Day 1 Convective Outlook
This product has been superseded. View the updated product →
Issued: · Valid: –
Summary
Severe thunderstorms capable of producing large hail and gusty winds are expected across parts of the northern Rockies and northern New England this afternoon and evening. Damaging winds may also occur in the Upper Midwest and Mid-Atlantic, while a brief tornado is possible in south-central or southwest Texas later today or tonight.
Product Text
000 ACUS01 KWNS 161636 SWODY1 SPC AC 161634 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1134 AM CDT Thu Jul 16 2026 Valid 161630Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF WESTERN MONTANA AND NORTHERN NEW ENGLAND... ...SUMMARY... Severe thunderstorms capable of producing large hail and gusty winds will be possible across parts of the northern Rockies this afternoon and evening. Isolated to scattered damaging winds may also occur over portions of northern New England, the Upper Midwest, and Mid-Atlantic. A brief tornado could occur across a small part of south-central/southwest Texas later today or tonight. ...Northern Rockies... A closed upper low will move slowly northward along the coastal Pacific Northwest through tonight. Upper ridging will persist across much of the Rockies to the Plains. Between these features, a belt of modestly enhanced south/southwesterly deep-layer flow will overspread the northern Rockies. Modest easterly low-level winds will transport generally 50s to low 60s F surface dewpoints across this region beneath steep mid-level lapse rates. As daytime heating occurs, moderate instability should develop. Scattered thunderstorms are forecast to initially form over the higher terrain during the afternoon. Veering wind profiles with height through mid/upper levels and gradually strengthening flow aloft will support around 30-40 kt of effective bulk shear. Organized cells will pose a risk for gusty winds and severe hail across much of the region. The greatest risk for 1+ inch hail appears to be across parts of western Montana. ...Northern New England... A vigorous mid-level shortwave trough will move quickly southeastward from southern Ontario/Quebec across New England today with strong west/northwest deep-layer flow. Boundary layer moisture will be somewhat limited compared to prior days, with surface dewpoints generally in the 50s F. Still, somewhat greater daytime heating is expected to the north of the more prominent smoke plume across southern New England, which should help steepening low-level lapse rates by late morning/early afternoon. While MLCAPE will remain modest (around 250-500 J/kg), the strong low/mid-level westerly flow and steepened low-level lapse rates should support scattered damaging winds as low-topped convection spreads southeast from Quebec and across portions of northern New England through the afternoon near a secondary/weak front. ...Mid-Atlantic... Enhanced west-northwesterly mid/upper-level winds will overspread the Mid-Atlantic today on the southern periphery of the mid-level shortwave trough moving across New England. A surface front is expected to sag southward through the day, approaching the Pennsylvania/Maryland border vicinity by late afternoon. Rich low-level moisture will be in place ahead of the surface front and beneath steepening mid-level lapse rates spreading in from the Ohio Valley. This, along with diurnal heating, will foster a corridor of moderate to locally strong instability this afternoon. Furthermore, various NAM/RAP forecast soundings show 30-40 kt of effective bulk shear and steep low-level lapse rates present south of the front. This environment would generally support organized cells/line segments. However, overall thunderstorm coverage remains uncertain given that stronger forcing for ascent should remain mostly north of the warm sector. Additionally, it is uncertain to what extent that smoke may continue to have a negative impact on an otherwise favorable environment for severe thunderstorms. ...Northeast North Dakota/Northern Minnesota... A series of convectively enhanced vorticity maxima will migrate across the Canadian Prairies north of the prominent upper ridge over the Plains/Rockies, and through northwesterly flow aloft into parts of North Dakota and northern Minnesota this afternoon into tonight. At the surface, a weak low and surface front will move across North Dakota into northern Minnesota during the evening and overnight hours. South/southeasterly low-level flow will maintain a moisture-rich boundary layer, supporting a narrow corridor of instability. NAM/RAP forecast soundings show supercell wind profiles, but also increasing capping through the late afternoon/evening. Even so, most high-resolution guidance develops convection across southern Manitoba into northern North Dakota during the evening, spreading east/southeast across northern Minnesota overnight. Isolated severe hail and damaging winds may occur with this activity, and a tornado risk cannot be ruled out. ...South-Central Texas... While low-level shear/SRH has weakened since last night, and ongoing convection remains extensive/repetitive, a northward drift of the MCV and potential re-establishment of stronger low-level winds later today into tonight could account for non-zero/brief tornado potential. ...Arizona... Thunderstorms will develop over the higher terrain of the Mogollon Rim and southeast Arizona this afternoon/evening, and subsequently spread westward across portions of central/southern Arizona. Modest instability and steep lapse rates amid strong heating could support sporadic strong gusts. ..Guyer/Squitieri.. 07/16/2026 $$