Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

Labrador… low risk of thunderstorms over northern areas today, low risk for south-central on Tuesday.

Newfoundland… Slight risk of near shore lightning today

PEI, NB and NS… No impacts from thunderstorms expected.

Convective Discussion

A push of drier air behind a departing trough of low pressure will help settle conditions over the next couple of days. There remains a slight risk that offshore thunderstorms could affect eastern Newfoundland today, but the associated surface low and its weather are expected to move away through the day.

Over Labrador, a weak shortwave may trigger a few isolated thundershowers over higher terrain today. A similar setup could extend slightly farther south tomorrow; however, confidence in this potential remains low.

Looking ahead to the remainder of the week, conditions should remain fairly quiet as a ridge of high pressure builds across the region.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

Mel Lemmon

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

 

Today

NB/PEI/NS: scattered risk of an embedded non-severe thundershower across the Maritimes this morning and again this afternoon/evening.

NFLD/LAB: isolated chance of a lightning strike or two later today near the Burin, and also south of Goose Bay along a deformation zone.

 

Tonight

NS/PEI/NFLD: embedded elevated non-severe convection is forecast to pull away to the SE over the marine district tonight. It may graze the Avalon overnight.

NB/LAB: none.

 

Monday

LAB : convection is possible near Nain throughout the day. Forecast to be non-severe in nature.

NB/NS/PEI/NFLD: no thunderstorms forecast. Much of Nfld is receiving synoptic scale rain.

 

Convective Discussion

The dewpoints rose last night as forecast to near 16 across the Maritimes, paving the way for this morning’s first round of early convection. CAPE remains very skinny today, with not much shear involved (in the effective levels). These warm frontal showers are giving bursts of heavy rainfall then subsiding to mist/fog patches. A partial clearing is possible for some areas of central and western Nova Scotia near noon today. Then a slumping cold front will force another round of scattered TS – main hazard again being lightning and heavier pockets of rain. Pwats on morning soundings to the west sit near 35mm. This is under severe alert criteria as long as storms continue moving and don’t sit too long over one location. There is decent flow at 850 and above so storms are expected to progress Ely. The adjacent gulf shores will be gustiest this evening behind the  passage of the front (G70km/h). Nfld will be getting the brunt of the rain from the “now forming” synoptic low tonight and tomorrow. Isolated thundershowers are possible off to its East (depicted in grey area). The Maritimes are stabilizing on Monday and quiet SVR weather wise. Summer heat builds in again this week.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

Forecaster: Tirone.

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

 

Today

NB: slight risk of an embedded non-severe thundershower across northern areas of the province near the Que border.

NS/PEI/NFLD/LAB: None.

 

Tonight

NS/NB/PEI: embedded elevated non-severe convection is forecast late overnight tonight across the Maritimes, and into early Sunday morning.

NFLD/LAB: None.

 

Sunday

NB/NS/PEI/NFLD: risk of non-severe embedded thundershower activity continues all day in the broad area of convective showers. There could be a few heavier downpours associated in the Annapolis Valley and Cobequid mountain areas. Late day the shower activity could approach Saint-Pierre and the Burin.

LAB : None.

 

Convective Discussion

The atmosphere will slowly begin to destabilize above 850mb over the next 12-24hrs. A broad area of low pressure is approaching the Maritimes tonight from the Great Lakes region of Ontario. This will bring a change in airmass and bump up dewpoints significantly from 4 to 18. Accordingly, embedded non-severe thundershowers are being forecast and will slowly traverse the Maritimes (and the marine district) this weekend. The greatest impact is repetitive showers, and lightning. Rainfall amounts will be highly variable across regions. There is a low level jet at 850 out of the WSW that strengthens both in the day Sat and again on Sunday. BUT – effective shear remains low at only 10-20kts. 0-3k shear is better at 30-40kts which just confirmed the nature of these cells being mostly elevated. CAPE for the whole column is 400J at best and very skinny.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

Forecaster: Tirone.

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

 

Today

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

 

Tonight

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

 

Saturday

NB: Slight risk of a late afternoon thundershower in NWern regions with brief heavy downpours.

NS/PEI/NFLD/LAB : None

 

Convective Discussion

Atlantic Canada remains fairly quiet today with a ridge of high pressure across the Martimes with a cold front exiting eastern Newfoundland this morning and a semi quasi-stationary low pressure system siting south of the Maritimes marine district. A weak trough across central and southern Quebec into central Maine along with increasing surface temperatures and cooler air aloft aid in the triggering of isolated thundershowers this afternoon and evening but are not expected to persist into New Brunswick.

For Saturday, the trough will move eastward and provide some scattered showers across New Brunswick in the morning.  An approaching low pressure system moves into southern Quebec by Saturday afternoon, ahead of this system within the warm sector, scattered showers with risk of non-severe isolated thundershowers are possible mainly for northwestern New Brunswick where convective temperatures are mostly like to be reached and there is sufficient lift and effective shear to maintain convection. Weak troughing is also expected across northern Quebec into central and southeastern Labrador, giving isolated showers.

The low pressure system will track across northern New Brunswick and into the Gulf of St. Lawrence Saturday night and into Sunday with possible embedded convection.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

Forecaster: McArthur

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

 

Today

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

 

Tonight

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

 

Friday

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

 

Convective Discussion

The quiet convective weather will persist over Atlantic Canada today and Friday. A ridge of high pressure over the southern Marine District will drift away as a weak trough currently over the Lower North Shore of Quebec continues moving southward.  Any instability today should be limited to areas of central Quebec and the Gaspe Peninsula.

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow