Alert archive / Pennsylvania / Special Weather Statements in 2021

Special Weather Statement, NWS State College, PA

August 18, 2021Lancaster County, Pennsylvania

NWS State College, PA issued this special weather statement at Aug 18, 2021, 8:45 PM EDT for Lancaster County, Pennsylvania. It was in force for 45 min. 1 report 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 18, 2021, 8:45 PM EDT (00:45 UTC)
Expired: Aug 18, 2021, 9:30 PM EDT
In force: 45 min
Issued by: NWS State College, PA
Hail: 0.00 in
Wind: 50

County Lancaster County, PA

The radar

The Dover AFB radar (KDOX), 153 km from the middle of the area, began a volume at 00:47 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 18, 9:21 PM EDT	TSTM WND DMG	1 N Willow Street, PA	TREES AND WIRES DOWN.

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

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 00:00Z, 0.8 hours before the alert went out and 156 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: 1288 J/kg
Mixed-layer CIN: -8 J/kg
Mixed-layer LCL: 1100 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: 126 m²/s²
0-3 km storm-relative helicity: 171 m²/s²
Significant tornado parameter: 0.6
Supercell composite: 5.9

Open this sounding in Storm Lab

The text

As transmitted.

311 
WWUS81 KCTP 190045
SPSCTP

Special Weather Statement
National Weather Service State College PA
845 PM EDT Wed Aug 18 2021
 
PAZ065-066-190130-
Lancaster PA-York PA-
845 PM EDT Wed Aug 18 2021

...A strong thunderstorm will impact portions of central Lancaster
and southeastern York Counties through 930 PM EDT...

At 844 PM EDT, Doppler radar was tracking strong thunderstorms over 
eastern York and western Lancaster counties, moving northeast at 
35 mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around 
         unsecured objects.

Locations impacted include...
Lancaster, York, Ephrata, Columbia, Lititz, Millersville, Willow
Street, Red Lion, New Holland, Spry, East Petersburg, Dallastown,
Akron, East York, Leola, Stonybrook-Wilshire, Paradise,
Salunga-Landisville, Denver and Tyler Run-Queens Gate.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building. 

Very heavy rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

A Tornado Watch remains in effect until 1100 PM EDT for south central
Pennsylvania.

&&

LAT...LON 3997 7672 4029 7610 4014 7587 4010 7594
      4006 7594 3977 7655
TIME...MOT...LOC 0044Z 237DEG 35KT 3998 7644 

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH

$$

Jurewicz

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 18, 8:08 PM EDT	Severe Thunderstorm Warning	CTP	Lancaster, Lebanon	37 min
Aug 18, 8:27 PM EDT	Areal Flood Advisory	CTP	Lancaster, Lebanon	3 hr
Aug 18, 8:48 PM EDT	Areal Flood Advisory	CTP	Tioga	76 min
Aug 18, 9:11 PM EDT	Flash Flood Warning Considerable damage threat	CTP	Lancaster	108 min
Aug 18, 9:12 PM EDT	Severe Thunderstorm Warning	CTP	York	33 min
Aug 18, 9:21 PM EDT	Severe Thunderstorm Warning	CTP	Lancaster	39 min
Aug 18, 10:28 PM EDT	Severe Thunderstorm Warning	CTP	Lancaster	47 min
Aug 18, 10:34 PM EDT	Areal Flood Warning	CTP	Lancaster, York	11 min
Aug 18, 10:48 PM EDT	Areal Flood Warning	CTP	Lancaster, York	2 hr
Aug 18, 10:53 PM EDT	Areal Flood Advisory	CTP	Lancaster, York	3 hr
Aug 18, 10:59 PM EDT	Areal Flood Warning	CTP	Lancaster	2 hr

Nearby

Special Weather Statements in Pennsylvania, 2021 Every special weather statement in 2021

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.