Area Forecast Discussion
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000 FXUS61 KPBZ 110209 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 909 PM EST Sat Dec 10 2016 .SYNOPSIS... Low pressure will bring snow later tonight through Sunday, followed by mixed precipitation Sunday night, changing to rain Monday. Much colder air arrives late in the week. && .NEAR TERM /THROUGH SUNDAY/...
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With 9pm update, delayed snowfall by another hour or two considering latest HRRR/RAP/NAM model runs, upstream observations and dry air observed in the local 00Z sounding. Although snowfall accumulations had some minor changes made, they were insignificant to overall trends. Previous discussion follows. Temperatures will remain in the 20s overnight as a warm front approaches with snow developing west to east mainly after midnight. Generally an inch or so by sunrise with lesser amounts across the far south, with slightly higher amounts toward the I-80 corridor. Deepening low pressure heading toward the Great Lakes will provide warm advection and lift for snow to continue Sunday with best amounts north of I-70, with higher amounts north of Pittsburgh where a winter weather advisory has been issued. Snow will diminish in the afternoon across the far south and mix with rain, as the warm front shifts north taking best lift and moisture with it.
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&& .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... Highest snow totals were placed across the northern counties where best lift and moisture will reside into Sunday evening and the winter weather advisory will continue. As surface low shifts north expect enough warming aloft to change precip over to rain across the south, with a period of freezing rain possible north of Pittsburgh and in the ridges. With less snow expected across the southern ridges, no headline was issued at this time, with any freezing precip not expected until Sunday night. Still expect all precip to mix with or change to plain rain before sunrise Monday, as southwest flow ahead of an approaching cold front warms the column. Temperatures will then level off Monday as the front sweeps east with rain and or snow showers ending. An arctic front will then be approaching Tuesday with low chance POPs for snow showers ahead of the front. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Upper troughing and cold W-WSW flow should persist across the eastern CONUS through Friday maintaining the chance for lake enhanced and upslope snow showers. Some accumulation is likely with a 13+ degree temperature difference between the lake and 850hpa. With uncertainty in band placement, have just upped PoPs for the likely locations through Saturday morning. A less amplified pattern sets up for the weekend through early next week, with several crossing shortwaves progged. Differences in the evolution of these systems prompted the use of the superblend for much of this timeframe. Much below average temperatures are expected to moderate by early next week. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... VFR / high MVFR conditions will deteriorate early in the morning as snow showers develop ahead of an approaching warm front. Conditions will quickly fall to low MVFR and IFR in snow with some improvement at the terminals from BVI/PIT/AGC southward by midday as drier air works in in the lower levels. Sunday night precipitation will start up again and IFR conditions will return as the warm front begins to lift over the forecast area. .OUTLOOK... Restrictions are likely to continue through Monday, returning again Wednesday, with crossing areas of low pressure. && .PBZ WATCHES/WARNINGS/ADVISORIES...
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MD...None. OH...None. PA...Winter Weather Advisory until 4 AM EST Monday FOR PAZ007>009- 013>016-022-023. WV...None.
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