Convective Discussion
No significant convective weather is expected for Atlantic Canada over the next 24 hours; however, there is a risk of thundershower activity over New Brunswick overnight tonight and into Monday morning as conditions favouring the development of thundershowers move into the region. In the short term over the marine districts, no signficiant convective weather is expected but there is a risk of thundershower activity along the wave moving through the southwestern grand banks.
Technical Discussion
A relatively dry air mass combined with surface and upper lever ridging over the region will inhibit the deveopment of severe convective weather today for Atlantic Canada. However, the ridge begins to degrade the fastest is over northwestern New Brunswick as a slow moving warm front will begin to track into the region later today… and will usher in larger dewpoints along with increasing 0 to 6 km shear. Recent changes in numerical weather guidance suggest that a weak trough will approach the western edge of the province prior to 12Z. This adjustment is met with some skepticism as there are currently thunderstorms active along its leading edge which may affect the NWP’s ability to project the true timing and subsequent arrival. Should a severe (or near-severe) thunderstorm form near 12Z over northwestern New Brunswick, the primary threats would be high rainfall rates and strong wind gusts near or exceeding 35 knots.
There is an increasing probability of conditions favouring severe convection moving into New Brunswick Monday afternoon…a day 2 outlook will be issued later today.
Regional Impacts
Newfoundland and Labrador: Nil significant convective weather.
Nova Scotia and PEI: Nil significant convective weather.
New Brunswick: There is a risk for non-severe convection over much of the province overnight tonight and into Monday morning as conditions favouring the development of thundershowers move into the region from the west. Over extreme northwestern New Brunswick there is a very slight risk of a severe thunderstorm by 12Z on Monday morning. At this time a severe thunderstorm watch for Monday morning is not anticipated due to lack of evidence supporting this more rapid eastward movement of the afformentioned trough; however should subsequent observations indicate that this trough is moving faster, adjustments to the forecast may be made. Should a faster scenario arise, primary threats for this region include downpours with rates near 25 mm/h and wind gusts near 35 knots. There is an increasing risk for severe convection Monday afternoon, please refer to the day 2 outlook (to be published later today).
Atlantic Marine Areas:
Chaleur-Miscou: Nil significant convective weather expected, chance of thundershowers tomorrow morning over the Baie de Chaleur, with a larger risk in the afternoon (refer to day 2 outlook when available).
Southwestern Grand Banks: No significant convective weather expected, chance of thundershowers along the wave as it continues to move eastward today.
Marshall Hawkins
Operational Meteorologist – Atlantic Storm Prediction Centre, Meteorological Service of Canada
Environment and Climate Change Canada / Government of Canada
Marshall.Hawkins@canada.ca / Tel: 902-426-7779
Météorologue opérationnel – Centre de prévision des intempéries - région Atlantique, Service météorologique du Canada
Environnement et Changement climatique Canada / Gouvernement du Canada
Marshall.Hawkins@canada.ca / Tél. : 902-426-7779
