Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Pittsburgh PA
1008 PM EDT Friday Aug 22 2014
unsettled weather will continue through the first half of the
weekend with occasional showers and thunderstorms. Warm and dry
weather is expected early next week.
Near term /through Saturday/...
10pm update...scattered showers/storms continue to stubbornly
drift across the southern half of the forecast area. The overall trend has
been a weakening in intensity...but with surface dew points in the lower
70s...rainfall rates have been impressive. Latest hires data is
showing a decrease through the remainder of the evening as
everything shifts southward. Temperatures updated to latest lamp numbers.
Coverage of showers and thunderstorms should still increase
through early evening as a nearly stationary boundary finally sags
southward across the region. Lingering cloud cover has kept cape
values rather low today...even with bulk shear increasing to near
30 kts. With this in mind...opted to keep only chance thunder
wording...and think that for the most part storms will remain
under severe thresholds.
While precipitable waters in our southernmost zones will still be in the 2 inch
range...a gradual decrease in these values is expected. Will
maintain the mention for isolated flooding in the severe weather potential statement since any
training showers and storms over already saturated areas could
cause problems...but overall think the threat will be minimal
versus the last several days.
Loss of heating as well as slow southward movement of front will
allow coverage to wane this evening and overnight.
Another shortwave will ride southward through the building upper
ridge tomorrow. With the boundary expected to be mainly south of
the forecast area by tomorrow afternoon...only chance probability of precipitation were
carried. Generally stayed close to guidance for
temperatures...which keeps US close to seasonal averages.
Short term /Saturday night through Monday/...
an exiting shortwave will continue low chances for showers into Sat night...then
strong ridging will build in across the Great Lakes/Ohio Valley region through Monday with dry
weather expd. Temperatures will average a few degree above seasonal levels.
Long term /Monday night through Friday/...
ridging will persist into middle weak with dry and warm weather. A crossing
shortwave and cold front is prognosticated for a Thursday passage with chance probability of precipitation for
shwrs/tstms...followed by building high pressure to finish the weak. Above average
temperatures will rtn to near or below average levels after the lt weak frontal passage.
Aviation /02z Saturday through Wednesday/...
maintained a vcsh mention with a period of MVFR at kmgw and kduj
based on radar trends. After diurnal showers subside...with low level
moisture pooling...expg IFR fog to develop overnight into Erly Sat as
well. A period of MVFR diurnal cumulus ceilings are expd Sat morning before VFR
rtns by afternoon. A shower is possible Sat but covg expd to be too low for a
taf mention at this time.
Outlook.../Saturday night through Wednesday/...
Erly Sun morning fog rstrns are possible.