Alert archive / Maine / Mesoscale Discussions in 2021
Mesoscale Discussion 1123
The Storm Prediction Center issued this mesoscale discussion at Jun 28, 2021, 4:40 PM EDT for 13 counties in Maine; Carroll County, Coos County, Grafton County, New Hampshire; 8 counties in Vermont. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Jun 28, 2021, 4:40 PM EDT (20:40 UTC)
- Expired
- Jun 28, 2021, 7:15 PM EDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 5%
All 24 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, Sagadahoc County, ME, Somerset County, ME, Waldo County, ME, Washington County, ME, Carroll County, NH, Coos County, NH, Grafton County, NH, Addison County, VT, Caledonia County, VT, Chittenden County, VT, Essex County, VT, Lamoille County, VT, Orange County, VT, Orleans County, VT, Washington County, VT
The radar
The Portland,ME radar (KGYX), 99 km from the middle of the area, began a volume at 20:42 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, 8.7 hours before the alert went out and 99 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
- 150 J/kg
- Mixed-layer CIN
- -148 J/kg
- Mixed-layer LCL
- 1426 m above ground
- 0-6 km bulk shear
- 24 kt
- 0-1 km storm-relative helicity
- 52 m²/s²
- 0-3 km storm-relative helicity
- 63 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
412
ACUS11 KWNS 282041
SWOMCD
SPC MCD 282040
MEZ000-NHZ000-VTZ000-282315-
Mesoscale Discussion 1123
NWS Storm Prediction Center Norman OK
0340 PM CDT Mon Jun 28 2021
Areas affected...Portions of VT...NH...and ME
Concerning...Severe potential...Watch unlikely
Valid 282040Z - 282315Z
Probability of Watch Issuance...5 percent
SUMMARY...An isolated threat for mainly strong/gusty winds may exist
this afternoon through the early evening. Watch issuance is not
expected.
DISCUSSION...Although low-level convergence remains weak, convection
may continue to increase in coverage this afternoon across parts of
the Northeast along/south of a weak front. 45-60 kt of mid-level
westerly flow is present over portions of southern Quebec and
northern ME, generally to the north of the surface front. Modestly
enhanced mid-level westerly flow around 30-40 kt is present farther
south over the warm sector across VT, NH, and central/southern ME.
Similar values of effective bulk shear should prove favorable for a
mix of multicells and marginal supercell structures. Amid breaks in
cloud cover, robust heating has occurred across this region, with
surface temperatures generally warming into the upper 80s to lower
90s. Mid-level lapse rates remain generally poor, but around
1000-1500 J/kg of MLCAPE has developed along/south of the front. As
low-level lapse rates continue to steepen, storms moving eastward
may pose a threat for occasional strong/gusty winds capable of
producing mainly tree damage through the early evening. Regardless,
this severe threat is expected to remain too isolated/marginal to
justify watch issuance.
..Gleason/Thompson.. 06/28/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...CAR...GYX...BTV...
LAT...LON 43917332 44477316 45047266 45057160 45307146 45437088
45567034 45706840 45616734 45356736 45246718 45146674
44886684 44596719 44396757 44076837 43716986 43647091
43687272 43917332Nearby
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.