Alert archive / Pennsylvania / Mesoscale Discussions in 2021
Mesoscale Discussion 37
The Storm Prediction Center issued this mesoscale discussion at Jan 26, 2021, 8:46 AM EST for 21 counties in Pennsylvania. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Jan 26, 2021, 8:46 AM EST (13:46 UTC)
- Expired
- Jan 26, 2021, 12:45 PM EST
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Freezing rain
All 21 counties
Bedford County, PA, Blair County, PA, Cambria County, PA, Cameron County, PA, Centre County, PA, Clearfield County, PA, Clinton County, PA, Elk County, PA, Forest County, PA, Fulton County, PA, Huntingdon County, PA, Indiana County, PA, Jefferson County, PA, Juniata County, PA, Mifflin County, PA, Northumberland County, PA, Perry County, PA, Snyder County, PA, Somerset County, PA, Union County, PA, Warren County, PA
The radar
The State College radar (KCCX), 51 km from the middle of the area, began a volume at 13:48 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 12:00Z, 1.8 hours before the alert went out and 143 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
- 389 m above ground
- 0-6 km bulk shear
- 103 kt
- 0-1 km storm-relative helicity
- 628 m²/s²
- 0-3 km storm-relative helicity
- 651 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted.
108
ACUS11 KWNS 261346
SWOMCD
SPC MCD 261346
PAZ000-NYZ000-261745-
Mesoscale Discussion 0037
NWS Storm Prediction Center Norman OK
0746 AM CST Tue Jan 26 2021
Areas affected...Portions of western/central PA and far southwestern
NY
Concerning...Freezing rain
Valid 261346Z - 261745Z
SUMMARY...Light to moderate freezing rain, with rates above 0.05
inch per 3 hours, should continue this morning.
DISCUSSION...The 12Z sounding from PIT shows a very pronounced warm
nose (nearly +8 degrees C) centered around 850 mb. Low-level warm
advection is forecast to strengthen further this morning as a
low-amplitude shortwave trough moves eastward from the OH
Valley/Great Lakes to the Northeast. Latest surface observations
show much of the higher terrain in western/central PA remains below
freezing. Light to moderate freezing rain with fairly widespread
ongoing showers is expected to continue across this region for at
least the next few hours as the shortwave trough approaches from the
west. Rates will likely exceed 0.05 inch per 3 hours in these
showers, with greater rates possible in the higher terrain. Given
surface temperatures across much of this region in the 28-30 degrees
F range, ice accretion should be fairly efficient on elevated and
sub-freezing surfaces. Across northern PA and far southwestern NY,
some mix of sleet and snow may also occur, as the low-level warm
nose should not be as pronounced across these areas.
..Gleason.. 01/26/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...BUF...CTP...PBZ...CLE...
LAT...LON 40447919 40657910 41137930 41437956 41717993 41977989
42177963 42217927 42077887 41757859 41327798 41147701
40967655 40707639 40397699 40257757 39757829 39757914
39897955 40447919Nearby
Mesoscale Discussions in Pennsylvania, 2021Every mesoscale discussion 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.