Area Forecast Discussion
Issued by NWS

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
034 FXUS61 KPBZ 210945 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 545 AM EDT Sun May 21 2017 .SYNOPSIS... Rain chances increase today ahead of a cold front arriving late tonight. Temperatures will be at or slightly below seasonal averages for most of next week. && .NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
Showers and thunderstorms will begin to move into the far western zones by 12-14Z. As the weakening pre-frontal wave lifts northeastward through the afternoon, rain chances will spread east. Thunderstorms are expected to develop, but will ultimately be limited in strength due to limited instability and weak forcing away from the parent low. Upper- level flow pattern will favor showers and thunderstorms moving southwest to northeast, quasi- parallel to a lagging cold front. Despite favorable moisture availability and cell motion, the aforementioned lack of strong ascent should keep precipitation efficiency from reaching a widespread flood concern. Still, a few localized water issues could arise in low spots or in areas of poor drainage through late this evening. With increasing clouds and rain chances, high temperatures will be moderated to just above averages. Lows tonight will remain above average, ahead of the approaching cold front.
-- End Changed Discussion --
&& .SHORT TERM /MONDAY THROUGH TUESDAY/... The large parent low pressure system will move through the western Great Lakes tonight, sweeping a cold front through our area Monday morning. The bulk of the remaining rain chances will be in the pre-dawn hours Monday, but a few showers could linger in the Ridges through midday. High pressure will begin to establish drier weather through Monday afternoon, despite a broad upper-level trough holding in the Great Lakes. Dry weather is expected to last through much of Tuesday. Some model differences exist on the northern extent of a system passing to our south Tuesday evening. For now, will continue to side with the drier solutions, ignoring the NAM as a fast and northern outlier. Temperatures are expected to be near seasonal averages Monday and Tuesday as we remain in southwesterly flow on the eastern periphery of the broad trough. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... The broad trough will remain steadfast over the Great Lakes through the latter part of the work week. A re-enforcing trough will dig into the Midwest Wednesday, bringing increased rain chances that will linger into Thursday night. By the early part of next weekend, the Great Lakes trough is finally shunted off to the east by a weak ridge building into the Midwest. Temperatures will be at or below average through the latter half of the week, but will begin to climb into next weekend. && .AVIATION /10Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
Condition deterioration from the west and veering sfc wind with gusts around 20kt can be expected beginning around daybreak as warmth and moisture surge over the region on the flank of strong Great Lakes low pressure and the associated/advancing cold front. Expect general MVFR by afternoon with local IFR in convective cells with heavier rain. Improvement is indicated early Monday via dry advection and subsidence in the wake of the front. .Outlook... The next chance for widespread restrictions is expected with mid week low pressure.
-- End Changed Discussion --
&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.