Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
512 PM EDT Thursday Jul 2 2015
a crossing upper disturbance will increase rain chances for the
start of the Holiday weekend.
Near term /through Friday/...
have removed probability of precipitation overnight as boundary and any forcing is well
south of region. Middle and high clouds will drift across overnight.
Lows were modified toward persistence and surrounding offices.
No changes for Friday with best rain chances across the southeast
ridges as a wave of low pressure moves along the frontal boundary
spreading showers northward...with no probability of precipitation along I-80. Temperatures still
a degree or two below seasonal average.
Short term /Friday night through Sunday night/...
keeping focus of higher precipitation probabilities along the
southeastern flank of the forecast area...which generally favors
the NAM/European model (ecmwf) track of the low. The middle-Atlantic surface low takes
over Saturday morning...but the 300mb jet corridor remains
overhead along with the upper-level trough axis. This will keep rain
showers possible through the early Independence day morning...but
will be diurnally less favorable.
Deeper moisture will remain across the far south Saturday
afternoon...so development of scattered showers and thunderstorms
is possible. The main focus of the system will be well to the east
at that point...so coverage and intensity of any rain will be
Much drier air invades for Sunday...keeping any remaining
diurnally driven showers/thunderstorms limited to our far
southeastern zones. Temperatures will remain near average through
the Holiday weekend...slowly warming towards early next week.
Long term /Monday through Thursday/...
compared to 24 hours ago...models are in much better agreement
with the broad scale features of the extended forecast. Still
cannot rule out the possibility that the seemingly-permanent
frontal boundary will linger near southern counties for one more
day and allow for isolated/scattered showers on Monday. Otherwise
the region should be dry. The prognosticated cold front that previously
had widely varying projected times for passage now has some
agreement from deterministic as well as ensemble models of a
Tuesday night and Wednesday passage. Have changed the forecast
accordingly. With the cold front to the west Monday and
Tuesday...this should allow for more sunshine and have also bumped
up high temperatures those two days.
Aviation /21z Thursday through Tuesday/...
generally VFR conditions will prevail overnight with some middle and
high clouds drifting across ports at times. Patchy MVFR fog
possible toward daybreak. As low pressure moves along a boundry
south of the Mason Dixon Friday...some showers expected especially into
northern WV. Vcsh included at kmgw.
Outlook.../Friday through Tuesday/...
afternoon showers/storms Saturday could provide additional