Area forecast discussion
National Weather Service Wilmington Ohio
207 am EDT Wednesday may 22 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 this 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 this morning through 6 PM Thursday/...
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 night 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 /06z Wednesday through Sunday/...
region will remain in a moist south to southwest flow at the
surface and aloft as the center of an upper level low pivots
southeast toward the western Great Lakes. As the low moves
southeast...a surface cold front will push east through our area
tonight.
Latest analysis and models indicate that our area is in an
instability minimum early this morning. As such...the low level
jet that is forecast to develop overnight should produce some
scattered showers and perhaps a rumble of thunder.
For today into this evening...the prospects of showers and
thunderstorms will increase through the day as daytime heating
interacts with large scale synoptic lift. Best chance for
widespread showers and thunderstorms will be from middle afternoon
into the evening hours. Have placed this in the tafs with a
predominant MVFR -shra and a vcts/cb. As storms become more apparent
and can be tracked on radar...tafs will be fined tuned
accordingly. With a moist airmass...some local MVFR ceilings and IFR
visibilities will be possible in thunderstorms. Daytime heating/mixing
will produce south/southwest winds of 10-15 knots with gusts
around 25 knots.
For tonight...a cold front is forecast to push east across the
region. Large scale lift decreases as does the instability.
However...models indicate that there could be a band of showers
and a few embedded thunderstorms along and ahead of the front.
Have indicated this with a vcsh as thunderstorms chances will wane
between 01z and 06z. After frontal passage...there should be a
reprieve in precipitation but low level moisture will likely result in some
MVFR ceilings.
Outlook...MVFR conditions possible Thursday into Thursday evening.
&&
Iln watches/warnings/advisories...
Ohio...none.
Kentucky...none.
In...none.
&&
$$
Synopsis...Novak
near term...Arkansas
short term...Novak
long term...coniglio
aviation...Hickman
