Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Boston, MA...Virginia Beach, VA...Norfolk, VA...Chesapeake, VA...Durham, NC...
Probabilistic Large Hail Graphic
Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
Day 1 Hail Risk
Area (sq. mi.)
Some Larger Population Centers in Risk Area
Reno, NV...Redding, CA...Sparks, NV...Medford, OR...Carson City, NV...
SPC AC 061621
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1121 AM CDT Wed Sep 06 2017
Valid 061630Z - 071200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS
AFTERNOON/EVENING FROM SOUTHEASTERN VA TO NORTHEASTERN SC...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM
SOUTHEASTERN NEW ENGLAND TO SOUTHEASTERN GA...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS
AFTERNOON/EVENING FROM THE NORTHERN SIERRAS TO SOUTHERN OR...
Isolated severe thunderstorms are possible today into this evening
from southeastern Virginia into eastern parts of the Carolinas, and
also across portions of the northern Sierra Nevada into southern
...Eastern NC and vicinity this afternoon...
Surface heating and some destabilization is ongoing in cloud breaks
from southeastern VA across eastern NC, to the east of a cold front
crossing the Piedmont as of late morning. The approach of an
upstream shortwave trough (now over the TN Valley) will help focus
ascent and support additional thunderstorm development along and
ahead of the front by early afternoon. Though midlevel lapse rates
will not be steep, MLCAPE of 1000-1500 J/kg and effective bulk shear
of 40-50 kt will favor a few organized clusters/supercells capable
of producing damaging gusts.
Isolated strong storms may also occur farther south into
southeastern GA along and ahead of the cold front this afternoon.
However, weaker vertical shear with southward extent, fairly
widespread clouds, and modest downdraft potential will tend to limit
the severe-storm threat.
...Northern Sierras to southern OR this afternoon/evening...
The 12z Reno sounding revealed the potential for high-based
thunderstorms this afternoon as surface temperatures warm, low-level
lapse rates steepen, and convective inhibition is removed.
Thunderstorm development is expected along the fringes of the
thicker cloud bands, as well as over the higher terrain, by mid-late
afternoon along the northeastern periphery of the midlevel trough
approaching central and northern CA. A deep mixed boundary layer
and deep-layer southeasterly flow/shear in excess of 30 kt will
support organized storm clusters capable of producing isolated
strong/damaging outflow winds, and perhaps some marginally severe
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z