Valid 311630Z – 011200Z
…THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
MID-ATLANTIC AND NEW ENGLAND REGIONS…AS WELL AS WESTERN NORTH
The greatest concentration of strong-severe thunderstorms today will
extend from the Mid-Atlantic up the coast of New England, as well as
parts of western North Dakota.
…Mid-Atlantic and eastern New England…
A broad upper trough remains over the northeastern US today, with a
band of slightly enhanced southwesterly flow aloft extending from
NC/VA up the Mid Atlantic and New England coast. Visible satellite
imagery shows that strong heating is occurring over much of this
region, with temperatures warming through the 80s and lower 90s.
Ample low-level moisture is in place, with a corridor of 1000-1500
J/kg expected later today. 12z CAM solutions indicate high
confidence that thunderstorms will develop along this axis.
Forecast soundings show relatively weak midlevel lapse rates. But
sufficient steering flow aloft and steep low-level lapse rates will
promote a risk of multiple clusters of storms capable of locally
gusty/damaging wind gusts. The threat should be strongly diurnal,
with rapid weakening a couple of hours after dark.
Multiple shortwave troughs are embedded in the relatively fast
mid/upper flow along the US/Canadian border. A pocket of strong
instability (3000 J/kg) is expected to develop this afternoon over
western ND. Forecast soundings suggest that any storm which forms
could be supercellular with a risk of large hail and severe winds.
Despite uncertain forcing mechanisms, strong consensus of 12z
guidance for storm initiation lends sufficient confidence to upgrade
parts of western ND to SLGT risk.
A cluster of elevated thunderstorms persists along the MO River.
This activity may continue through the afternoon, with occasional
robust updrafts along the outflow boundary over eastern NE/KS.
MLCAPE values over 2000 J/kg and sufficiently strong northwest flow
aloft suggest a potential for isolated cells capable of hail and
gusty winds. Other more isolated storms are possible over central
KS during the max heating period with some downburst potential.
Ample midlevel moisture is streaming northward around the upper
ridge into parts of UT/ID/WY. As this moisture overspreads the High
Plains of northeast WY later today, scattered thunderstorm
development is expected. Sufficient flow aloft and steep low-level
lapse rates will promote a risk of damaging wind gusts and hail.