Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

NFLD… today eastern Labrador and northern NFLD, isolated thunderstorms with some stronger wind gusts. Rainfall likely less than 15mm, unless back build storms develop. Tomorrow western Labrador, isolated thunderstorms possible.

PEI and NS… no thunderstorms expected

NB… Thunderstorms tomorrow could bring some gusty winds and locally heavy downpours.

Convective Discussion

A ridge of high pressure currently across the region will dominate the weather in the short term as it slowly slides eastward over the next couple of days. The upper jet is not in a favourable position, with most of the Atlantic region on the left exit side of the departing jet streak.

A weak trough will approach the region overnight, and by tomorrow afternoon, it is expected to extend from Labrador through the Saint Lawrence River Valley. Surface moisture is relatively limited today, with dew point temperatures around 10–15°C, but values are expected to increase somewhat tomorrow ahead of the approaching surface trough — possibly exceeding 16°C in northern New Brunswick and reaching over 14°C in western Labrador.

Over eastern Labrador and the Northern Peninsula of Newfoundland, surface CAPE values could exceed 1000 J/kg today. As a result, scattered thunderstorms are expected to continue. Although updrafts are expected to remain weak, some locally heavier downpours are possible. Quasi-stationary or back-building thunderstorms may also develop and should be monitored.

With improving dynamics tomorrow, there will still be a limited amount of potential energy, with surface CAPE values possibly reaching 1500 J/kg. While updrafts are not expected to be particularly strong overall, small changes in surface dew points could significantly impact updraft strength. Nonetheless, the environment will remain marginally supportive of isolated wind gusts and locally heavy downpours.

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: 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