Scientific Forecaster Discussion
fxus61 kcle 192031
Area forecast discussion
National Weather Service Cleveland Ohio
431 PM EDT Wed Jun 19 2019
a persistent stationary front will linger over the area tonight as
low pressure moves northeast along the front. The low pressure
system is expected to be over Northern Ohio and northwest
Pennsylvania by Thursday morning. The low will move to the east
Thursday night and force a cold front south across the area. High
pressure will build east across the area Friday followed by a warm
front that will lift northeast across the area Saturday night.
Near term /through Thursday night/...
an upper level trough of low pressure will move east across the area
Thursday with a series of positive vorticity maximums moving
northeast as well. The upper level support in combination with the
track of the surface low will cause more showers and thunderstorms
to move east across the area this evening through Thursday evening.
Latest surface observations show a lake breeze along the northern
tier counties with winds north to northeast at this time. This held
temperatures in the lower 70s along the Lakeshore. Just south of the
boundary, temperatures have climbed into the upper 70s to lower 80s.
The lake breeze boundary caused a few showers to develop over Erie
County in Pennsylvania and this will be the trend through the rest
of the afternoon.
The more aggressive convective activity developed along a line from
Michigan through Indiana with more convection to the east near the
Ohio/Indiana border. This activity is in response to an inverted
surface trough and the leading edge of the upper level positive
vorticity advection. The thunderstorms will continue to advance
east through the afternoon and evening hours. Rainfall rates will
be on the high side as precipitable water values are up around 1.70"
across the area. Already received reports in Indiana of rainfall
rates over 1 inch in an hour. Latest model soundings support
helicity values approaching 200 with surface winds from the south
and southeast veering to southwest aloft. So, any thunderstorms
overnight will need to be watched for rotation and possibility of
strong damaging winds and can't rule out an isolated tornado.
The surface low track position is slightly different in the models
but the overall track places the stationary front across the
northern portions of the forecast area. Heaviest rainfall will
likely occur just north of this boundary and back southwest across
Northwest Ohio and northwest of the low track. As low moves east
across the area, the heavy rain area will progress east and move out
of the area Thursday night. High pressure will begin to build into
the western portions of the forecast area Thursday night.
Temperatures north of the front will remain in the lower 60s and to
the south of the boundary int he middle 60s overnight. Highs
tomorrow will top out in the middle 70s much of the area and middle
60s with northeast flow in Northwest Ohio.
Short term /Friday through Saturday night/...
high pressure and dry conditions will be overhead on Friday bringing
a welcomed break from precipitation. Upper level ridge will build
overhead on Saturday with moisture starting to sneak back into
western Ohio. Conditions look a little less unstable on Saturday
with a tightly packed west to east Theta-E gradient over the
area. With that said, backed off on pops a little, especially
over eastern Ohio. Chances of precipitation will expand
eastward through the weekend with gradually warming
Long term /Sunday through Wednesday/...
warm front lifts north on Sunday allowing temperatures to push into
the 80s. Scattered thunderstorms remain possible but warm mid-levels
may be somewhat of a limiting factor. The next upper trough is on
our doorstep Monday with increased coverage of showers and
thunderstorms expected. Low pressure will track northeast across the
central Great Lakes Monday into Monday night with convection firing
along the pre-frontal trough. Timing looks a little faster and sped
precip up more into the Monday period than Monday night. Somewhat of
a zonal patter follows heading into mid-week. Confidence is low
beyond Monday in timing showers and thunderstorms.
Aviation /18z Wednesday through Monday/...
mainly high clouds will persist across much of western half of
the area over the next few hours. Some cumulus clouds developed
at Cleveland and Mansfield east with a bit more extensive cloud
cover at Youngstown, Erie and Akron-Canton. Some showers will
develop over the far eastern portions of the forecast area this
afternoon into the evening. The big story will be the changing
conditions this afternoon into tonight. Areas of thunderstorms
continue to develop over Indiana and western Ohio. This activity
will begin to move east into the western portions of the
forecast area this afternoon. A more extensive area of showers
and thunderstorms will push east across the entire area tonight
in association with the surface low pressure moving northeast
toward the area. The low will have some upper level support to
produce moderate to heavy rain at times late tonight into
tomorrow. Expecting winds to remain fairly light and variable
through the forecast period but will begin to increase beyond
the first 24 hours at Cleveland to 10 to 20 knots as the low
pressure system gets closer to the area causing gradient to
Outlook...non-VFR possible through Thursday night and again
Saturday through Monday.
low pressure will track across Northern Ohio overnight, shifting
east of the region on Sunday. Northeast winds will increase to 10-20
knots on the lake which will result in rising water levels along the
shoreline on the western basin. The period of easterly flow is
fairly short before shifting to northeasterly. This will shift the
flooding threat from closer to Toledo towards Marblehead. Flooding
is expected to be fairly minor given the backing flow so have not
issued a Lakeshore Flood Watch at this time. We will monitor water
levels and may still need to issue a statement or watch depending on
timing. At this time it looks like we will remain below small craft
levels but it will be something to monitor.
Better marine conditions expected on Friday with high pressure
overhead. We will see another window of light easterly winds on
Saturday with minor rises in water levels again. A warm front will
lift north across the area on Sunday.
Ohio...Flash Flood Watch from 8 PM EDT this evening through Thursday
evening for ohz009>013-019>023-033.
Flash Flood Watch through Thursday evening for ohz003-006>008-