Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

Today: Risk of some non-severe pop up thundershowers in parts of Labrador this afternoon.

Tonight: No thunderstorms forecast.

Tomorrow: Risk of some non-severe pop up thundershowers in southeastern Labrador and the Northern Peninsula tomorrow afternoon.

Convective Discussion…

A quiet day is in store for most of Atlantic Canada today as a ridge of high pressure settles into the central Maritimes. Over Labrador, a weakly unstable environment may be enough to trigger some non-severe pop up thundershowers today. The 12Z Goose Bay sounding this morning showed some relatively weak lapse rates, though a cool airmass aloft will only require convective temperatures of around 16 or 17 degrees. However a lack of moisture (PWATs <15 mm) and effective shear (10 to 20 knots) will limit the intensity and lifespan of any storms that do fire today.

Tomorrow a similar environment is expected over southeastern Labrador, where the risk once again exists for some non-severe pop up thundershowers.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

Forecaster: Copp

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

Today: scattered to numerous thunderstorms for a portion of Labrador giving locally strong wind gusts, small hail and brief downpours. A risk of a thunderstorm for central/northeastern NL giving brief downpours and gusty winds.

Friday: slight risk of a thunderstorm across most of Labrador.

Convective Discussion

Looking like an active day up in the Big Land with non-severe thunderstorms expected. Looking at the 12Z tephi out of YYR the convective temp will be reached for most areas before lunchtime, and sure enough lightning is being detected as I type this up. The freezing levels are low, the shear is relatively weak (just ahead of the upper low), and the instability is only modest which all point to nothing reaching severe limits. Even the PWATs are below 20 mm, but locally strong wind gusts to 70 km/h, small hail and heavy rainfall will likely occur in the stronger cells. There will also be a risk of a thunderstorm this afternoon and evening across central and northeastern NL in association with a weak short wave ahead of that upper low over Labrador. Lastly a frontal trough south of NS will continue to give scattered thunderstorms to the southern Maritimes marine district today.

On Friday there will be the risk of a thunderstorm in most of Labrador once again in the vicinity of an upper trough moving through the region.

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for Tomorrow

 

Jeremy

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts…

 

Today

NB/NS/PEI/NL/Labrador: A chance of non-severe thunderstorms with small hail.

 

Tonight

NS/PEI/NL:  A chance of a thundershower.

NB/Labrador: None

 

Thursday

NL/Labrador: A chance of non-severe thunderstorms with small hail.

NS/NB/PEI: None

 

Convective Discussion

A trough of low pressure will move across New Brunswick this afternoon and across Nova Scotia and Newfoundland overnight. MLCAPE values near 500 J/kg are expected ahead of this trough with effective shear of 40 to 50 knots. The limited CAPE should restrict any potential weather to near severe only. The wild card is the strong approaching upper jet which will have northern New Brunswick in the favourable left exit region. All that being said, moderate winds gusts, small hail and downpours are possible in the moist airmass ahead of the trough (precipitable water of 30-40 mm). Over Labrador, a descending cold pool will give scattered thundershowers with the potential for small hail and gusty winds. Over Newfoundland, a slowly departing trough with give a chance of thundershowers this afternoon and into the late evening. On Thursday, the cold pool over Labrador will again give non-severe thunderstorms with gusty winds and a chance of small hail associated with the cold pool low freezing levels.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts…

 

Today

NB/NS/PEI/NL/Labrador: A chance of non-severe thunderstorms with small hail.

 

Tonight

NS/NL:  A chance of a thundershower.

NB/PEI/Labrador: None

Wednesday

NB/NS/PEI/NL/Labrador: A chance of non-severe thunderstorms with small hail.

 

Convective Discussion

A trough of low pressure will move across New Brunswick this afternoon and across Nova Scotia and Newfoundland later tonight. MLCAPE values near 1000 J/kg are expected ahead of this trough but effective shear is relatively low at around 20 knots. This should limited any severe weather potential. That being said, moderate winds gusts and downpours are possible in the moist airmass ahead of the trough (precipitable water of 30-40 mm). Over Labrador, a separate trough will give scattered thundershowers with the potential for small hail and gusty winds. On Wednesday, the slow moving trough over Labrador will sweep into New Brunswick. Again non-severe thunderstorms are possible however the shear is quite high (40-50 kts) but the MLCAPE values will be 500 J/kg or less.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

Today:

NL: Risk of an embedded thundershower.

Maritimes/LAB: None

Tonight:

Slight risk of a thundershower in northwestern New Brunswick.

Tomorrow:

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

NS: Risk of an isolated thundershower across the spine of the province.

LAB: Risk of isolated thundershowers giving small hail and strong wind gusts.

NL: None

Convective Discussion

A lingering cold front from a low pressure system south of Greenland tracks across Newfoundland while a trough weakens over western Labrador as a ridge sits over the Maritimes. A few lightning strikes were noted in Newfoundland along the front this morning, with the risk continuing into the afternoon.

For the Maritimes today, heat and humidity builds under a ridge, but with sufficient sea breeze convergence, there will be some showers that develop across southern New Brunswick, PEI and the spine and northern Nova Scotia but no thunderstorms are expected with these showers today. 

A quick moving short-wave trough will move into Central Quebec tonight and into New Brunswick and Labrador tomorrow. There could be a lingering thunderstorm reach northwestern New Brunswick before the threat diminishes overnight. The threat of showers or thundershowers increases on Tuesday and further on Wednesday as a series of  troughs affect the region. MLCAPE values increase to 1000Jkg across New Brunswick and with increasing precipitable water and effective shear increasing to 35kt, there is the possibility of organization into multicells or lines that develop. Over Labrador, the troughing will aid in thundershowers across western Labrador and topographical lift and convergence south and east of Lake Melville could also aid in thundershowers tomorrow. As freezing levels lower across western Labrador, small hail will also be possible.

 

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

 

 

Roberta McArthur