Alert archive / Pennsylvania / Mesoscale Discussions in 2012

Mesoscale Discussion 2132

December 7, 201221 counties in Pennsylvania

The Storm Prediction Center issued this mesoscale discussion at Dec 7, 2012, 3:44 AM EST for 21 counties in Pennsylvania. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
Dec 7, 2012, 3:44 AM EST (08:44 UTC)
Expired
Dec 7, 2012, 9:45 AM EST
In force
6 hr
Issued by
the Storm Prediction Center
All 21 counties

Bradford County, PA, Cameron County, PA, Centre County, PA, Clearfield County, PA, Clinton County, PA, Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Huntingdon County, PA, Juniata County, PA, Lycoming County, PA, Mifflin County, PA, Montour County, PA, Northumberland County, PA, Perry County, PA, Potter County, PA, Schuylkill County, PA, Snyder County, PA, Sullivan County, PA, Tioga County, PA, Union County, PA

The radar

The State College radar (KCCX), 66 km from the middle of the area, began a volume at 08:47 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.

The nearest sounding before it

Buffalo Intl Airport, NY (KBUF), launched 00:00Z, 8.7 hours before the alert went out and 235 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, Buffalo Intl Airport, NY at 00:00Z on 2012-12-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Buffalo Intl Airport, NY at 00:00Z on 2012-12-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 229 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
3529 m above ground
0-6 km bulk shear
47 kt
0-1 km storm-relative helicity
229 m²/s²
0-3 km storm-relative helicity
252 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

626 
ACUS11 KWNS 070844
SWOMCD
SPC MCD 070844 
PAZ000-071445-

MESOSCALE DISCUSSION 2132
NWS STORM PREDICTION CENTER NORMAN OK
0244 AM CST FRI DEC 07 2012

AREAS AFFECTED...CNTRL PA

CONCERNING...FREEZING RAIN 

VALID 070844Z - 071445Z

SUMMARY...AREAS OF LIGHT FREEZING RAIN ARE EXPECTED EARLY THIS
MORNING...ENDING FROM SW TO NE AS TEMPERATURES WARM...AND CHANGING
TO ALL RAIN AFTER 15Z.

DISCUSSION...A COLD SURFACE RIDGE IS IN PLACE ACROSS THE NERN STATES
WITH TEMPERATURES IN THE 20S F. SWLY FLOW OFF THE SURFACE IS HELPING
TO ENHANCE ISENTROPIC LIFT ALONG A WARM FRONT...WITH WIDESPREAD
SHOWERS ACROSS OH INTO WRN PA. WITH SURFACE WET BULB TEMPERATURES
WELL BELOW 32 F...INITIAL PRECIPITATION SHOULD BE FREEZING RAIN
ACROSS CNTRL AND NRN PA. MODELS INDICATE A FEW HUNDREDTHS PER HOUR
WILL BE POSSIBLE FOR SEVERAL HOURS...BEFORE WARM ADVECTION BRING
TEMPERATURES ABOVE FREEZING.  UPSTREAM SURFACE OBSERVATIONS ALSO
INDICATE HOURLY AMOUNTS GENERALLY NEAR 0.05".

..JEWELL.. 12/07/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...BGM...CTP...

LAT...LON   41967685 41767620 41407596 40827604 40427655 40097709
            39937749 40347795 40857846 41277862 41727843 41937785
            41967685

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.