Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

Today: Isolated risk of a thunderstorm in extreme northwestern New Brunswick late this evening. Heavy downpours are the main risk.

Tonight: Some isolated thunderstorms possible over northern and central New Brunswick tonight. Heavy downpours are the main risk.

Tomorrow: Scattered strong thunderstorms expected across southern New Brunswick tomorrow afternoon. Strong wind gusts and torrential downpours are the main risk.

Convective Discussion…

A quiet day is in store for the Maritimes today as a ridge of high pressure sits off the Atlantic coast. Late this evening, a trough expected to bring widespread severe weather to Ontario today will slowly make its way into New Brunswick. With much of the region largely capped (evident on the 12Z Caribou and Maniwaki soundings), only extreme northwestern New Brunswick will see the potential for any thunderstorm activity late this evening. By this time, daytime heating will have dropped off, so storms are not expected to be severe as they cross northern New Brunswick tonight. Weak lapse rates out ahead of the trough will also diminish the severe potential here tonight, so the main hazard will be heavy downpours.

Tomorrow looks to be more interesting, as an intense cold front will sweep across New Brunswick during the day, which will likely trigger some marginally severe thunderstorms. The main area of interest exists across the southern half of New Brunswick, where adequate daytime heating ahead of the cold front could help increase MLCAPE values upwards of 1000 J/kg. Dynamics look really good as well out ahead of the front, but once again lapse rates remain fairly weak so hail is not likely. A few discrete cells might fire early in the afternoon ahead of the cold front, but things are expected to line out fairly quickly as upwards of 60 knots of bulk shear crosses the region late in the afternoon with the passage of the cold front. An abundance of moisture will also be fed into this system, with PWATs expected to rise above 50 mm over southern New Brunswick tomorrow, increasing the potential for torrential downpours. As such, the main threats with these storm will be very strong wind gusts, and torrential downpours.

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: Nil sig weather.

Tonight: No thunderstorms expected.

Tomorrow: Trof starts to enter NW NB and western Lab late in the evening, may lead to a lightning strike or 2 in embedded showers.

Convective Discussion

Weather today and Thursday is dominated by a building ridge of high pressure. No thunderstorm activity is expected, until a late day trof starts to sweep thru central and northern Quebec late in the day on Thursday. High heat and humidity may set the stage for a thundershower or 2. Nil sig weather forecast at this time in the Atlantic AOR.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

Forecaster: Jimmy.

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

Today: Scattered embedded thundershower activity within the boundary that’s in the vicinity of the Grand Banks. No severe hazards forecast.

Tonight: No thunderstorms expected.

Tomorrow: No convection forecast. Strong cap.

Convective Discussion

Upper trof is departing Nfld this morning. Convection is possible out ahead of the trof, but would be non-severe and embedded. The risk would only be 5-10mm of rain. Stability increases tonight from a Ridge building in from the west. Building heights are preventing any deep convection on Wednesday. The next trof approaches late in the day on Thursday, and may bring a lightning strike or 2 before midnight over extreme western Lab and NWrn NB.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

Thunderstorm Outlook for Thursday

Forecaster: Tirone.

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

Today: scattered thunderstorms this afternoon and evening for portions of the MRTMs and southern NL giving gusty winds, small hail and downpours. I do not anticipate severe cells, but rainfall could become a concern in the MRTMs if convection is slow-moving.

Tonight: risk of a thunderstorm for eastern NL giving heavy downpours.

Convective Discussion

Today will feature an incoming sharp upper trough that will swing down across the southern Gulf of St. Lawrence then eventually move east of NL by Tuesday morning. At first glance the trough looks inviting for a good active day but, much like yesterday, there is a lack of instability. There should be some scattered thunderstorms develop but nothing to write home about. As the upper trough continues moving into the region the freezing levels will be dropping so under some of the heavier precipitation bands there could be a fair amount of hail locally…but small in nature (a cm or less in diameter). The shear will be in the 30-40 knot range just ahead of the upper trough, so some strong gusts are possible as well. The PWATs favour the best rainfall potential in eastern NS and southern NL. The risk for thunder will persist tonight for eastern/southeastern NL just ahead of the upper trough.

Things will get quiet for several days after today with nothing expected until later this week.

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for Tomorrow

 

Jeremy

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

Today: scattered thunderstorms across southern/southwestern NB giving a threat for localized flooding. Further north just some airmass CBs giving brief downpours and possibly small hail. A risk of an afternoon/early evening thunderstorm across the interior of NL.

 

Monday: scattered thunderstorms likely for eastern NB, eastern NS, PEI, and southern areas of NF giving brief downpours, small hail, and gusty winds.

 

Convective Discussion

 

The main area of concern today would be high rainfall rates across southern areas of NB, as PWATs are up around 40 mm (based on the KALB sounding). The instability is on the weak side though, and given the current cloud clover we will need to see formation upstream in ME that could advect into NB this afternoon/evening. Some gusty winds could also accompany the cells as effective shear will be increasing throughout the day. There will likely be some scattered thunderstorms across the northern half of NB this afternoon as an upper trough approaches from QC. Given the increase in shear and lowering of the FZLVLs small hail and gusty winds are possible. Lastly a slight risk of an afternoon/early evening thunderstorm for the interior of NL giving brief downpours and gusty winds.

 

On Monday, the upper trough will be moving through eastern regions of the MRTMs and into southwestern NL, so there should be some scattered thunderstorms associated with it. Small hail looks possible given the lowering of the FZLVLs, but also brief downpours and gusty winds. Like today, the instability looks weak so could be a balance issue with the strong wind shear and updrafts…which would lead to less in the way of activity if the shear is too high.

 

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for Tomorrow

 

Jeremy