Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Cleveland Ohio
641 PM EDT Wednesday Jul 29 2015
a cold front will cross Northern Ohio/northwest PA tonight. High pressure will
build across the lower Ohio Valley through the weekend...but this
will still allow a weak cold front to come across the Great
Lakes Friday night/Saturday morning.
Near term /until 6 am Thursday morning/...
outflow from earlier convection over Northwest Ohio has created enough
convergence to keep scattered thunderstorms going from the middle
of Lake Erie southward to Morrow County. This line has varied in
coverage but for the most part it will remain in the
chance/scattered pop range. Many locations will get a quick tenth
to half inch of rainfall as it moves eastward. The higher amounts
look to be closer to the Lakeshore but will monitor the evolution
through the evening.
The cold front also has some thunderstorm activity along it. The
cold front as of 2330z looks to be near a Detroit to east of
Indianapolis line. As the front passes winds will snap around to
the west and quickly bring much drier air back into Northern Ohio
and northwest PA.
front has reached Northwest Ohio and a few showers/thunderstorms
have developed along the front as expected. Still not expecting
anything to reach severe limits. Only the storms with the best
cores would have the potential to get a little gusty. The limiting
factors have been weak middle level lapse rates...displaced upper
dynamics to the north...limited shear and weak frontal forcing.
Have maintained just mentioning scattered showers and
thunderstorms for tonight as front takes a good portion of the
night to cross the area.
Stayed on the warmer side of guidance for temperatures tonight.
Expect lows to dip into the 60s for most locations. The slow
movement of the front will keep lows closer to 70 across the
eastern portions of the County Warning Area.
Short term /6 am Thursday morning through Saturday night/...
a drier airmass will move in on Thursday. The front will be east
of the area by Thursday morning. Expecting dewpoints to get
pulled back near 60...with upper 50s with daytime mixing. A much
more comfortable situation. Cloud cover will rather scant. High
pressure will be building in from the northwest. Will go with
seasonable temperatures and a dry forecast. Pretty much the same
GOES for Friday.
That high settles in across the lower Ohio Valley for the weekend.
Aloft we will have returned to a northwest flow...on the edge of
the stronger westerlies. This will allow a minor shortwave and
weak surface trough to cross the Great Lakes on Friday and cross
the local area on Friday night/early Saturday morning. The models
have struggled with this feature. There was enough consistency
today though to be able to raise precipitation chances. Have 20 to 50
percent chances for Friday night and for the first part of
Saturday. It should be dry Saturday night as the high attempts to
temporarily nudge a little closer. Again temperatures will be
Long term /Sunday through Wednesday/...
model trends are consistent pushing the next cold front through late
Monday into Tuesday. Could be a few lingering showers in the
south Tuesday morning...but the front should push south to the
Ohio River during the day...providing drier and cooler conditions.
High pressure will remain over the area Wednesday while Wednesday
night still up in the air. GFS with dry conditions until Thursday
while European model (ecmwf) moves short wave through Wednesday night. Even though
GFS solution appears more reasonable...this far out will just go
with low chance probability of precipitation Wednesday night.
Aviation /18z Wednesday through Monday/...
weak warm front now into mfd. West of warm front dew points in
the 70s and convective available potential energy around 2000 j/kg. Believe scattered thunderstorms and rain will
develop west of the forecast area and move into Northwest Ohio next couple
of hours ahead of approaching cold front. For western taf sites
put in tempo group to cover it. As caped as atmosphere is aloft not sure
how far east the storms will make it. For cle and cak just put in
thunderstorms in the vicinity. For now will continue with dry forecast for yng and eri.
Expect front into northwest toward 00z and will move east of area shortly
after midnight local.
Outlook...non VFR possible Sunday night in shra/tsra.
scattered thunderstorms and rain expected this evening ahead of approaching
cold front. Cold front now just southeast of Lake Huron and will
move across the lake this evening. Winds turn to the west overnight
behind the front and increase to 10 to 15 knots. For now will go
with 2 to 4 foot waves...but if winds any stronger may need a
Small Craft Advisory east of cle for Thursday. West to southwest
flow hovering near Small Craft Advisory criteria will continue