Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Cleveland Ohio
105 PM EDT Friday Sep 4 2015
an upper air disturbance over lower Michigan will continue to
drift southeast and weaken today. A broad area of high pressure
at the surface and aloft from the Midwest to eastern Canada will
remain nearly stationary through Labor Day.
Near term /until 6 PM this evening/...
upper level low with pieces of energy rotating around it today.
Outflow from the morning activity across the east may still be a
actor for this afternoon. Locations that heat up the fastest
today should see at least scattered convection this afternoon.
Believe the best coverage will be across the western County
Warning Area but will also have to monitor the lake boundary
across NE Ohio into northwest PA. NE Indiana in Northwest Ohio are already
seeing some strong convection this afternoon which should drift
into the southwestern portion of the County Warning Area.
Kcle got to 90 yesterday and see no reason why temperatures will be much
cooler today as temperatures aloft remain about the same. Kcak has been
89 or 90 the past three days as well. Will go with a persistence
forecast until further notice. Upper 80s likely most areas.
Short term /6 PM this evening through Monday night/...
upper ridging will occur over the area this weekend but it will
take some time for the disturbance over the region to dissipate.
Expect ongoing precipitation this evening but will try to dry things out
after midnight. Expect more isolated to scattered showers and
storms on Saturday as a warm and humid airmass will remain
overhead. Boundaries left over from the previous day and nights
storms will be the main trigger for weekend convection. Will try
for dry days Sunday and Monday but will probably still see a few
pop ups each day. The next frontal system will begin to approach
from the northwest on Monday night. The 00z models have different
opinions on when the front will arrive with the European model (ecmwf) slower than
the GFS. Already had chance probability of precipitation over the northwest half of the area
Monday night and it is probably prudent to leave them in even
though better chances will occur in the long term period.
Not much change in temperatures is expected over the weekend with
persistence the way to go for temperatures.
Long term /Tuesday through Thursday/...
one more day of well above normal temperatures on Tuesday to start
the extended forecast with temperatures falling to below normal by
the end of the week. The upper level pattern will feature a broad
trough over the middle-section of the country that slowly moves east
and flattens the persistent upper level ridge. A stalled frontal
boundary will be located near or just north of Lake Erie to start
the day on Tuesday. The GFS remains faster than the Canadian/European model (ecmwf)
with what appears to be some spurious upper level energy driving the
forward progression of the front. The atmosphere remains relatively
dry out ahead of the front and opted to keep probability of precipitation fairly low in the
east on Tuesday in agreement with the slower models. Chances for
precipitation increasing during the Tuesday night through Wednesday
night period as the upper trough moves through the central Great
Lakes with the eventual passage of a strong cold front early
Thursday. Suspect there will be good coverage of precipitation at
least one of the periods but still too much uncertainty in evolution
to go more than chance probability of precipitation.
Temperatures will start out in the upper 80s on Tuesday...drop back
to the lower 80s with increasing clouds and thunderstorms on
Wednesday and settle into the low to middle 70s with lower humidity to
end the week.
Aviation /12z Friday through Tuesday/...
remnants of overnight mesoscale convective system continue to move southeast with showers and
thunderstorms continuing from cle-cak at taf issuance. This area of
precipitation will tend to decrease from the north through 15z.
Additional showers and thunderstorms are expected to develop today
with an upper wave over lower Michigan. Several of the high- res
models are showing scattered showers developing by 15-16z with
diurnal heating. Thunderstorms will increase through the afternoon
in areas of convergence and remnant outflow
boundaries...especially across Northwest Ohio where instability
will be greatest. Any thunderstorm today will result in brief
heavy rain with MVFR to locally IFR visibilities. Coverage of
showers and thunderstorms will decrease tonight with patchy ground
fog developing if we clear out. Most sites will drop to MVFR
visibilities late tonight.
Outlook...areas of non VFR each morning in fog and haze. Scattered
thunderstorms may develop again Saturday...becoming more isolated
easterly winds today will veer to southerly overnight. With high
pressure over the eastern Great Lakes...expect to See Lake breezes
develop on Saturday and to possibly on the east end of the lake on
Sunday. Otherwise light south to southwest winds will continue
during the first half of the week with a strong cold front pushing
south across the lake early Thursday.