Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington Ohio
948 am EDT Wednesday Apr 1 2015
high pressure and dry airmass will move east today. A frontal
zone will develop on Thursday and remain in the area through
Friday. Several waves of low pressure traveling along the front
will provide forcing for multiple rounds of rainfall. High
pressure and dry air will move back in for Saturday.
Near term /until 6 PM this evening/...
high pressure centered to the east will continue to provide dry
weather today. Sunny skies and modest warm advection on a
southerly flow will allow highs in the 60s. Light winds will
greatly reduce fire threat compared with Tuesday.
Short term /6 PM this evening through Friday night/...
the beautiful weather of today will quickly come to an end
Thursday as an upper level low over the southern Canadian
provinces heads to the east. At the same time a shortwave
currently over central Texas will be pulled north towards Ohio
Thursday morning. Rain looks to start Thursday morning around or
just after sunrise as the remnants of the Texas shortwave bring
positive vorticity advection across the area. Precipitable waters for Thursday morning are forecasted to
quickly rise from 0.3" to around 1.4" by Thursday afternoon. As
the upper level low over southern Canada pulls east it will begin
to wash out and allow a cold front to stall over the area. The
Euro... NAM... and CMC all stall the front across the area through
Friday. The GFS pushes the front through Friday but seems to be
the outlier here and continues to slow the front down model to
model run. Have leaned towards the Euro/ Canadian/ and NAM given
that another shortwave forecasted to move through the area Friday
evening is what will finally give the required push to get the
front out of the area.
Late Thursday the jet also begins to split over southwestern
Kentucky with Ohio falling into a rrq. This widespread diffluence
and divergence looks impressive and should provide ample lift
across the area. As mentioned above precipitable waters also climb to near 1.40"
or 90th percentile according to the situational awareness table.
The GFS and NAM also differ here on the amount of instability
present. The NAM allows for more warming Thursday across the area
which helps boost cape values to near 1500 j/kg in our southern
zones. The NAM also has effective shear values around 35 knots.
The low level jet is impressive Thursday afternoon maxing out near 60 kts.
The GFS cape values are much more tame with cape values of only
100 -300 j/kg. Storm Prediction Center has also issued their new day two outlook which
includes a slight risk across the central and western parts of the
County Warning Area. Given the parameters above some storms could be strong and
As the frontal boundary stalls across the area late Thursday into
Friday heavy rain will be possible. Widespread upper level lift...
above average precipitable waters ... near parallel boundary flow... and sufficient
instability point to possibility of flooding. Wpc also has the area
in a slight risk for excessive rainfall for this this time period.
Have added the mention of heavy rain to the grids to account for
Another shortwave will push across the area Friday afternoon into
evening finally allowing the front to clear the County Warning Area. Positive vorticity advection from the
shortwave will allow precipitation to continue some behind the front
though as the drier air lags. This will bring the chance of snow
back into the forecast Friday night into early Saturday morning.
Long term /Saturday through Tuesday/...
after the active weather pattern of Thursday and Friday high
pressure will begin to build southwards towards Oklahoma/ Arkansas
bringing an end to the snow. Precipitable waters fall to around a quarter of an
inch Saturday which will make for a beautiful day. Temperatures
will be below normal though as cold air advection along with 850 temperatures around
-6 degrees c work into the area.
On Sunday another shortwave will rotate around an upper level low
in Quebec as it begins to occlude and eventually shear out. The
shortwave will move across the northeastern area of Michigan Saturday
night into Sunday and bring a slight chance of rain/ snow to our
far northeastern counties. Omega values and placement of shortwave
all show best lift if mostly north of the area though.
The chance of rain then returns to the area late Monday/ early
Tuesday as another shortwave approaches from the west. Models
start to diverge here with the upper level pattern as the GFS is
again quick with a front for the area Wednesday while the Euro
stalls the front across the area through Friday. Due to the
mentioned above Tuesday and Wednesday again looks to be rainy with
rain possibly continuing through the remainder of the next work
Aviation /14z Wednesday through Sunday/...
we have seen some patchy MVFR br develop during the pre dawn
hours in some of the more favorable locations like kluk and klck.
Any br should burn off fairly quickly once the sun comes up.
Surface high pressure will shift off to the east through this afternoon.
With a little bit of lingering lower level moisture...a few cumulus
will be possible...especially across central Ohio. Otherwise...we
will begin to get into return flow on the back side of the high
later tonight. Increasing southwesterly low level flow will
eventually lead to a chance of showers later Thursday morning.
Outlook...MVFR ceilings and visibilities are possible from
Thursday afternoon into Friday night.