Convective Outlook
— Day 2
Enhanced Risk
Summary
Severe thunderstorms will be possible during the afternoon and evening across portions of New England on Tuesday. Additional strong-to-severe thunderstorms will be possible across parts of western and central Montana.
Synopsis and Discussion
Upper-level ridging will continue across much of the CONUS on Tuesday. A strong upper trough will move into New England during the evening/overnight along with a surface cold front. Additional moderate mid-level flow will be present over the northern Rockies along with weaker shortwave troughs moving through the region.
New England ?
Strong northwesterly flow aloft will be present at the start of the forecast period. Models suggest that a subtle perturbation may be moving through the region early in the day. Some convection may be associated with this feature, though the expectation is that this activity will be weakening with time. Any cloud cover from this activity would delay surface heating in some areas. Nevertheless, heating/moistening ahead of the cold front appears more than sufficient for severe storm development by late afternoon into the evening. Initial development will likely occur in southern Quebec along the front and move into New England. The strongest forcing for ascent within the region will also be after 03Z. 2500-3000 J/kg MLCAPE near the Canadian border during the late afternoon with around 2000 J/kg MLCAPE persisting into early evening across parts of New England. Linear forcing along the cold front will not be overly strong and large component of the 50+ kt of effective shear will be perpendicular to this boundary. Supercell structures will be favored, though bowing structures may also develop due to storm interactions or locally greater linear forcing. Large hail, including potential for 2+ in. with supercells, is possible. Severe/damaging winds are also expected. Bowing segments that develop will have potential for significant wind gusts. Low-level hodographs will also support a threat for a few tornadoes. A strong tornado is possible, but will be conditional on a discrete supercell persisting into the early evening.
...Montana... Development of a surface low in parts of eastern Montana/Wyoming will draw low-level moisture westward along a stalled surface boundary. Additionally, mid-level moisture will increase from the southwest around the western edge of the upper-level ridge. This, coupled with a shortwave trough during the late afternoon, will promote widely scattered to scattered thunderstorms within the higher terrain of southwest/central Montana. Around 30-35 kt of effective shear will promote a mix of marginal supercells and linear segments. Moisture will be more modest with western extent and outflow production will be more efficient. This should generally lead to more linear modes quickly. Buoyancy will also be modest (750-1250 J/kg MUCAPE) given 50s F dewpoints into western Montana. North of the surface low there will likely be a belt of greater surface moisture (low 60s F, potentially) that advects into the higher terrain of central Montana. Here, a couple of supercells could develop and be surface based. This could also be an area where linear structures could better organize due to more moist inflow. At present time, this more favorable environment appears too spatially limited for an increase in wind/hail probabilities.
000 ACUS02 KWNS 131733 SWODY2 SPC AC 131731 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1231 PM CDT Mon Jul 13 2026 Valid 141200Z - 151200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS NORTHERN NEW ENGLAND... ...SUMMARY... Severe thunderstorms will be possible during the afternoon and evening across portions of New England on Tuesday. Additional strong-to-severe thunderstorms will be possible across parts of western and central Montana. ...Synopsis... Upper-level ridging will continue across much of the CONUS on Tuesday. A strong upper trough will move into New England during the evening/overnight along with a surface cold front. Additional moderate mid-level flow will be present over the northern Rockies along with weaker shortwave troughs moving through the region. ...New England... Strong northwesterly flow aloft will be present at the start of the forecast period. Models suggest that a subtle perturbation may be moving through the region early in the day. Some convection may be associated with this feature, though the expectation is that this activity will be weakening with time. Any cloud cover from this activity would delay surface heating in some areas. Nevertheless, heating/moistening ahead of the cold front appears more than sufficient for severe storm development by late afternoon into the evening. Initial development will likely occur in southern Quebec along the front and move into New England. The strongest forcing for ascent within the region will also be after 03Z. 2500-3000 J/kg MLCAPE near the Canadian border during the late afternoon with around 2000 J/kg MLCAPE persisting into early evening across parts of New England. Linear forcing along the cold front will not be overly strong and large component of the 50+ kt of effective shear will be perpendicular to this boundary. Supercell structures will be favored, though bowing structures may also develop due to storm interactions or locally greater linear forcing. Large hail, including potential for 2+ in. with supercells, is possible. Severe/damaging winds are also expected. Bowing segments that develop will have potential for significant wind gusts. Low-level hodographs will also support a threat for a few tornadoes. A strong tornado is possible, but will be conditional on a discrete supercell persisting into the early evening. ...Montana... Development of a surface low in parts of eastern Montana/Wyoming will draw low-level moisture westward along a stalled surface boundary. Additionally, mid-level moisture will increase from the southwest around the western edge of the upper-level ridge. This, coupled with a shortwave trough during the late afternoon, will promote widely scattered to scattered thunderstorms within the higher terrain of southwest/central Montana. Around 30-35 kt of effective shear will promote a mix of marginal supercells and linear segments. Moisture will be more modest with western extent and outflow production will be more efficient. This should generally lead to more linear modes quickly. Buoyancy will also be modest (750-1250 J/kg MUCAPE) given 50s F dewpoints into western Montana. North of the surface low there will likely be a belt of greater surface moisture (low 60s F, potentially) that advects into the higher terrain of central Montana. Here, a couple of supercells could develop and be surface based. This could also be an area where linear structures could better organize due to more moist inflow. At present time, this more favorable environment appears too spatially limited for an increase in wind/hail probabilities. ..Wendt.. 07/13/2026 $$