Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
703 FXUS61 KPBZ 181755 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 155 PM EDT Tue Jun 18 2024 .SYNOPSIS... A dangerous heat wave will impact the region this week. A Heat Advisory and Excessive Heat Warning are in effect through Friday. This event is highly unusual for our region and could be worse than the 1994 heat wave. && .NEAR TERM /THROUGH TONIGHT/... KEY MESSAGES: - Excessive Heat Warning was issued for the urban areas of western PA; Heat Advisory continues elsewhere. - Heat index values could range from 100F to 110F. - Isolated to scattered downbursts are possible once again this afternoon. - Isolated flash flooding may occur with slow training storms. ------------------------------------------------------------------- 2PM Update: The Heat Advisory for the Pittsburgh metro region have been upgraded to an Excessive Heat Warning due to urban heating impacts and prolonged period of historic heat. This event may be comparable to the 1994 heat wave or worse and needs to be taken seriously. Previous Discussion: The ridge will continue to amplify today, with surface high pressure centered off the east coast. Rising heights aloft should boost temperatures to range between the mid-90s to upper-90s. Isolated thunderstorms may disturb the heat process. However, due to the potential of downbursts today, the impacts may be considered worse due to potential power outages. Despite strong subsidence from the ridge, orographic effect, and a minefield of outflow boundaries from Monday`s storms, isolated to scattered thunderstorms are likely again today. Rapid destabilization resulting from strong surface heating along with weak shear will favor downbursts once again, with potential for severe winds. The Storm Prediction Center (SPC) continues to highlighted much of the region in a Marginal (1/5) risk. Along with strong winds, PWAT values are abnormally high (PIT 12Z sounding measured 1.80", while the climatological average suggests values of 1.12") and with weak flow flash flooding could be problematic. Given the unknowns of initiation and complexity of the outflow boundaries currently lying across the area, location and coverage of storms is difficult to pinpoint. Best timing once again appears to be in the mid/late afternoon, with storms quickly diminishing in the evening hours. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... KEY MESSAGES: - Heat continues to build with probabilities pointing to Thursday and Friday being the hottest days of the week. - Chances for afternoon convection decreases. ------------------------------------------------------------------- The ridge becomes centered over the region by Wednesday, with ensembles continuing to show heights of 597-599dm. With surface high pressure centered a little farther west, the threat for convection will be decreased Wednesday afternoon, through ensembles do indicate low-end probabilities mainly north and west of Pittsburgh. For this reason, did introduce low-end PoPs primarily across the I-80 corridor for Wednesday afternoon. Probabilities for storms look even lower on Thursday and Friday afternoons, but remain non-zero. Focus again would likely be north of Pittsburgh. With similar conditions, temperatures on Wednesday look to be similar to Tuesday. Probabilities for high temperatures > 95 both Thursday and Friday are the highest of the week, though the ridge will begin to break down on Friday. The higher probabilities are also more widespread Thursday and Friday, with much of the area in the 50-85% range both days. Elevated high temperatures and dewpoints will keep heat indices at and above 100 through the period. Low temperatures will also remain elevated with the probability > 70 around 50-80% both nights. Considering heat effects will be cumulative, late week looks 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. Please see the Climate section below for more numerical details on the kinds of records that may be in jeopardy. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... KEY MESSAGES: - Hot temperatures continue into the weekend, but the heat wave will begin to break. - Cooler temperatures are possible, at least temporarily by early next week. ------------------------------------------------------------------- The upper level ridge will break down this weekend and become suppressed well to the south as an upper trough crosses the Great Lakes. However, ensembles indicate this is unlikely to have a significant impact on Saturday`s temperatures, with hot weather continuing into the first half of the weekend. Ensembles show good agreement on the upper trough crossing into the Great Lakes by Sunday, which should finally bring relief from the heat and an increase in rain probabilities. At present, Sunday`s temperatures still appear well above average, but much more tolerable than prior days. Post frontal cold advection on Monday may finally drop temperatures back to a semblance of normal, at least temporarily. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... Any impacts to terminals today will be solely due to thunderstorms. However, the lack of strong forcing and multiple boundaries put down by the convective activity from the previous day will lead to less confidence in timing and location of development. With daytime heating and remnant boundaries, expect initiation to take place between 16Z and 18Z. Convection is expected to then persist into the late afternoon and evening, possibly dissipating earlier than the previous day by 00Z. Thus have put VCTS to all terminals today to account for the uncertainty in location ands timing. Once again, conditions due to fog tomorrow night will be dependent on location of convection. Expect light and variable winds through the day with the exception of thunderstorms. .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 Wednesday, 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: 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>009-013-015-016- 022-031-074-076>078. Excessive Heat Warning until 8 PM EDT Friday for PAZ014-020- 021-029-073-075. 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...Hefferan NEAR TERM...Hefferan SHORT TERM...Rackley/22 LONG TERM...Rackley/34 AVIATION...Shallenberger CLIMATE...