FXUS61 KPBZ 060026 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 826 PM EDT Sun May 5 2024 .SYNOPSIS... Showers and thunderstorms will continue to impact the region through the late evening. A few storms could be severe and produce strong wind, hail, and heavy rainfall. Wet, warm conditions are anticipated to continue throughout the week as an elongated trough builds to our west and deep southwest flow remains. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... KEY MESSAGES: - Localized flooding concerns remain from evening heavy rain. - All other hazards will continue to diminish. ------------------------------------------------------------------- Outflow collisions led to stalled thunderstorms over far northeastern Washington County, prompting a flash flood warning until 1030pm EDT. Those same thunderstorms will see greater eastward progression the rest of the evening following a weak crossing upper level shortwave. The rest of the overnight period will be primarily dry given loss of diurnal heating and waning upper level support. Slow progression of a surface boundary may still spark an isolated shower (low probability thunderstorm), with most convection dying off by midnight. Localized fog may become a bit of concern in rain-soaked areas due to the influx of boundary layer moisture and precipitation-cooling. But the likelihood of widespread fog remains low as area cloud cover will persist to limit radiational cooling of surface. Temperature is expected to remain above the daily average with little change to the airmass. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... KEY MESSAGES: - Temperatures will remain above normal Monday. - Convection will likely redevelop south of I-70 Monday afternoon/evening, along a stalled frontal boundary as a low pressure system passing to our south. ------------------------------------------------------------------- After dawn, Hi-Res model guidance suggest that the frontal boundary will likely stall near or south of I-70. A passing shortwave out of the Mississippi River Valley will near West Virginia Monday afternoon, showers and storms will redevelop south of Pittsburgh along the weak frontal boundary. Probability of precipitation will remain low between Pittsburgh and I-80, likely due to ridging over the Great Lakes filtering drier air from the north. The probability of severe storms will remain low despite MUCAPE ranging between 700J/Kg to 1000J/kg during peak heating. Bulk wind shear will only range between 20kt to 25kts and downdraft potential will be low given shallow layers of potential dry air available aloft. A ejecting trough out of the Rockies into the northern Plains and ridging over Florida will reinforce a surge of moisture into the Ohio River Valley Tuesday under southwest flow. Severe storms have the potential to develop Tuesday afternoon/evening under a destabilizing airmass and effective shear rapidly increasing from 20kts to 50kts just before sunset. The Storm Prediction Center has noted the severe potential with issuing a Slight/Marginal Risk for portions on Day 3. Based on model soundings and hodographs, hail and damaging winds will likely be the biggest threat. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... KEY MESSAGES: - Ridging over the Great Lakes is expected to reduce precipitation chances briefly Wednesday. - A new disturbance is expect to return showers and thunderstorms late Wednesday night into early Thursday morning. - Ensemble models suggest a very wet pattern into the weekend. ------------------------------------------------------------------- An active weather pattern will remain in place for our region, with decent daily precipitation chances through the weekend. Therefore, flooding concerns will need to be monitor in the long term. The potential of a period of severe weather Wednesday night into early Thursday with a passing disturbance will need to be monitored closely. Organized convection could be initiated if sufficient moisture advances north into the Ohio River Valley. Confidence is high that the wind shear will be available, it is a matter of destabilization that could pose a problem for severe convection development. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... Expect some lingering showers and thunderstorms impacting terminals through the first 6 hours of the TAF period. Especially PIT, AGC, and LBE. These will drop cigs and vis through the evening hours at times. Cigs will become variable through the evening, but as the thunderstorms and showers dissipate through the overnight, expect some low cigs and vis throughout the area late tonight behind the weakened cold front. In fact, NBM probs in DESI show a near 90% chance of IFR conditions across the area overnight. Some improvement is possible tomorrow towards the end of the TAF period as dry air begins to push into the northern areas. Winds will be light at times but may increase to 10 to 15 knots from the west northwest tomorrow afternoon. .Outlook... Some improvements to the restrictions are expected Monday with influence of high pressure to the north, but shortwave movement across the TN River Valley may maintain some restriction/precipitation chances for southern terminals. The rest of the week will remain active with varying periods of precipitation and restrictions amid low pressure passage. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...Hefferan NEAR TERM...Frazier SHORT TERM...Hefferan LONG TERM...Hefferan AVIATION...Shallenberger