Alert archive / Pennsylvania / Mesoscale Discussions in 2012
Mesoscale Discussion 36
The Storm Prediction Center issued this mesoscale discussion at Jan 21, 2012, 12:59 AM EST for 35 counties in Pennsylvania. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Jan 21, 2012, 12:59 AM EST (05:59 UTC)
- Expired
- Jan 21, 2012, 5:00 AM EST
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
All 35 counties
Adams County, PA, Allegheny County, PA, Armstrong County, PA, Bedford County, PA, Berks County, PA, Blair County, PA, Butler County, PA, Cambria County, PA, Centre County, PA, Clarion County, PA, Clearfield County, PA, Clinton County, PA, Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Fayette County, PA, Franklin County, PA, Fulton County, PA, Huntingdon County, PA, Indiana County, PA, Jefferson County, PA, Juniata County, PA, Lancaster County, PA, Lebanon County, PA, Mifflin County, PA, Montour County, PA, Northumberland County, PA, Perry County, PA, Schuylkill County, PA, Snyder County, PA, Somerset County, PA, Union County, PA, Washington County, PA, Westmoreland County, PA, York County, PA
The radar
The State College radar (KCCX), 54 km from the middle of the area, began a volume at 05:59 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 (KPIT), launched 00:00Z, 6.0 hours before the alert went out and 158 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.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 2294 m above ground
- 0-6 km bulk shear
- 87 kt
- 0-1 km storm-relative helicity
- 248 m²/s²
- 0-3 km storm-relative helicity
- 355 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
029
ACUS11 KWNS 210559
SWOMCD
SPC MCD 210559
PAZ000-211000-
MESOSCALE DISCUSSION 0036
NWS STORM PREDICTION CENTER NORMAN OK
1159 PM CST FRI JAN 20 2012
AREAS AFFECTED...SRN AND CNTRL PA
CONCERNING...HEAVY SNOW
VALID 210559Z - 211000Z
HEAVY SNOWFALL IS EXPECTED TO DEVELOP ACROSS SRN AND CNTRL PA LATER
TONIGHT. SNOWFALL RATES COULD REACH 1 INCH PER HOUR ACROSS PARTS OF
THE MCD AREA.
WATER VAPOR IMAGERY CURRENTLY SHOWS A SHORT-WAVE TROUGH EXTENDING
FROM THE ERN GREAT LAKES SWWD ACROSS THE OH VALLEY. A LARGE AREA OF
PRECIPITATION IS LOCATED JUST AHEAD OF THE AXIS OF THE SHORTWAVE
TROUGH FROM SRN OH EXTENDING EWD INTO THE CNTRL APPALACHIAN MTNS. A
THREAT FOR FREEZING RAIN OR SLEET MAY EXIST ACROSS SW PA FOR A FEW
MORE HOURS DUE TO WARMER AIR IN PLACE SOUTH OF THE PITTSBURG AREA.
HOWEVER...FROM PITTSBURG EWD TO NEAR HARRISBURG...THE PRECIPITATION
SHOULD BE ALL SNOW WHERE FORECAST SOUNDINGS SHOW TEMPS BELOW -10C IN
THE 850 TO 700 MB LAYER. IN ADDITION...MODEL FORECASTS MARKEDLY
STRENGTHEN ISENTROPIC LIFT ACROSS SRN AND CNTRL PA LATER TONIGHT AS
THE SHORTWAVE APPROACHES FROM THE WEST. THIS SHOULD RESULT IN ENOUGH
LIFT FOR HEAVY SNOWFALL WITH SNOWFALL RATES REACHING 1 INCH PER HOUR
MAINLY DURING THE OVERNIGHT PERIOD.
..BROYLES.. 01/21/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...PHI...BGM...CTP...PBZ...
LAT...LON 39797947 39747714 39887592 40297556 40827565 41267634
41357866 41247982 40928027 40458034 40088024 39797947SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jan 21, 7:07 AM EST | Mesoscale Discussion | SPC | Chester, Delaware, Philadelphia | 3 hr |
Nearby
Mesoscale Discussions in Pennsylvania, 2012Every mesoscale discussion in 2012
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.