Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
544 am EDT Wednesday Oct 1 2014
other than isolated showers today...dry and warm weather is
expected until the passage of a Friday cold front.
Near term /until 6 PM this evening/...
plenty of low level moisture continues to allow for fog/St and this will continue
into the morning before surface heating initiates some mxg. Webcams
indicate dense fog not widespread enough for an advisory at this time...but will continue
with an Special Weather Statement to highten awareness of the fog. Water vapor satellite and
upper air charts show an upper low spinning across western PA. The low will
begin a slow eastward exit later today. The proximity of the low will keep
isolated showers across the region today...though lack of deep moisture and
instability should lmt precipitation covg. Temperatures should continue a few degree above
Short term /6 PM this evening through Saturday/...
middle and upper level ridging will build into the region tonight through Thursday bringing
dry and warm weather. A cold front will advance across the Great Lakes and upper Ohio Valley
region Friday with sufficient spprt for widespread showers. GFS/European model (ecmwf) prognosticated
instability fields remain low so only maintained a chance for thunderstorms...though
increasing winds aloft will increase shear values some by the lt Friday afternoon/evening
Upper trofg and cool air aloft by Sat will keep shower chances in the
forecast...with the best chances north of pit where better moisture/upper spprt
Above average lt weak temperatures will drop to well below seasonal levels by the
Long term /Saturday night through Tuesday/...
cold air aloft will help to keep showers north of I-80 Sunday with
dry and cool conditions elsewhere. Strong closed low aloft will
wobble north of Lake Huron Monday and Tuesday with shortwaves
riding under the low bringing periods of showers. By midweek upper
trough will lift north with zonal flow developing across the Ohio
Temperatures will be below seasonal averages to start the
week...moderating by middle week.
Aviation /10z Wednesday through Sunday/...
IFR stratus has developed on the backside of closed low aloft
over western PA from kpit to kfkl and looks to spread back to kzzv for
much of the overnight. Elsewhere quite variable conditions with
variable MVFR/IFR fog at times south. Expect stratus and MVFR/IFR
fog at times to fill in across the eastern tafs to the ridges
before daybreak. As low departs Wednesday morning gradual
improvement to VFR through the afternoon. Winds will be light
through the period.
Outlook.../Wednesday night through Sunday/...
restrictions expected in early morning fog Thursday...otherwise
the next chance for widespread restrictions will come with a
Friday/Friday night cold front.