Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

Today: Organized thunderstorms today across the SErn marine district, approaching the Nfld coastline early this afternoon. Lightning is the main hazard. An isolated cell or 2 may also pop up this evening in western Labrador and the Edmundston valley area of NWrn NB. A quick 5-10mm of rain could fall.

Tonight: No thunderstorms forecast in ATL Canada.

Tuesday: Late-day thunderstorms are forecast, with the progression of a destabilizing trof out of the Great Lakes region of Ontario. The timing of this trof is quite slow. The main hazards would be gusty winds ahead of the system and pockets of moderate rain. Rainfall rates are forecast to exceed 40 mm/h in the tri-counties area of NS *if* the system develops as models suggest.

Wednesday: Atmospheric conditions remain unstable, so afternoon storms are possible across Labrador, NB, NS, and portions of PEI with daytime heating, and relatively high humidity.

Convective Discussion

The first forcing at play is pulling out of the eastern marine region this afternoon. Mid-levels behind this feature on this morning’s soundings are prohibitively dry. However, Caribou is expected to moisten at 700 throughout the afternoon and as such could produce enough lift late day to spark a cell or 2. They will remain non-severe in nature. The regime tomorrow is somewhat more complex. Another trof is cutting across the Great Lakes and will de-stabilize the now moistened (and near heat warning) Maritimes environment. This will lead to both a wind gust hazard and moderate rainfall hazard on Day 2. If the total energy can be realized before sunset, some cells could approach severe limits. This is being closely monitored as many factors have to line up just right. The Day 3 outlook remains unstable across much of the Maritimes and Labrador with humid sfc conditions and cool air aloft from a developing upper low. This will create pockets of moderate shear with organized convection developing in the afternoon.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Canada Day

Thunderstorm Outlook for Wednesday

Forecaster: Tirone.

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

Today: No thunderstorms forecast over land regions of the Maritimes. Not enough lift available with an advancing warm nose between 850 and 700 mb.

Tonight: No thunderstorms forecast.

Monday: Non-severe thundershowers are possible in extreme NWrn NB late in the day, as well as in extreme western Labrador. The main hazard with these cells would be lightning.

Tuesday (Canada Day): A broader area of convection is possible across a large portion of the Maritimes and forecasters will be updating hazards in next 24hrs.

 

Convective Discussion

Warm air advection is advancing into the Maritimes and as such, there is a cap in place. Dominant showers and drizzle lack the colder mid levels and cloud tops to produce charge separation and lightning. There is an area of organized convection across the southern marine district which will slowly drift SE today, enhanced by warmer sfc waters of the gulf stream. Humidity is forecast to increase early this week and an advancing trof late in the day on Tuesday may be enough to destabilize and trigger organized convection. However, there remains uncertainty about the timing of this slow-moving feature. Details will be honed in coming forecasts, as the feature is timed across the Great Lakes region. (The Grey hazard area on day3 may be upgraded.)

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

Thunderstorm Outlook for Tuesday

Forecaster: Tirone.

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

Today: risk of non-severe thunderstorms across the interior of NF and southeastern LAB. Risk of embedded thundershowers for some southwestern areas of the MRTMs this evening.

 

Tonight: continuing with that risk for embedded thundershowers across far southwestern NS.

 

Sunday: nil.

 

Convective Discussion

There will likely be some isolated cells this afternoon form over the traditional area of inland southwestern NF then advect E/NEward during the afternoon hours, in association with a weak short wave trough moving through the area. The 12Z sounding out of YJT supports some small hail and gusty winds to about 70 km/h. Pwats are super low so rainfall is not a concern at all. Expect isolated cells for inland areas of southeastern LAB as well but are not anticipated to impact any of the coastal communities. Lastly a frontal zone will remain over the western MRTMs today and tonight so there will be a risk of embedded, elevated thundershowers for some counties tonight that will give intense rainfall at times, as model Pwats will be running up around 40 mm. Sunday looks rather quiet across the entire 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:

NL/Lab: Risk of thundershowers with small hail and strong wind gusts.

Maritimes/NL: None

Tonight:

Lab: Risk of thundershowers with small hail and strong wind gusts early this evening.

Maritimes/NL: None

Tomorrow:

NL/Lab: Risk of thundershowers with small hail and strong wind gusts.

Maritimes: None

Convective Discussion

A weak trough over eastern Newfoundland and associated cold pool aloft has triggered a few thunderstorms producing small hail this morning over the Avalon Peninsula and this may continue into the early afternoon as the trough moves eastward. Another weak trough and destabilization from surface based heating will aid in the triggering of non-severe thundershowers across western Labrador this afternoon. This feature will then move southeastward on Saturday. Daytime heating and this trough will help trigger non-severe thundershowers over southeastern Labrador and across Newfoundland tomorrow afternoon. Overall, precipitable water is low to moderate and the CAPE in realized could reach 300 J/kg and effective shear are low to moderate, but freezing levels area low, thus some stronger showers may have small hail and with somewhat inverted V profiles, locally strong wind gusts are also possible.

Thunderstorm Outlook for TODAY

 

Thunderstorm Outlook for TONIGHT

Thunderstorm Outlook for TOMORROW

 

Roberta McArthur

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts…

 

Today

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

NB/NS/PEI:  None.

 

Tonight

NB/NS/PEI/NL/Labrador: None

 

Friday

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

NB/NS/PEI: None

 

Convective Discussion

A cold pool is descending across Newfoundland and Labrador today. A few non-severe lightning strikes are possible. Additionally with the low freezing levels (3000-5000 feet) there is a chance of small hail. CAPE values are very low (300-500 J/kg) so that will limit any hail growth. Friday morning the cold pool may kick off a couple thunderstorms across the Avalon and extreme eastern Newfoundland. Friday afternoon a weak trough in associated with continued cold air across Labrador may trigger some non-severe thundershowers across western areas.  Continued low freezing levels but limited CAPE will provide the opportunity for small hail.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts…

 

Today

NL: A chance of non-severe thunderstorms extreme northeast.

NB/NS/PEI/Labrador:  None.

 

Tonight

NB/NS/PEI/NL/Labrador: None

 

Thursday

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

NB/NS/PEI: None

 

Convective Discussion

A cold front will move across Newfoundland this afternoon. There is a small chance of a lightning strike or two over northeastern Newfoundland before its departure. On Thursday, a cold pool will descend across Newfoundland and Labrador. A few non-severe lightning strikes are possible. Additionally with the low freezing levels (3000-5000 feet) there is a chance of very small hail. CAPE values are very low (300 J/kg) so that will limit any hail growth.

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:  A chance of severe thunderstorms bringing heavy rain, hail and strong wind gusts.

NL/Labrador: None.

 

Tonight

NB/NS/PEI/NL/Labrador: None

 

Wednesday

NB/NS/PEI/NL/Labrador: None

 

 

Convective Discussion

Low-level moisture advection continues this morning ahead of a cold front which will move across northern New Brunswick this afternoon and into southern New Brunswick this evening.  Dew point temperatures in the low 20s are occurring throughout most of the Maritimes. The combination of this warm, moist airmass and the approaching cold front should be sufficient to trigger severe weather across portions of New Brunswick, Nova Scotia and Prince Edward island this afternoon and into the evening. CAPE values of 1000-2000 J/kg and precipitable water values of up to 50 mm could produce very high rainfall rates in thunderstorms. Additionally, relatively dry mid levels and a low level jet near 30 knots will allow strong downdraft potential to exist. Effective shear of 30 to 40 knots means that some supercell storms could develop, leading to potentially damaging wind gusts. After the frontal passes tonight, quiet weather will return for a few days.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

NB… No impacts expected today. Some thunderstorms tonight and overnight bringing frequent lightning and possibly heavy downpours. Tomorrow… Some severe thunderstorms bringing heavy rain and potentially strong wind gusts.

PEI… No impacts expected today. Some thunderstorms overnight bringing lightning and possibly some heavier rainfall. Tomorrow… Thunderstorms possible with gusty winds and possibly heavy downpours.

NS… No impacts expected today. Some thunderstorms overnight over north areas, bringing lightning and possibly some heavier rainfall. Tomorrow… Thunderstorms possible with gusty winds and possibly heavy downpours for central and eastern regions.

NFLD… No Impacts today… Tomorrow… A chance of thunderstorms over western parts of the island tomorrow with some heavier rain possible.

Convective Discussion

For the most part, thunderstorm activity will remain upstream over Quebec and Ontario today, as a low-pressure system and its associated cold front gradually move eastward. An area of high pressure to the southwest will likely help suppress thunderstorms over the Atlantic region until the unstable airmass reaches the Maritimes tonight.

We will continue to see low-level moisture advection ahead of the approaching cold front today and overnight, with dew point temperatures likely reaching the low 20s in some areas by tomorrow. The combination of this warm, moist airmass and the surface low-pressure system will be sufficient to generate CAPE values around 2000 J/kg. With precipitable water values near 50 mm, rainfall rates in thunderstorms are likely to be very high. Additionally, strong downdraft potential exists, and it is possible that some supercell storms could develop, leading to potentially damaging wind gusts.

The timing of the cold front’s passage may prove critical; if it arrives earlier than expected, the threat of severe weather may shift somewhat eastward. Thunderstorm development over Quebec today will give us a general idea of what to expect tomorrow for New Brunswick. However, as is often the case, these systems do not always unfold as predicted, and timing may shift. Keep an eye out for alerts, not just for tomorrow but also overnight, as the system approaches.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight/Overnight

Thunderstorm Outlook for Tomorrow

Convective Outlook Valid for Today, Tonight, Tomorrow and Tuesday

Regional Impacts

Today:

NS: Risk of embedded thundershowers early this afternoon with locally heavy downpours.

Tonight:

None.

Tomorrow:

None.

Tuesday:

NB/PEI: Risk of severe thunderstorms with locally heavy rainfall, small hail and strong wind gusts.

NS /NL: Risk of thundershowers giving local heavy downpours and strong wind gusts.

Convective Discussion

A short-wave trough is moving through the Maritimes today. Based off the 12Z Caribou sounding, the 500 mb temperatures would suggest that convection will remain capped as the rain moves through, although the band has produced some 10-15 mm/hr rainfall rates over northwestern New Brunswick this morning as precipitable water is in the mid 30s.  These heavier showers are expected to diminish by the time the band moves into eastern Nova Scotia as the wave buts against the ridge of high pressure over Newfoundland. There have been a few strikes over the western Maritime marine waters this morning and the small threat of embedded thundershowers may continue into western Nova Scotia early this afternoon where they may be enough lift between 700 and 850mb to break the cap.  A cold front will move southeastward across Labrador this afternoon and evening, but the 500 mb temperatures also will be a limiting factor in any convection that develops.

For tomorrow, the weakened trough keeps Newfoundland under cloud and showers for most of the day, while the Maritimes most of Labrador are under a ridge of high pressure. This ridge extends across most of the eastern US, with building heat and humidity into New Brunswick. A low pressure system over central Ontario moves into Central Quebec in the evening. An area of destabilization will move towards the Gaspe Peninsula and into northern New Brunswick later in the evening with the risk of a thunderstorm lingering into the overnight but given the timing, the risk of anything severe is limited.

For Tuesday, there is increasing heat and humidity for all the Maritimes with dewpoints into the low 20s.  A cold front is expected to track across New Brunswick in the afternoon. The high surface temperatures combined with cooling in the mid-levels with the cold front along with decent CAPE and wind shear, will provide the potential for severe thunderstorms mainly for New Brunswick and Prince Edward Island. Details will become more clear in the coming day.  

Thunderstorm Outlook for TODAY

Thunderstorm Outlook for TONIGHT

Thunderstorm Outlook for TOMORROW

Thunderstorm Outlook for TUESDAY

 

Roberta McArthur

 

 

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

Today:

Lab: Slight risk of a thundershower.

Maritimes/NL: None

Tonight:

None.

Tomorrow:

None.

Convective Discussion

A low pressure system will continue to move eastward across the Northeastern Gulf into the Labrador Sea today. There is not much support remaining for convection with this low  other than north of the low in an easterly flow aided by the lift from the higher terrain in Eagle River forecast region which has sparked some thundershowers this morning and may persist into the early afternoon. There is also a slight risk remaining along the cold front over the southwestern Grand Banks.

Behind the low there is a ridge of high pressure that will dominate the Maritimes and western Labrador today, suppressing convection. Tonight, an active short-wave will bring rain through the Maritimes on Sunday but the convective threat is limited as the mid level are too warm. A cold front will push through Labrador tomorrow afternoon bringing showers but the mid-level temperatures also appear to warm to allow convection.

Thunderstorm Outlook for TODAY

Thunderstorm Outlook for TONIGHT

Thunderstorm Outlook for TOMORROW

 

Roberta McArthur

 

 

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

Today:

NB: Chance of thunderstorms giving locally heavy rain and strong wind gusts.

NL: Slight risk on a thundershower over the northern Peninsula

NS/PEI/Labrador: None.

Tonight:

NB/Gulf waters: Chance of embedded thunderstorms.

NS/PEI/NL/Labrador: None.

 

Tomorrow:

None.

Convective Discussion

A deep upper trough over central Quebec with a surface low pressure system currently over northwestern New Brunswick with track eastward today across the northern Gulf of St. Lawrence and into the Labrador Sea tomorrow. Embedded thunderstorms have moved across northwestern New Brunswick this morning ahead of the low, and further convection may fire along the cold front, which will move across New Brunswick this afternoon and evening. Meanwhile, along the warm front there has been isolated strikes across northern Newfoundland and the risk will continue into the early afternoon. The air mass in the warm sector is quite humid with dew points exceeding 20C. With a stalled ridge across northern Quebec into Labrador, ahead of the low, rainfall amounts are expected to reach upwards of 70 mm.

Along the cold front, thunderstorms will trigger this afternoon into the evening across New Brunswick into the Gulf waters with heavy rainfall being the biggest threat with precipitable water reaching 45 mm. Mixed CAPE values across northern New Brunswick may reach 500 J/kg if we get some clearing, and with effective shear of 30 to 40 kt, some organization is possible into line segments capable of producing strong wind gusts.  Storms will move fairly quickly towards the northeast under a 40 kt 700 mb flow.  Some overnight convection may hold across eastern New Brunswick and over the Gulf before the threat weakens overnight and into tomorrow.

Tomorrow the low continues eastward into the Labrador Sea and a ridge moves into the Maritimes with no thunderstorms are expected at this time.   

Thunderstorm Outlook for TODAY

Thunderstorm Outlook for TONIGHT

Thunderstorm Outlook for TOMORROW

 

 

Roberta McArthur

 

 

 

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts…

 

Today

NB: Chance of non-severe thunderstorms.

Labrador: Chance of embedded thunderstorms.

NS/PEI/NL: None.

 

Tonight

NB/NS/PEI/NL/Labrador:  None.

 

Thursday

NB: Chance of non-severe thunderstorms.

NS/PEI/NL/Labrador: None.

 

Convective Discussion

A low pressure system will move across northern Labrador today. A frontal boundary will extend southwest from the low into the St. Lawrence River Valley. Isolated thundershowers will be possible along this boundary this afternoon over northwestern New Brunswick. Limited CAPE should keep anything from getting too organized. Over Labrador some embedded thundershowers are possible today. On Thursday, a low pressure system will track from the Great Lakes toward the St. Lawrence Valley. Severe weather is likely over portions of New England and southern Quebec however once again limited CAPE should keep it to just a risk of thundershowers over northwestern New Brunswick on Thursday. Increasing precipitatal water values may allow for periods of heavy rain for northwestern New Brunswick Thursday afternoon and into the evening.  

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

 

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts…

 

Today

NL: Chance of non-severe thunderstorms.

NB/NS/PEI/Labrador: None.

 

Tonight

NB/NS/PEI/NL/Labrador:  None.

 

Wednesday

NB: Chance of non-severe thunderstorms.

Labrador: Chance of embedded thunderstorms.

NS/PEI/NL: None.

 

Convective Discussion

A trough will track across Newfoundland later today. Isolated thundershowers are possible ahead and near the trough over northeast Newfoundland this afternoon. Limited CAPE will keep anything from getting too organized. On Wednesday, a low pressure system will move into Labrador, with a frontal boundary extending from the low back into the St. Lawrence River Valley. Isolated thundershowers will be possible along this boundary Wednesday afternoon over extreme northwestern New Brunswick. Limited CAPE should keep anything from getting too organized. Over Labrador some embedded thundershowers are expected on Wednesday.

 

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

Convective Outlook Valid for Today, Tonight and Tomorrow

For June 15^th, 2025

 

Regional Impacts

 

Today: Some scattered thunderstorms possible in southeast Labrador today, main threat is strong wind gusts. Isolated chance of a thundershower over north-central Newfoundland and west-central New Brunswick this afternoon.

 

Tonight: No thunderstorms expected.

 

Tomorrow: No thunderstorms expected.

 

Tuesday: Slight risk of a thundershower over north-central Newfoundland on Monday afternoon.

 

Convective Discussion...

 

A few areas of interest are at play today, with the most prominent being southeast Labrador. Here, scattered thunderstorms are expected to develop in the warm sector this afternoon ahead of an approaching cold front moving through the region. Modest mixed-layer CAPE and effective shear will aid in the organization of some of these thunderstorms, however a lack of surface moisture and very dry low-levels will likely keep storms fairly elevated. Strong dynamics over the region may be enough to support an isolated supercell given enough CAPE, though this risk is low. As such, strong winds are the main hazard with these storms, with gusts of 70 to 80 km/h possible. Small hail and some locally heavy downpours are also possible.

 

In addition, a few isolated thundershowers are possible in west-central New Brunswick and north-central Labrador this afternoon under a diverging 500 mb jet with some embedded pockets of weak vorticity. Low CAPE and minimal shear will keep these storms from becoming organized and are not likely to be very long-lived, however some locally heavy downpours will be possible.

 

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for Tomorrow

 

Thunderstorm Outlook for Tuesday

 

Forecaster: Copp

 

Convective Outlook Valid for Today, Tonight and Tomorrow

Today: Isolated non-severe thundershowers possible over central Nova Scotia and south-central Labrador this afternoon. Main threat is brief heavy downpours, with no significant accumulations.

Tonight: No thunderstorms expected.

Tomorrow: Isolated risk of a thundershower along a cold front extending from Labrador to New Brunswick tomorrow afternoon.

Monday: No thunderstorms expected.

Convective Discussion...

A fairly quiet day is expected today, with a few areas that may see a couple lightning strikes this afternoon. First, a weak shortwave moving across New Brunswick this morning will pass over PEI this afternoon, triggering some showers along the Cobequids in central Nova Scotia. Higher dewpoints and a slight upslope enhancement are expected to aid in convection here today. These showers will have a slight chance to produce a lightning strike or two as they move east, however very little shear and minimal CAPE will likely inhibit the lifespan of these cells.

A second weak shortwave moving southeast along the Labrador coast is producing some scattered showers today across south-central Labrador. Some stronger low and mid-level jets over this region highlight the risk for some of these showers to produce some lightning strikes early this afternoon, though this risk remains low.

Tomorrow, a weakening cold front moving across Atlantic Canada may trigger some thundershowers in parts of New Brunswick and Labrador, but at this time the risk is low.

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for Tomorrow

 

Thunderstorm Outlook for Monday

 

Forecaster: Copp