Day 1 Convective Outlook
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Summary
Severe thunderstorms capable of large hail and damaging winds are possible in the Mid-Atlantic Wednesday afternoon and evening, while isolated damaging wind gusts may occur in northern New England, the northern Rockies, and Arizona.
Product Text
000 ACUS01 KWNS 150554 SWODY1 SPC AC 150552 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1252 AM CDT Wed Jul 15 2026 Valid 151200Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NEW ENGLAND...THE MID-ATLANTIC...NORTHERN ROCKIES...AND ARIZONA... ...SUMMARY... There is a conditional risk for severe storms capable of large hail and damaging winds in the Mid-Atlantic Wednesday afternoon and evening. Isolated occurrences of mainly damaging wind gusts appear possible in northern New England, the northern Rockies, and Arizona. ...Synopsis... A high-over-low blocking pattern will remain anchored over central North America with an embedded shortwave trough and associated 70 kt mid-level jet streak translating through New England and the northern Mid-Atlantic Wednesday afternoon. That system will be attended by a surface front, which will settle south into the central Mid-Atlantic during the peak of the diurnal heating cycle. ...Mid-Atlantic... Temperatures in the 90s to around 100 are forecast south of the front, which coupled with dewpoints in the upper 60s to low 70s, will contribute to a moderately unstable air mass by afternoon with MLCAPE of 1500-2500 J/kg. The strongest height falls/forcing for ascent associated with the shortwave trough are expected to remain north of the surface frontal zone, and as a result, the extent of thunderstorm development along the boundary remains uncertain. Another factor that could limit storm development is the potential for instability reduction along the front due to the existence of wildfire smoke, as depicted in recent HRRR runs. Given the uncertainty in storm initiation and sustenance, a level 1/Marginal Risk will be maintained with this forecast. However, on the condition that surface-based storms develop, the presence of seasonably strong mid-level winds and resultant 40-50+ kt of effective bulk shear will support supercells capable of large hail and damaging winds. ...Northern New England... Within the zone of strongest forcing for ascent associated with the shortwave trough, a band of low-topped showers and thunderstorms is expected to develop during the afternoon amidst a marginally unstable environment. Steepening low-level lapse rates and a unidirectional wind profile with 35-40 kt winds as low as 1.5-2.0 km AGL will support the potential for locally damaging wind gusts. ...South-central Montana and north-central Wyoming... Heating along the high terrain coupled with the glancing influence of a subtle disturbance is expected to foster widely scattered afternoon thunderstorms amidst a moderately unstable air mass featuring a relatively deep, well-mixed boundary layer. A number of the 00Z CAMs indicate the potential for some cold pool organization with an attendant risk for isolated severe wind gusts into the evening. ...Arizona... Scattered afternoon and evening thunderstorms are expected from the Colorado and San Francisco Plateaus into the Sonoran Desert amidst a moderately unstable air mass with a deep and well-mixed boundary layer. That thermodynamic environment will be supportive of isolated strong downbursts; however, more organized severe wind gust potential is expected to be limited by the weak vertical shear that is forecast. ..Mead/Lyons.. 07/15/2026 $$