Area Forecast Discussion
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664 FXUS61 KPBZ 241139 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 739 AM EDT SUN JUL 24 2016 .SYNOPSIS...
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Hot and humid conditions will continue. The best chance for showers and thunderstorms will return on Monday with the passage of a weak cold front. Above normal temperatures continue through the week...however they should stay in the 80s.
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&& .NEAR TERM /THROUGH MONDAY/... Quite the dewpoint discontinuity remains over the area early this morning as the weak surface boundary has sagged southward. Regardless of where that boundary is this morning, low level flow looks to quickly turn west-southwesterly after sunrise. This will bring the air currently residing over southwestern Ohio toward our CWA. As a result, dewpoints should climb rapidly into the daytime on as the boundary lifts back north of the area. A convective complex currently decaying while slowly trudging eastward across far southern lower Michigan will manage to spread high clouds toward the area for portions of the day on as model RH projections do surge above 500 mb through the morning. However, even in the upper levels, flow does manage to back a bit more southwesterly through the day, which should shunt a bit of that moisture northward by afternoon. However, to be complete, some of the hi-res guidance does sag the remnants of the complex southeastward toward the CWA by afternoon. Satellite trends would suggest that even if this were to occur, there would likely be scant activity remaining with it. What was particularly unusual on Saturday was the spread of 90F+ temperatures across the area with 850 mb temperatures that really didn`t even manage to meet 20C. That said, the drier boundary layer present in some areas on Saturday will not be readily apparent on today with dewpoints surging toward and above 70F. However, consensus 850 mb temperatures manage 22C with 23C likely toward Morgantown. This should put the majority of the area into the 90s for highs...and even well into the 90s over Ohio. Thus with dewpoints increasing and high temperatures at least as high as Saturday even with more high clouds, a heat advisory has been coordinated for all Ohio, non-mountainous West Virginia, and southwestern Pennsylvania counties generally south of the turnpike. Yet another warm front does start to move through the area by late Sunday, increasing the chances of showers and thunderstorms as it does. This will bring increasing clouds and dewpoints into tonight, which will likely keep low temperatures well above 70 in most spots. The associated cold front looks poised to advance southeastward by Monday afternoon and evening. However, strong mixing and warm advection with a very humid air mass ahead of it will again mean a day with heat index values possibly reaching 100 degrees again on Monday. Fries && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
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A sweeping cold front will bisect the forecast area Monday night, as the parent upper-level low shifts into the eastern Great Lakes. The boundary will be slow to sag south of the area, prolonging shower and thunderstorm chances into midday Tuesday. By Tuesday afternoon, surface high pressure and drier air will invade from the north and quell rain chances north of I-70. Wednesday is expected to be mostly dry, with the exception coming in the ridges where the elevated heat source could generate a few showers or thunderstorms. Relief from the recent high dewpoints will finally come with fresh air behind the front. Dewpoints will drop precipitously into the low to mid 60s by Tuesday afternoon, and upper 50s to low 60s by Wednesday. Despite temperatures holding above average, the lower dewpoints will feel much more comfortable than the current air mass. TAX
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&& .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... A bit of a pattern shift expected later this weekend carrying into the weekend. High pressure that has led to the current heat wave will gradually retrograde back to the four corners region of the southwest CONUS. This will allow a broad trough to replace the zonal flow over our region by Thursday. Several shortwaves will pass through the upper-level flow pattern, bringing periodic rain chances through the weekend. With the broad upper-level trough firmly in place, temperatures will return to near-normal by the weekend. TAx && .AVIATION /12Z SUNDAY THROUGH THURSDAY/...
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Medium to high confidence forecast. IFR fog at AGC will lift by 13z owing to VFR much like remainder of the terminals through early afternoon. Daytime heating combining with the thunderstorm complex crossing the periphery of the H5 ridge in MI as of 1130Z will lead to scattered thunderstorms this afternoon. While the actual probability of a airport being directly impacted is low continue with just CB mention. Diurnal cumulus clouds around 4KFT will develop by midday and persist through sunset. Overnight mid and high clouds shall keep widespread ifr fog from developing...however if an airport experiences a shower or storm this afternoon then the chance of IFR fog increases. .OUTLOOK /SUNDAY THROUGH THURSDAY/... Restrictions will be possible Monday with the approach and passage of a weak cold front.
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&& .CLIMATE... Hot temperatures across the region today may approach record levels at some sites. Here are a few selected records and forecasts... Site Forecast Record Year Pittsburgh Int`l Airport 94 98 1934 New Philadelphia 97 94 1999 Morgantown 95 93 1987 Zanesville 96 95 1999 && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...Heat Advisory from noon today to 8 PM EDT this evening FOR OHZ039>041-048>050-057>059-068-069. PA...Heat Advisory from noon today to 8 PM EDT this evening FOR PAZ020-021-029-031-073-075. WV...Heat Advisory from noon today to 8 PM EDT this evening FOR WVZ001>004-012-021-509. && $$ aviation...98 climate...fries

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