Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Cleveland Ohio
331 PM EDT Friday Jul 25 2014
high pressure over the Ohio Valley this evening will shift off the
middle Atlantic coast Saturday as a warm front moves northeast across
the lower Great Lakes. A warm front will push through the Ohio
Valley on Saturday. A cold front will move into the region on Sunday
and a trough of low pressure will linger into Monday across Lake
Near term /until 6 am Saturday morning/...
Fair Pleasant weather of late will modify overnight as warm
advection/isentropic lift spread northeast across the region.
Moisture advection will also occur. Short range models are not in
agreement in the development of convection over night. With dry
boundary layer air in place and not favorable diurnal timing will
continue with low chance probability of precipitation for mainly after midnight over the
western counties and near Lake Erie. Have used mav guidance for
low temperatures with minor changes.
Short term /6 am Saturday morning through Monday night/...
A rather complicated stormy forecast period as the upper flow
becomes more amplified. A warm front will move through the region
Saturday morning with 850 mb temperatures warming to near 18c.
Deep shear increases to 40-50 knots Saturday along with low level
shear( 0-1 km) rising to near 20 knots. The sref tornado ingredients
parameter increases to 30 over NE Ohio and northwest PA toward 00 UTC sun
so we will need to be mindful of the increase potential for
rotating storms. Timing of convective development is difficult at
this time. There may be scattered morning convection in the north
with a lull until middle afternoon when significant destabilization
is expected which will persist into Saturday evening.
More storms are expected on Sunday as a strong short wave with
attendant cold front approaches the region. The highest chance for
storms will be in the east and south during the afternoon. Wind
shear still looks elevated with ample cape so severe storms are
The cold front will move south of the region Sunday night and
Monday and some lake induced instability will remain mainly in the
snowbelt counties. Upward motion in the combination with a Warm
Lake near 23c and cooling temperatures will likely allow for low
topped lake enhanced showers to persist Sunday night and Monday.
There should be a slow decrease in coverage Monday afternoon.
Much cooler air will pour into the region for Monday.
Long term /Tuesday through Friday/...
we cannot shake the amplified trough over the eastern United States
through the end of the work week. This will keep temperatures
running 5-10 degrees below normal. With the cool upper trough
overhead...showers cannot be really ruled out any point yet. So
continue the mention of chance/scattered showers until the subtle
precipitation producing features can be picked out...as we get
closer in time to those days.
Aviation /18z Friday through Wednesday/...
high pressure shifts east of the area by Saturday morning and a
warm front will be pushing northeast. Scattered
showers/thunderstorms are expected to develop at some point on
Saturday. While there may be some old convection nearing tol/fdy
in the morning...best chances for the area come after 18z
Saturday. Some of these may be strong to severe. There is still a
lot of uncertainty as to coverage and timing. So before then
expect VFR conditions with a light southwest flow to continue.
Outlook...non VFR in showers and thunderstorms Sat through Monday.
a fine evening on the lake tonight. Unsettled weather will be around
for the weekend and into early next week.
Showers/thunderstorms/complexes possible at some point/S Saturday and
Sunday. Timing yet is uncertain. Some of these storms could be
strong to severe. Winds on the lake variable as a warm front pushes
north of the lake Saturday and then a cold front crosses Sunday.
Another cold front crosses Monday. Winds on Monday will shift to the
north-northwest and small craft conditions will likely be met. High
pressure at the surface shifts slowly east Tuesday and Wednesday.