Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2015

Severe Thunderstorm Warning 172, NWS Pittsburgh, PA

September 4, 2015Clarion County, Pennsylvania

NWS Pittsburgh, PA issued this severe thunderstorm warning at Sep 4, 2015, 6:16 PM EDT for Clarion County, Pennsylvania. It was in force for 14 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Sep 4, 2015, 6:16 PM EDT (22:16 UTC)
Expired
Sep 4, 2015, 6:30 PM EDT
In force
14 min
Issued by
NWS Pittsburgh, PA
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

County Clarion County, PA

The radar

The Pittsburgh radar (KPBZ), 99 km from the middle of the area, began a volume at 22:19 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Pittsburgh, PA (KAGC), launched 12:00Z, 10.3 hours before the alert went out and 104 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Pittsburgh, PA at 12:00Z on 2015-09-04Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 36 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Pittsburgh, PA at 12:00Z on 2015-09-04The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -15 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
36 J/kg
Mixed-layer CIN
-156 J/kg
Mixed-layer LCL
1202 m above ground
0-6 km bulk shear
3 kt
0-1 km storm-relative helicity
-15 m²/s²
0-3 km storm-relative helicity
18 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, 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 this severe thunderstorm warning went out at Sep 4, 2:43 PM EDT, 3 hours 33 minutes earlier.

Area forecast discussion, Sep 4, 2:43 PM EDT, 3 hours 33 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
243 PM EDT FRI SEP 4 2015

.SYNOPSIS...
WARM AND HUMID CONDITIONS WILL CONTINUE THROUGH THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
SHORTWAVE/WEAKNESS IN THE UPPER RIDGE WILL MAINTAIN THE CHANCE
FOR SHOWERS AND THUNDERSTORMS THROUGH THE EVENING. IN
ADDITION...RESIDUAL OUTFLOW BOUNDARIES FROM THIS MORNINGS COMPLEX
WILL ALSO BE A CONTRIBUTING FACTOR...AND A FEW STORMS HAVE ALREADY
DEVELOPED IN THE HIGHER TERRAIN. WITH NO SHEAR/UPPER LEVEL
FLOW...MOST OF THESE STORMS WILL BE RATHER SHORT LIVED.
THUS...SLIGHT TO LOW CHANCE POPS WERE MAINTAINED THROUGH THE
PERIOD WITH MOST OF THE CONVECTION EXPECTED TO DISSIPATE WITH THE
LOSS OF HEATING AT NIGHTFALL. WHILE TEMPERATURES WILL BE
CONTINGENT ON CLOUD COVER AND COVERAGE OF STORMS THIS
AFTERNOON...GENERALLY STAYED WITH A PERSISTENCE FORECAST WITH
TEMPERATURES REMAINING 5 TO 10 DEGREES ABOVE SEASONAL AVERAGES.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/...
H500 RIDGE WILL REESTABLISH ITSELF OVER THE WEEKEND AND CONTINUE
TO KEEP MOST WEATHER SYSTEMS AT BAY. WEAK FLOW OUT OF THE EAST AND
SOUTHEAST...AROUND A SURFACE HIGH TO OUR EAST...WILL BRING A
SLIGHTLY DRIER AND MORE STABLE AIRMASS ON SATURDAY. WITH PWATS
FALLING AND H500 TEMPERATURES RISING...EXPECTING LESS DIURNAL
CONVECTIVE COVERAGE. LIMITING POPS TO SLIGHT CHANCE...WITH AREAS
NORTH AND EAST OF PIT STAYING DRY.

RIDGE REACHES ITS BEST STRENGTH ON SUNDAY WITH H500 HEIGHTS AROUND
590DM. THINK CAPPING WILL BE STRONG ENOUGH TO SUPPRESS CONVECTION
AND WILL KEEP THE DRY FORECAST GOING. IF POPS NEED TO BE ADDED
EVENTUALLY...IT WOULD BE ALONG THE RIDGES.

THE RIDGE STARTS TO WEAKEN ON MONDAY AS A LARGE UPPER LOW ACROSS
CANADA MOVES EASTWARD...CAUSING HEIGHTS DOWNSTREAM TO BEGIN TO
FALL. STILL...THE LACK OF MOISTURE...CONTINUED CAPPING...AND
PERSISTENT SPRAWLING SURFACE HIGH WILL KEEP POPS BELOW 15. ANY
SIGNIFICANT PRECIPITATION CHANCE WILL WAIT UNTIL MIDWEEK.

TEMPERATURES WERE BASED ON A BLEND OF 12Z BIAS-CORRECTED MOSGUIDE
AND PREVIOUS NUMBERS...WITH CONTINUED VALUES OF AROUND 10 DEGREES
ABOVE NORMAL.
CL

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
THE STRONG MID/UPPER RIDGE IS PROGGED TO REMAIN THROUGH EARLY
NEXT WEEK...WITH CONTINUED WARM AND MUGGY CONDITIONS. RELIEF FROM
THE QUITE WARM CONDITIONS MAY COME WITH COLD FRONT LATER WEDNESDAY
INTO THURSDAY...AS WELL AS AN INCREASING CHANCE FOR THUNDERSTORMS.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
EXPECT PREVAILING VFR CONDITIONS FOR MUCH OF THE AFTERNOON AND
EVENING WITH A SMALL CHANCE OF RESTRICTIONS IN ANY SHOWER OR
THUNDERSTORM THAT PASSES DIRECTLY OVER A TAF SITE. WITH LIMITED
CONFIDENCE IN ANY ONE SPECIFIC PORT BEING IMPACTED...OPTED TO
LEAVE TS MENTION OUT FOR NOW.

EXPECT ANOTHER ROUND OF FOG OVERNIGHT WITH PLENTY OF LOW LEVEL
MOISTURE AND LITTLE MIXING.

OUTLOOK...FRIDAY THROUGH TUESDAY...
GENERAL VFR WITH BRIEF RESTRICTIONS IN EARLY MORNING FOG IS
ANTICIPATED EACH DAY.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&
Hazardous weather outlook, Sep 4, 4:23 AM EDT, 13 hours 53 minutes before
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PITTSBURGH PA
423 AM EDT FRI SEP 4 2015

MDZ001-OHZ039>041-048>050-057>059-068-069-PAZ007>009-013>016-020>023-
029-031-073>076-WVZ001>004-012-021>023-041-050830-
GARRETT-TUSCARAWAS-CARROLL-COLUMBIANA-COSHOCTON-HARRISON-
JEFFERSON OH-MUSKINGUM-GUERNSEY-BELMONT-NOBLE-MONROE-MERCER-VENANGO-
FOREST-LAWRENCE-BUTLER-CLARION-JEFFERSON PA-BEAVER-ALLEGHENY-
ARMSTRONG-INDIANA-WASHINGTON-GREENE-WESTMORELAND-WESTMORELAND RIDGES-
FAYETTE-FAYETTE RIDGES-HANCOCK-BROOKE-OHIO-MARSHALL-WETZEL-MARION-
MONONGALIA-PRESTON-TUCKER-
423 AM EDT FRI SEP 4 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN MARYLAND...EAST
CENTRAL OHIO...NORTHWEST PENNSYLVANIA...SOUTHWEST
PENNSYLVANIA...WEST CENTRAL PENNSYLVANIA...NORTHERN WEST VIRGINIA
AND NORTHERN PANHANDLE OF WEST VIRGINIA.

.DAY ONE...TODAY AND TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

In the hours before

Special weather statement, Sep 4, 5:21 PM EDT, 55 minutes before
<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>
Special weather statement, Sep 4, 5:26 PM EDT, 50 minutes before
<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>
Special weather statement, Sep 4, 5:31 PM EDT, 45 minutes before
<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>
Special weather statement, Sep 4, 5:51 PM EDT, 25 minutes before
<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>
Local storm report, Sep 4, 6:02 PM EDT, 14 minutes before
<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>
Special weather statement, Sep 4, 6:09 PM EDT, 7 minutes before
<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

The office that day

Everything else NWS Pittsburgh, PA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 3, 8:21 PM EDTSpecial Weather StatementPBZVenango24 min
Sep 4, 3:43 PM EDTSpecial Weather StatementPBZIndiana32 min
Sep 4, 5:21 PM EDTSpecial Weather StatementPBZWestmoreland24 min
Sep 4, 5:26 PM EDTSpecial Weather StatementPBZFayette19 min
Sep 4, 5:31 PM EDTSpecial Weather StatementPBZArmstrong14 min
Sep 4, 5:51 PM EDTSpecial Weather StatementPBZClarion24 min
Sep 4, 6:09 PM EDTSpecial Weather StatementPBZClarion36 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2015Every severe thunderstorm warning in 2015

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.