Area Forecast Discussion
Issued by NWS Wilmington, OH-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KILN 221709
Area Forecast Discussion
National Weather Service Wilmington OH
109 PM EDT Sat Oct 22 2016
The region will find itself under northerly flow today as it is
trapped between a strong low pressure system over New England and
building high pressure in the lower Mississippi Valley. This will
bring cool conditions today. By Sunday, the high will be over the
southeast U.S. which will turn the winds to the south bringing a
quick warm up. Another cold front will drop temperatures for the
beginning of the work week.
.NEAR TERM /THROUGH TONIGHT/...
Surface high pressure is extending from the lower Mississippi
Valley region into IL/IN, with a similar pattern at 925mb. Cool
northwesterly flow exists on the east side of the axis of the
high. A much broader 700mb ridge over the western two-thirds of
the country is leading to a longer spread of northwesterly
flow...keeping temperatures fairly cool in the lowest couple
kilometers off the surface. Because moisture through 700mb is not
especially thick, clouds have formed in patches across the ILN
forecast area, with some big breaks in between. Not easy to put
this pattern into a sky grid, but the overall trend through the
next 6-12 hours will be for generally cloudier conditions in the
northeastern ILN CWA, and generally clearer conditions in the
southwestern ILN CWA. Temperatures will be similarly arranged,
with warmer conditions near Cincinnati and cooler conditions near
Columbus. Overall, however, no significant changes were made to
the going forecast.
Previous discussion >
With a closed H5 low located over the ne U.S., the region is under
a northerly CAA flow. This is bringing lake effect clouds down
across the area. However, the low level flow is beginning to back,
allowing breaks in the clouds. These breaks will work se into the
fa this morning. Unfortunately, H8 temperatures will remain below
0C today and as diurnal heating kicks in, lapse rates should kick
over and the sc will redevelop. Therefore increased the cloud
cover for the late morning into the afternoon.
Winds will pick up again today as mixing occurs. Gusts will range
from 10-15 in the Tri-state to 20-25 in Central OH.
With the cloud cover to help limit the solar insolation,
temperatures will be well below normal again, reaching the lower
to mid 50s. This will be 5-10 degrees below normal.
.SHORT TERM /SUNDAY THROUGH MONDAY/...
The upper level low will kick e tonight allowing the H5 heights to
rise. At the surface, high pressure will work from the lower MS
valley into the se U.S. Still expect some lingering clouds tonight
as this transition occurs. Temperatures aloft will be warming
tonight, but feel that there will be enuf decoupling of the
boundary layer that sfc temperatures will see a normal diurnal
By Sunday, sfc winds will have turned to the sw. This will bring
in warmer air and with a lack of cloud cover temperatures will
warm to near 70 in the Tri-state and mid to upper 60s elsewhere.
Models bring a H8 jet of 40 to 50 kts across the fa, so expect
some wind gusts to around 30 mph on Sunday.
Sunday night a cold front will drop down from Lake Erie. There is
enuf moisture will the system to produce some clouds with fropa,
but right now it is looking like the front will come through dry.
By sunrise Monday, the front will be south of the Ohio River,
leaving the fa mostly clear. Monday will be a little cooler under
northerly surface winds. Highs will range form the upper 50s in
Central and West Central OH to the mid 60s in nrn KY.
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Tuesday morning surface high pressure will move in from the north
allowing winds to go mostly calm . Some high clouds may be moving
in from the west, but chances seem to be growing that frost may be
During the day Tuesday a shortwave will move over the midwest and
head east. At the same, the upper level trough axis over New England
will pull east. In response to the shortwave, a surface low will
form near the Nebraska/ Iowa border. During the day Wednesday the
shortwave will strengthen and start to wrap up. Both the GFS and
ECMWF are in pretty good agreement with this and have the shortwave
wrapping up into a low over Wisconsin Wednesday evening. Across
southwest Ohio low level flow will continue to increase ahead of the
low with strong upper level divergence. Divergence will come from
the RRQ of the upper level jet streak along with upper level
diffluence from the splitting of 250 mb winds. Instability at this
time looks limited but shear profiles are impressive (SFC-1km ~35kts
via GFS forecast soundings). Any change in the placement of the low
will easily change the values and orientation of the bulk shear
vectors though. Future model runs will help to continue to refine
this. Thursday afternoon into Friday the shortwave will push east
but the ECMWF and GFS differ on how the shortwave ejects. The ECMWF
picks up the shortwave in the main flow moving a cold front through
the area. The GFS on the other hand washes the shortwave out and
slowly pushes it southeast. The CMC has the shortwave diving into
southeast Texas and appears to be the outlier. For now have kept the
forecast trended towards ECMWF.
.AVIATION /17Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --Scattered to broken cumulus clouds have developed across the
region. Most of these clouds are now VFR, though there have been
some brief MVFR ceilings at times. Winds today will remain out of
the northwest, with gusts of up to around 20 knots.
Skies will gradually clear tonight, as winds back to the west and
weaken. Clear skies should continue into Sunday, with
southwesterly winds expected to gust to around 20 knots.
OUTLOOK...No significant weather expected.
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