Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Cleveland Ohio
701 am EDT Sat Aug 23 2014
upper level ridging and surface high pressure will build over the
region this weekend. This will bring warming temperatures to the
Ohio Valley until the next frontal system on Thursday.
Near term /through tonight/...
areas of fog continue to develop with visibilities dropping under
1sm in a few locations. Not expecting widespread dense fog this
morning but will need to monitor observation over the next few hours. The
fog will lift this morning but with little change to the airmass
fog will be possible again tonight.
areas of fog will develop through early morning due to calm
winds and high low level moisture present. Some clouds advecting
in from Michigan will impact mainly the Lakeshore counties through
morning...which could prevent dense fog development in those
areas. The forecast challenge for today is the precipitation chance. Middle
level ridge building in from the west will make shower development
difficult in our western counties. However our eastern counties
will remain sufficiently unstable and moist enough to support some
isolated to scattered storms. With the main front to our south the
best chance for storms locally will be along weak convergence
zones. Temperatures today will be a degree or two warmer than
yesterday as we see more warming aloft.
Short term /Sunday through Tuesday night/...
potential for fog looks to be higher overnight as the high builds
more east mostly clear skies expected. Temperatures will once
again bottom out in most areas...and a weak southeast flow will support
increased low level moisture. The ridge axis expands east with
more of a cap developing (h700 10c). For this reason have left out
rain chances for Sunday...though wouldn't be surprised is a stray
shower develops given ongoing northwest flow aloft. By Monday the ridge
strengthens and with no appreciable forcing aloft will keep out
all probability of precipitation. The strengthening ridge will support warming
temperatures each afternoon with highs on Monday approaching 90.
Long term /Wednesday through Friday/...
the upper ridge should keep most of the convection suppressed Tuesday
then the ridge weakens some for Wednesday to allow a better threat for
thunderstorms and rain...especially for the northwest half of the County Warning Area. Temperatures will stay above
normal Tuesday and Wednesday.
The models differ for Thursday and Friday on the strength of a cold front
that is expected to push through or into the area with the GFS being
stronger and more progressive with the front. Due to the
uncertainty of the models will keep a little higher pop going for
Friday along with a little warmer temperatures.
Aviation /12z Saturday through Wednesday/...
fog and stratus should dissipate around 14z. There will be
transition where MVFR ceilings may occur from 14z into midday as daytime
heating lifts the low level moisture producing the MVFR clouds. Ceilings
should rise above 3k feet by early in the afternoon.
Enough upper troughing still exists in the far east to help a few
rain showers/thunderstorms and rain to develop with daytime heating but the highest
probability is at yng but it is 20% or less so nothing will be shown
in the taf. Any convection should die off shortly after sunset.
NE winds off of leri should have a damping effect on the cumulus field so
eri and cle should see scattered or less cumulus in the afternoon.
Light winds and fairly clear skies should allow for fog to again
develop tonight and most sites will likely see IFR again.
Outlook...VFR except for morning fog and then non VFR possible
Wednesday as showers and thunderstorms develop.
Lake Erie will be between high and low pressure through sun so expect
an east to NE wind of 8 to 15 knots most of the time...turning more to
the south for Monday through Wednesday. Waves should mostly run 1 to 3 feet through
sun then decrease to 2 feet or less as the winds turn more south by