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fxus61 kcle 240441 
afdcle

Area forecast discussion
National Weather Service Cleveland Ohio
1141 PM EST Thu Feb 23 2017

Synopsis...
a weak cold front will settle south into the area this evening
and stall for several hours before turning back north as a warm
front by morning. Low pressure over the central Mississippi
Valley will track into western lower Michigan by Friday evening.
A trailing strong cold front will sweep east across the area
Friday night. Much colder high pressure will build over the Ohio
Valley over the weekend.

&&

Near term /until 6 am Friday morning/...
update...made a number of changes tonight through Saturday
night from pops and thunder chances to precip type (saturday
transition).



Original...the weak cold front just to the north of the area
will settle south into the area this evening and stall. Some
instability is present with about 500-1000 j/kg of cape present
with little inhibition over the southern half of the County Warning Area.
Cloudiness is increasing from the west and the radar mosaic
shows rain spreading east into Indiana with a few light returns
aloft over NW Ohio. Expect this activity to continue to spread
east across the area tonight. Some elevated cape is expected to
persist overnight so we will mention the chance of thunder.

The frontal boundary will lift northward toward morning
lessoning the chance of rain so we can expect a decrease in
pops.

&&

Short term /6 am Friday morning through Sunday night/...
a big swing in the weather is expected during this period as we
change from very warm conditions to more seasonal weather with
dramatic cooling along with the chance of severe weather.

By Friday morning the warm front will have lifted north of the
region taking much of the shower activity with it. That will
leave the region in the warm sector with unseasonably warm and
humid air flowing north across the region. Expect most of the
day to be dry and springlike with readings soaring well into
the 70s. A capping inversion will be present during much of
Friday which should limit convection.

By around 23 UTC we expect convection to develop/move into the
western counties from near fdy to tol. The environment is
favorable for severe weather with cape near 1000 j/kg with
strong deep layer and low level wind shear along with local
heights below 1000m. Damaging winds will be the main threat but
we cannot rule out a few tornadoes in the tol to fdy to the Lake
Erie islands region shortly after dark. The threat for severe
weather will gradually diminish as the activity progresses east
during the evening. Colder air will sweep into the region after
the frontal passage.

For Saturday we can expect windy and sharply colder conditions.
Temperatures will be slowly falling with gradually decreasing
chances of rain. We can expect early morning high temperatures
from about 40 to 50.

Cold advection will continue into the overnight with a more
typical low in the 20s. We can expect scattered lake effect snow
showers but the activity will be limited with the inversion
quickly lowering to below 5000 ft.

Improving conditions are expected Sunday as high pressure builds
into the region.

&&

Long term /Monday through Thursday/...
temperatures will be in the mid 40s on Monday as a low
approaching from the west brings southerly winds to the region.
There are significant differences between the GFS and ECMWF,
however. The European model (ecmwf) is nearly 24 hours slower than the GFS with
bringing an upper- level shortwave trough and its associated
weak surface low across the Ohio Valley. The GFS also has a
stronger shortwave compared to the ECMWF, so it therefore has
more quantitative precipitation forecast. The European model (ecmwf) has been consistently winning these battles
this winter, so continued to only go with a chance of
precipitation for this time frame as the slower solution is more
favored at the moment.

Due in part to the timing differences, the GFS is much cooler on
Tuesday compared to the European model (ecmwf). Have once again sided with the warmer
ECMWF, which would bring temps up into the lower 50s Tuesday
afternoon with a chance of showers.

Both models bring a stronger cold front across the region sometime
on Wednesday, though they vary considerably with the placement of
the low. Both models do have a broad upper level trough moving
across the Midwest during this time frame. It looks like there will
at least be a chance of showers and perhaps some storms ahead of the
front, with colder air arriving behind the cold front. We could see
a few snow showers Wednesday night as temperatures drop below
freezing and some wrap around moisture works its way into the area.
Confidence in the long range forecast is quite low at this time, so
expect changes to the forecast in the coming days as our confidence
grows.

&&

Aviation /06z Friday through Tuesday/...
frontal boundary currently draped from west to east across
Northern Ohio and northwest PA will lift northward through the first
half of the taf period. Scattered showers will accompany this
boundary, with potential MVFR ceiling reductions. Best chance
for MVFR will be at ktol early in the period with the boundary
south of the terminal. Shower chances will diminish after 10z-
12z time frame with gradual clearing across the region. Gusty
southerly winds expected, especially from kmfd to kcle and
westward. Strong cold front will push east through the region
after 00z Saturday. Showers and thunderstorms are anticipated,
possibly impacting western terminals as early as 03z and kcle
after 06z.

Outlook...non-VFR across mainly the snowbelt by later Saturday
into Sunday. Areas on non-VFR Monday.

&&

Marine...
a cold front currently along northern portions of Lake Erie will
continue to slowly drop across the lake this evening, veering winds
from SW to north then NE for tonight. Winds will continue to veer around
to the south by Friday afternoon as the front lifts back north
across the lake as a warm front. A deep low will move NE across the
central Great Lakes Friday night, forcing a strong cold front across
Lake Erie overnight into Saturday morning. Winds will increase to 20
to 30 knots out of the west on Saturday then gradually diminish late
Saturday night into Sunday. A Small Craft Advisory will be needed
for Saturday.

&&

Cle watches/warnings/advisories...
Ohio...none.
PA...none.
Marine...none.

&&

$$
Synopsis...laplante

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