Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington Ohio
350 PM EDT Thursday Aug 27 2015
high pressure will continue to build across the region tonight
through Friday. A weak upper level disturbance will result in the
chance for a few showers and thunderstorms...primarily Saturday
night into Sunday. Seasonable temperatures are expected through
Near term /through tonight/...
cumulus field across the area has been becoming more cellular looking
this afternoon so would expect it to dissipate fairly quickly as
we head into this evening. Surface high pressure pushing east
across the southern Great Lakes should then result in mostly
clear skies overnight. With good radiational cooling...expect
lows tonight down into the low to middle 50s with a few upper 40s
possible in outlying areas.
Short term /Friday through Saturday night/...
surface high pressure will push off to the east Friday into
Friday night...with return flow then developing. This will help
push temperatures up into the upper 70s to lower 80s for Friday.
Southwest low level flow will continue to increase Saturday into
Saturday night ahead of an approaching upper level trough. As
temperatures climb into the low to middle 80s on Saturday...ml convective available potential energy
will push into the 1000-1500 j/kg range through the
afternoon...especially across northwest portions of our forecast area. The
combination of this and a 20-30 knot low level jet rotating up
across Indiana into Northwest Ohio...may be enough to produce
isolated shower and thunderstorm development across mainly the
northwest portions of our forecast area Saturday afternoon. As the upper
level trough approaches...will then allow for slight chance probability of precipitation
across the remainder of the forecast area Saturday night.
Long term /Sunday through Wednesday/...
the 27.12z models are starting to come into a little better
agreement with upper level flow patterns for at least the first half
of the extended period. Given the continued significant spread
amongst the gefs members however...confidence is still below normal
so have generally used a blend of the GFS/European model (ecmwf) and wpc guidance.
An approaching cold front will wash out across our area on Sunday as
a slow-moving middle/upper shortwave weakens over the lower Great
Lakes. These features will allow for a chance of showers and storms
mainly Sunday into Sunday night. Once the shortwave dissipates...the
GFS/European model (ecmwf) differ in their treatment of the associated lingering vorticity
maxes and produce noisy quantitative precipitation forecast fields through Monday evening as a
result. Have therefore gone with broad brushed slight chance probability of precipitation
for much of the County Warning Area on Monday. The remainder of the extended period
looks generally dry at this time.
There is general agreement on a developing upper ridge over the
plains early next week that will broaden as it shifts eastward over
the eastern Continental U.S.. this will lend itself to warmer than normal
temperatures given gefs 850mb temperature and 500mb height anomalies
are around 1 to 2 Standard deviations above normal for parts of the
area. Expect high temperatures to warm by a degree or two each day
Monday through Wednesday with highs generally in the middle to upper
80s. Would not be surprised by some 90s near and south of the Ohio
Aviation /19z Thursday through Tuesday/...
northwest flow aloft with mean trough shifting to our east. This
will allow surface high pressure to build into a position centered
over Southern Lower Michigan this afternoon. With 800 mb thermal trough over the
area a good amount of cumulus has developed around 5000 feet today.
These diurnally driven clouds are expected to dissipate from SW
to NE between 22z and 00z. Light north to northeast winds will
veer to easterly tonight and southeast on Friday. With clear skies and
light winds overnight expect MVFR visibility restrictions to
develop at kcvg...klck and kday. IFR conditions are expected at
kluk and Kiln. Fog to burn off quickly Friday morning with VFR
conditions and only some high level expected through the remainder of
the taf forecast period.
Outlook...no significant weather expected.