Alert archive / Vermont / Mesoscale Discussions in 2026
Mesoscale Discussion 1621
The Storm Prediction Center issued this mesoscale discussion at Jul 15, 2026, 12:44 AM EDT for Merrimack County, Sullivan County, New Hampshire; 5 counties in New York; 6 counties in Vermont. It was in force for 91 min.
The area
The outline as issued.
The facts
- Issued
- Jul 15, 2026, 12:44 AM EDT (04:44 UTC)
- Expired
- Jul 15, 2026, 2:15 AM EDT
- In force
- 91 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 489
Counties Merrimack County, NH, Sullivan County, NH, Clinton County, NY, Essex County, NY, Franklin County, NY, St. Lawrence County, NY, Warren County, NY, Addison County, VT, Chittenden County, VT, Orange County, VT, Rutland County, VT, Washington County, VT, Windsor County, VT
The radar
The Burlington radar (KCXX), 47 km from the middle of the area, began a volume at 04:45 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 watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Albany, NY (KALY), launched 00:00Z, 4.7 hours before the alert went out and 163 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
- 957 J/kg
- Mixed-layer CIN
- -316 J/kg
- Mixed-layer LCL
- 2034 m above ground
- 0-6 km bulk shear
- 56 kt
- 0-1 km storm-relative helicity
- 260 m²/s²
- 0-3 km storm-relative helicity
- 316 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.7
The text
As transmitted.
948
ACUS11 KWNS 150445
SWOMCD
SPC MCD 150444
NHZ000-VTZ000-NYZ000-150615-
Mesoscale Discussion 1621
NWS Storm Prediction Center Norman OK
1144 PM CDT Tue Jul 14 2026
Areas affected...portions of northern New York into Vermont and New
Hampshire.
Concerning...Severe Thunderstorm Watch 489...
Valid 150444Z - 150615Z
The severe weather threat for Severe Thunderstorm Watch 489
continues.
SUMMARY...Strong to severe storms are expected to persist across the
western portions of WW489 into the overnight hours. Hail and
damaging winds are the most likely hazards.
DISCUSSION...As of 0440 UTC, a cluster of severe storms, including a
robust supercell over St Lawrence County NY, are ongoing across
western portions of WW489. Moderate buoyancy and strong deep-layer
shear remain in place ahead of this convection, and new storm
development just across the ON border. Hail is the most likely
threat tonight, especially with the aforementioned supercell showing
peak MRMS MESH of 2+ inches and a persistent cellular storm mode.
Damaging winds are also possible with the stronger cells, though
upscale growth appears limited given the very strong deep-layer
shear. A tornado also cannot be ruled out given the ongoing
supercells and strong vertical shear.
With the favorable parameter space likely to persist tonight, severe
potential should be maximized across parts of northern NY, into VT
and southern NH. Storm should begin to weaken late tonight as they
approach a more stable air mass into southern New England.
..Lyons.. 07/15/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GYX...BTV...ALY...
LAT...LON 44537274 44167218 43637149 43287141 42997161 42977210
43277331 44137519 44527574 45027513 45177451 44997374
44537274
MOST PROBABLE PEAK TORNADO INTENSITY...85-110 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 INSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 14, 8:24 PM EDT | Severe Thunderstorm Watch | SPC | Belknap, Carroll, Coos, Grafton, Strafford | 7 hr |
| Jul 14, 10:11 PM EDT | Mesoscale Discussion | SPC | Belknap, Carroll, Coos, Grafton, Merrimack, Strafford and 1 more | 94 min |
| Jul 15, 1:00 AM EDT | Severe Thunderstorm Watch | SPC | Cheshire, Hillsborough, Merrimack, Rockingham, Sullivan | 5 hr |
| Jul 15, 2:56 AM EDT | Mesoscale Discussion | SPC | Cheshire, Hillsborough, Merrimack, Rockingham, Sullivan | 94 min |
| Jul 15, 4:26 AM EDT | Mesoscale Discussion | SPC | Hillsborough, Merrimack, Rockingham, Sullivan | 94 min |
| Jul 15, 3:55 PM EDT | Mesoscale Discussion | SPC | Richmond | 65 min |
Nearby
Mesoscale Discussions in Vermont, 2026Mesoscale Discussions in New York, 2026Mesoscale Discussions in New Hampshire, 2026Every mesoscale discussion in 2026
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.