Convective Outlook Valid for Today and Tomorrow

Regional Impacts

NB/NRN NS/WRN PEI/CNTL NL: scattered thunderstorms this afternoon and evening giving some gusty winds and torrential downpours.

NRN LAB: isolated thunderstorms giving some heavy downpours early this afternoon.

ERN mainland NS: An isolated thunderstorm is possible later this afternoon (mainly TCU).

 

Convective Discussion

A strong area of PVA has been triggering some isolated thundershowers along the north coast of Labrador this morning which will likely continue for another couple hours into the early afternoon. Further to the south we get into the hot and humid air mass that has settled into the MRTMS and central NL. An approaching frontal zone currently in the vicinity of the St. Lawrence river is sliding southeastward as too is the 500 mb upper trough. The shear will be increasing this afternoon and will be approaching 50 knots (unidirectional). Looking at the 12Z tephis does show the potential for some strong winds and torrential downpours with MLCAPE of up to 1000 j/kg. Freezing levels are pretty high so hail is not a concern. There is a load of low level moisture so torrential downpours are a pretty sure thing.

 

There are several things pointing at an active day, but the history of the front is not too impressive and the instability is not that strong. We do expect to see some scattered thunderstorms this afternoon and evening with some of them strong to possibly severe (winds and torrential rainfall). For now there was no yellow area drawn into the convective map due to the lower level of confidence in seeing an active day. It could be one of those shifts were we wait to see development on the radar and go from there with possible watches (any warnings) for some counties in NB.

 

Thunderstorm Outlook for Day 1

 

Thunderstorm Outlook for Day 1 Night

 

Thunderstorm Outlook for Day 2

 

Jeremy

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

 

Today

NS: Isolated thunderstorms with downpours and gusty winds.

NB/PEI/NL/Labrador: None

 

Tonight

Labrador: Isolated thunderstorms

NS/NB/PEI/NL: None.

 

Sunday

NB/NL/Labrador:  Isolated thundershowers

NS/PEI: None

 

Convective Discussion

A remnant/dissipating cold front lies over western Nova Scotia today. Also a ridge is trying to push into that area and model guidance suggests a cap developing at 700 mb. Regardless…dew points remain enhanced over that region and will likely help lead to some thundershowers this afternoon. There is not much shear (10 kts) and the ML Cape is 500-1000 J/kg. PWAT values of 35-45 mm may allow downpours if the convection initiates. With the low shear, training cells giving high rainfall potential is the most obvious threat. Dry mid levels support wind gusts of

60-70 km/h. Vey small hail is also a possibility. Tonight and Sunday, embedded convection will develop associated with a system pushing into Labrador and its associated trailing cold front. Labrador will be affected tonight and Sunday. On Sunday the front will impact northern New Brunswick and western Newfoundland.

 

Thunderstorm outlook for today

 

Thunderstorm outlook for tonight

 

 

Thunderstorm outlook for Sunday

 

 

 

 

 

 

 

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

 

Today

NL: Scattered thunderstorms with small hail, downpours and gusty winds

NB/NS/PEI: Isolated thunderstorms.

Labrador: None.

 

Tonight

NB/PEI/NL/NS/Labrador: None.

 

Saturday

NS:  Isolated thundershowers

NB/PEI/NL/Labrador: None

 

Convective Discussion

A weakening cold front over central New Brunswick will track southeastward to lie on a line stretching from Newfoundland to Nova Scotia tonight. There is not much shear (20 kts and linear) over the Maritimes and the ML Cape is 500-1000 J/kg. PWAT values of 35-45 mm may allow downpours if the convection initiates. With the low shear, training cells giving high rainfall potential is the most obvious threat. Over Newfoundland the shear is 20-30 kts so more organized thunderstorms are likely. Dry mid levels support wind gusts to 70 km/h. Also downpours are likely with PWAT values of 35-45 mm. Small hail is also a possibility. Tonight and Saturday little convection is expected. The front may linger over western Nova Scotia Saturday afternoon giving the risk of a thundershower.

 

Thunderstorm outlook for today

 

Thunderstorm outlook for tonight

 

Thunderstorm outlook for Saturday

 

 

 

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

 

Today

NB/Labrador: Isolated thunderstorms.

NS/PEI/NL: None.

 

Tonight

NB/PEI/NL: Isolated thunderstorms.

NS/Labrador: None.

 

 

Friday

NB/NS/PEI/NL:  Isolated thundershowers

Labrador: None

 

 

Convective Discussion

A weakening cold front will track southeastward to lie over the St. Lawrence River tonight and over a line stretching from Newfoundland to New Brunswick on Friday. There is not much shear (20 to 30 knots and linear) and the ML Cape is 500 J/kg or less. PWAT values of 35-45 mm may allow downpours if the convection initiates. Dry mid levels support the model guidance suggested wind gusts to 70 km/h. Guidance is suggesting that hail will not be a factor.

 

Thunderstorm Outlook for today

 

 

Thunderstorm Outlook for tonight

 

 

Thunderstorm Outlook for Friday

Convective Outlook Valid for Today and Tomorrow

Regional Impacts:

 

Today

NL: Rainfall rates 25-35mm/hr, wind gusts 70-80 km/h.

 

Tonight

None

 

Tuesday:

NB: isolated lightning.

 

Convective Discussion:

Significant instability exists across Newfoundland today. A 25/18.5 modified 12z RAOB from Stephenville yields a MLCAPE of 1000 J/kg, providing ample energy for storms to develop. Nevertheless effective shear of 20-25 kts should limit storm structure to the pulse variety. Moisture is quiet abundant with PWAT ranging from 35-45mm, giving a primary rainfall rate hazard this afternoon with storms that develop. Steep lapse rates from 900mb to the surface and widespread MLCAPEs in excess of 1000 J/kg present a secondary wind hazard, especially if shear ends up being locally enhanced (allowing for the odd storm to take on some super cellular characteristics).  Hail is anticipated to be small if it occurs due to a high HGZ and lower shear values.

 

Thursday:

Another upper trough moving through Ontario today will weaken and move eastward into northern NB tomorrow. Ongoing moisture advection throughout the day in southwest flow ahead of the upper trough should allow for some free lift late in the afternoon. Bulk shears of 30 to 40 kts in combination with MLCAPES up to 750 J/Kg could yield some stronger storms, however there remains some uncertainty in terms of the timing of upper trough.

 

 

Thunderstorm outlook for today:

 

Thunderstorm outlook for tonight:

 

 

Thunderstorm outlook for Thursday: