Regional Impacts
SE Labrador/NE Newfoundland: Scattered strong to severe thunderstorms expected this afternoon and evening for central and eastern Newfoundland, and southeastern Labrador. Main hazards will be lightning, gusty winds, hail and locally heavy downpours.
New Brunswick: Scattered strong to severe thunderstorms possible late this afternoon and evening for Northwestern New Brunswick. Main hazards will be lightning, gusty winds, hail and locally heavy downpours.
Convective Discussion
Several areas of concern for this afternoon/evening for the Atlantic region with particular focus for eastern Newfoundland, Labrador and northwestern New Brunswick where a very hot and humid air mass resides over the region.
For Newfoundland and Labrador, a strong short wave tracking into eastern Labrador extending into Newfoundland will help enhance convection today. Interior parts of central to eastern Newfoundland will see high temperatures near 30C and dewpoints between 17-19C. MUCAPE values near 2000 J/kg, 0-6k shear at 35kts and precipitable water above 30 mm combined with increasingly favourable upper dynamics will help maintain strong storms that develop. Strong multicell type storms are most likely but there could be the risk of supercells. A funnel cloud or short lived tornado cannot be completely ruled out, however the probability of that remains very low at this time. Storms will weaken in the evening as they head out over much cooler ocean waters and become de-coupled from the surface. There is a bit of a low-level capping inversion to break based on the 12Z Goose Bay sounding, limiting surface based convection over southeastern Labrador, however, a 500mb cold trough over the southeastern regions could kick off some elevated convection this afternoon. Dynamics are a bit weaker but heavy rain is possible.
For New Brunswick, an approaching trough currently over SW Ontario will move eastward into southern Quebec today and to the Maine/New Brunswick border this evening/overnight. 12Z KCAR sounding suggest ample energy given temperatures near 30C and high dewpoints near 19C, MUCAPE values reaching 2000 J/kg and strong 0-6km shear near 40KT. There is also the enhancement of being in the left exit region of a 100KT 250mb jet. This will promote severe limits on convection especially over Maine this afternoon which will move northeastward into parts of western New Brunswick later this afternoon into this evening. With a dryer 500-700mb, strong winds associated with organized multicell or bowlines will be the biggest threat.
Thunderstorm Outlook for Today (Sunday July 24th)
Thunderstorm Outlook for Day 1 night (Monday July 25th)
For Monday, isolated thunderstorms are expected for western Labrador, parts of Newfoundland and possible storm to severe storms for New Brunswick/Prince Edward Island. A cold front will move through New Brunswick in the afternoon. With ample energy still in place over much of the region, the risk of severe thunderstorms continues further into New Brunswick then into Nova Scotia in the evening/overnight.
Thunderstorm Outlook for Day 2 (Monday July 25th)
