Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

NS… no thunderstorms expected.

PEI… no thunderstorms expected.

NB… tomorrow, some isolated thunderstorms possible with heavy downpours.

Newfoundland and Labrador… isolated pulse storms possible, showers with small hail or graupel possible.

Convective Discussion

For today, little convective activity is expected. A few lightning strikes are possible over central Newfoundland and western Labrador. Although upper-level support is fairly benign, a cold trough at 500 hPa may support weak updraft development. No hazardous weather is expected; however, any thunderstorms that do develop could produce locally heavier rainfall rates.

For tomorrow, stronger dynamics will move across western New Brunswick, with approximately 40 knots of deep-layer shear and total precipitable water values increasing to above 35 mm. However, surface-based convection may struggle to develop due to extensive cloud cover and a lack of strong low-level forcing. Earlier in the day, some embedded convection is possible, but the main potential for hazardous weather would occur later in the day if surface-based convection can develop.

Updraft strength is expected to remain a limiting factor, and mixed-layer CAPE values may not be sufficient to support deep convection. Additional guidance and observations tomorrow should provide a clearer picture of the overall severe weather potential.

 

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

 

Forecaster: Mel Lemmon

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

 

Today

NFLD: A chance of thundershowers.

NS/NB/PEI/LAB: None.

 

Tonight

NS/NB/PEI/NFLD/LAB: None.

 

Sunday

NFLD: A chance of thundershowers.

NS/NB/PEI/LAB: None.

 

Convective Discussion

A departing low pressure system will give a chance of afternoon thundershowers across portions of Newfoundland this afternoon. MLCAPE values are expected to be 250-500 J/kg and the effective shear will be 10 to 20 knots so any thundershowers will be weak in nature. On Sunday, weak troughing over Newfoundland will give similar or weaker atmospheric conditions as today and a chance of afternoon thundershowers.  

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

 

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

 

Today

NS/NB/PEI: Thundershowers giving potential significant rainfall amounts.

NFLD/LAB: Scattered thundershowers.

 

Tonight

NS/NB/PEI/NFLD/LAB: None.

 

Saturday

NFLD: A chance of thundershowers.

NS/NB/PEI/LAB: None.

 

Convective Discussion

A surface low pressure system and supporting upper low will continue to slowly move across Atlantic Canada today and then depart Newfoundland on Saturday. The main area of concern today is once again over Nova Scotia, New Brunswick and Prince Edward Island where MLCAPE values are expected to be near 1000 J/kg and the effective shear will be 20 to 25 knots. The main hazards with any storms that develop will be small hail, gusty winds and locally heavy downpours. Any storms that do develop will be slow moving so any heavy downpours may lead to significant rainfall accumulations.  On Saturday, CAPE values will be 500 J/kg or less and will give a chance of thundershowers for Newfoundland.

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

 

Today

NS/NB/PEI/NFLD/LAB: Scattered thundershowers.

 

Tonight

NS/NB/PEI: Chance of thundershowers.

NFLD/LAB: None.

 

Friday

NS/NB/PEI/NFLD/LAB: Scattered thundershowers.

 

Convective Discussion

A trough of low pressure and supporting upper low will slowly move across Atlantic Canada today and Friday. The main area of concern today is over Nova Scotia and New Brunswick where MLCAPE values are expected to be 1000-1500 J/kg and the shear will be 20 to 30 knots. The main hazards with any storms will be small hail, gusty winds and locally heavy downpours. Any storms that do develop will be slow moving so any heavy downpours may lead to significant rainfall accumulations.  On Friday, any potential impacts are expected to less than today due to lower CAPE, shear and precipital water values.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

Today

NB: Chance of an isolated thundershower within a greater area of showers in central and southern NB this afternoon and evening. Main hazard is simply lightning.

LAB/NFLD: Chance of scattered thunderstorms over parts of Labrador today, and Nfld. Heavy downpours are possible.

Tonight

Gulf of St. Lawrence waters: Slight chance of an isolated thunderstorm cell to develop in the late evening and carry into the overnight hours.

Western Labrador: Isolated non-severe thundershowers possible before noon on Thursday, in area of showers.

Tomorrow

Atlantic Canada: Chance for numerous embedded thunderstorms with locally heavy downpours and potentially a few gusty winds.

Convective Discussion…

A persistent trof line continues to affect Labrador and Nfld today, bringing the chance of a few thundershowers. These cells will have ample moisture to work with, but not much lift in comparison. The prevailing cloud deck is the competition. Over the Maritimes, parts of NB are forecast to destabilize this afternoon (according to the high resolution model suite). Again, the storms have limiting CAPE today.

Tomorrow is looking to be a different story. The atmosphere is forecast to moisten even further in the next 24hrs – bringing Pwats on the Atlantic coast of NS up to 35 by tmrw morning. Thunderstorms that develop tomorrow within the broader precip field will enhance local rainfall totals further. This will be monitored closely (Rain Rates already being flagged near 30 to 40 mm/h). Some early day cells could also bring gusty winds if they can get into clearer skies, before the storm mode becomes clustered.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

Forecaster: Tirone.