Area Forecast Discussion
Issued by NWS Cleveland, OH

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FXUS61 KCLE 271959

Area Forecast Discussion
National Weather Service Cleveland OH
359 PM EDT Thu Apr 27 2017

Strong low pressure over the northern Great lakes will move
across eastern Canada and the associated cold front will move east
of the area early tonight. High pressure will build across the area
tonight into Friday. A warm front will develop over the lower
Ohio Valley Friday night and lift north of the area on Sunday.
Another strong low pressure system will develop over the
Mississippi Valley on Sunday and push a cold front across the
area late Sunday night and Monday.


The showers remain essentially in two lines, the first on the trough
from the outflow from the old convection. The second line is with
the actual front. Mid level lapse rates remain rather marginal
for significant convection and the SBCape is weak across
central Ohio but east of the I-71 corridor the SPC analysis
progs are a bit more favorable for convection. Given the time
of day, it would seem reasonable that we will see showers flair
up some. Updrafts will be able to reach high enough to generate
thunder in the stronger cells as well as hail given that the
freezing level is about 11k. The wind field is such that we are
already maxing out our gusts in the mixed layer but there is
enough wind aloft that taller cells could produce additional
wind. The severe threat will likely remain isolated late this
afternoon/early evening. The front should be east of the
forecast area by 9 PM.

Plenty of subsidence following the front and the stratocumulus
out west seems flat and diurnal looking and we should see clearing
spread across the area tonight. The air mass is seasonable (I keep
having to remind myself that it is April) and with winds lightening
before daybreak we should be able to sneak down into the mid 40s in
most areas with some lower 40s in the cooler spots. high clouds will
begin to increase toward daybreak which may keep the bottom from
falling out on temps.


The fast flow aloft will redevelop as the trough lifts out on
Friday. Hard to get excited about the prospects for any significant
showers, at least for Friday. Frontogenetic forcing will slowly
increase and the jet is slowly progged to lift north across
the Great Lakes as we go into Friday night and the weekend. Upward
motion will likely increase in the entrance region of the jet.
Friday may be one of those days where radar echoes increase but it
takes a while for much of anything to reach the ground. Will have a
small chance of showers, mainly across northwest Ohio later in the
day. The wind field in the mid and lower layers is progged to
increase significantly Friday night and the threat of showers and
thunderstorms will increase as a short wave moves east in the
fast flow. The GFS develops a surface low over the lower Great Lakes
early Saturday while the ECMWF just drifts the front north and then
south again. In any case, temperatures near Lake Erie could
slide back down Saturday afternoon as the flow comes around more
from the north, the type of pattern where Toledo never does warm up
during the day.

The ridge builds on Sunday and it looks as if the warm front will
move north. Temperatures should shoot up in the south flow as 850 mb
temperatures are progged to rise to 16C or so. Not quite as
confident farther north at Toledo and Erie where the warm air may
arrive slightly later in the day so will hedge a  bit on
temperatures there.

The cold front will approach from the west later Sunday n night or
early Monday morning from the west and the chance of showers and
thunderstorms will begin to increase again. Sunday night will be a
warm night ahead of the front.


The main upper trough over the US will set up over the MS river
valley into the Great Lakes thru the period. S/W`s rotating thru the
upper trough will induce surface lows that move thru the region
Monday and again by Thu night while a front remains near the area
thru the period. Expect good chances for shra/tsra Mon then a lesser
chance for Mon night thru Thu. Temps will start out near normal on
Mon then trend below normal for Tue thru Thu.


.AVIATION /18Z Thursday THROUGH Tuesday/...
A cold front crossing the area will trigger shra and tsra that will
progress east with the front and should exit the ERI area around 01z
to 02z. Isolated storms could be strong to marginally severe with
winds that could gust to 50 knots. Cigs will probably drop to mvfr
levels for the west half of the area into this evening with a lesser
chc for this to occur in the east half. South winds gusting 20 to 25
knots will veer to WSW with fropa then diminish the first half of
tonight before backing back to south late tonight and Friday morning.

Any mvfr cigs should be breaking up by late Fri morning while higher
clouds start to move back into the area.

OUTLOOK...Non-VFR at times in showers and thunderstorms Sat through
Mon then just showers Tue.


A cold front crossing the lake this evening will veer winds more to
the west while wind speeds should stay just under that needed to
produce sca conditions. Weak high pressure moving across Ohio should
diminish the winds late tonight and cause a backing to mainly south
for Fri as the front pushes back north of the lake briefly before
shifting back south across the lake Sat. Winds will veer to north
then ne sat into Sat night and increase enough to produce sca
conditions for a while into Sun until the front moves back north
thru the lake turning winds to south.

South winds will increase Sun night to 30 knots then turn sw then
west as a deep low passes by and pulls a series of cold fronts
across the lake Mon. West winds could be near gale force on Tue as
cool air pushes across the lake.




NEAR TERM...Kosarik
SHORT TERM...Kosarik
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