SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Wed Jun 18 2025 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE CAROLINA PIEDMONT INTO PARTS OF THE MID ATLANTIC AND NEW ENGLAND... ...SUMMARY... Strong to potentially severe thunderstorms are forecast on Thursday from parts of New England into the Mid Atlantic and Carolinas. ...Synopsis... A positively tilted mid-level shortwave trough will move from the Great Lakes to the Northeast on Thursday. Mid-level flow will strengthen east of this trough from the Mid-Atlantic to the Northeast. A surface low will deepen as it moves from the eastern Great Lakes to northern Maine during the period. A cold front will extend southwest from this surface low and will begin from the eastern Great Lakes to the Mid-Mississippi Valley Thursday morning and near or off the Atlantic Coast by 12Z Friday. ...New England into the Mid-Atlantic/Southeast... Strong heating is expected across a broad, moist warm sector with dewpoints in the upper 60s to low 70s east of the Appalachians by Thursday afternoon. This will result in moderate to potentially strong instability across much of the East Coast. The best chance for more organized storms will be from central Virginia northward where stronger shear will be present beneath 50 knot mid-level flow. A zone of potentially greater severe weather probabilities may be present across the Mid-Atlantic where the greatest instability/shear are expected to overlap. It appears the cold front will lag well behind with the majority of convection developing along a pre-frontal trough during the afternoon. Without the stronger frontal forcing, some concerns about convective coverage/intensity exist, precluding higher probabilities at this time. South of this area, mid-level flow will not be as strong. Therefore, more modest shear will limit greater storm organization. Nonetheless, modest (25 knot) shear will support some multicell storms capable of damaging wind gusts across North Carolina. Even weaker shear will be present across the southeast where strong instability is expected. Storms are not expected to be as organized here, but the strong instability and moist environment could support some water-loaded downdrafts capable of damaging wind gusts. ...Southern Montana... Weak midlevel height falls are still expected across parts of western MT Thursday afternoon/evening, in response to the approaching mid/upper-level trough. Low-level moisture will remain limited, but strong diurnal heating will support high-based storm development. Steep low-level lapse rates and relatively strong midlevel flow will result in potential for isolated severe gusts during the afternoon and evening as convection spreads eastward. ...Upper Midwest... Low-level warm advection related to the southeastward-moving midlevel shortwave trough may aid in storm development on Thursday from northern MN into parts of WI and upper MI. Moderate instability and sufficient deep-layer shear will support potential for a few stronger cells/clusters capable of producing large hail and damaging wind. Additional strong to locally severe storms may redevelop later Thursday night across parts of this region, in response to a nocturnally strengthening low-level jet. ...Northern Plains... Diurnal heating of an increasingly moist airmass will result in moderate to strong buoyancy across parts of the northern Plains by Thursday afternoon. Deep-layer shear will be sufficient for organized storms, but diurnal storm development remains highly uncertain amid background midlevel height rises associated with a building ridge. Development of a storm or two cannot be ruled out through evening near a surface trough/weak dryline. Elevated storm coverage may increase somewhat Thursday night in response to a strengthening low-level jet, which could pose a threat of hail and localized strong gusts. ...Central High Plains... Moderate to strong buoyancy will develop across the central High Plains amid strong surface heating. Shear will not be as strong this far south, but a dryline/surface trough may provide sufficient forcing for a few high-based storms Thursday afternoon/early evening. ..Bentley.. 06/18/2025