A lingering upper level low pressure system drifting across Pennsylvania promoted low convective temperatures, allowing numerous showers and thunderstorms to develop, which concentrated near disturbances around the upper low. Decent instability and strong low-level lapse rates promoted damaging wind gusts.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS PBZ wrote it up.
A lingering upper level low pressure system drifting across Pennsylvania promoted low convective temperatures, allowing numerous showers and thunderstorms to develop, which concentrated near disturbances around the upper low. Decent instability and strong low-level lapse rates promoted damaging wind gusts. Moisture overall was not excessive for August, but thanks to weak flow near the upper low, storm motion was generally 10 knots or less. This promoted a few instances of flash flooding as well.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Pittsburgh, PA wrote its last area forecast discussion before the first event at Aug 13, 2:50 PM EST, 0 minutes earlier.
Area Forecast Discussion...UPDATED National Weather Service Pittsburgh PA 350 PM EDT Mon Aug 13 2018 .SYNOPSIS... Scattered showers and thunderstorms persist through Tuesday. Dry weather should briefly return Wednesday under high pressure. && .NEAR TERM /THROUGH TUESDAY/... 355pm update...quick update to adjust PoPs in line with the latest radar imagery and hires model guidance. Also increased QPF amounts in areas of heavier rain. Temperatures were also changed to account for the ongoing cooling due to all the rain. Previous discussion... Slow moving showers and thunderstorms on the back side of the mid level low pressure will decrease in coverage toward dusk. With spokes of energy rounding the cyclone can not rule out a shower during the overnight period across western Pennsylvania and northern West Virginia. High res models depict what in the cool season is a TROWAL setup along lake erie, thankfully all the rain associated with that feature will stay north of our area. Tuesday will be more of the same scattered showers and storms during the peak heating hours. Column moistens up with PWATS pushing 1.6" and storm motion remaining less than 10 knots. Hard to pinpoint any particular area, but high water remains a threat and confidence in coverage precludes a flash flood watch. The good thing regarding Tuesday is jet dynamics won't be as favorable being on the anticyclonic shear side so coverage won't be numerous. Under morning sunshine temperatures will climb early and top our in the lower 80s much like today. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... Once the diurnal trend sets in Tuesday evening showers will dissipate. H5 heights build to 588dm Wednesday, so once any valley fog erodes look for a very warm afternoon. H8 temps approach 16C which corresponds to values in the upper 80s save for the mountains and north of interstate 80. Wednesday will be the only dry day of the week. A digging mid level trough returns moisture /mid and high clouds/ Wednesday night. This should offset fog formation save for the mountains and deeper river valleys. Thursday is a tricky forecast as a baroclinic zone sets up north of Lake Erie with impulses ridging south of it. There will be plenty of moisture to tap for shower and thunderstorm development. Downbursts are possible given delta thete-e values of 20K between 10-20KFT. For now will keep chance pops, largely because atmosphere will be messy with residual outflow boundaries and they are pegging a lot of DCVA pockets. Could see pop numbers increase as we head through the week, but for now, will keep continuity going perhaps a tweak upward over eastern Ohio. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... Highlights: - Wet Weather Returns Thursday night - Saturday - Dry Sunday and Monday - Temperatures above normal GEFS/EPS have a good handle on the late week weather system, but diverge on arrival of the next system just beyond day 7. Surface cold front has been pushed back 12 hours from the forecast late last week. It will be crossing Thursday night into Friday. With this timing, potential for severe weather is very low. There will be plenty of clouds not to mention best upper level dynamics cross through the Great Lakes. GEFS has over a 60% probability of greater than 0.01" of rain which is in lock step with forecast, so may tweak pops a smudge higher given increased confidence. After the front crosses Friday morning, mid level trough remains over the region allowing impulses to cross in northwest flow. Will keep chance pops given cooling aloft interacting with daytime heating. A transitory ridge arrives Sunday and Monday allowing dry weather. H8 temps don't move much over the next seven days, so daytime will be in the lower to mid 80s && .AVIATION /20Z MONDAY THROUGH SATURDAY/... Showers and thunderstorms will weaken by 22-24Z as we lose the daytime heating and most of the area is worked over. VFR weather should return area wide by 0Z before MVFR fog develops across airports that experienced a shower this afternoon between 8-14Z. More of the same Tuesday, however there won't be as much coverage with the upper level low pressure off to the east. Best chance of for showers would be north of I80 and terminals in western Pennsylvania. Still don't think if confidence exists to include VC at this time. Winds will be less than 10kts the duration of the forecast. OUTLOOK... Patchy overnight fog is again possible where rain falls and skies can clear. Sub VFR weather is possible Thursday evening into Friday morning with a cold front. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...Flash Flood Watch until 10 PM EDT this evening for MDZ001. OH...None. PA...None. WV...None. &&
Hazardous Weather Outlook National Weather Service Pittsburgh PA 308 AM EDT Mon Aug 13 2018 MDZ001-OHZ050-059-069-PAZ007>009-013>016-020>023-029-031-073>076- WVZ001>004-012-021-509>514-140715- Garrett-Jefferson-Belmont-Monroe-Mercer-Venango-Forest-Lawrence- Butler-Clarion-Beaver-Allegheny-Armstrong-Indiana-Washington-Greene- Westmoreland-Westmoreland Ridges-Fayette-Fayette Ridges-Hancock- Brooke-Ohio-Marshall-Wetzel-Marion-Monongalia- Ridges of Eastern Monongalia and Northwestern Preston-Preston- Eastern Preston-Western Tucker-Eastern Tucker- 308 AM EDT Mon Aug 13 2018 This Hazardous Weather Outlook is for western Maryland, east central Ohio, northwest Pennsylvania, southwest Pennsylvania, west central Pennsylvania, western Pennsylvania, northern West Virginia and northern panhandle of West Virginia. .DAY ONE...Today and Tonight. Scattered to numerous slow moving showers and thunderstorms are expected today. Locally heavy rain could result in isolated flooding, especially in the afternoon and early evening. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to Standard Operating Procedures. OHZ039>041-048-049-057-058-068-140715- Tuscarawas-Carroll-Columbiana-Coshocton-Harrison-Muskingum-Guernsey- Noble- 308 AM EDT Mon Aug 13 2018 This Hazardous Weather Outlook is for east central Ohio. .DAY ONE...Today and Tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to Standard Operating Procedures.
Special Weather Statement National Weather Service Pittsburgh PA 312 PM EDT MON AUG 13 2018 PAZ031-131945- Greene- 312 PM EDT MON AUG 13 2018 ...A STRONG THUNDERSTORM CAPABLE OF PRODUCING HAIL...GUSTY WIND AND HEAVY RAIN WILL AFFECT CENTRAL GREENE COUNTY... At 312 PM EDT, a strong thunderstorm was located over Waynesburg, moving southwest at 5 mph. Wind gusts up to 45 mph and hail up to the size of nickels are possible with this storm. Locations impacted include... Waynesburg... Rogersville... This includes Interstate 79 in Pennsylvania between mile markers 11 and 18. Torrential rainfall also is occurring with this storm and may cause localized flooding. Do not drive your vehicle through flooded roadways. This storm may intensify, so monitor local radio or television stations for additional information and possible warnings from the National Weather Service. LAT...LON 3998 8025 3994 8011 3981 8013 3991 8036 TIME...MOT...LOC 1912Z 027DEG 6KT 3993 8020 Kramar
Special Weather Statement
National Weather Service Pittsburgh PA
319 PM EDT MON AUG 13 2018
OHZ050-WVZ001-002-131945-
Jefferson-Brooke-Hancock-
319 PM EDT MON AUG 13 2018
...A STRONG THUNDERSTORM CAPABLE OF PRODUCING SMALL HAIL...GUSTY WIND
AND HEAVY RAIN WILL AFFECT NORTHEASTERN JEFFERSON...NORTH CENTRAL
BROOKE AND CENTRAL HANCOCK COUNTIES...
At 318 PM EDT, a cluster of strong thunderstorms was located near
New Cumberland, or near Weirton, moving south at 5 mph.
Wind gusts up to 45 mph and small hail are possible with this storm.
Locations impacted include...
Weirton... Steubenville...
Wellsville... Toronto...
Wintersville... Follansbee...
New Cumberland... Richmond...
Irondale... New Manchester...
Empire... Stratton...
Torrential rainfall also is occurring with this storm and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.
LAT...LON 4050 8052 4034 8057 4042 8083 4056 8078
4058 8068 4058 8067 4059 8067 4060 8062
TIME...MOT...LOC 1918Z 012DEG 6KT 4049 8059
KramarSpecial Weather Statement National Weather Service Pittsburgh PA 328 PM EDT MON AUG 13 2018 OHZ058-132000- Guernsey- 328 PM EDT MON AUG 13 2018 ...A STRONG THUNDERSTORM CAPABLE OF PRODUCING HAIL...GUSTY WIND AND HEAVY RAIN WILL AFFECT EAST CENTRAL GUERNSEY COUNTY... At 328 PM EDT, a strong thunderstorm was located near Barnesville. the storm is nearly stationary. Wind gusts up to 55 mph and hail up to the size of nickels are possible with this storm. Locations impacted include... Fairview... This includes Interstate 70 in Ohio between mile markers 191 and 198. Torrential rainfall also is occurring with this storm and may cause localized flooding. Do not drive your vehicle through flooded roadways. This storm may intensify, so monitor local radio or television stations for additional information and possible warnings from the National Weather Service. LAT...LON 4010 8138 4011 8123 4002 8123 3998 8136 TIME...MOT...LOC 1928Z 081DEG 4KT 4006 8126 Kramar
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PITTSBURGH PA
332 PM EDT MON AUG 13 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0252 PM FLASH FLOOD 2 SE BRYANT 40.55N 79.92W
08/13/2018 ALLEGHENY PA TRAINED SPOTTER
&&
EVENT NUMBER PBZ1803372
JDPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PITTSBURGH PA
333 PM EDT MON AUG 13 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0332 PM HAIL 2 S EMPIRE 40.48N 80.62W
08/13/2018 M0.88 INCH JEFFERSON OH TRAINED SPOTTER
&&
EVENT NUMBER PBZ1803373
98PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PITTSBURGH PA
338 PM EDT MON AUG 13 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0330 PM HAIL JACKSON CENTER 41.27N 80.14W
08/13/2018 M1.00 INCH MERCER PA BROADCAST MEDIA
&&
EVENT NUMBER PBZ1803374
98The Pittsburgh radar (KPBZ), 33 km away, was scanning. The volume nearest the first event began at 19:49 UTC.
2 thunderstorm wind, 1 flash flood. Local standard time, as filed.
A trained spotter reported that trees were uprooted near Colliers.
The county Department of Highways reported that trees were blown down along Rogers Road.
County 911 officials reported flooding along 1st Street where Pharaoh Run enters into the Monongahela River.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in West Virginia in 2018Every state in 2018This day in weather historyWarnings in West Virginia, August 2018
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 779983, 779984, 779982.