Area Forecast Discussion
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202 FXUS61 KPBZ 242336 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 736 PM EDT Mon Apr 24 2017 .SYNOPSIS... Low pressure tracking along the East Coast should result in periodic rain chances mainly east of I-79 early in the week. Dry and warm weather is expected with mid-week high pressure. && .NEAR TERM /THROUGH TUESDAY/... Forecast soundings along the ridges indicate a strong inversion just above ridge-top level coupled with ely wind around 20-25 kt. These conditions may be conducive to development of a mountain wave that could provide strong wind gusts overnight /especially 03-09UTC timeframe/ along and in the wrn lee of the mountains. A broad collection of hi-res models and ensembles also provide a coherent signal for this possibility. As such, wind grids overnight were manipulated to enhance wind speed and gusts in these focused locations. An update was made to PoPs to reflect current radar data, which have shown an upswing in overall reflectivity. While most precipitation is not expected to measure, what does will be light. Broader coverage of sprinkles also was included in the forecast through mid-evening, in addition to greater areal coverage of categorical pops in sern zones. Previous discussion follows... Latest satellite imagery showing the cloud shield has made very little northward advancement. These clouds will slowly creep northward this afternoon as the southeastern CONUS low turns the corner and moves northeast. Rain chances will ramp back up this afternoon across the Ridges as mid-level dry air evacuates and moisture begins to advect back in from the Mid- Atlantic. Away from the high terrain, a lack of organized ascent will necessitate only slight rain chances through the night. The upper low will track along the coast Tuesday, keeping us on along the northwestern periphery of the system. Rain chances will remain best confined to the higher elevations, but a weak area of deformation could spill rain west, closer to Pittsburgh during the day Tuesday. Temperatures tonight will be above seasonal averages with uniform cloud cover. Another west to east gradient of high temperatures is expected Tuesday as cool air advects into the eastern zones, under overcast skies. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... The upper-level low will finally move out of the region Wednesday morning as a ridge of high pressure builds over the Ohio Valley. This will bring tranquil weather back to the local area for Wednesday and Wednesday night. Strong southerly flow through the mid- levels will establish as heights build Wednesday. This and relatively cloud-free skies will lead to strong warming, with temperatures topping out around 15 degrees above average. Highs in the low 80s should be common. && .LONG TERM /THURSDAY THROUGH MONDAY/... Ridging is progged to shift east early in the period as a trough advances out of the Midwest, returning rain chances to the forecast. Gradually increasing heights and SW upper flow are expected through the weekend in response to a deepening wrn CONUS trough. Embedded shortwaves in the SW flow should result in periodic shower/thunderstorm chances from late week through the weekend. Temperatures are expected to average 10-20 degrees above seasonal levels. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/...
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VFR conditions will generally prevail through much of the overnight period, with deeper moisture confined to the ridges in southeasterly flow. Some very light precip has been reported west of the terrain but this should not promote more than brief visibility restrictions, if any. Some stronger wind gusts may continue through 09z, mainly at LBE, as low level winds increase at or just below the strengthening inversion. Ceilings should generally stay around 5kft, but some lower cigs are possible in the easternmost TAF locations Tuesday afternoon, with deeper moisture spilling over the terrain. .Outlook... The next chance for general restrictions is expected with mid week low pressure.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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