Mesoscale Discussion 1010

Issued

Jun 19, 2021, 12:38 PM EDT (16:38 UTC)

Expired

Jun 19, 2021, 2:15 PM EDT

In force

97 min

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch unlikely

Chance of a watch

20%

Counties Androscoggin County, ME, Aroostook County, ME, Franklin County, ME, Oxford County, ME, Piscataquis County, ME, Somerset County, ME, Carroll County, NH, Coos County, NH, Grafton County, NH, Caledonia County, VT, Essex County, VT, Lamoille County, VT, Orange County, VT, Orleans County, VT, Washington County, VT

The Portland,ME radar (KGYX), 167 km from the middle of the area, began a volume at 16:39 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.

949 
ACUS11 KWNS 191638
SWOMCD
SPC MCD 191638 
MEZ000-NHZ000-VTZ000-191815-

Mesoscale Discussion 1010
NWS Storm Prediction Center Norman OK
1138 AM CDT Sat Jun 19 2021

Areas affected...Northern Vermont/New Hampshire into
western/northern Maine

Concerning...Severe potential...Watch unlikely 

Valid 191638Z - 191815Z

Probability of Watch Issuance...20 percent

SUMMARY...A few supercells capable of marginally severe hail and
wind damage are possible through the afternoon.

DISCUSSION...An upper-low is moving across Quebec which is bringing
cool temperatures aloft across the Northeast. Meanwhile, at the
surface, temperatures have warmed into the mid 70s to low 80s. As
the boundary layer has warmed, deep mixing has dropped dewpoints
into the low to mid 50s across the region. This has kept instability
limited to around 500 J/kg which should be maintained throughout the
day and may increase to around 1000 J/kg as the surface continues to
warm and dewpoints stabilize within the well mixed boundary layer.
The 1630Z VWP from CCX indicates around 40 to 45 kts of westerly
flow between 3 and 4 km. This shear will support rotating updrafts
which may be strong enough for some marginally severe hail and
isolated damaging winds (given the well mixed sub cloud layer and
moderately strong flow above 2km) despite an otherwise less than
favorable thermodynamic environment.

A watch is not likely given the isolated and marginal nature of the
threat.

..Bentley/Hart.. 06/19/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...CAR...GYX...BTV...

LAT...LON   45047255 45037157 45397137 45437099 45897044 46597015
            47116975 47466919 47596855 47396824 45766865 45106923
            44516971 44077028 43717144 43587231 43827289 44067301
            44357308 45047255

Mesoscale Discussions in Maine, 2021Mesoscale Discussions in Vermont, 2021Mesoscale Discussions in New Hampshire, 2021Every mesoscale discussion in 2021

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.