Area Forecast Discussion
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005 FXUS61 KPBZ 210145 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 945 PM EDT Sat May 20 2017 .SYNOPSIS... Rain chances will increase Sunday with the approach of a cold front. Temperatures will be at or slightly below seasonal averages for most of next week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
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Forecast on track and no updates are needed at this time. Will need to monitor elevated convection currently moving into southwestern Ohio...but at this time it is expected to pass west of the forecast area as it gradually weakens. Previous discussion follows.. Mid-level ridging over the forecast are will provide stable conditions overnight. Cannot completely rule out a few stray showers but overall the forecast area should remain largely dry.. Cloud coverage will increase as the ridge continues to shift east and moisture advection increases as flow aloft becomes southwesterly. Sufficient warming aloft and increasing cloud cover will support warmer than average low temperatures.
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&& .SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/... Rain and thunder chances will increase rapidly into Sunday as the deepening upper low swings a cold front across the region by Monday morning. Deep moisture through the entire column and weak steering flow may allow for a brief period for slow moving/training storms Sunday afternoon until the boundary gets closer. That being said, there is some uncertainty to this, despite the rather high PWAT values based on climatology. Will leave HWO mention out at this juncture, with concerns mainly being locally heavy rain and poor drainage flooding. Severe threat appears to be minimal but non-zero with limited instability, modest shear, and warmth aloft. However, if we were to break out, i.e, have more sunshine tomorrow than currently projected, this threat could be slightly higher. Boundary will be east of the region by Monday morning but return southerly flow will quickly rebound values to near seasonal norms by Tuesday. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Average-or-below temperature is forecast as broad upper troughing remains in place through the end of the week. Differences amongst the deterministic guidance suggest using a blend, given the placement differences in shortwaves and resolved surface lows through the period. Only small adjustments were made to the blend of guidance through the period. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... Increasing cloud coverage will offset any fog or stratus development overnight. Showers and thunderstorm chances will increase through the morning as a front approaches from the west...with the best chances expected around early afternoon in ZZV than moving east through the mid and late afternoon hours over PA and WV. MVFR conditions may accompany any showers or storms early on but expect conditions to deteriorate to IFR in the evening several hours after warm frontal passage as all guidance shows saturated lower levels until the cold front follows Monday morning. Winds from the east will slowly veer to the south by Sunday afternoon. Sustain speeds will be around 10 knots. .Outlook... Restrictions are expected Sunday night into Monday morning as a frontal system crosses the region. At this time the next weather system to impact the region is not expected until Wednesday night. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$ is the U.S. government's official web portal to all federal, state and local government web resources and services.