Area Forecast Discussion
Issued by NWS Cleveland, OH

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000
FXUS61 KCLE 072343
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
743 PM EDT Tue Apr 7 2020

...00z Aviation TAFs and Evening Forecast Update...

.SYNOPSIS...
Low pressure tracking east through the Great Lakes tonight will
bring a cold front southeast across the area. Another low and a
stronger cold front will move southeast across the region
Wednesday night. An upper low will linger over the northern
Great Lakes Thursday, moving to New England by Friday. High
pressure will build across the Friday into the weekend.

&&

.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
Mid evening update discussion...
High res model data continue to indicate a very active and
likely severe weather late this evening through the overnight
hours. We are watching the storm developing over Michigan this
evening and will likely organized into a squall line or MCS type
structure as it moves southeastward towards northern Ohio into
NW PA. We are thinking the time will be 10 pm to 3 am as the
worse for our local area with 10 pm to 12 am for northwest Ohio,
over Lake Erie and approaching the Lakeshore areas. We predict
this line of severe storms will race at 50 to 60 mph across the
area and be along and south of the lakeshore between 12 am and 2
am. The line of storms should be mostly out of our local area
moving into central and southern Ohio after 3 am.

The main threats will be damaging wind gusts up to 70
mph...isolated higher gusts possible, large hail up to the size
of tennis balls possible, and an isolated tornado threat. The
highest threat for an isolated tornado or two will be near
northwestern Ohio and wherever the squall line of storms
interacts with the warm front.Scattered power outages will be
likely tonight across the area. Frequent, dangerous cloud to
ground lightning will be likely. Stay safe and weather aware!

Previous discussion...
Main focus of the forecast is severe weather potential across
the area this evening. A few storms are possible across the
southern part of the area this afternoon on the nose of a low
level theta-e ridge, although MLCAPE remains low in this area
will a decent amount of MLCIN across the southeast portion of
the area. The main threat with any storm that gets going would
be hail, with damaging winds possible as well.

Anticipating convection to develop upstream across lower MI
later this afternoon/evening in an area of appreciable surface
pressure falls ahead of an advancing cold front. The atmosphere
continues to destabilize northeast into this area, where
1500-2500 j/kg SBCAPE is expected. A robust EML will advect
northeast into the region, with mid level lapse rates up to
8.5C/km. The convection will persist and organize into the area
coincident with a 60-70 kt 500mb jet max. Expecting the
convection to grow upscale into a MCS and track southeast across
the area, with 50-65 kts of effective bulk shear, with MLCAPE
values maintaining in the 1500 j/kg range. The primary threats
with this convection are large hail and damaging winds,
especially if the convection becomes more organized. A low end
tornado threat exists as well, especially across the northwest
part of the area as the convection enters the area, with
effective SRH values of 200 m2/s2, LCLs of 250-500m, and 0-3km
bulk shear vectors out of the west/north west around 35 kts. The
convection is expected to quickly move south out of the area
shortly after/around 6Z, with a stabilizing atmosphere
curtailing severe weather potential regardless.

Clearing skies will build across the area from the west through
the day tomorrow, with highs ranging from the mid/upper 60s west
to the mid 50s to around 60s across far northeast OH/northwest
PA. A stronger cold front will push southeast across the
area tomorrow night, with rain showers expected to move across
the region, mainly after 03Z into Thursday morning.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Upper level troughiness will move southeast into the area Wednesday
night and move east during the day Thursday.  However, a much more
vigorous upper level trough will rotate south out of northern Canada
into the Great Lakes with a potent positive vorticity maximum by
Thursday night.  This trough will swing quickly east Friday keeping
the forecast areas in a cyclonic flow pattern. An upper level ridge
will slide southeast in the mean flow toward the area by late Friday
night.  The upper level low pressure system and associated trough
will cause a surface low pressure system to move southeast through
central Ontario, Canada to near Maine by Thursday afternoon.  As the
upper level system cranks up and trough becomes negatively tilted,
the surface low is expected to rapidly intensify during this
forecast period. This will force strong cold air advection southeast
into the local area Friday into Saturday.  Eventually, surface high
pressure builds northeast toward the area allowing winds to diminish
and a bit of warm air advection. As a result, showers associated
with the cold front will move east of the area leaving behind some
lake effect rain showers becoming mixed with snow Thursday evening
and mostly snow by early Friday morning away from the lake in the
snowbelt.  Otherwise fair over the rest of the forecast area. Cold
air advection will keep temperatures in the 40s Thursday and Friday
and drop them into the lower 30s Thursday night and upper 20s to
lower 30s Friday night.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Upper level ridging will move quickly east across the area Saturday
into Saturday night followed by a fast moving upper level low
pressure system from the deep south that eventually weakens to a
trough by Sunday night.  Large amplitude upper level trough develops
over the Plains states and becomes a dominant feature across the
entire Lower 48 States into early next week.  Strong cold air
advection will be the rule as a lobe of Arctic air plunges south
toward the area.  Needless to day, winter is not giving up just yet.

Surface high will build east Saturday with fair weather but next
warm front will begin to lift north across the area by evening.
Moisture associated with the boundary will push into the area late
Saturday. Surface low pressure over the southern Rockies by Friday
night will swing south into Texas and track northeast toward the
area with the weak upper level low pressure system.  As the upper
level low tracks northeast and becomes a negatively tilted trough,
the surface low is expected to rapidly intensify as it moves into
the forecast area. There are some indications coastal low
development will take place Monday but since upper level trough is
so robust, the inland low will remain the dominant feature.

Fair weather returns Saturday followed by a threat for rain from
there on out and the best chance comes in the east half by Sunday
night. As cold air advection takes place, snow will mix in with the
rain over the entire area Monday night into Tuesday.

Area will see a slight warming trend Saturday into Sunday followed
by cold air returning Monday and Tuesday.

&&

.AVIATION /00Z Wednesday THROUGH Sunday/...
Active weather through the period with the main threat of strong
to severe TSRA generally between 02Z and 07Z across the region.
A line of TSRA expected to develop a move southeast across the
area between 02z and 07z tonight, with damaging wind gusts up to
50 kts or higher and possible GS. Ceilings lower behind the
storms to MVFR likely with possible IFR. The MVFR/IFR ceilings
will scatter or lift late in the period during Wednesday.
Southwest winds 5 to 12 knots will precede the convection, with
winds becoming northwest about 10 knots behind the cold front
generally around/after 09Z. Have included a TEMPO group for each
TAF location for a two hour window when the winds will likely
be very strong to severe with gusts over 40 knots likely during
the line of convection.

.OUTLOOK...Non-VFR again possible Thursday into Friday with
rain and low ceilings.

&&

.MARINE...
Generally light winds expected Wednesday but will begin to increase
from the west-northwest by Wednesday night in the wake of the low
pressure system.  Will likely need small craft advisories Wedneday
night into early Friday night when winds begin to diminish to light
northwest.  Light south-southwest flow is expected Saturday and
Sunday.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...None.

&&

$$
SYNOPSIS...Greenawalt
NEAR TERM...Greenawalt/Griffin
SHORT TERM...Lombardy
LONG TERM...Lombardy
AVIATION...Griffin
MARINE...Lombardy


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