Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
1018 PM EDT Tuesday Jun 30 2015
showers and thunderstorms will end early tonight as a weak front
Near term /until 6 am Wednesday morning/...
showers exiting the ridges by 01z. Another area of scattered
showers across Ohio with the middle level trough...so have left
diminishing chance probability of precipitation across the region overnight. Have again
adjusted hourly temperatures and dew points toward latest trends...which
lowered overnight lows a degree or two.
Short term /6 am Wednesday morning through Friday/...
new model guidance suggests that most of the area save for the
northern counties and the ridges may remain dry...as subsidence
and warming takes place aloft and mixing dries out the surface.
This may take most of the day though...so some showers may be
possible...in the aforementioned areas...where better instability
may be in place per the latest NAM soundings.
In addition...the 12z guidance wants to shunt most of the
precipitation southward through the remainder of the short
term...with high pressure building at the surface and a surface
boundary remaining just south of the Mason Dixon line. Have pushed
chance probability of precipitation southward from the previous forecast with these
trends. Have increased probability of precipitation slightly over northern WV Thursday
afternoon as model consensus has a low pressure system riding
along the stalled boundary from Kentucky to West Virginia during
this time frame.
Temperatures are forecast to stay just below or near seasonal
averages with the upper trough remaining in place.
Long term /Friday night through Tuesday/...
have not needed to make much in the way of changes to the extended
portion of the forecast. A stalled frontal boundary will continue
to provide a focus for daily showers and storms...but compared to
earlier in the week...the boundary will be shifted farther to the
south. As a result...the northern half of the forecast area has a
better chance to see some dry days. Hard to pinpoint any
particular point when rain is likely...but so far Friday night and
Saturday appear to have the best chances for rain. Temperatures
should not shift much during the period...with highs around 80 and
lows in the middle 60s.
Aviation /02z Wednesday through Sunday/...
VFR is expected for most ports this evening...though MVFR in
showers may brush Ohio ports before midnight as a cold front
approaches. Low level moisture pooling near the front is expected
to bring increasing MVFR/isolated IFR in stratus and fog
overnight into Wednesday morning. A return to VFR is expected by
Wednesday afternoon as ceilings lift and eventually scatter out
under building ridging.
Outlook.../Thursday through Sunday/...
late week and early weekend restrictions are possible mainly
south of pit with a crossing disturbance.