Alert archive / Pennsylvania / Flood Watches in 2008

Flood Watch 5, NWS State College, PA

April 20, 200813 counties in Pennsylvania

NWS State College, PA issued this flood watch at Apr 20, 2008, 9:25 AM EDT for 13 counties in Pennsylvania. It took effect at Apr 20, 2008, 2:00 PM EDT. It was in force for 14 hr.

The area

The counties it named.

The facts

Issued
Apr 20, 2008, 9:25 AM EDT (13:25 UTC)
In effect from
Apr 20, 2008, 2:00 PM EDT
Expired
Apr 21, 2008, 4:21 AM EDT
In force
14 hr
Issued by
NWS State College, PA
Flood severity
None

Counties Adams County, PA, Bedford County, PA, Blair County, PA, Cambria County, PA, Cumberland County, PA, Franklin County, PA, Fulton County, PA, Huntingdon County, PA, Juniata County, PA, Mifflin County, PA, Perry County, PA, Somerset County, PA, York County, PA

The radar

The State College radar (KCCX), 81 km from the middle of the area, began a volume at 13:25 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

Washington/Dulle, VA (KIAD), launched 12:00Z, 1.4 hours before the alert went out and 145 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, Washington/Dulle, VA at 12:00Z on 2008-04-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 497 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, Washington/Dulle, VA at 12:00Z on 2008-04-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 112 square meters per square second.193958Sfc1 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
497 J/kg
Mixed-layer CIN
-4 J/kg
Mixed-layer LCL
530 m above ground
0-6 km bulk shear
36 kt
0-1 km storm-relative helicity
112 m²/s²
0-3 km storm-relative helicity
154 m²/s²
Significant tornado parameter
0.3
Supercell composite
1.4

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flood watch 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 flood watch went out at Apr 20, 7:39 AM EDT, 1 hour 46 minutes earlier.

Area forecast discussion, Apr 20, 7:39 AM EDT, 1 hour 46 minutes before
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Hazardous weather outlook, Apr 20, 2:38 AM EDT, 6 hours 47 minutes before
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE STATE COLLEGE PA
238 AM EDT SUN APR 20 2008

PAZ004>006-010>012-017>019-024>028-033>037-041-042-045-046-049>053-
056>059-063>066-210645-
WARREN-MCKEAN-POTTER-ELK-CAMERON-NORTHERN CLINTON-CLEARFIELD-
NORTHERN CENTRE-SOUTHERN CENTRE-CAMBRIA-BLAIR-HUNTINGDON-MIFFLIN-
JUNIATA-SOMERSET-BEDFORD-FULTON-FRANKLIN-TIOGA-NORTHERN LYCOMING-
SULLIVAN-SOUTHERN CLINTON-SOUTHERN LYCOMING-UNION-SNYDER-MONTOUR-
NORTHUMBERLAND-COLUMBIA-PERRY-DAUPHIN-SCHUYLKILL-LEBANON-CUMBERLAND-
ADAMS-YORK-LANCASTER-
238 AM EDT SUN APR 20 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL PENNSYLVANIA.

.DAY ONE...TODAY AND TONIGHT

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

LOW PRESSURE WILL DRIFT SLOWLY SOUTHEAST ACROSS THE CENTRAL
APPALACHIANS TODAY INTO MONDAY BRINGING LOCALLY HEAVY RAIN TO THE
LAUREL HIGHLANDS AND PORTIONS OF SOUTH CENTRAL PENNSYLVANIA. 1 TO
2 INCHES OF RAIN WILL LIKELY FALL OVER THE REGION NEAR AND TO THE
SOUTH OF THE PENNSYLVANIA TURNPIKE...AND TO THE WEST OF INTERSTATE
81.

THIS AMOUNT OF RAIN WILL NOT CAUSE FLOODING...EVEN ON SMALLER
STREAMS. HOWEVER...SOME COMPUTER MODEL INFORMATION INDICATES A LOW
PROBABILITY FOR LOCALLY AROUND 3 INCHES OF RAIN NEAR THE
PENNSYLVANIA...MARYLAND BORDER...WHICH WOULD APPROACH THE
THRESHOLD NEEDED TO PRODUCE MINOR FLOODING ON SMALL STREAMS.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

DEVOIR

The office that day

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

IssuedProductOfficeCountiesLasted
Apr 20, 6:32 PM EDTSevere Thunderstorm WarningCTPAdams, York43 min
Apr 20, 6:44 PM EDTTornado WarningCTPYork31 min

Nearby

Flood Watches in Pennsylvania, 2008Every flood watch in 2008

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.