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.
Day 1 Wind Risk
Area (sq. mi.)
Some Larger Population Centers in Risk Area
Jacksonville, FL...Virginia Beach, VA...Raleigh, NC...Tampa, FL...St. Petersburg, FL...
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.
SPC AC 041628
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1128 AM CDT Thu May 04 2017
Valid 041630Z - 051200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS CASCADES OF OR...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS PACIFIC
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SOUTH ATLANTIC
Isolated severe storms will most likely occur across parts of the
Cascades this evening with hail as the primary hazard. Localized
damaging winds and a brief tornado are also possible across the
South Atlantic Coast States, mainly tonight.
An upper trough centered near -135W will shift east across the
northeast Pacific with mid-level height falls overspreading the
Cascades by evening. Presence of 50s surface dew points in
conjunction with steepening mid-level lapse rates should support a
moderately buoyant air mass at peak heating. Isolated to widely
scattered storms should develop over the higher terrain in the
evening amid strengthening mid-level south-southwest flow. A couple
supercells should form, most likely over parts of the Cascades in OR
with risks of severe hail and wind.
...South Atlantic Coast States...
12Z observed soundings sampled poor mid-level lapse rates and
minimal buoyancy north of FL. While destabilization is ongoing
downstream of an extensive (yet weakening) QLCS over the Gulf and
eastern FL Panhandle, parallel stratiform across a large part of GA
should confine weak surface-based buoyancy to the coastal plains
this afternoon before possibly developing towards the Piedmont
tonight. Localized damaging winds and a brief tornado will remain
possible with the remnant northern portion of the QLCS, which may
progress across parts of north FL to south SC this afternoon.
A shortwave impulse currently over the Lower MS Valley should eject
through the base of the upper trough towards the Carolinas. This
will yield strengthening meridional flow overspreading the modifying
warm sector in the eastern Carolinas/southeast Virginia tonight.
Although instability should remain limited, enlarging low-level
hodographs will support risks of a brief tornado and locally
damaging winds. Should greater instability become observationally
evident, parts of the region may be upgraded to Slight Risk in later
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z