SPC MD 1565

MD 1565 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR LOWER GREAT LAKES REGION/ST. LAWRENCE VALLEY AND ADJACENT NEW YORK STATE

Mesoscale Discussion 1565
NWS Storm Prediction Center Norman OK
1148 PM CDT Mon Aug 24 2020

Areas affected...Lower Great Lakes region/St. Lawrence Valley and
adjacent New York state

Concerning...Severe potential...Watch unlikely 

Valid 250448Z - 250645Z

Probability of Watch Issuance...20 percent

SUMMARY...A line of thunderstorms may continue to develop and
strengthen while spreading across the lower Great Lakes region and
adjacent portions of the upper St. Lawrence Valley.  While this
activity may pose a risk for hail and gusty winds as it spreads into
portions of western and northern New York state by 4-6 AM, it may
remain generally below severe limits.  A severe weather watch
currently appears unlikely, but trends will continue to be
monitored.

DISCUSSION...In advance of a significant, digging short wave trough,
scattered thunderstorms have recently initiated over southern
Ontario.  Activity is in the process of increasing, near or just
ahead of an initial southeastward advancing cold front.  A narrow
corridor of seasonably high boundary-layer moisture (upper 60s to
around 70 F surface dew points) appears to be contributing to
mixed-layer CAPE up to around 1500 J/kg, despite somewhat modest
initial mid-level cooling.  This air mass is forecast to advect
southeastward across the lower Great Lakes region and adjacent St.
Lawrence Valley vicinity, into portions of western and northern New
York state through 08-10Z.  Coupled with ongoing modest
strengthening of cyclonic deep-layer west-northwesterly mean flow
(to around 30-35 kt), the environment may be conducive to further
upscale growth and organization of convection, with the potential to
produce small to marginally severe hail, and at least locally strong
surface gusts which may approach severe limits.

..Kerr/Grams.. 08/25/2020

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

ATTN...WFO...BTV...ALY...BGM...BUF...

LAT...LON   45147702 45537503 44557399 42887687 42647898 42798040
            43917976 45147702 

Read more

from SPC Forecast Products http://www.spc.noaa.gov/products/md/md1565.html