Area forecast discussion
National Weather Service Wilmington Ohio
421 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 /20z Wednesday through Monday/...
scattered showers and thunderstorms are expected to develop during
the early part of the taf period. There is low confidence when/if
storms may affect the terminals. So for the initial issuance have
kept a thunderstorms in the vicinity in for the period of higher probability. Outside of
any storms conditions will remain VFR this afternoon and well into
the night. Gusty south winds will diminish around 00z and slowly
veer. Appears that MVFR ceilings may develop region wide late
tonight although confidence is only moderate in this occurring.
Clouds should lift to VFR at most places late in the taf period.
Winds will continue to veer on Thursday.
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...
