Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Cleveland Ohio
800 PM EDT sun Apr 19 2015
low pressure will track north from western Kentucky to the
central Great Lakes tonight and pull a warm front north across
the area. A cold front will sweep east across the area on Monday.
A cool pattern will persist through the week with intervals of
Near term /until 6 am Monday morning/...
update...nam12 and RUC show 925mb winds increasing to 50 knots or
better through the evening and hrrr and NAM show this causing an
increase is surface winds with the highest impact occurring in a
corridor from mnn/mfd areas north-northeast to the central Lakeshore through
the evening. Through the late evening this expands northeast
across the rest of the Lakeshore while diminishing a bit back
across the Central Highlands. Since peak gusts are already close
to criteria at several locations feel this increase would cause
more areas to be at or above criteria.
Original...low pressure making its way from western Kentucky
north- northeastward. An expansive area of rain/showers is
advancing northward and has reached Mount Vernon...Marion...and
Findlay. So far lightning has been none and have no mention of
thunder. Will continue to be stable with limited lapse rates.
Other than the rain...winds will remain gusty through the night.
In fact the downslope wind for Erie PA is expected to surpass Wind
Advisory criteria. The most critical time is between midnight and
4 am. Without the added effect of the downslope...gusts for others
will be dampened by the showers. Temperatures tonight will be mild
in the 50s. Lows for the Toledo area and others along the
immediate Lakeshore tricky. These locations were left out of the
Summer like 70s today with a wind off of the lake and temperatures
that did not get out of the 50s. Winds will eventually come around
to the southeast tonight. So will go with a low that is actually a
few degrees warmer than their late afternoon temperatures. The same GOES
for Erie PA.
A lull is expected in the rain later tonight as a middle level dry
slot arrives...although an isolated shower is still possible at
any time. The timing of the next round of enhanced precipitation
chances may arrive just before morning for Findlay/Marion. Thunder
may accompany these showers...but have not put any mention in the
tonight portion of the forecast.
Short term /6 am Monday morning through Wednesday night/...
will have to contend with the advancing cold front for
Monday...along with vigorous dynamics aloft. The degree of
instability in the warm sector will dictate the potential
strength of thunderstorms. The area that has the best chances is
across eastern Ohio and possibly into northwest PA. Have raised precipitation
chance for Monday. Will stick fairly close to guidance temperatures for
Monday...with temperatures in the 60s and possibly touching 70 across the
Showers/thunderstorms exit with the passage of the cold front by
Monday evening. The pattern through middle week will feature a
stagnant upper low fixated over the northern lakes/Canada. Cold
advection...although at a slow rate...continues some each day.
Temperatures will struggle to reach 60 Tuesday...and then struggle
even more Wednesday. With the cyclonic flow and steep lapse rates...any
impulse working its way around the upper low will generate
showers. While there is still timing differences...it appears one
of these impulses may move across the area both Tuesday and
Wednesday. With the Wednesday impulse looking a little
stronger...have increased precipitation chances some. By Wednesday night
800 mb temperatures are reaching -5c and that may add a Few Lake effect rain
showers to the mix. It will remain on the breezy side with west-
southwest flow and a relatively tight gradient persisting into middle
Long term /Thursday through Sunday/...
below normal temperatures are expected through the long term
forecast as upper level low pressure takes up residence. This low
will wobble across the region with each piece of jet energy that
rotates around the base of it. This will be the periods of time
where precipitation will have an uptick. All locations will have a
chance of a passing shower or two each afternoon. However the best
chances of seeing the rain/snow showers will be across NE Ohio into
northwest PA. Any snow showers will be limited to the overnight and early
High temperatures will generally be in the 50s through the period.
We will need to monitor low temperatures closely through the long
term. If cloud cover decreases more than anticipated there could be
some patchy frost.
Aviation /00z Monday through Friday/...
large area of rain moving north across the area at this time. Main
band should be quick to lift through the region with scattered
activity later tonight. Some thunder activity being reported well
south of the area but will leave mention out of the tafs since
confidence is low at this time. MVFR to IFR conditions expected
overnight and then gradual improvement tomorrow especially after
cold frontal passage. Winds will be the big problem overnight with
gusts pushing 40 knots at the surface over the next several hours.
Expecting winds to diminish somewhat once wind shifts to more
southerly. Wind shear is marginal but expecting winds to reach 45
knots at 1000 feet and may cause some problems so decided to
include in the tafs.
Outlook...non VFR at times Monday evening and then mainly VFR.
low pressure will move through the central Great Lakes tonight
lifting a warm front across the lake. Ahead of the warm front east
to southeast winds have been in the 15 to 25 knot range which is
high enough to hoist a Small Craft Advisory. Will keep these in
their current configuration. However the upper level low will
persist over the central Great Lakes through the week. As a couple
pieces of jet energy rotate around the base of this low we expect
westerly winds to remain elevated. In all likelihood the eastern
half of Lake Erie will see small craft advisories continue into
Wednesday. Will let later shifts pinpoint this a bit more.
Ohio...Wind Advisory until 6 am EDT Monday for ohz008>014-017>021-
PA...Wind Advisory until 6 am EDT Monday for paz001-002.
Marine...Small Craft Advisory until 10 am EDT Monday for lez148-149.
Small Craft Advisory until 4 am EDT Monday for lez142>147.