Convective Outlook Valid for Today , Tonight and Tomorrow

 Regional Impacts…

 

Today

Labrador: Scattered severe thundershowers.

NB/NS: Scattered non-severe thundershowers.

PEI/Newfoundland: None.

 

Tonight

NB/NS/PEI/Labrador: Scattered non-severe thundershowers.

Newfoundland: None.

 

Thursday

NB/NS/PEI/Newfoundland/Labrador: Scattered non-severe thundershowers.

 

Convective Discussion

A slow moving cold front will drift across Labrador today and Thursday. The same front will move across New Brunswick on Thursday. Over Labrador, severe weather is possible ahead of the front this afternoon and evening.  CAPE values near 1500 J/kg are expected and effective shear will be 30-40 knots. Additionally, a supportive right entrance region of the upper jet will move over western Labrador this afternoon. Over New Brunswick and western Nova Scotia today non-severe thundershowers are possible. CAPE values near 2000 J/kg are expected but effective shear will only be 10-20 knots and only weak forcing mechanisms are anticipated. On Thursday, the convection should become more embedded in nature but  some surface based convection is still possible. CAPE values of 500-1000 J/kg are expected. Effective shear near 20 knots is anticipated over the Maritimes and closer to 30 knots over Labrador. Cells could become near severe with rain and wind but should stay below warning conditions.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

 

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

Newfoundland and Labrador… some thunderstorms can be expected in southern Labrador with strong winds and possibly heavy downpours.

PEI…none expected.

NS… a low chance of an isolated thunderstorms inland.

NB… a risk of thunderstorms tomorrow, some isolated downpours possible.

Convective Discussion

Yesterday was fairly active across Labrador, although most thunderstorms occurred well north of the forecast regions. Today, the southern part of Labrador is more likely to see similar activity. The zonal upper jet will remain quasi-stationary through central Labrador and is generally aligned with the flow down to the surface. While updrafts are not expected to be particularly strong, low-level winds exceeding 30 knots could mix down to the surface in some thunderstorms.

Over the Maritimes, dynamics are less favourable; however, potential energy is relatively strong, with mixed-layer CAPE values near 1000 J/kg. A lack of forcing will limit the ability for convective clouds to reach their level of free convection, with the exception of a very slight chance over southwest Nova Scotia.

Tomorrow, weak surface troughing may provide slightly more favourable conditions for scattered thunderstorms across New Brunswick. These are expected to be very isolated and are unlikely to produce widespread rainfall.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

 

Mel Lemmon

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

Newfoundland and Labrador… Some isolated thunderstorms over Labrador today and tomorrow, strong wind gusts and heavy downpours possible.

NB… No impacts expected.

NS… No impacts expected.

PEI… No impacts expected.

Convective Discussion

Labrador will experience the bulk of convective activity over the next two days, with the potential for severe thunderstorms, including discrete supercells. Atmospheric dynamics are generally favourable, with deep-layer wind shear between 40–50 knots and 0–3 km shear values of 30–40 knots. Moderate CAPE values will also contribute to storm development, with some areas exceeding 1000 J/kg.

For the most part, the shear is predominantly linear, and triggering mechanisms will be somewhat limited. Troughing and surface convergence are expected to be subtle, and differential heating may play an ongoing role. Clear skies will enhance solar insolation, further aiding destabilization.

If severe storms develop, it is unlikely that any single community will be directly affected unless an organized mesoscale convective system (MCS) forms, producing a more continuous gust front. We will monitor satellite and lightning detection closely as the day progresses.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

 

Mel Lemmon

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts…

 

Today

NB/NL/Labrador: Scattered non-severe thundershowers.

NS/PEI: None

 

Tonight

NB/NS/PEI/NL/Labrador: None

 

Monday

Labrador: Scattered non-severe thundershowers.

NB/NS/PEI/NL: None

 

Convective Discussion

 

A weak trough over northern New Brunswick may trigger scattered thundershowers this afternoon. CAPE values near 1000 J/kg are expected but the effective shear is low at less than 20 knots. Gusty winds and downpours in the moistening airmass are possible in the non-severe cells. Weak troughing over Newfoundland and Labrador may produce scattered thundershowers this afternoon. CAPE values of 500 J/kg or less should limit any weather to non-severe. On Monday, a cold front sweeping across Labrador will give scattered thundershowers. Again, CAPE values of 500 J/kg or less should limit any weather to non-severe.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

 

 

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

Today:

LAB: Risk of isolated thunderstorms giving locally heavy downpours and strong wind gusts.

NB: Risk of isolated thundershowers.

NS/PEI/NL: No thunderstorms forecast.

Tonight:

LAB: Risk of isolated thunderstorms.

NS/NB/PEI/NL: No thunderstorms forecast.

Tomorrow:

LAB: Risk of isolated thunderstorms giving locally heavy downpours and strong wind gusts.

NB/NL: Risk of an isolated thundershower.

NS/PEI: No thunderstorms forecast.

Convective Discussion

A ridge of high pressure is slowly sinking southeastward into the southern Maritime waters today and a trough moves eastward into northern Quebec and across northern Labrador. Ahead and along the trough, scattered showers and risk of thundershowers are expected, mainly across southern to central Labrador where CAPE values could exceed 500 J/kg. Shear is generally weak to moderate, so expecting single to multicell potential with brief winds gusts and with precipitable water in of 35 mm, so locally heavy downpours are also possible. Weak troughing also reaches northwestern New Brunswick, where there is a slight risk of showers or thundershowers in the afternoon but conditions are still fairly dry and with some residual smoke aloft, this may cap convection.

Tomorrow, troughing lingers over Newfoundland while another trough quickly moves across central northern Quebec, affecting southwestern Labrador by the evening. With moderate shear or 30 kts and high precipitable water reaching 40 mm, there is more potential for organization into lines into western Labrador but timing may be too late for any severe potential to maintain in the evening. Some isolated showers with a small risk of a thundershower is possible over the higher terrain in northern New Brunswick and Newfoundland but again the lingering smoke aloft could cap convection.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

 

Roberta McArthur