Alert archive / Maine / Mesoscale Discussions in 2021
Mesoscale Discussion 1698
The Storm Prediction Center issued this mesoscale discussion at Sep 6, 2021, 1:40 PM EDT for 5 counties in Maine; Coos County, New Hampshire; 4 counties in Vermont. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Sep 6, 2021, 1:40 PM EDT (17:40 UTC)
- Expired
- Sep 6, 2021, 3:45 PM EDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
Counties Aroostook County, ME, Franklin County, ME, Oxford County, ME, Piscataquis County, ME, Somerset County, ME, Coos County, NH, Caledonia County, VT, Essex County, VT, Orange County, VT, Orleans County, VT
The radar
The Portland,ME radar (KGYX), 165 km from the middle of the area, began a volume at 17:43 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
Gray, ME (KGYX), launched 12:00Z, 5.7 hours before the alert went out and 165 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
- 10 J/kg
- Mixed-layer CIN
- -46 J/kg
- Mixed-layer LCL
- 627 m above ground
- 0-6 km bulk shear
- 49 kt
- 0-1 km storm-relative helicity
- -38 m²/s²
- 0-3 km storm-relative helicity
- 125 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
265
ACUS11 KWNS 061741
SWOMCD
SPC MCD 061740
MEZ000-NHZ000-VTZ000-061945-
Mesoscale Discussion 1698
NWS Storm Prediction Center Norman OK
1240 PM CDT Mon Sep 06 2021
Areas affected...Northern New Hampshire...central/northern Maine
Concerning...Severe potential...Watch unlikely
Valid 061740Z - 061945Z
Probability of Watch Issuance...20 percent
SUMMARY...Storm coverage across parts of New Hampshire and
central/northern Maine will increase this afternoon. Isolated
damaging winds and small hail are possible. Lack of greater
destabilization will limit coverage of intense storms. No watch is
expected.
DISCUSSION...Weak convection has continued to occur within a
pre-frontal trough in central/northern Maine. As the shortwave
progresses to the northeast this afternoon, some combination of
deepening convection within the surface trough and along the
advancing cold front will lead to an increase of thunderstorm
coverage in northern New England. Cold temperatures aloft,
particularly with northward extent, should support a few marginally
intense updrafts capable of isolated damaging wind and small hail.
Greater surface heating in central and northern Maine increases the
potential for stronger convective winds to reach the surface.
Temperatures and dewpoints will be greater in coastal southern
Maine, but warmer temperatures aloft will limit updraft depth and
intensity. Weak buoyancy will limit the coverage of intense storms
enough that no watch is expected this afternoon.
..Wendt/Hart.. 09/06/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...CAR...GYX...BTV...
LAT...LON 43877239 44167250 45127238 45627186 45707174 46167074
46896987 47286842 46826818 45986834 44906923 44357040
43997163 43877239SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 6, 10:47 AM EDT | Mesoscale Discussion | SPC | Addison, Caledonia, Chittenden, Franklin, Grand Isle, Lamoille and 5 more | 118 min |
Nearby
Mesoscale Discussions in Maine, 2021Mesoscale Discussions in Vermont, 2021Mesoscale Discussions in New Hampshire, 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.