Scientific Forecaster Discussion
fxus61 kcle 182302
Area forecast discussion
National Weather Service Cleveland Ohio
702 PM EDT Thu Jul 18 2019
a trough of low pressure will move east across the area this
evening. A ridge of high pressure will build northeast over the
eastern United States and linger through Saturday night. A cold
front will move south across the area Sunday. High pressure will
build east out of the middle Mississippi Valley region Tuesday
to the Ohio Valley by Wednesday.
Near term /through Friday night/...
the line of showers and thunderstorms that have been moving
through the forecast area over the past few hours is quickly
diminishing as it hits dry and stable air. Have a brief likely
pop for the next hour, but have the forecast quickly going to
dry across the eastern half of the forecast area. Some
additional shower development may occur late overnight near the
lake and will keep slight chance pops. With clouds lingering in
the area, expecting lows to remain warm in the mid to upper 70s.
a potent little upper level shortwave trough will move east
across the local area this afternoon and evening. This feature
has a positive vorticity maximum associated with it along with a
reflection to the surface as a trough of low pressure. The
combination of the weather features will support the line of
storms and will advance them from west to east across the area.
Receiving some good wind gusts with some of the bowing segments.
Locally heavy rain is occurring with the thunderstorms as they
move through the area. Areas in the east took some time to
destabilize due to the extensive cloud cover over that area this
morning. There have been a few cells trying to pop-up over the
east with little Success deeper in the ridge and little upper
level support downstream.
The big story is the heat and humidity. Southwest flow will
develop with strong warm air advection and advancing high
dewpoints into the forecast area. Looking at highs tomorrow in
the lower to middle 90s across the area and dewpoints rising
into the lower to middle 70s. This should push heat index values
well above 105; especially in the western portions of the area.
Slightly lower heat index values expected over the eastern half
of the area.
The warm front will lift north across the area tonight and
extend southeast across the northeast snowbelt Friday afternoon.
Another shortwave trough and associated moisture will move
southeast along the warm front by afternoon and evening and will
likely kick off another round of showers and thunderstorms. So,
will introduce a round in the northeast tomorrow afternoon and
evening. Due to instability and being along the warm front,
can't rule out a few severe thunderstorms so will have to
monitor once again.
Friday night will be quite warm and muggy and would not be
surprised some of the cities with high potential for heat
island effects will keep low temperatures in the lower 80s.
Tried to highlight those areas in the grids.
So, all in all, it is going to be hot and muggy.
Short term /Saturday through Sunday night/...
still hot and muggy on Saturday. Ohio counties will be under the
second day of excessive heat warnings. Northwest PA may be just
under the threshold and keep heat indices under triple digits.
Precip will be hard to come by Saturday with the ridge firmly in
place for much of the day. Saturday night though those chances begin
to increase from north to south as a cold front sinks south from the
central Great Lakes. Will still have another very warm night with
lows in the mid/upper 70s. Sunday's highs will be a step down with
clouds/precip around, but still humid. Frontal timing still has some
wiggle room to it, but by Monday, temperatures and humidity will be
back toward seasonal averages.
Long term /Monday through Thursday/...
much of next week we will be under the influence of an upper trough
and northwest flow. The surface high from the central Great Lakes
will build to the Ohio Valley. This will leave US with limited
shower chances. A sharpening of the trough may bring some of those
chances to the area by the Wednesday/Thursday time frame.
Temperatures will be seaonable through the period.
Aviation /00z Friday through Tuesday/...
convective activity from earlier this afternoon has greatly
diminished as rain has hit a dry and stable air mass. Will have
just some vicinity shower mentions at the eastern taf sites for
the next couple hours but rain chances have greatly decreased.
Mid-to-high clouds will linger overnight and should abate fog
development over the region. High pressure building into the
region will keep the area mostly dry with just some diurnal
cumulus on Friday. The atmosphere has a chance to mix fairly
well on Friday afternoon and could see winds gust to 20 to 25
knots across the region, out of the southwest.
Outlook...non-VFR possible in showers and thunderstorms
Friday evening and again Saturday night through Monday.
showers/thunderstorms will be in the vicinity of the lake this
evening and overnight with complexes in the area. The background
flow will be southwesterly both Friday and Saturday with afternoon
onshore components, but any thunderstorms would disrupt that flow
for a time. Flow by mid/late afternoon may be strong enough to be
borderline for a Small Craft Advisory off of Erie, but confidence is
not high enough to hoist the advisory. Similar situation for
Saturday. Saturday night a cold front will sink south across the
Lake. A secondary trough will cross on Monday night. High pressure
will build across the Central Lakes early week through mid week. The
north flow on Monday will be strong enough for a least a chop on the
it will be hot over the next 3 days but most of the records
will be tough to reach. Here is a list of the record highs
and the warmest minimum temperature today through Saturday.
Location today Friday Saturday
Canton/Akron 96 in 193098 in 1930 100 in 1980
79 in 2013 78 in 1930
Cleveland96 in 187895 in 1930* 98 in 1930
79 in 1930* 78 in 1926*
Erie94 in 196893 in 1946 93 in 1926
77 in 1930 78 in 1987*
Mansfield96 in 1942 100 in 1930102 in 1930
78 in 1977 79 in 1977
Toledo97 in 1942 102 in 1930102 in 1930
77 in 1930* 76 in 1934*
Youngstown98 in 194298 in 1942 95 in 1991
76 in 1942* 75 in 1977*
* records that may be exceeded
Ohio...excessive heat warning from noon Friday to 8 PM EDT Saturday
Excessive heat warning until 8 PM EDT Saturday for ohz003-
Heat advisory from noon Friday to 8 PM EDT Saturday for ohz089.
PA...heat advisory from noon Friday to 8 PM EDT Saturday for