Scientific Forecaster Discussion
fxus61 Kiln 251507
Area forecast discussion
National Weather Service Wilmington Ohio
1007 am EST sun Feb 25 2018
surface high pressure will build into the region today offering
dry weather and cooler temperatures. This high will build across
the Ohio Valley providing continued dry conditions through
Tuesday. Moisture looks to return in the southerly flow on the
back side of retreating high pressure Wednesday.
Near term /until 6 PM this evening/...
negatively tilted mid level S/W to pivot northeast from the
Great Lakes into southern Canada with a broad swrly flow over
the Ohio Valley. Surface high pressure will build in from the
southwest. Based on the latest visible satl imagery have slowed
the clearing with partial sunshine developing this afternoon.
Temperatures will recover a little this afternoon after falling
this morning in the wake of a strong cold front. Expect
afternoon readings from the mid 40s northwest to the mid 50s
Short term /6 PM this evening through Tuesday/...
even though high pressure will build in at the surface, cirrus
will spread north tonight as 500 mb vort lifts northeast in the srn
stream. Low temperatures will be cooler tonight ranging from
the lower 30s in west central Ohio to the mid to upper 30s in
High pressure will affect the region Monday into Tuesday.
The center of the high will move across the fa Monday afternoon,
reaching the East Coast Tuesday. Skies will generally be
sunny/clear through the period. Highs on Monday will be in the
lower to mid 50s. After morning lows in the lower to mid 30s,
highs on Tuesday will warm to the upper 50s as southerly flow on
the back side of the high will bring the warmer conditions.
Long term /Tuesday night through Saturday/...
the main concern through the extended forecast period is the complex
weather system moving into the region between Wednesday morning and
some indeterminate time later in the week -- the latter statement a
reflection on the inconsistency in the way the developing mid-level
low is being handled by the models. Initially, an expansive area of
precipitation is expected to develop early Wednesday morning through
the day across the Tennessee Valley and southern Ohio Valley
regions, largely forced by low-level warm advection and upper-level
divergence and jet support. This first round of precipitation will
affect the iln County Warning Area but will be more of an issue further to the
south, with a fairly consistent signal for the heavier rainfall to
miss the forecast area. Rapidly strengthening forcing ahead of the
sharpening mid-level trough (which eventually will close off into a
low) will spread greater rainfall chances across the forecast area
on Wednesday night into Thursday, with the potential for wrap-around
precipitation in the cold advection behind the low. The main
differences in the models regarding this system are in the speed of
the development of the mid-level low and its eventual progression to
the east. While the 06z/12z GFS runs were fairly consistent, the
00z/12z European model (ecmwf) runs swung wildly from a flat and progressive solution
to one that is more wound up and even slower than the GFS.
Nonetheless, even the GFS ensemble members show a wide spread in the
position of the low. Overall, given these issues, pops were changed
very little from the previous forecast -- with some slight extension
outward in time to allow for some light rain/snow to continue into
Friday morning. Though there is likely attention on this system with
regards to rainfall potential, given the very wet conditions over
the Ohio Valley, it currently looks a little too soon and too
uncertain to say if this expected rainfall will lead to additional
On the warm side of the mid-week system, temperatures will remain
fairly warm -- with highs in the upper 50s to lower 60s. Once a cold
front moves through (currently expected in the Thursday night time
frame) cooler conditions will move in for Friday and into the
weekend. Even still, conditions at the end of the extended period
will be fairly close to normal.
Aviation /15z Sunday through Thursday/...
aside from some high end MVFR cigs that will persist over
northern County Warning Area through 18-19z, conditions today will be VFR and
windy from the west with gusts to 30 and 35kt early. These cigs
will be more prevalent early this morning and mix out in the
late morning, being primarily scattered with an occasional cig.
Wind gusts will calm down some as the morning progresses to a
more manageable 20-25kt and lessen even further in the
afternoon. By 22-23z, any winds will have calmed down and they
will begin to shift northwest overnight under 5-6kt with
generally clear skies.
Outlook...MVFR conditions possible Wednesday and Thursday in