A Mesodiscussion is issued by the National Weather Service's Storm Prediction Center when there is a chance of a significant weather event impacting an area. These are routinely issued before weather watches or as updated to weather watches.

SPC MD 762

MD 0762 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF NORTH CENTRAL PENNSYLVANIA INTO SOUTHERN NEW YORK
MD 0762 Image

Mesoscale Discussion 0762
NWS Storm Prediction Center Norman OK
0354 PM CDT Fri May 29 2020

Areas affected...Parts of north central Pennsylvania into southern
New York

Concerning...Severe potential...Watch unlikely 

Valid 292054Z - 292300Z

Probability of Watch Issuance...20 percent

SUMMARY...A few locally strong wind gusts may continue with
convection overspreading the region through 6-8 PM EDT.  The need
for a severe weather watch is now not anticipated, but trends will
continue to be monitored.

DISCUSSION...Fairly vigorous thunderstorm development is being
maintained along the leading edge of an east-northeastward advancing
convectively generated surface cold pool.  Forward propagation is
around 35 kt, largely parallel to the sheared 40-50 kt southerly
deep-layer ambient mean flow.  With easterly low-level system
relatively inflow emanating from boundary-layer air characterized by
rather weak CAPE on the order of 500 J/kg, substantive further
intensification seems unlikely.  However, strong peak gusts
approaching severe limits could persist with the convective system
another couple of hours.

..Kerr/Grams.. 05/29/2020

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

ATTN...WFO...BGM...BUF...CTP...PBZ...

LAT...LON   40967913 41457893 42097867 42527828 42717765 42377671
            41597704 40977804 40967913 

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SPC MD 761

MD 0761 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR EASTERN IDAHO...FAR SOUTHWEST MONTANA...AND WESTERN WYOMING
MD 0761 Image

Mesoscale Discussion 0761
NWS Storm Prediction Center Norman OK
0312 PM CDT Fri May 29 2020

Areas affected...Eastern Idaho...far southwest Montana...and western
Wyoming

Concerning...Severe potential...Watch unlikely 

Valid 292012Z - 292215Z

Probability of Watch Issuance...5 percent

SUMMARY...Isolated thunderstorms will pose a risk for severe wind
into the early evening hours. Due to the isolated nature of the
threat, a watch is not likely.

DISCUSSION...Recent radar and satellite trends over the past hour
have shown a gradual increase in convective activity across
southeast ID and western WY as well as developing cumulus across
central ID. Although instability continues to increase via
insolation, limited low and mid-level moisture along with weak
forcing for ascent have largely stunted convective maturation thus
far. An increase in thunderstorm activity is possible as low-level
parcels continue to warm closer to their convective temperatures
through late afternoon and ridge top convergence continues due to
diurnal upslope flow. 

If storms can become established in this environment, 25-35 knots of
effective bulk shear across eastern ID into northwest WY, coupled
with 1000-1500 J/kg MUCAPE, should support one or two strong
thunderstorms. Steep, 8-9 C/km low-level lapse rates and a dry 1-2
km sub-cloud layer will pose the potential for downburst winds.
Although deep layer shear is not overly strong, isolated instances
of severe hail will be possible. In the near term, a severe risk is
most likely across southeast ID where convective initiation is
underway. Thunderstorm development will likely hold off for another
1-2 hours further north across central/northeast ID and surrounding
areas. Due to the limited coverage of storms a watch is not likely.

..Moore/Grams.. 05/29/2020

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

ATTN...WFO...BYZ...RIW...TFX...PIH...MSO...BOI...

LAT...LON   42141429 43111479 44061491 44911453 45481318 45251124
            44820964 44250841 43510770 42670828 42241017 42041146
            42141429 

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