Alert archive / Pennsylvania / Flash Flood Warnings in 2018

Flash Flood Warning 54, NWS State College, PA

August 31, 2018York County, Pennsylvania

NWS State College, PA issued this flash flood warning at Aug 31, 2018, 5:08 PM EDT for York County, Pennsylvania. It was in force for 3 hr. 2 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Aug 31, 2018, 5:08 PM EDT (21:08 UTC)
Expired: Aug 31, 2018, 8:00 PM EDT
In force: 3 hr
Issued by: NWS State College, PA
Area: Storm-based polygon
Flood severity: None

County York County, PA

The radar

The Sterling radar (KLWX), 131 km from the middle of the area, began a volume at 21:08 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.

What was reported inside it

Time	Report	Where	Remark
Aug 31, 6:00 PM EDT	FLASH FLOOD	Leibharts Corner, PA	KLINES RUN RD WASHED OUT NEAR TRINITY CHRUCH RD.
Aug 31, 6:20 PM EDT	HEAVY RAIN 3.9	New Park, PA

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

Did it verify

Verified. The Iowa Environmental Mesonet's Cow matched one storm report to this flash flood warning; the first came 52 minutes after it went out.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 9.1 hours before the alert went out and 129 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 425 J/kg
Mixed-layer CIN: -35 J/kg
Mixed-layer LCL: 930 m above ground
0-6 km bulk shear: 16 kt
0-1 km storm-relative helicity: 20 m²/s²
0-3 km storm-relative helicity: 68 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

273 
WGUS51 KCTP 312108
FFWCTP
PAC133-010000-
/O.NEW.KCTP.FF.W.0054.180831T2108Z-180901T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service State College PA
508 PM EDT FRI AUG 31 2018

The National Weather Service in State College PA has issued a

* Flash Flood Warning for...
  South central York County in south central Pennsylvania...

* Until 800 PM EDT.

* At 504 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Flooding is ongoing in the 
  Hallam and Wrightsville area due to earlier heavy rains. In 
  addition, more than three inches of rain have already fallen near 
  Brogue and Shrewsbury. Flash flooding is expected to begin 
  around these areas shortly.

* Some locations that will experience flooding include...
  Red Lion, Dallastown, East York, Stonybrook-Wilshire, Shrewsbury,
  Hallam, Wrightsville, Stewartstown, Glen Rock, Yorklyn, Jacobus,
  Windsor, Yoe, Cross Roads, Railroad, Yorkana, Brogue, Loganville,
  East Prospect and Winterstown.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.

Excessive runoff from heavy rainfall will cause flooding of small
creeks and streams, urban areas, highways, streets and underpasses as
well as other drainage areas and low lying spots.

In hilly terrain there are hundreds of low water crossings which are
potentially dangerous in heavy rain. Do not attempt to cross flooded
roads. Find an alternate route.

&&

LAT...LON 3989 7673 3990 7666 4007 7668 4004 7657
      4005 7654 4002 7653 3999 7650 3997 7650
      3994 7647 3972 7648 3972 7677

$$

RXR

What forecasters said that day

The local office's own words before this flash flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS State College, PA wrote its last area forecast discussion before this flash flood warning went out at Aug 31, 4:55 PM EDT, 13 minutes earlier.

Area forecast discussion, Aug 31, 4:55 PM EDT, 13 minutes before

Area Forecast Discussion
National Weather Service State College PA
455 PM EDT Fri Aug 31 2018

.SYNOPSIS...
It will remain warm and humid for over the next seven days. A
stalled out frontal boundary will stay near the Mason-Dixon line
through at least mid day Saturday keeping the chance for showers
and thunderstorms in the forecast. High pressure will ridge in
from the northeast later Saturday through early next week
bringing a decreased chance for showers and thunderstorms.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
The radar lit up as expected over my SERN zones with severe
Flash Flooding in progress in portions of Lancaster County. .
SPC meso anal page shows a wedge of PWATs in excess of 2 inches
from the Chesapeake Bay up into SERN PA, with the mean flow out
of the S or SE into the area of deepest moisture.

Low level Theta-E field shows a weak boundary stalled from just
west of Chesapeake Bay north into Franklin County then westward.
Moderate instability is being acted upon by low level
convergence and weak upper divergence up into the right entrance
region of a mid/upper jet streak over SRN NY and NERN Pa
resulting in a small area of slow moving very heavy
thunderstorms. The risk for today will continue to be flooding
rains more than gusty/damaging wind.

The HRRR shows activity waning this evening with little more
than some scattered showers remaining after about 9-10PM. With
the easterly maritime flow expected to continue, we will likely
see precip transition into more of a light rain/drizzle scenario.

Mins will stay mild and in the 60s thanks to the extensive and
rather thick low level clouds. as the clouds move in.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
Saturday looks like it could be a rather gloomy and damp day
over much of the region as the surface high noses in from the
east continuing the maritime flow. By afternoon the best chance
for skies to brighten will be over my far NRN zones perhaps
along the NY border. While temperatures will not be especially
warm, dewpoints well up into the 60s to even mid 70s will make
for a sticky uncomfortable day.

&&

.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
Strong upper ridge will rebuild over the region Sunday through
Tuesday with very warm to hot and humid conditions prevailing
for much of the coming week. Anomalous PWATS spread northward
on Sunday and remain over the region through this period.
Well above normal temperatures, high humidity and scattered
diurnally- driven convection are expected each day under this
regime.

&&

.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
Updated TAFS late aft.

Large area of convection near MDT and LNS slowly moving
southward.

Earlier discussion below.

A moist easterly flow will support a rather extensive shield of
MVFR/IFR ceilings along with localized visibility restrictions
due to the scattered showers and locally heavy thunderstorms.

The most favorable conditions today will be over the NW part of
the flying area where KBFD will likely be on the western edge
of the MVFR cigs.

Persistent southeast flow, combined with overnight cooling is
likely to result in deteriorating cigs tonight. Model soundings
support the idea of widespread IFR/LIFR cigs late tonight with
occasional light rain/drizzle.

.Outlook...

Sat...AM low cigs/drizzle likely. Slow improvement in the
afternoon.

Sun...AM low cigs likely. Isold PM tsra impacts poss western Pa.

Mon-Wed...Patchy AM fog possible. Isold PM
showers/thunderstorms.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
None.

&&

SYNOPSIS...La Corte
NEAR TERM...La Corte
SHORT TERM...La Corte
LONG TERM...Fitzgerald/Ceru
AVIATION...DeVoir/La Corte/Martin

Hazardous weather outlook, Aug 31, 5:22 AM EDT, 11 hours 46 minutes before

Hazardous Weather Outlook
National Weather Service State College PA
522 AM EDT Fri Aug 31 2018

PAZ004>006-010-011-037-010930-
Warren-McKean-Potter-Elk-Cameron-Tioga-
522 AM EDT Fri Aug 31 2018

This Hazardous Weather Outlook is for central Pennsylvania.

.DAY ONE...Today and Tonight.

The probability for widespread hazardous weather is low.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

PAZ012-017>019-024>028-033>035-041-042-045-046-049-050-010930-
Northern Clinton-Clearfield-Northern Centre-Southern Centre-Cambria-
Blair-Huntingdon-Mifflin-Juniata-Somerset-Bedford-Fulton-
Northern Lycoming-Sullivan-Southern Clinton-Southern Lycoming-Union-
Snyder-
522 AM EDT Fri Aug 31 2018

This Hazardous Weather Outlook is for central Pennsylvania.

.DAY ONE...Today and Tonight.

Slow moving showers and isolated thunderstorms will produce
localized heavy rainfall amounts of over one inch in just 30 to 60
minutes. Ponding of water in poor drainage areas and rapid rises on
streams and creeks will be possible. The greatest threat for the
heavy rain will be during the mid to late morning hours across the
Central Mountains, and through the mid afternoon closer to the
Susquehanna Valley.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report significant hazardous weather.

PAZ036-051>053-056>059-063>066-010930-
Franklin-Montour-Northumberland-Columbia-Perry-Dauphin-Schuylkill-
Lebanon-Cumberland-Adams-York-Lancaster-
522 AM EDT Fri Aug 31 2018

This Hazardous Weather Outlook is for central Pennsylvania.

.DAY ONE...Today and Tonight.

Slow moving showers and scattered thunderstorms will combine
with a nearly stationary frontal boundary and a very moist
airmass to bring the chance for highly localized, very heavy
rainfall in excess of 2 inches within just an hour or two.
The heavy rain could lead to rapid rises on small streams,
along with flooding of poor drainage areas in cities and towns.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report significant hazardous weather.

In the hours before

Local storm report, Aug 31, 4:28 PM EDT, 40 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE STATE COLLEGE PA
428 PM EDT FRI AUG 31 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0426 PM     HEAVY RAIN       1 E MOUNT JOY           40.11N  76.49W
08/31/2018  M9.65 INCH       LANCASTER          PA   PUBLIC

            5 HOUR TOTAL.

&&

EVENT NUMBER CTP1802232

COLBERT

Local storm report, Aug 31, 4:29 PM EDT, 39 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE STATE COLLEGE PA
429 PM EDT FRI AUG 31 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0428 PM     HEAVY RAIN       3 SW NAUMANSTOWN        40.14N  76.47W
08/31/2018  M8.88 INCH       LANCASTER          PA   PUBLIC

            5 HOUR TOTAL.

&&

EVENT NUMBER CTP1802233

COLBERT

Local storm report, Aug 31, 4:30 PM EDT, 38 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE STATE COLLEGE PA
430 PM EDT FRI AUG 31 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0429 PM     HEAVY RAIN       1 SSW NAUMANSTOWN       40.15N  76.44W
08/31/2018  M9.41 INCH       LANCASTER          PA   PUBLIC

            5 HOUR TOTAL.

&&

EVENT NUMBER CTP1802234

COLBERT

Local storm report, Aug 31, 4:33 PM EDT, 35 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE STATE COLLEGE PA
433 PM EDT FRI AUG 31 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0431 PM     HEAVY RAIN       1 SSW SCHAEFFERSTOWN    40.29N  76.30W
08/31/2018  M8.88 INCH       LEBANON            PA   PUBLIC

            9 HOUR TOTAL.

&&

EVENT NUMBER CTP1802235

COLBERT

Local storm report, Aug 31, 4:35 PM EDT, 33 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE STATE COLLEGE PA
435 PM EDT FRI AUG 31 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0434 PM     HEAVY RAIN       2 N KREUTZ CREEK        40.03N  76.62W
08/31/2018  M6.20 INCH       YORK               PA   PUBLIC

            5 HOUR TOTAL.

&&

EVENT NUMBER CTP1802236

COLBERT

Local storm report, Aug 31, 4:59 PM EDT, 9 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE STATE COLLEGE PA
459 PM EDT FRI AUG 31 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0440 PM     HEAVY RAIN       PINE GROVE              40.53N  76.41W
08/31/2018  M2.00 INCH       SCHUYLKILL         PA   CO-OP OBSERVER

            2 INCHES IN 1 HOUR.

&&

EVENT NUMBER CTP1802237

COLBERT

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 31, 6:29 AM EDT	Areal Flood Advisory	CTP	Blair	3 hr
Aug 31, 6:47 AM EDT	Areal Flood Advisory	CTP	Centre, Huntingdon, Mifflin	3 hr
Aug 31, 9:41 AM EDT	Areal Flood Advisory	CTP	Lebanon	2 hr
Aug 31, 9:58 AM EDT	Flash Flood Warning	CTP	Lebanon	3 hr
Aug 31, 10:44 AM EDT	Areal Flood Advisory	CTP	Schuylkill	2 hr
Aug 31, 12:11 PM EDT	Areal Flood Advisory	CTP	Lancaster, Lebanon	3 hr
Aug 31, 1:02 PM EDT	Areal Flood Warning	CTP	Lebanon	118 min
Aug 31, 1:31 PM EDT	Flash Flood Warning Emergency	CTP	Lancaster	9 hr
Aug 31, 2:19 PM EDT	Areal Flood Advisory	CTP	York	3 hr
Aug 31, 2:55 PM EDT	Flash Flood Warning	CTP	York	3 hr
Aug 31, 3:06 PM EDT	River Flood Warning	CTP	Lebanon, Schuylkill	14 hr
Aug 31, 3:26 PM EDT	Areal Flood Advisory	CTP	Schuylkill	3 hr
Aug 31, 3:35 PM EDT	Areal Flood Advisory	CTP	Lebanon	115 min
Aug 31, 3:35 PM EDT	Areal Flood Advisory	CTP	Lancaster, York	3 hr
Aug 31, 4:09 PM EDT	Areal Flood Advisory	CTP	Adams, Cumberland	3 hr
Aug 31, 4:38 PM EDT	Flash Flood Warning	CTP	Lancaster, York	3 hr
Aug 31, 4:44 PM EDT	Flash Flood Warning	CTP	Adams, Cumberland	3 hr
Aug 31, 5:44 PM EDT	Areal Flood Advisory	CTP	Lancaster	2 hr
Aug 31, 6:13 PM EDT	Areal Flood Advisory	CTP	Somerset	2 hr
Aug 31, 7:35 PM EDT	Areal Flood Warning	CTP	Lancaster, York	3 hr
Aug 31, 7:54 PM EDT	Areal Flood Warning	CTP	York	3 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2018 Every flash flood warning in 2018

Sources

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