Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
449 PM EDT sun Sep 21 2014
dry weather can be expected for the remainder of the week while
initially cold temperatures slowly moderate.
Near term /through Monday/...
a strong cold front will complete a sweep of the upper Ohio region by early
evening with dry air encroachment and strong shear inhibitiing
updrafts for thunderstorms.
Cold advection in the wake of the front will intially spprt some isolated to
scattered showers via a sufficiently deep mixing level...but by Monday
daybreak...projected inversion levels are low enough despite upper trofg
to eliminate probability of precipitation and downward trend was thus adjusted.
Nevertheless...the cold flow off the lakes will maintain an
extensive stratocu blanket on Monday and temperatures will likely be
confined to the 50s for most areas.
Short term /Monday night through Wednesday/...
the middle/upper trough if projected to lift out quickly at the start
of this period with broad ridging ensuing over much of the Continental U.S..
the cold start to the week with thus be gradually moderated by
Wednesday...with dry conditions throughout the short term.
Temperatures were forecast using GFS MOS...although tweaks for a greater
diurnal range in the dry airmass were included.
Long term /Wednesday night through Sunday/...
temperatures are forecast to continue warming above the seasonal avgs as the
aforementioned upper ridge expands. Although the European model (ecmwf) continues to
hint at a weak inverted trough developing over the middle Atlantic
coast...that solution is again out of phase with the GFS...and
persistence in a dry forecast must rule undr the anticipated ridge.
Aviation /21z Sunday through Friday/...
cold advection in the wake of the front will promote development of a stratocu
deck as the evening progresses. That blanket is expected to persist at
MVFR levels into Monday afternoon. Isolated to scattered showers are also
anticipated as the upper low digs over the region...but inversion
levels lake sufficiently low by Monday daybreak to suppress further precipitation.
Outlook.../Monday night through Friday/...
genl VFR is expected for the remainder of the week.