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.
SPC AC 071300
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0800 AM CDT Fri Jul 07 2017
Valid 071300Z - 081200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
IN/OH/KY...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE OH
VALLEY/GREAT LAKES...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
HIGH PLAINS TO THE NORTHEAST STATES...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
CAROLINAS VICINITY...
...SUMMARY...
Severe thunderstorms are expected across the Ohio Valley and
portions of the lower Great Lakes mainly this afternoon and early
evening. Other more isolated strong to severe thunderstorms can be
expected across the central High Plains to the Ozark Plateau and
possibly the Carolinas vicinity.
...Synopsis...
A relatively amplified large-scale pattern will exist over the CONUS
today, with multiple shortwave impulses crossing the Midwest,
Northeast States and Plains to the east of an upper-level ridge
centered over the Great Basin and Four Corners area.
...Ohio Valley/Great Lakes...
Strengthening mid/high-level west-northwesterly winds are expected
today amidst cyclonic upper flow. Several subtle and/or convectively
related disturbances will cross the region today ahead of a more
consequential disturbance/speed max that will spread southeastward
from northern MN and reach the Lake MI vicinity by early evening.
Increasing early-day storms across northern IN could persist
southeastward today, especially in areas along and west of
MCS-related early-day outflow across OH, with other peripheral
development expected near a southeastward-moving front within an
increasingly moist and unstable environment especially from southern
IL into IN/OH. For additional early-day details, see Mesoscale
Discussions 1253 and 1254.
12Z observed soundings from Davenport IA/Lincoln IL sample a plume
of relatively steep mid-level lapse rates that will continue to
advect east-southeastward across the region today, while the
Davenport IA sounding in particular sampled 40-55 kt high-level
northwesterly winds. Steepening lapse rates/moderate buoyancy in
conjunction with strengthening wind aloft will support some
supercells aside from more prevalent line segments/bows. Bouts of
severe hail and damaging winds will be possible as storms spread
southeastward through the afternoon and evening hours, with parts of
IN/OH into northern KY currently expected to have the greatest
concentration of severe-caliber storms.
...Central High Plains to Ozark Plateau...
On the periphery of the western states upper ridge, a few weak
disturbances may top the ridge over the northern Rockies and dig
southeast toward the High Plains of WY/CO. Forecast soundings across
the High Plains exhibit surface-6km bulk shear on the order of 35-40
kt, more than adequate for sustaining organized convection including
a few supercells where storms develop.
Elsewhere, strong heating across southern KS/northern OK into
southern MO should encourage relatively high-based convection along
southward-moving cold front. Gusty winds are the primary threat with
this convection.
...Carolinas vicinity...
Isolated strong to severe thunderstorms capable of wind damage
appear possible across the region mainly this afternoon.
..Guyer.. 07/07/2017
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