Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Cleveland Ohio
127 PM EDT Monday Jul 6 2015
a weak disturbance will move north into eastern Ohio and western
Pennsylvania today. A slowing cold front will push south into the
area on Tuesday then stall across southern Ohio Tuesday night.
This boundary will lift back north on Wednesday night as a wave of
low pressure moves along the front and crosses Northern Ohio on
Near term /until 6 PM this evening/...
Showers and thunderstorms focused across western PA early this
afternoon. Some subsidence has been noticed in NE Ohio with
dissipating middle-level clouds. Models still insisting that some
lift will spiral westward this afternoon...allowing for scattered
showers and thunderstorms to develop. Cin has been eroding and cumulus
field is increasing as ml cape increases to 500-1000 j/kg.
Surface winds are light with little convergence noted...but looks
like a marginal increase late this afternoon in the
Geauga/Portage area will be a focus for activity...expanding after
3 PM. Only minor tweaks to the probability of precipitation/sky cover with update to try
to improve timing/coverage.
Previous discussion...spotty returns and a shower being reported
at kyng at 7am. No big changes with this early morning update.
Upper low spinning over southeast Ohio will continue to lift
northeast across western PA today while opening up and shearing
out. At the surface an inverted trough extends north into eastern
Ohio. This trough will be around all day...dissipating toward
sunset. Therefore expect an increase in radar returns as the day
GOES on...diurnally enhanced. The deeper moisture for all of this
remains across eastern Ohio/northwest PA and left the previous forecast
largely in tact with a Cleveland to Mount Vernon line on the
western most extent of precipitation chances. Further west it will
be much too try and too removed from this system and the weather
will be fair. Temperatures will be suppressed some across the
east...but will still allow them to get into the upper 70s/around
80. Across the west it will be one of the warmest days in
while...expecting middle 80s. Toledo has not even hit 90 yet this
Summer...the last occurrence was in sept 2014. Cleveland has only
hit 90 once this year...in June. Area is running well below normal
in number of 90 degree days. Toledo averages 16 a year and cle 10.
Cloud cover...showers...wet soils all keeping temperatures in check.
Short term /6 PM this evening through Thursday night/...
eastern system pulls away this evening and shower chances diminish
as the evening progresses. Next system upstream across the upper
Midwest will be approaching the Chicago area Tuesday morning.
There likely will not be any precipitation into our area that early
Tuesday. Timing of the front still varies some...but have leaned
toward a GFS/European model (ecmwf) blend with the front just past cle around
8p/0z. Any severe chances seem minimal. Lacking better middle level
lapse rates and better middle level flow remains to the north. Front
will be slowing...eventually stalling Wednesday across southern
Ohio. Temperatures across the west on Tuesday will be dependent
upon shower timing...while those across the east will have a
better chance at getting into the middle 80s. Have lingered the
precipitation chances through the overnight across the east and south
into Wednesday morning. Even with precipitable waters Tuesday reaching 2
inches Tuesday...not too concerned about any widespread flooding
concerns. The break in the weather over the weekend has helped
with that and storms will be progressive. Brief heavy rain is
still possible. Weak ridging will be over the area on Wednesday
and temperatures will be limited in the 70s.
The front will settle somewhere to our south...but models continue
to want to advertise a wave to develop along the front and pull
that boundary back north Wednesday night. Cannot rule out a stray
shower/thunderstorm with its return.
The general consensus is that this wave crosses Northern Ohio/northwest PA
on Thursday but how fast and how far south the boundary will
actually get remains in question. Upper shortwave this is
associated with is hard to time and determine its strength this
far out. Therefore have not gone any higher than 40 to 55
percent. Continued precipitation chances into Thursday night.
Seventies again for highs Thursday.
Long term /Friday through Sunday/...
most of the models try to build the ridge aloft over the Midwest
and Ohio Valley late in the week. Clean warm ups have been hard
to come by this Summer and that may well be the case again as
various amounts of warm frontal precipitation are forecast by the
models Friday into the weekend.
No confidence on trying to time any of these warm frontal showers or
thunderstorm complexes this far out. Will have to have a "chance" of
showers and thunderstorms each day. Will not forecast the pop
too high...generally 30-50 percent chance...until we can resolve the
Temperatures are tricky...depending on the exact location of the
front and the amount of clouds and showers. Temperatures could well be
above normal given the building heights but if the warm front is
just to the south and we have clouds and showers then it may be a
few degrees below normal. Will forecast temperatures near normal during the
day and a couple of degrees above normal at night by the weekend.
Aviation /18z Monday through Saturday/...
a small threat for rain showers/thunderstorms and rain will exist into this evening for NE
Ohio and northwest PA but the chance is so small that will only use vcsh
unless something is imminent at taf issuance Time. Lake breeze at
cle and eri should dominate until just after sunset when winds
will turn back to the south. Think winds will stay up enough
tonight to keep fog from forming but still could see a few spots
of MVFR br/haze near daybreak.
A cold front crossing the area on Tuesday will bring a band of
shra/tsra. Some of this convection could arrive at tol and fdy by
Outlook...non VFR conditions possible at times Tuesday afternoon through
Sat in rounds of showers and thunderstorms and late night fog.
the gradient is light enough today that a light east flow will
likely become onshore over much of the lake by this afternoon. The
flow will come around from the south for the entire lake this
evening as the south flow begins to increase ahead of the next cold
front. Showers and thunderstorms will likely develop on Tuesday and
mariners will have to be alert for the threat of gusty
thunderstorms. The showers and storms may sprint out ahead
of the front and winds may be somewhat variable until the front
clears the lake sometime Tuesday evening. Winds will veer toward the
north and northeast Wednesday as high pressure crosses the Great
Lakes but the front will not be far to the south. A wave of low
pressure is expected to develop on the front. The low pressure will
likely come close to Lake Erie on Thursday and the weather will
likely be unsettled. The frontal boundary may still be in the vicinity
of Lake Erie on Friday so not a lot of confidence that the weather
will clear up.