Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington Ohio
1009 PM EDT Wednesday Jul 1 2015
an area of low pressure will ride east along a stalled boundary
near the Ohio River tonight into Friday. This will keep a chance
of showers and thunderstorms across portions of the region each day.
Temperatures will remain slightly below normal for the next
Near term /until 6 am Thursday morning/...
stalled front continues to reside across southern Ohio...close to
the Ohio River. There have been a few showers that have brushed our
southeast Indiana and northern Kentucky counties but for the most
part County Warning Area has been dry this evening.
Will continue with low probability of precipitation for showers across these areas
through the overnight...but it looks like the bulk of the
convection instigated by a middle level shortwave will remain
southwest of the County Warning Area. Main impact across the County Warning Area will be some
clouds...which should also help to inhibit fog formation.
Lows tonight should be a little warmer than last night with a
little more cloud cover expected. Ranged the lows from the upper
50s in west central Ohio to the lower 60s along the Ohio River.
Short term /6 am Thursday morning through Friday night/...
models swing a surface low up the Ohio Valley tomorrow. The Canadian
hemispheric is the quickest and strongest with the low...pushing a
large area of precipitation across the southern half of the forecast area. The 00z European model (ecmwf)
keeps things more muted with the precipitation limited to Kentucky. The GFS and
NAM are in between the two extremes...so will go with the compromise
solution. Went with high chance probability of precipitation across northern Kentucky...tapering up
to a dry forecast in west central Ohio.
The surface low slides across eastern Kentucky Thursday night...kept a
chance of precipitation going...especially across northern Kentucky. Another 500 mb short wave
swinging through the Ohio Valley on Friday will bring another
round of scattered convection.
Highs on Thursday and Friday will be in the middle to upper
70s...about 7-10 degrees below normal. Lows on Thursday night will
be similar to tonight range from the upper 50s north to the middle
Long term /Saturday through Wednesday/...
500 mb vorticity maxima will be departing Ohio Valley to the east to start
the day Saturday but another stronger 500 mb short wave and vorticity will cross the
Great Lakes region during the day. NAM probability of precipitation convection over the County Warning Area
but this is not supported by synoptic models and an unfavorable
lower atmospheric profile with surface high pressure building in. Both
the surface and an upper ridge builds over the region Sunday and
some moisture to the southwest of the surface ridge may permit
storms during the heating of the day over Kentucky.
Southerly flow kicks in overnight Sunday and continues until the
next cold front crosses later Tuesday. While Monday does not appear
to be the best day for convection to fire...the southerly flow and
closing proximity of a cold front necessitates low chances for
storms in the forecast. The breakdown of the upper ridge and diurnal
heating also support inclusion of probability of precipitation during this time.
While there are still some timing differences it appears the cold
front will cross the Ohio Valley during peak heating Tuesday and
this is the best chances for storms in this forecast period.
Model guidance on temperatures had very little variability and a
blend was used with the earlier official forecast. Raised temperatures a
bit Monday night ahead of the front in the warm sector...generally
around 70 but not quite as warm as mex guidance. Trending that
direction and think the mex numbers are not unreasonable in the
lower 70s. Highs in the upper 70s to lower 80s will be slightly
below climatology for much of the area through this time.
Aviation /02z Thursday through Monday/...
prevailing VFR conditions were observed across the terminals this
evening. Radar showed a few showers over southeast Indiana...moving
E/se. Can/T rule out one of those showers making it to cvg/luk
middle-late evening but confidence is low. Main challenge revolves
around potential for low visible in fog development overnight. Do not
believe conditions are as ideal as last night...and have generally
kept visible above guidance. Main concern is at luk/cvg. Allowed for a
period of IFR at luk...otherwise generally kept tafs in VFR.
There is the potential that visible could be lower than forecast at
Synoptically...a frontal boundary remains draped along the Ohio
River. Near/south of the front is where the chance of rain showers/thunderstorms and rain
will reside into Thursday. For now have vcsh at luk/cvg. Some
guidance suggests may need inclusion further north into the
afternoon/evening...but have not introduced into the end of the
taf valid period at this time.
Outlook...thunderstorms possible Thursday night through Sunday.