Alert archive / Maine / Severe Thunderstorm Watches in 2021
Severe Thunderstorm Watch 327
The Storm Prediction Center issued this severe thunderstorm watch at Jun 30, 2021, 12:06 PM EDT for 4 states. It was in force for 7 hr.
The area
The outline as issued.
The facts
- Issued
- Jun 30, 2021, 12:06 PM EDT (16:06 UTC)
- Expired
- Jun 30, 2021, 7:00 PM EDT
- In force
- 7 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1 in
- Strongest gust expected
- 60 kt
All 35 counties
Androscoggin County, ME, Cumberland County, ME, Franklin County, ME, Hancock County, ME, Kennebec County, ME, Knox County, ME, Lincoln County, ME, Oxford County, ME, Penobscot County, ME, Piscataquis County, ME, Sagadahoc County, ME, Somerset County, ME, Waldo County, ME, Washington County, ME, York County, ME, Belknap County, NH, Carroll County, NH, Cheshire County, NH, Coos County, NH, Grafton County, NH, Hillsborough County, NH, Merrimack County, NH, Rockingham County, NH, Strafford County, NH, Sullivan County, NH, Essex County, NY, Addison County, VT, Caledonia County, VT, Chittenden County, VT, Essex County, VT, Lamoille County, VT, Orange County, VT, Rutland County, VT, Washington County, VT, Windsor County, VT
The radar
The Portland,ME radar (KGYX), 106 km from the middle of the area, began a volume at 16:08 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.
What SPC expected
The probabilities SPC published with the watch, for the watch area over its life.
- Two or more tornadoes
- 10%
- One or more EF2 to EF5 tornadoes
- 2%
- Ten or more severe wind reports
- 60%
- One or more gusts of 65 knots or more
- 20%
- Ten or more severe hail reports
- 20%
- One or more hailstones of 2 inches or more
- 10%
- Six or more combined severe hail and wind reports
- 80%
Warnings issued inside it
18 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 30, 12:46 PM EDT | Severe Thunderstorm Warning | BTV | Essex | 59 min |
| Jun 30, 1:15 PM EDT | Severe Thunderstorm Warning | BTV | Chittenden, Lamoille, Washington | 60 min |
| Jun 30, 1:37 PM EDT | Severe Thunderstorm Warning | BTV | Essex | 53 min |
| Jun 30, 2:22 PM EDT | Severe Thunderstorm Warning | GYX | Kennebec, Somerset, Waldo | 53 min |
| Jun 30, 2:24 PM EDT | Severe Thunderstorm Warning | BTV | Addison, Rutland, Windsor | 66 min |
| Jun 30, 2:25 PM EDT | Severe Thunderstorm Warning | CAR | Hancock, Penobscot | 65 min |
| Jun 30, 3:02 PM EDT | Severe Thunderstorm Warning | GYX | Grafton, Sullivan | 43 min |
| Jun 30, 3:10 PM EDT | Severe Thunderstorm Warning | CAR | Hancock | 50 min |
| Jun 30, 3:10 PM EDT | Severe Thunderstorm Warning | GYX | Carroll, Coos, Grafton | 17 min |
| Jun 30, 4:01 PM EDT | Severe Thunderstorm Warning | GYX | Belknap, Carroll, Grafton, Merrimack, Strafford | 27 min |
| Jun 30, 4:05 PM EDT | Severe Thunderstorm Warning | GYX | Cheshire, Sullivan | 35 min |
| Jun 30, 4:11 PM EDT | Severe Thunderstorm Warning | GYX | Belknap, Carroll, Merrimack, Strafford | 49 min |
| Jun 30, 4:25 PM EDT | Severe Thunderstorm Warning | GYX | Cheshire, Hillsborough | 50 min |
| Jun 30, 4:38 PM EDT | Severe Thunderstorm Warning | GYX | York | 52 min |
| Jun 30, 4:53 PM EDT | Severe Thunderstorm Warning | CAR | Hancock | 52 min |
| Jun 30, 4:58 PM EDT | Severe Thunderstorm Warning | GYX | Rockingham | 32 min |
| Jun 30, 5:12 PM EDT | Severe Thunderstorm Warning | GYX | Hillsborough, Rockingham | 33 min |
| Jun 30, 5:31 PM EDT | Severe Thunderstorm Warning | CAR | Aroostook, Washington | 29 min |
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Gray, ME (KGYX), launched 12:00Z, 4.1 hours before the alert went out and 106 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
- 906 J/kg
- Mixed-layer CIN
- -60 J/kg
- Mixed-layer LCL
- 1312 m above ground
- 0-6 km bulk shear
- 33 kt
- 0-1 km storm-relative helicity
- 95 m²/s²
- 0-3 km storm-relative helicity
- 102 m²/s²
- Significant tornado parameter
- 0.2
- Supercell composite
- 1.3
The text
As transmitted.
741 WWUS20 KWNS 301604 SEL7 SPC WW 301604 MEZ000-NHZ000-NYZ000-VTZ000-CWZ000-302300- URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 327 NWS Storm Prediction Center Norman OK 1205 PM EDT Wed Jun 30 2021 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Southern Maine New Hampshire Extreme northeastern New York Vermont Coastal Waters * Effective this Wednesday afternoon and evening from 1205 PM until 700 PM EDT. * Primary threats include... Scattered damaging wind gusts to 70 mph likely Isolated large hail events to 1 inch in diameter possible SUMMARY...Scattered thunderstorm development is expected through the afternoon across northern New England, in an environment supporting both supercells and clusters/line segments capable of producing damaging winds and isolated large hail. The severe thunderstorm watch area is approximately along and 60 statute miles north and south of a line from 50 miles north northwest of Glens Falls NY to 40 miles east of Bar Harbor ME. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU7). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && OTHER WATCH INFORMATION...CONTINUE...WW 326... AVIATION...A few severe thunderstorms with hail surface and aloft to 1 inch. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 27035. ...Thompson
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 30, 11:04 AM EDT | Mesoscale Discussion | SPC | Androscoggin, Cumberland, Franklin, Hancock, Kennebec, Knox and 8 more | 116 min |
| Jun 30, 1:52 PM EDT | Mesoscale Discussion | SPC | Androscoggin, Cumberland, Oxford | 83 min |
| Jun 30, 4:16 PM EDT | Mesoscale Discussion | SPC | Androscoggin, Cumberland, Hancock, Kennebec, Knox, Lincoln and 4 more | 89 min |
| Jun 30, 11:47 AM EDT | Severe Thunderstorm Watch | SPC | Albany, Allegany, Broome, Cattaraugus, Cayuga, Chautauqua and 27 more | 7 hr |
| Jun 30, 2:16 PM EDT | Mesoscale Discussion | SPC | Albany, Columbia, Dutchess, Greene, Orange, Putnam and 2 more | 119 min |
| Jun 30, 3:21 PM EDT | Severe Thunderstorm Watch | SPC | Columbia, Dutchess, Greene, Orange, Putnam, Rockland and 3 more | 7 hr |
| Jun 30, 4:48 PM EDT | Mesoscale Discussion | SPC | Albany, Columbia, Delaware, Greene, Schoharie, Sullivan and 1 more | 87 min |
| Jun 30, 6:58 PM EDT | Mesoscale Discussion | SPC | Bronx, Orange, Putnam, Rockland, Westchester | 92 min |
Nearby
Severe Thunderstorm Watches in Maine, 2021Severe Thunderstorm Watches in New Hampshire, 2021Severe Thunderstorm Watches in Vermont, 2021Every severe thunderstorm watch 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.