Area forecast discussion
National Weather Service Wilmington Ohio
756 PM EDT Wednesday may 22 2013
Synopsis...
low pressure will continue to lift northeast along a frontal
boundary this evening...before a weak cold front swings into
the region overnight. A secondary front will bring a chance of
rain again on Thursday. Much cooler air will move into the region
on Friday... as high pressure builds into the Ohio Valley through
Saturday.
&&
Near term /until 6 am Thursday morning/...
radar continues to show scattered convective activity over the forecast area. While
the best instability is in the southeast...the better forcing is across
the west...due to lift from an upper level short wave and surface front. This
disjointedness should act to limit the overall coverage of the
convection this evening and into tonight. So have gone with 40-50
probability of precipitation for the next few hours and went with scattered wording. With
the loss of daytime...we should see a decrease in activity...but
with the front entering the region cant totally rule something
out later in the night.
Lows should fall back into the upper 50s in the west...with eastern
locations staying in the lower 60s.
&&
Short term /6 am Thursday morning through Friday night/...
initial front kind of washes out early Thursday...but a secondary
front drops in behind it. In addition...a pretty sharp 500 mb trough
swings up the Ohio Valley. This should provide the best lift of
this system. Instability will be very weak...but just
enough for some risk of thunder. The air mass aloft will be
increasingly cold...helping to lead to the possibility of
convective showers. So upped probability of precipitation on Thursday. Went categorical in the
northwest...likely probability of precipitation for a much of the rest of the forecast area.
Convection will linger into Thursday evening as the short wave continues to
swing through. High pressure will build in for Friday. Could see
some fair weather cumulus as cold air aloft kicks the lapse rates over.
Skies should then clear for Friday night.
Highs on Thursday will have a wide range. This is due to the cold
front pushing through the region. Highs in the northwest will be limited to
the upper 60s...while in the southeast they will push into the middle 70s.
Lows will fall pack into the 40s Thursday night and only will
rebound into the lower to middle 60s.
&&
Long term /Saturday through Wednesday/...
large area of high pressure will hold sway over the Ohio Valley and
Great Lakes region for the weekend. Previous models were showing a
narrow tongue of quantitative precipitation forecast/probability of precipitation pushing southeast from the Iowa/Illinois area but
were keying on a 500 mb short wave cutting through the established ridge and
dissipating as it went downstream into the Ohio Valley. This
scenario is still a possibility but seen as a distant outlier at
this time.
GFS is still showing these 500 mb disturbances undercutting the ridge
and nosing into the region Monday/Tuesday where European is somewhat
similar with an elevated convergent layer but much further southwest
and out of County Warning Area.
Surface high moves offshore early next week with drying southeast
surface winds over the Ohio Valley. Upper level flow is showing a
broadening of the 500 mb ridge as it moves over the eastern third of the
country. Have increased the chances for middle level disturbances to
undercut the ridge at this time but keep the threat for showers low
at 20% towards the middle of next week.
Expect a gradual warmup each day...starting in the upper 60s to
around 70 Saturday...warming to near 80/low 80s by Wednesday. PM lows will
be comfortably cool in the 40s through Monday morning under a dry
airmass and then warm to the climatological norms in the middle 50s by
middle week.
&&
Aviation /00z Thursday through Monday/...
showers and isolated thunderstorms around the area at the start of
the taf period will decrease in coverage the next few hours. A few
light showers will still be possible through the first half of the
night as a subtle frontal boundary moves through the area. Not
expecting much in the way of a wind shift with this boundary.
Models are indicating the potential for some MVFR to IFR ceilings late
in the overnight time frame for a few hours. Decided to limit ceilings
to MVFR at this time. Also kept a few hour time period of MVFR
visibilities at kluk.
A secondary cold front will move through during the day on
Thursday this time with a more pronounced wind shift. In addition
expect showers to develop during the day across the taf sites. A
few rumbles of thunder will also be possible. Due to the cooler
air moving in aloft expect some small hail to also be possible
during the afternoon and early evening hours on Thursday. Winds
will begin to gust during the afternoon and early evening hours on
Thursday with the secondary front and ceilings will lower into the
MVFR category.
Outlook...MVFR ceilings likely late Thursday into Thursday night.
&&
Iln watches/warnings/advisories...
Ohio...none.
Kentucky...none.
In...none.
&&
$$
Synopsis...sites
near term...sites
short term...sites
long term...franks
aviation...Novak
