In an environment with weak winds aloft, an isolated thunderstorm developed over eastern sections of Allegheny county. This produced significant flash flooding along Route 51 and the Baldwin area.
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.
In an environment with weak winds aloft, an isolated thunderstorm developed over eastern sections of Allegheny county. This produced significant flash flooding along Route 51 and the Baldwin area. Numerous roads were closed with a video of a dumpster floating down State Route 51. Rainfall amounts ranged from 2.43 in Mount Oliver to a trace at Pittsburgh International Airport.
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 May 16, 4:43 PM EST, 2 hours 37 minutes earlier.
Area Forecast Discussion
National Weather Service Pittsburgh PA
543 PM EDT Wed May 16 2018
.SYNOPSIS...
Warm weather with periodic showers and a few thunderstorms will
continue through the weekend.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Despite the moist airmass, and weak impulse moving in, showers
have been very slow to develop and coverage so far is quite
low. The weak shortwave trough will advance on our area tonight
in light southwest flow. This should generate at least isolated
to scattered showers, but limited instability should cap
thunderstorm strength and coverage. Disorganized showers that
do manage to develop will move very little as steering flow
magnitude is quite low. While this does elevate the potential
for some localized water issues, the low coverage will keep
widespread water issues at bay for the time being.
Limited instability will wane late this evening and coverage of
showers should drop further. The exception to this will be over
the high terrain where pooling moisture and easterly flow on the
northeastern quadrant of the surface low will focus light to
moderate rain showers. Lows will again be well above average.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/...
Models continue with their earlier depiction of a mid-level
cutoff low over the Lower Ohio Valley by Thu night, with little
movement until it is caught up in another shortwave this
weekend.
Of primary concern is the Thu/early Fri scenario of a moist low
level (~H85) conveyer developing off the Atlantic in conjunction
with a converging tropical tap. The resulting PWAT with
potential for warm rain processes could spell flood trouble for
areas along and south of I-70, primarily the ridges/Cheat and
Mon basins. Given the repeated rounds of convection that have
affected the area during the last several days, at this time,
confidence is sufficient along the ridges and Cheat/upper Mon
basins to issue a Flood Watch for rain beginning Thu and
continuing into Fri morning.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Little change to the overall pattern is expected into next week.
The front will move little through Mon, until another cold
front comes from the northwest and definitively sweeps through.
This should finally bring an end to precipitation by Monday
night. After a warmup over the weekend, temperature will fall
back closer to seasonal average early next week.
&&
.AVIATION /22Z WEDNESDAY THROUGH MONDAY/...
Low VFR will carry into the late evening, marred only by scattered
showers. Coverage of thunderstorms will be far too limited for
inclusion.
The moist airmass stagnates over the area tonight, resulting in
a drop in ceilings and perhaps visibilities tonight. Low MVFR or
IFR will be fairly common by daybreak Thursday as surface low
approaches from the south. With little change to the airmass,
only gradual improvement is expected through the day Thursday.
Surface flow will remain light and largely out of the northeast
through the period.
OUTLOOK...
Periodic restrictions are likely for much of this week as a the
area remains under the influence of moist upper troughing.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...Flood Watch from Thursday morning through Friday evening for
MDZ001.
OH...None.
PA...Flood Watch from Thursday morning through Friday evening for
PAZ031-073>076.
WV...Flood Watch from Thursday morning through Friday evening for
WVZ021-509>514.
&&Hazardous Weather Outlook...UPDATED National Weather Service Pittsburgh PA 135 PM EDT Wed May 16 2018 OHZ039>041-048>050-PAZ007>009-013>016-020>023-029-WVZ001>003-171745- Tuscarawas-Carroll-Columbiana-Coshocton-Harrison-Jefferson-Mercer- Venango-Forest-Lawrence-Butler-Clarion-Beaver-Allegheny-Armstrong- Indiana-Washington-Hancock-Brooke-Ohio- 135 PM EDT Wed May 16 2018 This Hazardous Weather Outlook is for east central Ohio, northwest Pennsylvania, southwest Pennsylvania, west central Pennsylvania, western Pennsylvania, northern West Virginia and northern panhandle of West Virginia. .DAY ONE...This Afternoon and Tonight. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. MDZ001-PAZ031-073>076-WVZ021-509>514-171745- Garrett-Greene-Westmoreland-Westmoreland Ridges-Fayette- Fayette Ridges-Marion-Monongalia- Ridges of Eastern Monongalia and Northwestern Preston-Preston- Eastern Preston-Western Tucker-Eastern Tucker- 135 PM EDT Wed May 16 2018 ...FLOOD WATCH IN EFFECT FROM THURSDAY MORNING THROUGH FRIDAY EVENING... This Hazardous Weather Outlook is for western Maryland, southwest Pennsylvania and northern West Virginia. .DAY ONE...This Afternoon and Tonight. Hazardous weather is not expected at this time. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Flood Watch. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. OHZ057>059-068-069-WVZ004-012-171745- Muskingum-Guernsey-Belmont-Noble-Monroe-Marshall-Wetzel- 135 PM EDT Wed May 16 2018 This Hazardous Weather Outlook is for east central Ohio, northern West Virginia and northern panhandle of West Virginia. .DAY ONE...This Afternoon and Tonight. Hazardous Weather is not expected at this time. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Increasing potential for flooding is expected Thursday and Friday. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. Kramar
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PITTSBURGH PA
744 PM EDT WED MAY 16 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0730 PM FLASH FLOOD WHITEHALL 40.36N 79.99W
05/16/2018 ALLEGHENY PA 911 CALL CENTER
RT. 51 AT GREENLEE RD. CLOSED DUE TO FLOODING.
&&
EVENT NUMBER PBZ1802992
RCCPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PITTSBURGH PA
751 PM EDT WED MAY 16 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0744 PM FLASH FLOOD PITTSBURGH 40.44N 79.98W
05/16/2018 ALLEGHENY PA 911 CALL CENTER
RT. 88 BETWEEN MCNEILLY RD. AND RT. 51 SHUT DOWN DUE TO
FLOODING.
&&
EVENT NUMBER PBZ1802993
RCCPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PITTSBURGH PA
756 PM EDT WED MAY 16 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0750 PM FLASH FLOOD CASTLE SHANNON 40.37N 80.02W
05/16/2018 ALLEGHENY PA TRAINED SPOTTER
FLASH FLOOD AT 3518 ELM ST. IS ERODING THE ROADWAY AND
A LANDSLIDE MAY BE EMINENT.
&&
EVENT NUMBER PBZ1802994
RCCPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PITTSBURGH PA
800 PM EDT WED MAY 16 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0751 PM FLASH FLOOD BETHEL PARK 40.32N 80.04W
05/16/2018 ALLEGHENY PA 911 CALL CENTER
VALLEY DR. AT LIBRARY RD. IMPASSABLE DUE TO FLOODING.
&&
EVENT NUMBER PBZ1802995
RCCPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PITTSBURGH PA
805 PM EDT WED MAY 16 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0749 PM FLASH FLOOD PITTSBURGH 40.44N 79.98W
05/16/2018 ALLEGHENY PA 911 CALL CENTER
A RETAINING WALL HAS COLLAPSED AT 2500 BROWNSVILLE RD.
DUE TO FLOODING.
&&
EVENT NUMBER PBZ1802996
RCCPRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE PITTSBURGH PA
817 PM EDT WED MAY 16 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0751 PM FLASH FLOOD CASTLE SHANNON 40.37N 80.02W
05/16/2018 ALLEGHENY PA 911 CALL CENTER
VALLEY DR. AT LIBRARY RD. IN CASTLE SHANNON IMPASSABLE
DUE TO FLOODING.
&&
CORRECTED LOCATION...REMARKS
EVENT NUMBER PBZ1802995
TAXThe Pittsburgh radar (KPBZ), 30 km away, was scanning. The volume nearest the first event began at 00:21 UTC.
2 flash flood. Local standard time, as filed.
State official reported several roads closed in and around Mount Lebanon, Bethel Park, Castle Shannon, and Bridgeville including Library Road, Becks Run Road, Route 51 and Route 88, and Brownsville Road.
County official reported that Plummer School Road was closed due to high water. Also, three feet of water was reported in some homes in Hutchinson. A woman had to be rescued from her vehicle near Sutersville.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Pennsylvania in 2018Every state in 2018This day in weather historyWarnings in Pennsylvania, May 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: 761243, 761240.