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Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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361 FXUS61 KPBZ 171603 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 1203 PM EDT Mon Jun 17 2024 .SYNOPSIS... Building high pressure will bring a prolonged period of hot temperatures, lasting through the week. Hottest temperatures are anticipated Wednesday through Friday. Isolated showers and storms are possible this afternoon and again on Tuesday. && .NEAR TERM /THROUGH TONIGHT/... KEY MESSAGES: - Heat begins to build in across the region. - Weak shortwave may stir isolated showers/storms this afternoon with the potential for a few storms to have strong/severe wind gusts. ------------------------------------------------------------------- Building eastern CONUS ridge will bring quite the stretch of hot temperatures to the region, with the potential to break heat records, as noted in the Climate section below. Temperatures are already in the mid to upper 80`s with dewpoints in the 70`s across the region with southerly flow. That being said, with some plenty of instability and modest shear the only thing needed will be a boundary/lifting mechanism to start the generation of showers and storms. Latest hi res model guidance suggests that the MCV over Lake Erie could be such a lifting mechanism, with CAMs initiating storms along the lake and propagating southeastward. Will bump up PoPs in this area and a bit further west into Ohio where some cu has already developed. ACARS soundings have steepening low level lapse rates supportive of a wind threat in any storms that do develop. SPC does have the region in a Marginal Risk for severe storms today, which appears to be appropriate given the combination of ingredients that support the potential for a few strong/severe storms. Given the influx of moisture on the periphery of the building ridge, PWAT values will also be increasing, so brief heavy downpours are also possible. Cloud cover and showers may be the limiting factor for some location`s hitting forecast high temperatures, but regardless with increasing dewpoints, heat indices will approach 100 degrees this afternoon across most of the forecast area. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY/... KEY MESSAGES: - Heat continues to build through midweek. - Isolated storms possible Tuesday afternoon. - Dry and hot Wednesday. ------------------------------------------------------------------- Ridge will continue to amplify on Tuesday, allowing surface heat to slowly increase. As with Monday, high temperatures Tuesday will depend heavily on the development of cu and possible afternoon showers and storms. CAMs are showing convection firing Tuesday afternoon, with focus on the higher elevations. This is due to the low level flow on the backside of the Atlantic high. A southeasterly surface wind will enhance orographic effects which could be enough to overcome the subsidence from the very strong ridge. If convection does fire Tuesday afternoon, outflows from storms could run down the western side of the ridges and develop more activity away from the mountains. This threat should come into better focus over the next couple of model runs. Probabilities for high temperatures > 95 on Tuesday increase and overspread more of the area. The most likely areas remain in the valleys and rural areas, but probs of 40 to 50% are now spread across a large portion of the region outside of the higher elevations. Ridge will be firmly in place by Wednesday with ensembles showing heights of 597-599dm. 850 temperatures will remain very warm and if much of the area stays dry Monday and Tuesday, we could see even hotter temperatures on Wednesday. The threat for convection should decrease on Wednesday with the region well underneath the large ridge. CAM models are showing no activity on Wednesday, which is in agreement with other operational models as well. Probs of > 95 degrees on Wednesday continue to increase with 40 to 60% covering most of the region outside of the mountains. With hotter temperatures and high dewpoints, heat indices will remain near or above 100 Tuesday and Wednesday. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... KEY MESSAGES: - High confidence in a dangerous heat wave holding through the end of the week with heat impacts possible. - Probabilities are pointing to Thursday and Friday being the hottest days of the week. ------------------------------------------------------------------- The highly anomalous ridge will remain in place Thursday, but ensemble data is now hinting the ridge will begin to slowly weaken on Friday. Thursday and Friday should be dry as the area will remain under the influence of the ridge`s subsidence. Probabilities for high temperatures > 95 both Thursday and Friday are the highest of the week. The higher probabilities are also spread out more Thursday and Friday. Generally looking at probs of 50 to 80% both days. With surface dewpoints remaining in the upper 60s to lower 70s, heat indices will continue to hold right around 100 degrees. This would mean at least 5 days of daytime heat indices near 100 degrees. Considering heat effect will be cumulative, late week is looking particularly dangerous. The early season event, and temperatures increasing slightly each day, will compound any existing heat issues. Potential impacts include heightened heat-related illnesses and power grid issues with increased demand. It is strongly encouraged to know where cooling shelters are located and stay hydrated. There may be little relief at night. Make a list of friends and family to check on and help them prepare. Prolonged exposure to excessive heat was the primary cause of weather-related fatalities in 2023. This certainly is increasing slightly that there will be some relaxation to the heat by early next week, but any relaxation will still leave temperatures well above average. In the Saturday-Sunday timeframe, all clusters reflect some flattening of the ridge, but disagree on the degree of flattening. Some maintain zonal flow or perhaps even weak eastern troughing early next week, but even the coolest scenarios have temperatures around average to start next week. The warmest scenarios maintain near-record heat. SHould we stay quasi-zonal into next week, we may get slight relief, but there as a notable fraction on ensemble guidance that redevelops eastern ridging. CPC maintains a moderate risk of excessive heat through 6/24. Please see the Climate section below for more numerical details on the kinds of records that may be in jeopardy. && .AVIATION /16Z MONDAY THROUGH FRIDAY/... Building high pressure will keep VFR conditions with light winds in the forecast through the TAF period. The exception to this may be isolated storms this afternoon as a weak shortwave passes. However, strong subsidence with the building ridge is likely to limit convective development, and with weak flow, confidence is low on the location of any storms that do form. Due to low probability and low confidence of occurrence/location, have opted to not mention impacts in the TAFs with this package. .Outlook... High probability for VFR and dry weather through the week as strong ridging develops aloft. The only variance may come with isolated afternoon convection on Tuesday, but upper ridging should suppress coverage and potential initiation. && .CLIMATE... The area has the potential to break various heat-related records. There is low probability that climate sites approach the highest temperatures recorded in the 21st century: Pittsburgh, PA: 98F (7/7/2012) Wheeling, WV: 98F (7/7/2012) Morgantown, WV: 101F (7/7/2012) New Philadelphia, OH: 101F (7/7/2012) Zanesville, OH: 101F (7/7/2012) DuBois, PA: 101F (7/22/2011) There is a modest probability many June all-time temperature records may be at stake: Pittsburgh, PA: 98F (1988) Wheeling, WV: 100F (1933) Morgantown, WV: 99F (1893) New Philadelphia, OH: 99F (1988) Zanesville, OH: 101F (1988,1934) DuBois, PA: 92F (1969) Daily high maximum (left) and high minimum (right) temperature records are at stake for: Monday, June 17th Pittsburgh, PA: 95F (1994) 75F (1892) Wheeling, WV: 99F (1936) 69F (2004) Morgantown, WV: 95F (1967) 72F (1939) New Philadelphia, OH: 95F (1967) 69F (2022) Zanesville, OH: 99F (1936) 72F (1994) DuBois, PA: 89F (1994) 66F (1892) Tuesday, June 18th Pittsburgh, PA: 97F (1994) 73F (1905) Wheeling, WV: 95F (1944) 71F (2018) Morgantown, WV: 95F (1994) 70F (2018) New Philadelphia, OH: 95F (1994) 72F (2017) Zanesville, OH: 99F (1944) 73F (1944) DuBois, PA: 89F (2018) 69F (2018) Wednesday, June 19th Pittsburgh, PA: 97F (1994) 74F (1905) Wheeling, WV: 95F (1933) 70F (2021) Morgantown, WV: 94F (1994) 72F (2018) New Philadelphia, OH: 92F (1994) 70F (2018) Zanesville, OH: 94F (1994) 75F (1897) DuBois, PA: 87F (2001) 66F (1975) Thursday, June 20th Pittsburgh, PA: 95F (1994) 78F (1924) Wheeling, WV: 97F (1933) 70F (1924) Morgantown, WV: 99F (1893) 75F (1924) New Philadelphia, OH: 95F (1994) 71F (2009) Zanesville, OH: 98F (1934) 75F (1924) DuBois, PA: 89F (1991) 66F (1996) Friday, June 21st Pittsburgh, PA: 95F (1933) 73F (1934) Wheeling, WV: 99F (1933) 69F (2016) Morgantown, WV: 95F (1953) 72F (1988) New Philadelphia, OH: 94F (1994) 72F (2016) Zanesville, OH: 97F (1988) 72F (1997) DuBois, PA: 89F (1991) 68F (1988) && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...Heat Advisory until 8 PM EDT Friday for PAZ007>009-013>016- 020>022-029-031-073>078. OH...Heat Advisory until 8 PM EDT Friday for OHZ039>041-048>050- 057>059-068-069. WV...Heat Advisory until 8 PM EDT Friday for WVZ001>004-012-021- 509>511. && $$ SYNOPSIS...34 NEAR TERM...34 SHORT TERM...22 LONG TERM...22/CL/Milcarek AVIATION...Rackley/88 CLIMATE...