the taf forecast period. Northern fringe of linear convective
system pushing through southeast Ohio will stay southeast of the taf sites this
evening. Short term trends continue to suggest that the possibility
of convection for this evening is decreasing. Therefore...start
the tafs off dry through the evening hours.
Next complex developing over the lower MS valley will track NE into the
Ohio Valley overnight. Mesoscale models indicating that convection
in a weakening phase pushes into western Ohio between 06z and
12z. There is a good deal of uncertainty regarding what will be
left. At this time...have increased clouds and added a mention of
vcsh to all tafs.
Southwest gusty winds will pick up again on Wednesday. Have gusts
as highs as 26 kts. There is a chance of showers and thunderstorms
any time after 12z...but the higher probability will be very late
in the taf period. Have mentioned thunderstorms in the vicinity during the afternoon and then
late in the taf period have prevailing showers and thunderstorms in the vicinity during this
higher threat period.
Outlook...thunderstorms likely Wednesday evening. MVFR to IFR
ceilings possible late Wednesday night into Thursday morning. MVFR
ceilings possible again Thursday night.
&&
Iln watches/warnings/advisories...
Ohio...none.
Kentucky...none.
In...none.
&&
$$
Synopsis...Novak
near term...Arkansas
short term...Novak
long term...coniglio
aviation...Arkansas
