Scientific Forecaster Discussion
fxus61 kcle 230129
Area forecast discussion
National Weather Service Cleveland Ohio
929 PM EDT Mon may 22 2017
high pressure over the Ohio Valley will move off the East Coast
on Tuesday. The next storm system will slowly move from the
Mississippi Valley across the Great Lakes Wednesday and
Thursday. High pressure will build in briefly Friday into
Saturday but another cold front is due this weekend.
Near term /until 6 am Tuesday morning/...
Fair weather is expected tonight as high cloudiness increases.
GOES imagery shows cirrus spreading northeast from the system
over the Tennessee Valley. Made slight changes to cloud cover
and updated for current conditions.
Previous discussion... only minor adjustments were made to the
forecast as fair weather prevails across the region as high
pressure slowly shifts away from the region. Cirrus over mainly
the east half of the area will thin for the next several hours
and then increase as more clouds associated with a short wave
rounding the base of a trough over the south central states
shifts towards the Middle Atlantic States. More clouds over the
mid Mississippi Valley will spread into NW Ohio this evening as
another short wave near NW Iowa digs southeast toward se Iowa by
morning. Current temperature forecast looks reasonable.
Short term /6 am Tuesday morning through Thursday night/...
the short wave should track across the central Great Lakes on
Tuesday. There has been a trend among most of the models to lower
the shower threat across Northwest Ohio for Tuesday. The air mass is
relatively dry and stable. The only thing that makes ME nervous is
that we will be in the right entrance region of the jet on Tuesday
but I suspect that we would see a little virga rather than rain with
varying amounts of mid and high clouds. With 850 mb temps about 9-
10c and at least partial sunshine, we should be good for highs in
the lower to mid 70s.
The models are in surprisingly good agreement with the upper
features of the developing storm system midweek. A strong short
wave will carve the trough deeply into the Mississippi Valley on
Wednesday. The jet on the east side of the trough is
essentially progged to couple with the jet across the Great
Lakes. A broad area of upward motion will likely develop from
the lower Ohio Valley to the lower Great Lakes. A surface low
will develop within this zone and drift north until it gets
stacked within the upper trough and stalls. Not sure how fast
the showers will spread east but there certainly seems a good
chance for showers across northwest and north central Ohio. Will
also mention thunder. Instability will probably not be too
impressive but with the strong upward motion this time of year
there will probably be at least some embedded thunder. High
temperatures depend on how quickly the rain develops. Will have
higher forecast highs across NE Ohio and northwest PA where the showers
will take longer to develop.
By Thursday, the upper low/trough is progged to be overhead.
Showers will likely be more random. There could be a dry slot
but it is too early to try and get that specific with the
forecast. High temperatures will likely be in the 60s. Lower 60s
if there are enough showers, mid/upper 60s with enough dry
Long term /Friday through Monday/...
active pattern setting up with waves through every couple of
days. Forecast problem is the timing since European model (ecmwf) and GFS
continue to differ on timing of the systems. Both models has
system exiting the area Friday with some lingering showers in
the east. After that models diverge. The European model (ecmwf) has next low
moving across southern Ohio Saturday with the second wave moving
across the forecast area on Sunday. The GFS has the same trend
but the models is 6-8 hours faster. Leaned toward the slower
European model (ecmwf) simply because models have been a little fast on the
timing of the systems recently.
Aviation /00z Tuesday through Saturday/...
VFR through the taf period. High pressure will shift east
tonight with light winds coming around to the south and then
east Tuesday afternoon. Expect a lake breeze for eri and cle
Tuesday. Next low pressure center will approach from the mid-
Mississippi Valley for Wednesday. Terminals will be on the
fringes of a mid deck by 00z Wed.
Outlook...non-VFR likely Wednesday and Thursday in showers and
thunderstorms and rain.
winds are slowly diminishing as the surface ridge moves into the
upper Ohio Valley. Have cancelled the Small Craft Advisory with
the diminishing trend continuing.
Winds will turn east-northeast Tuesday as the next low
approaches from the mid-Mississippi Valley and high pressure
shifts east. Expecting winds to remain below 15 knots Tuesday,
but will increase a bit more for Wednesday as the low deepens.
The western basin will likely be choppy at times. The low will
reach Western Lake Erie Wednesday night and redevelop off the
East Coast Thursday. High pressure returns over the lake for
Friday, shifting east for Saturday.