Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

Today: scattered thunderstorms for western Labrador giving some gusty winds. Isolated thunderstorms for parts of the Maritimes giving torrential rainfall and gusty winds.

 

Tonight: risk of a thunderstorm for portions of Labrador and the Maritimes. Mainly heavy rainfall possible in the Maritimes.

 

Wednesday: an afternoon risk of thunderstorms for southeastern Labrador. New Brunswick and western PEI.

 

Convective Discussion

An elongated trough of low pressure stretching from LAB and NE will progress slowly eastward today giving some scattered thunderstorms for western LAB this afternoon. Some gusty winds to about 70 km/h seem to be the main threat in the stronger cells. The dynamics are slightly weaker as we head south to NB, but the Pwats increase so locally heavy rainfall, along with some decent wind gusts, are the main concern. Instability is relatively weak, so I don’t expect much of a hail threat anywhere today. Will have to see if we get some elevated convection fire up west of NS later this afternoon that could give some hefty downpours for some counties this evening. There has been some history of lightning but currently there is a lull. We shall see…

 

That same trough will continue tracking eastward tonight and into Wednesday giving the risk of a thunderstorm to a good chunk of the region. It will be weakening so the risk is marginal at this time.

 

There is no prog sent for D3 but based on current guidance, there could be some strong, possibly severe, thunderstorms across parts of NB. I just don’t have the confidence to draw a threat area this far in advance.

 

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for Tomorrow

 

Jeremy

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