Area Forecast Discussion
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114 FXUS61 KPBZ 251612 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 1212 PM EDT Sun Jun 25 2017 .SYNOPSIS... Upper low pressure will maintain cooler temperature and a periodic shower chance for the first half of the week. && .NEAR TERM /THROUGH TONIGHT/...
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Mid-level temperatures look to fall off another 4-5C by this afternoon as a mid-level short wave crosses the area concurrent with peak heating. A fairly vigorous upper jet streak will be transiting likewise, and the combination of DPVA, right entrance region upper divergence, and increasing lapse rates will yield a good combination of forcing for ascent and instability. This will at the very least generate a marked uptick in cumulus development along a boundary that moves through this afternoon. The mitigating factor will likely be fairly lean layer moisture. However, given the instability profiles, 12z sounding convective temperature of 71F that should easily be eclipsed, and hi-res model depictions, isolated showers with the passing short wave seem like a fairly good bet and were added to the forecast for most areas. Furthermore, model soundings suggest wet bulb zero heights falling off toward 5 kft, which would favor some small hail development in the more vigorous updrafts. With cold advection underway through the day through the column, high temperatures will be largely restricted to several degrees below normal. Even with the cold pool overhead, stabilization should occur fairly efficiently overnight due to dry air, a weakening wind field, and loss of favorable jet streak dynamics. This should allow temperatures to fall off rapidly with the lower dewpoints in place, resulting in low temperatures well below normal. Fries
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&& .SHORT TERM /MONDAY THROUGH TUESDAY/... A series of shortwaves are projected to cross the region during the short term period. Improved dynamics and an improved, but still limited moisture tap support better precip probability for the period. Temperatures under the persistent troughing remain progged about 10 degrees under the averages. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... The long term period will feature moderating temperature as flow aloft flattens/ridges in response to a trough digging out of Western Canada. Humidity and warmth will enhance with the progress of that trough over the Plains/Midwest, and precip chances escalate as the system erodes the Eastern ridge by the weekend. && .AVIATION /16Z SUNDAY THROUGH THURSDAY/... Only some minor restrictions with patchy fog this morning, mainly for FKL/DUJ through sunrise. Otherwise, VFR conditions will continue through the period despite a broad upper-level trough. Diurnal cumulus will return again today, along with scattered showers, primarily north of Pittsburgh. Winds will generally remain westerly increasing to near 10kts during the day, with gusts 15-20kts. .OUTLOOK... Chance for restrictions will come with afternoon convection on Monday as an upper trough axis moves through the region. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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