Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

Today

NB: Chance of some scattered embedded thundershowers over southern New Brunswick this afternoon and evening with some locally heavy downpours.

Lab: Chance of scattered/frequent thunderstorms through southern Labrador today. These could be marginally severe with gusty winds and heavy downpours (locally).

NS: Scattered embedded thundershowers over most of mainland NS this afternoon and evening. Rain is the biggest hazard.

Tonight

NS: Thunderstorms continue over eastern sections as well as much of the marine district.

Tomorrow

NB: Thunderstorms are forecast to develop late afternoon and early evening. Severe storms are possible along and south of Highway 2, with gusty winds and moderate hail.

 

Convective Discussion

Labrador has lit up quite quickly today with lightning across the southern tier. These storms (spawning from a low centre anchored way back to the west) have a lack of a dominant steering flow and so they could drop quite a bit of rain locally. Elsewhere across the southern Maritimes, an embedded TS risk exists within the broader precip shield that has enveloped the region. Later this afternoon, greater jet support advances east from New England and should create enough lift and charge separation to spark more lightning. Dewpoints remain fairly high near 15 at the noon hour. CAPE is relatively low today given the setup - so severe hazards are not forecast. Tomorrow is a different story across NB. The freezing levels will be much lower creating a possible hail-favoured setup. Additionally, if organized cells do form, they will bring an inherent wind risk. G90 are possible and are depicted by the yellow hazard area. This severe weather risk will be re-analyzed and potentially alerted for on Wednesday.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

Forecaster: Tirone.

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

Today

NB: Chance of some scattered thundershowers over western New Brunswick this afternoon with some locally heavy downpours.

Lab: Chance of some isolated thundershowers through central Labrador this afternoon.

NS/PEI/NFLD: None.

Tonight

NS/NB/PEI/NFLD/LAB : None.

Tomorrow

LAB: Risk of some marginally severe thunderstorms over southern Labrador in the afternoon with small hail, strong wind gusts, and locally heavy downpours.

NS: Risk of an elevated thundershower over southern mainland Nova Scotia through the day.

NB/PEI/NFLD: None.

 

Convective Discussion…

A ridge of high pressure sits over central Atlantic Canda this morning with a weak surface trough extending from central Maine up into central Quebec, just west of Labrador. This trough will be the main focus for any convection today, as it slowly begins to move east. A small but strong upper low over central Ontario will combine with a shortwave near New England and approach the trough this afternoon, which will act as the main trigger for convection. MLCAPE values over western New Brunswick are forecast to be around 500 to 750 J/kg today, with effective shear around 15 to 25 knots. One of the limiting factors however is how quickly the shortwave is advected East into New Brunswick, as well as some warm air aloft between 500 and 700 mb. This could limit the higher shear and some better thermodynamics from reaching the risk area until later this evening, which would lead to more isolated and short-lived thundershowers this afternoon. The risk for more organized storms could still increase into this evening however as the shortwave approaches, which could be capable of producing some locally heavy downpours of 10 to 20 mm per hour.

There is also a slight risk of some isolated thundershowers with a weak trough over central Labrador today which is in a similar environment to western New Brunswick, however there is a lack of moisture evident over this area which will reduce the risk of storms here today. Current surface observations show dewpoints only in the 5 to 7 degree range, with temperatures already above 20. Nonetheless, the potential for some isolated thundershowers exists which could produce some gusty winds.

Tonight, the shortwave will reach the Gulf of Maine, bringing with it the risk of an elevated thundershower over the marine areas west of Nova Scotia in the early morning hours. Into tomorrow, the shortwave will track across Nova Scotia, continuing to bring the chance for an elevated thundershower across the southern half of the mainland during the day and into the evening. Elsewhere, the upper low currently over central Ontario will sit over central Quebec by tomorrow morning with today’s surface trough now extending east from the upper low into southern Labrador. This will be the main focus for convection tomorrow, as MLCAPE values in the warm sector just south of the trough could reach 750 to 1000 J/kg by the afternoon. Slightly better moisture being advected in from the south and effective shear in the range of 20 to 30 knots should be sufficient to get some organized, marginally severe thunderstorms tomorrow afternoon. The surface trough is initially forecast to remain fairly stationary before eventually shifting south in the late afternoon/early evening. This in combination with an expected easterly storm motion could lead to some multi-cell training storms early in the day which would increase the risk of heavy rainfall for some areas. Some small hail and strong wind gusts are also possible with these storms. Luckily, the main risk area is expected to remain over unpopulated areas but could impact a few communities early in the afternoon.

 

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

Forecaster: Copp

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

NS… Chance of thunderstorms today, some heavy downpours possible.

NB.. Chance of thunderstorms today and tomorrow. Heavy downpours possible with small hail.

PEI.. No thunderstorms expected.

Newfoundland.. No thunderstorms expected.

Labrador.. Low chance of thunderstorms expected tomorrow.

Convective Discussion

Instability will persist over western areas today as an upper trough slowly exits the region. CAPE values are expected to remain modest, reaching around 1000 J/kg, with generally weak low-level shear and deep-layer shear staying below 25 knots across most of New Brunswick.

As a result, severe thunderstorms are unlikely. However, isolated cells may still produce small hail and locally heavy downpours.

Looking ahead to tomorrow, shear will increase somewhat, but the relatively cool airmass will limit the available energy for convection. Non-severe showers or thunderstorms may once again develop over western areas. With limited heating and only modest increases in dew points expected in the coming days, overall conditions are not anticipated to change significantly.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

NB: Low chance of thunderstorms this evening, with little to no impacts expected.
NS: Some thunderstorms possible today, mainly over eastern areas. Locally heavy downpours and gusty winds possible.
Labrador: Low chance of thunderstorms today, no significant impacts expected.
Newfoundland: Low chance of thunderstorms today. Western/interior areas may see locally heavier rain.
PEI: Slight risk of thunderstorms today, with brief heavier showers possible.

Convective Discussion

A weak low pressure system over the region will continue to track northeastward today, with an associated surface trough moving across Nova Scotia through the day. Low-level convergence along this trough, as well as over parts of Newfoundland, will support isolated thunderstorm development.

Across Nova Scotia, the convective window will be relatively short-lived, ending by late afternoon as the trough exits. Slightly higher CAPE and shear in this region may support locally heavier rainfall rates and a risk of gusty winds in any storms that develop.

Over Newfoundland, thunderstorm activity may persist into the evening hours, with locally heavier downpours embedded within broader area of shower activity.

Over western Labrador, a weak thunderstorm cannot be ruled out, though no impacts are expected.

Looking ahead to Sunday into Monday, generally unsettled conditions will continue over New Brunswick and parts of Nova Scotia, with occasional weak thunderstorms possible.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

 

Mel Lemmon

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

NB.. Low chance of thunderstorms today, strong gusts possible if thunderstorms form.

NS.. Some thunderstorms possible tomorrow with heavier downpours.

Labrador.. low chance of thunderstorms today.

Newfoundland.. Low chance of embedded thunderstorms today over the east. Low chance of weak thunderstorms tomorrow interior.

PEI.. Slight risk of thunderstorms this evening.

 

Convective Discussion

Some dynamic support exists for convection today, though cooler temperatures and low dew points will limit updraft potential. Any storms that develop may produce locally strong wind gusts due to enhanced downdraft potential.

A low chance of embedded thunderstorms exists over eastern Newfoundland, with no expected impacts.

For tomorrow, a low-probability but higher-impact scenario exists over eastern Nova Scotia if training develops; localized rainfall rates near 25 mm/h are possible.

Sunday may be more active as another upper trough crosses the region. Modest instability and shear could support heavier downpours and small hail.

 

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow