Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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339 FXUS61 KPBZ 192249 AAA AFDPBZ Area Forecast Discussion...UPDATED National Weather Service Pittsburgh PA 649 PM EDT Fri Jul 19 2024 .SYNOPSIS... Dry weather is expected through Monday apart from shower chances southeast of Pittsburgh Saturday. A wetter and more unsettled pattern is favored for next week. && .NEAR TERM /THROUGH SATURDAY/... KEY MESSAGES: - Increasing clouds overnight. - Seasonably cool temperatures. __________________________________________________________________ Evening update...overnight forecast in good shape. Updated clouds and temperatures with the latest blended guidance. The biggest question, will any showers be able to sneak into the far southern ridges? The probability remains low and leaned toward the hires guidance here. An isolated shower or sprinkles is possible this evening on the ridge tops, but the rest of the region should remain dry. Previous discussion... Apart from the low probability of orographically forced showers in eastern Tucker County this evening, dry and seasonable weather is expected to continue. Mostly clear skies are expected to close out the day with high clouds encroaching from the south along a transient shortwave. Cloud cover and low-level warm advection will govern nocturnal temperatures and fog. Areas southeast of Pittsburgh are more likely to remain slightly above average with lower chances of fog save in any patchy rain in eastern Tucker County. Northwest of Pittsburgh, temperatures are more likely to fall below average with patchy valley fog. && .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... KEY MESSAGES: - Dry weather is expected through Monday, save shower and storm chances south and east of Pittsburgh Saturday. _________________________________________________________________ The vorticity maximum embedded in southwest flow will encroach the area early Saturday morning. Around 10kts to 20kts of southwest flow in the 850mb layer will act to saturate and warm the low levels. With daytime heating, this will come together to allow convective temperatures to be reached in roughly 500 J/kg CAPE. Spotty showers and storms are expected in the ridges, with chances dropping of to the northwest. Severe weather is not expected. For Pittsburgh and points north and west, remnant dry air is favored to keep the rain away. A low-probability camp of NAM guidance has precipitation focused farther northwest and shows much higher totals than other guidance with moisture pooling and stagnant convection, but this solution remains an outlier. This surge of southwest flow will bring temperatures a few degrees higher than the day prior, with a fairly sharp dew point gradient setting up between the Pittsburgh and Morgantown area, with more humidity favored for the latter. The wave is expected to clear overnight and allow for radiative cooling to drop temperatures near-normal. Fog is most likely for locations that experienced rain the day prior and typical valley locations. Seasonably warm temperatures and passing high clouds with dry conditions are favored Sunday. && .LONG TERM /MONDAY THROUGH FRIDAY/... KEY MESSAGES: - Periodic shower and thunderstorm chances increase through the week - Above average temperatures expected ________________________________________________________________ Model ensembles indicate a trough will deepen across the Central CONUS early next week, before drifting eastward by mid to late week. This trough should approach the Upper Ohio Valley region by Thursday. Southwest flow ahead of this persistent trough will result in warm, moist advection across the region. A series of shortwaves embedded in the southwest flow, and diurnal instability, will lead to periodic shower and thunderstorm chances across the area. At this time, it appears the more significant shortwave passages will be mid-week where highest POPs are focused in the forecast. Uncertainty still exists though in the exact timing and coverage of the rain. Above average temperatures are expected through the period, with increased humidity levels as well. && .AVIATION /22Z FRIDAY THROUGH WEDNESDAY/... VFR expected through the TAF period. Low probability exists for river valley fog near FKL/DUJ (around 30% for less than 3 mile), but dry air mixing today should limit impact compared to prior night. Weak shortwave movement may support Saturday morning to early afternoon showers (low probability thunderstorms) along the WV high terrain. Added mention of low end potential at MGW but more likely result is increase in mid-level clouds decks. .Outlook... VFR is expected through the Monday under the influence of high pressure. A series of shortwave troughs lifting NE from the Tennessee River Valley will support increased shower/tstm chances along with area restrictions mid-week. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...Milcarek NEAR TERM...22/Milcarek SHORT TERM...Milcarek LONG TERM...Milcarek AVIATION...22/Frazier