Convective Outlook Valid for Today and Tomorrow

Regional Impacts

NB: None

NS: None

PEI: None

NF: None

Labrador: None, isolated thunderstorms possible over northwestern sections on Wednesday.

Marine waters: Isolated Thunderstorms over southwestern Grand Banks. Isolated thunderstorms for Laurentian Fan and East Scotian Slope by Wednesday evening into Thursday.

 

Convective Discussion: Upper trough in the process of being cut-off to the south of the Maritimes as heights rise in Labrador. To the east of this feature moist unstable profiles and a moderately strong 850 mb jet can support isolated elevated convection over the southwestern Grand Banks.

As this cut-off feature retrogrades to the southwest, the instability associated with this jet structure will gradually advect westward allowing for isolated convection over Laurentian fan and the East Scotia Slope on Wednesday night into Thursday respectively. On Wednesday afternoon northwestern most Labrador has profiles that support elevated instability on the order of 300-500 J/kg however a sufficient triggering mechanism may be lacking as a warm front remains well to the east over north-central Quebec. Regardless an isolated strike cannot be ruled out, especially if this feature advects eastward faster than advertised by our current guidance.  

 

Thunderstorm outlook for today:

 

 

Thunderstorm outlook for tonight:

 

Thunderstorm outlook for Wednesday:

 

 

Thunderstorm outlook for Wednesday Night and Thursday:

 

 

TEST

Thunderstorm Outlook for Day 1

 

Regional Impacts

 

Convective Discussion

 

Thunderstorm Outlook for Day 2

Atlantic Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Today, June 20^th.

 

Regional Impacts

Isolated non-severe thundershowers are possible over the Gulf waters as well as offshore over Laurentian fan. These cells are expected to be embedded in showers being driven by the upper trof. Only a few lightning strikes are forecast in the risk areas.

 

Convective Discussion

The upper low is still the dominant weather forcing for today. Not much has changed since yesterday, other than sfc temperatures cooling further in NB. As a result, the atmosphere although saturated/moisture rich in the low levels is fairly stable. Shearwater this AM is moist yet stable up to 9,000ft. Much more of a springtime fog/drizzle airmass regime than a summer severe weather day. East of CYQY, there is even thermal ridging above 700 to prevent anything further. And, back to the west, the airmass is far too dry (across Maine).

 

 

Thunderstorm Outlook for Tomorrow, June 21^st.

 

Regional Impacts

No thunderstorms expected at this time.

 

Convective Discussion

Atmosphere continues to stabilize further as upper low fills. Forecast highs quite cool across Atlantic Canada for first day of summer.

 

 

HTTP://WEATHER.GC.CA

 

END/ASPC

Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Today

Isolated non-severe thunderstorms

 

Regional Impacts

NB: None

NS: Towering Cumulus cloud over northern regions possibly giving a brief shower

PEI: Towering Cumulus cloud possibly giving a brief shower

NF: None

Marine waters: Isolated Thunderstorms over northern Gulf of St. Lawrence today, and south coast of NF tonight.

 

Convective Discussion

Current satellite imagery is showing an Upper / Surface Low pair over Maine / NB producing extensive cloud cover and occasional rain. At the surface, a warm front extends from the low northeastward to great northern peninsula of NF. The intersection of this feature with a strong southerly low-level jet will continue to support isolated non-severe thunderstorms over the northern Gulf of St. Lawrence. A strong southern flow of moist air prevails over NF ahead of the upper low feature and it is producing pockets of heavy rain along the west coast.

The strong southerly flow has been advecting very stable air in the mid-levels which is favoring a corridor of dry air over central NS this morning. The sounding at Shearwater has a very strong inversion at a height of 3-4 km which will likely limit the amount of vertical development of the cumulus cloud. In fact, a max temperature of 24 (and dew point of 10) only renders about 200 J/kg of MUCAPE, however topographic features such as the Cobequid Mountains could potentially provide the necessary lift for an isolated tall TCU/CB.

 

 

Thunderstorm Outlook for Monday

 

No thunderstorms expected

Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Today

 

Regional Impacts

New Brunswick: Scattered thunderstorms with brief heavy downpours, Hail of 2 cm, and wind gusts to 80 km/h

Nova Scotia: Numerous Strong thunderstorms with Hail of 2 cm or more, heavy downpours and wind gusts to 90 km/h

PEI: Hail 1 cm or more, heavy downpours and wind gusts 70 km/h or more

Newfoundland: Chance of a thundershower late in the day and tonight in the southwest

Labrador: Turning much colder with brief heavy showers, no thunderstorms expected

 

Convective Discussion

An upper low over Maine will advance over the Maritimes today and remain in place on Sunday. A cold trough extends southeastward from the low and will be rotating over the region today.. this will be the focus for convective initiation. Strong surface heating over NS-PEI-Ern NB will further contribute in the destabilization of the environment, and modified soundings can easily push mixed layer cape values between 500-1000 J/kg with a temperature/dewpoint combination of 25/15. This very buoyant air mass will produce CB with tops to 7 or 8 km and max overshooting tops to 12 km especially over regions along the Northumberland Strait. The early morning soundings were also indicating deep layer shear strong enough to support multi-cellular clusters with some capable of producing damaging wet macrobursts. The main threat will be large Hail, torrential downpour and damaging winds.  

 

 

Thunderstorm Outlook for Sunday

 

Slight risk of a thunderstorm over eastern Maritimes.