Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Cleveland Ohio
958 am EDT Wednesday Jul 30 2014
an upper level trough will bring unsettled weather and below
normal temperatures to the area today. The trough will shift east
of the area on Thursday...then strengthen over the southern Great
Lakes region on Friday and Saturday.
Near term /until 6 PM this evening/...
A surface trough analyzed over far western Ohio this morning has
initiated a few light showers in the fdy area. Showers and
thunderstorms continue across nwpa and neoh...with conditions
still favorable for waterspouts offshore. The bulk of the rain
has stayed offshore...and the expectation is that the heaviest
rain will continue to stay over the water. A weakening trend has
been observed with these showers and storms over the past few
hours...so the logic remains they will slowly taper over the next
By middle-afternoon a weak impulse evidenced on animated water vapor
imagery will drop south across Ohio and steepen middle level lapse
rates. At the surface...low pressure will form across central
Michigan and drag the surface trough east. Instability
parameters..in concert with the features described above...will
support convection this afternoon...however...0-6 km shear appears
to be marginal for supporting strong updrafts. Expect storms will
be scattered in nature and short lived this afternoon...but with a
freezing level less than 10k feet above ground level...some of these storms could
have nickel hail or larger. All in all probability of precipitation will increase
throughout the afternoon.
Short term /6 PM this evening through Saturday night/...
diurnally driven convection expected to diminish quickly this
evening although an uptick in showers/thunderstorms expected over
Lake Erie again overnight. Another fairly compact shortwave trough
will move across mainly Eastern Lake Erie after midnight with
showers and thunderstorms filling back in. A chance of
thunderstorms will also be possible across the NE Ohio counties.
Lows will range from middle 50s inland to near 60 along the
Upper level trough axis will shift east of the area on Thursday and
expect a fair amount of large scale subsidence behind it. We will
also have a ridge build over central Ohio at the surface so lowered
probability of precipitation. Held onto chance probability of precipitation downwind of Lake Erie on
Thursday...mainly for whatever may move in off the lake. Highs will
range from the upper 70s in Northwest Ohio to low 70s in northwest PA.
The closed upper low near James Bay will pull away to the NE from
Friday into Saturday while the next piece of energy slides across
the Midwest and leads to some deepening of the trough over the
southern Great Lakes region again. Chances of thunderstorms will
be best in Northwest Ohio on Friday as this feature approaches. It shifts
eastward on Saturday with scattered thunderstorms expected most
areas...especially NE Ohio. Skies will be partly to mostly cloudy
on Saturday. Highs will be in the upper 70s to near 80 for Friday
Long term /Sunday through Tuesday/...
the upper trough over the eastern Continental U.S. The past week should finally
start to break down during the extended period. This should lead to
a slightly more progressive pattern. Surface high pressure will
remain to the west on Sunday so will need to hang on to precipitation
chances...especially in the east. Will try to dry things out Sunday
night into Monday as the high finally wins out. The quiet weather
will be short lived as a cold front is expected to settle south
across the region on Tuesday. This means more chance probability of precipitation.
Temperatures will remain just a tad below normal during the
Aviation /12z Wednesday through Sunday/...
showers and thunderstorms continue along the east Lakeshore
morning. Keri may see some thunder the next hour or two with
showers at kcle and kyng. Another upper level disturbance will
move over the area toward midday. All of the new guidance showing
precipitation breaking out across the area. Instability will be lacking
but still think some embedded thunder is possible eastern areas.
Most of the area should see a 3 to 5 hour period of precipitation. Think
ceilings will remain except in the thunderstorms. Things should dry
out after 00z Thursday. SW to west flow under 10 knots will continue.
Outlook...periodic non VFR in showers Wednesday night and through
a series of weak troughs will continue to move across the area the
next 36 hours or so. The first is departing now and a second will
arrive this afternoon. A third will impact the lake on Thursday.
Each one will bring a good chance of precipitation and perhaps a few
waterspouts to the lake. Southwest winds will shift to the west
behind each trough. For the most part speeds will top out in the 10
to 15 knot range so small craft headlines appear unlikely. High
pressure will be positioned across the western lakes for Friday
through Sunday with a light northeast flow on the lake. &&