Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Cleveland Ohio
issued by National Weather Service Buffalo New York
923 PM EDT Tuesday may 26 2015
high pressure will remain centered off the East Coast and low
pressure will move northeast across the western Great Lakes
through tonight. A weakening cold front will reach Northwest Ohio
Wednesday afternoon. High pressure will regain control across the
region for Thursday and the first part of Friday.
Near term /through Wednesday/...
thunderstorms have weakened substantially late this evening due to
a combination of nocturnal boundary layer destabilization and the
weakening of the cold pool that was supporting the convective line
earlier this evening. The severe weather risk is now very low...so
with this in mind we have cancelled the watch early for the entire
Another area of more organized thunderstorms just east of Columbus
will continue to more north-northeast and cross much of the area from south
and east of Cleveland into northwest PA overnight. This area of
storms will produce locally heavy rainfall and gusty winds. An
isolated severe storm with marginal wind and hail cannot be ruled
out...but in general the very marginal instability and deep layer
shear will prevent any organized severe weather risk overnight.
Convective threat will likely diminish late tonight as the pre-
frontal trough moves across eastern sections of the area as
instability wanes but there still could be some lingering
convection through the night...as it appears the upper system will
try to pull another weaker lobe of vorticity through the region
while the middle level cool pool slides through southern Great
Lakes/Ohio Valley. Temperatures will stay mild in the lower to middle
60s as a southerly flow continues ahead of the upstream cold
The region will remain well within the warm sector Wednesday ahead
of approaching cold front. Convective potential will likely be tied
to the diurnal cycle with with greatest coverage of showers and
thunderstorms during the afternoon. Persistence in the thermodynamic
profiles suggests similar instability parameters as today with
MLCAPE values generally 1000-1500 j/kg. The surface boundary/weak
cold front is expected to work through the area during the afternoon
which will provide sufficient forcing. Shear profiles look a bit
weaker than today therefore severe threat will be rather limited. It
will be another warm day with highs in the lower to middle 80s.
Short term /Wednesday night through Thursday night/...
a potent shortwave will lift from northern lower Michigan across
eastern Ontario Wednesday night...forcing a surface cold front
across Northern Ohio. Expect showers and thunderstorms to track from
west to east across the forecast area along/just ahead of the
surface frontal boundary. While instability is not expected to be
particularly deep with surface-based convective available potential energy running around
1000j/kg...bulk shear will be around 30kts and there will be good
surface convergence/upper level forcing to focus convection...so expect
a marginal severe wind threat across the area.
Convection will taper off from west to east Wednesday night as the front
crosses the area. High pressure will build in behind the
front...providing what should be a mostly sunny and rain-free the
area on Thursday. The fair weather should persist through Thursday
night as the surface high settles across the northeastern U.S. And
As high pressure consolidates off the East Coast on Friday...return
flow will once again take hold across the Midwest and Ohio Valley.
This will push highs back into the middle 80s with surface dewpoints
surging back into the mid-60s. As such...we may see enough
instability develop to overcome a fairly weak cap and fire off a few
showers and perhaps a rumble of thunder or two in the
afternoon...mainly west of I-71 where deeper moisture/instability
will be found. The eastern portions of the forecast area should
remain close enough to the departing ridge to remain dry throughout
the day. Any convection should quickly dissipate after sunset with
the loss of diurnal instability. Otherwise it will be a dry...but
sticky Summer night across Northern Ohio as dewpoints will remain
locked in the mid-60s...keeping lows in the middle to upper 60s.
Long term /Friday through Tuesday/...
current guidance is in decent agreement that the coming weekend
will be unsettled across much of the Buckeye state as a cold front
dropping out of the upper Great Lakes advances across Ohio
Saturday. Showers and thunderstorms will likely accompany the
passage of the cold front Saturday into Saturday night. Previous
guidance stalled the front out across Ohio...however 12z runs have
been much more aggressive in pushing the front all the way
through. For now...will stick close to continuity and at least
maintain chance probability of precipitation on Sunday into Monday.
Regarding temperatures...readings in the lower 80s Saturday will
give way to cooler readings in the wake of the cold frontal passage
with highs in the 70s through the rest of the period as the front
either stalls out...leading to cloudy and hence cooler
conditions...or pushes completely through...allowing cooler and
drier air to advect across the region. Lows should run in the upper
50s...near to or just above climatology.
Aviation /00z Wednesday through Sunday/...
several bands of convection will continue to move east across the
area tonight with a general weakening trend after midnight. The
most organized thunderstorms will move across northeast Ohio
especially just south and east of Cleveland from late evening
through the early overnight...reaching northwest PA late tonight.
Overnight expect some patchy br to develop in the wake of the
convection...especially where heavier rain fell. There is some low
potential for patchy IFR ceilings/visibility late tonight especially across
the slightly higher terrain well inland from Lake Erie.
Wednesday morning showers will be exiting northwest PA. This will
leave mainly dry conditions for the bulk of the area with VFR
through midday. During the afternoon showers and scattered
thunderstorms will increase in coverage again from west to east as
a surface trough and upper level disturbance cross the area.
Similar to today...VFR will prevail but any heavier thunderstorm
may contain brief/local MVFR/IFR conditions.
Outlook...VFR Thursday and Friday. A chance of showers and
thunderstorms Saturday and Sunday with local/brief MVFR/IFR
southerly winds will continue on Lake Erie increasing to 10 to 20
knots overnight. Scattered thunderstorms are possible this
evening in the Ohio waters of Lake Erie...some of which could be
strong to severe with locally higher winds and waves.
Winds will shift to the northeast and east on Thursday as high
pressure builds in behind a weak cold front. Southerly winds will
develop again on Friday...shifting to the northeast behind a
stronger cold front late Saturday. Small craft advisories may be
needed for the onshore flow during the second half of the weekend.