Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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813 FXUS61 KPBZ 100553 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 153 AM EDT Mon Jun 10 2024 .SYNOPSIS... Below average temperatures are expected through early Tuesday under an upper-level through pattern. Rising temperatures and dry weather will characterize the mid to late week period. Heat index vales Thursday and Friday will be well into the 80s. && .NEAR TERM /THROUGH TODAY/... KEY MESSAGES: - Cool conditions will persist today under northwest flow. - A few light showers may develop after 2pm. -------------------------------------------------------------- Cloud coverage will increase just before dawn from the north as a new shortwave ejects across the Great Lakes. With spots of clearing early this morning, temperatures will drop five degrees below average due to radiational cooling. Dry, quiet is likely through early afternoon. A few stray showers may develop downstream of Lake Erie as the shortwave enters eastern Ohio/western PA. With 850mb temps only ranging between 5 to 6 degrees Celsius, MaxT temps will struggle to reach 70F north of I-70. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... KEY MESSAGES: - Shortwave movement and additional cold front will create low probability light rain showers Monday. - Well below average temperature Monday is expected to become near normal by Wednesday as dry weather persists. ------------------------------------------------------------------- In response to ridge building just west of the upper Mississippi River Valley, another embedded shortwave will round the New England trough and cross the region Monday. Isolated light rain showers may develop along the associated surface cold front, but weak ascent and moisture origins mainly associated with Lake Erie should limit activity to the I-80 corridor and (later in the day) higher terrain. More notably, an uptick in cloud cover and additional cool advection will keep high temperature 10 to 15 degrees below the daily average while strong radiational cooling keeps similar temperature transparencies for the overnight low. Gradual height rises as the New England trough heads out to sea and flow out west becomes more zonal will rising temperature Tuesday into Wednesday. Surface high pressure will cross the region during this time as well, ensuring plenty of insolation and dry weather. && .LONG TERM /THURSDAY THROUGH SUNDAY/... KEY MESSAGES: - Increasing precipitation chances late Thursday into Friday with shortwave movement. - Upstream convective evolution will play role in timing and storm mode during that period. ------------------------------------------------------------------- The late week period will feature embedded shortwaves within fairly progressive zonal flow across the north central CONUS that will shirt towards the Great Lake region late Thursday into Friday. Ahead of it, confidence if high for above normal temperature with an uptick in warm, moist surface flow as the surface high shifts east. With it, the expectation is for an increased precipitation chances that generally favor northwest PA. There remains notable variation in timing/strength of the upper shortwave, with potential the prior convective evolution near the western Great Lakes may dictate the quickness of its eastward progression. Storm timing and strength of the upper trough will be key in accurately assessing any lightning potential, but severe weather appears unlikely as the probability for daytime SBCAPE values to exceed 1000K/kg are less than 10%. How quickly the shortwave traverse the area will dictate weather Saturday, but the general trend is for ridging to develop over the Ohio River Valley heading into the start of the next week. There is fairly high confidence in this pattern which would support dry weather and near to above 90 degree weather (75% probability of hitting 90+ on Monday 6/17 in Pittsburgh). && .AVIATION /06Z MONDAY THROUGH FRIDAY/... VFR will prevail through the overnight with winds 5 knots or less. Ceiling restrictions will return early Monday as another weak cold front crosses the area and cold advection in northwest flow reinforces low level moisture. Latest ensemble probabilities have trended less aggressive with restrictions reaching as far south as PIT with about a 30-50% chance there. Confidence is highest that FKL/DUJ see MVFR CIG restrictions as probability continues to advertise near an 80% chance. Will evaluate the incoming guidance overnight, but trends are toward possibly sparing most sites from MVFR and instead bottoming out at low-end VFR. Post-frontal cold air will keep low to mid level clouds in place through much of the afternoon, eventually scattering from NW to SE by Monday evening with an incoming push of drier air. There may be a brief, isolated shower or two up around FKL/DUJ in the 09Z-15Z timeframe, but confidence in that occurring remains low and impacts (in addition to the ongoing MVFR CIGs) would be minimal. Gradient induced northwesterly wind will see a slight uptick from around 4-7 kts ahead of the front to around 7-10 knots with occasional gusts to 15 kts behind the front. .Outlook... VFR conditions are expected under building high pressure Tuesday through Thursday. Restrictions in showers and thunderstorms return Thursday night and Friday with another passing disturbance. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...Hefferan NEAR TERM...Hefferan SHORT TERM...Frazier LONG TERM...Frazier AVIATION...Rackley/MLB