Area Forecast Discussion
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168 FXUS61 KPBZ 231732 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 1232 PM EST Mon Jan 23 2017 .SYNOPSIS... Low pressure will bring rain to much of the area into tonight, with mixed precipitation at times along and north of I-80, and in the higher ridge elevations. The next cold front arrives Wednesday. && .NEAR TERM /THROUGH TONIGHT/... Early afternoon update for precip types and a bit more afternoon accumulation in the highest elevations of the southeast ridges. No other significant changes. Main band of rain from KDUJ southwest to near KZZV and slowly shifting northwest, as closed low shifts to the Carolinas and a coastal low develops. Colder air is working into the system from the north and east, and do expect sleet and wet snow to mix in along and north of I-80 later this afternoon, with a sleet to snow mix developing in the Laurel Ridges, as well as higher elevations of northern WV and Garrett county MD. Biggest change to forecast is lowering of QPF through tonight, especially the southeast ridges, as models are not seeing amount of mid level drying that has already become entrained into the system. Snow amounts in the higher elevations this afternoon and tonight have been adjusted with more of a mix expected. Late tonight as coastal low heads offshore of New Jersey, precip will diminish with rain and snow showers into the higher elevations, with light accumulations expected. Not much in the way of cold air behind departing low, with Tuesday max temps near 10 degrees above the seasonal average. && .SHORT TERM /TUESDAY THROUGH THURSDAY/... The vertically-stacked low pressure system will advance up the East Coast Tuesday, loosening it`s grip on the Mid-Atlantic and Upper Ohio Valley. As a result, deep moisture will erode eastward, leading to a general decrease in shower activity through midday Tuesday. Any lingering showers that do remain will be light, transitioning from snow or a rain/snow back to all liquid as temperatures rise. We`ll see a brief lull in precipitation Tuesday afternoon through at least early Wednesday with a transient high pressure. The next low will move through the western Great Lakes Wednesday evening, draping a relatively dry cold front through the region. Will keep only chance PoPs along the front as the low nears. The better chance of precipitation areawide will come Wednesday night stretching into Thursday with the passing upper trough axis, as cooler air pours into our mid-levels. Steepening lapse rates and injection of Great Lake aggregate moisture will allow for rain showers to eventually transition to at least a rain/snow mix. Temperatures will remain well-above average in through the middle part of the week. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... A conglomeration of upper lows will lead to broad troughing of the upper-level flow through at least the weekend. This will bring the return to more seasonal conditions. Several impulses passing through the mean flow, will result in periodic snow chances. Some accumulation potential exists through the weekend, especially north and into the high elevations. While the Great Lakes are still generally ice-free, surface temperatures of Lake Erie, in particular, have dipped into the mid 30s. This will help limit any lake enhancement as colder air arrives. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... MVFR conditions should slowly deteriorate to IFR in rain through the afternoon as low pressure tracks across N Carolina. A strong pressure gradient on the N side of the low will also result in gusty E winds through the afternoon before diminishing this evening. Winds should gradually back to the NW tonight through Tuesday. The precip could mix with and change to snow this afternoon/evening especially for elevated ports and areas N of PIT. The low should exit the E coast Tuesday with precip ending, though MVFR ceilings are expected to persist with low level moisture in place. .OUTLOOK... Periodic restrictions are expected late Wed through Sat with a crossing cold front and subsequent upper troughing. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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