Alert archive / New Hampshire / Mesoscale Discussions in 2021
Mesoscale Discussion 101
The Storm Prediction Center issued this mesoscale discussion at Feb 16, 2021, 2:51 AM EST for 4 states. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Feb 16, 2021, 2:51 AM EST (07:51 UTC)
- Expired
- Feb 16, 2021, 6:45 AM EST
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Freezing rain
All 21 counties
Berkshire County, MA, Franklin County, MA, Hampden County, MA, Hampshire County, MA, Belknap County, NH, Carroll County, NH, Cheshire County, NH, Grafton County, NH, Hillsborough County, NH, Merrimack County, NH, Strafford County, NH, Sullivan County, NH, Albany County, NY, Columbia County, NY, Greene County, NY, Montgomery County, NY, Rensselaer County, NY, Schenectady County, NY, Schoharie County, NY, Bennington County, VT, Windham County, VT
The radar
The Albany radar (KENX), 140 km from the middle of the area, began a volume at 07:55 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
Albany, NY (KALY), launched 00:00Z, 7.9 hours before the alert went out and 118 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
- 603 m above ground
- 0-6 km bulk shear
- 54 kt
- 0-1 km storm-relative helicity
- 79 m²/s²
- 0-3 km storm-relative helicity
- 227 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
461
ACUS11 KWNS 160752
SWOMCD
SPC MCD 160751
MEZ000-NHZ000-MAZ000-VTZ000-CTZ000-NYZ000-161145-
Mesoscale Discussion 0101
NWS Storm Prediction Center Norman OK
0151 AM CST Tue Feb 16 2021
Areas affected...east-central NY...northwest CT...western
MA...southern VT...NH...southern ME
Concerning...Freezing rain
Valid 160751Z - 161145Z
SUMMARY...Freezing rain rates ranging from 0.05 to 0.15 inch per 3
hours are likely from southern NY into NH and southern ME as a
precipitation shield moves north tonight.
DISCUSSION...Radar mosaic as of 245am shows a broken precipitation
shield from PA/NJ northward into New England. Strong low-level warm
air advection in the right-entrance region of a powerful jet, which
is centered over the St. Lawrence Seaway, will continue to favor
episodic moderate precipitation overnight. Forecast soundings show
a layer of above-freezing air around 850 mb atop a shallow
sub-freezing airmass at the surface. The profile will favor
freezing rain as the preferred precipitation type for much of the
discussion area. Model forecast soundings indicate some erosion of
the sub-freezing airmass from southern NY into parts of MA (in
closer proximity to the coast) as temperatures warm to at or above
32 degrees F between 5-7am EST. Some supporting evidence for this
trend is showing across southern NY with temperatures rising above
freezing during the past 1-2 hours. Farther inland, freezing rain
will likely continue through 7am EST.
..Smith.. 02/16/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GYX...BOX...BTV...ALY...BGM...
LAT...LON 43597059 42137214 41857330 41977392 42387458 42927454
43327288 44287140 44127053 43597059SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Feb 15, 8:06 PM EST | Mesoscale Discussion | SPC | Allegany, Cattaraugus, Cayuga, Chautauqua, Erie, Franklin and 18 more | 5 hr |
| Feb 15, 9:16 PM EST | Mesoscale Discussion | SPC | Orange, Sullivan | 5 hr |
Nearby
Mesoscale Discussions in New Hampshire, 2021Mesoscale Discussions in New York, 2021Mesoscale Discussions in Massachusetts, 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.