Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

 

Today

Southern New Brunswick and western Nova Scotia: Embedded thundershowers are possible this evening continuing until midnight, with the hazard being moderate rain.

Labrador: over western portions non-severe thunderstorms are possible this afternoon and evening.

 

Tonight

Elevated convection is forecast for most areas in the Maritimes overnight tonight, continuing into the morning hours of Tuesday.

 

Tuesday

Maritimes: Thunderstorms are forecast for many areas, with the hazard being heavy rain.

 

Wednesday

Energetics and dynamics are the most favourable in New Brunswick for organized storm development. Some cells could produce heavy rain and moderate sized hail.

Nova Scotia: Surface convergence is expected to aid in development of storms on the spine in western NS near Kejimkujik NP to the community of New Ross.

Newfoundland and Labrador: Embedded thundershower risk continues under same forcing progressing east slowly.

 

 

Convective Discussion

 

An approaching long wave trough will track eastward today with instability increasing over the AOR today. Thundershowers are in the forecast this evening and tonight into Tuesday morning in the maritime region. The biggest threat with any cells that develop is lightning, and moderate rain. Tomorrow, more widespread synoptic rain is forecast over parts of the Maritimes. VILs are over 60 in model guidance (70+ offshore). This tropical air mass with very high dew points will certainly be a rain producer in pockets. The shear environment today is complex. Low level flow is straight out of the SE. Aloft, we are W-ly. This gives a 0-6k shear of 20-25kts. CAPE today is only 200-300 J per kg in central NB in clearing. This gives an LI of only -1, so no severe hail is expected. Pwats are near 35 in most prog soundings in the RDPS. Most of this moisture can be realized so no correction factor needs to be applied (RH greater than 90 this week).

 

Thunderstorm Outlook for TODAY

 

Thunderstorm Outlook for TONIGHT

 

Thunderstorm Outlook for TUESDAY

 

Thunderstorm Outlook for WEDNESDAY

 

Forecaster: Tirone

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

 

Today

New Brunswick: Isolated non-severe thunderstorms are possible near the Quebec border at Aut. 85 and Hwy2.

Labrador: over western portions non-severe thunderstorms are possible this evening.

 

Tonight

Energetics do not support nocturnal convection tonight.

 

Monday

New Brunswick: thunderstorms are possible across central and southern portions of the province ahead of an advancing area of low pressure.

Nova Scotia: as air mass destabilizes, thunderstorms are possible. Heavy rain is the greatest threat.

 

 

Convective Discussion

 

An approaching trough over central Quebec will track northward with instability increasing over western Labrador and northwestern New Brunswick today. The biggest threat with any cells that develop is lightning. Tomorrow, more widespread development is forecast over the southern Maritimes with rain being the biggest hazard. VILs are over 60 in model guidance. The key here will be if any discrete cells form before the synoptic rain and showers take over.

 

Thunderstorm Outlook for TODAY

 

Thunderstorm Outlook for TONIGHT

 

Thunderstorm Outlook for MONDAY

 

Forecaster: Tirone

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

 

Today

New Brunswick: Isolated near-severe thunderstorms possible giving locally heavy downpours over central to northern regions.

Labrador: Isolated to scattered near-severe thunderstorms possible giving locally heavy downpours, strong wind gusts and small hail.

Newfoundland: Isolated non-severe thunderstorms possible giving locally heavy downpours.

 

Tonight

New Brunswick: Isolated non-severe thunderstorms giving locally heavy downpours.

 

Sunday

New Brunswick: Isolated non-severe thunderstorms possible giving locally heavy downpours over  northwestern regions.

Labrador: Isolated non-severe thunderstorms possible giving locally heavy downpours over western regions.

 

Convective Discussion

 

The main threat of showers and thunderstorms will be over central to northern New Brunswick and southeastern Labrador under a hot and humid air mass today. Elevated convection this morning over northern New Brunswick is expected to clear with high temperature expected to exceed 30C. Some initiation is already occurring over the eastern Townships in Quebec and central Maine that will drift slowly northeastward into New Brunswick late this afternoon or this evening. Although there is ample potential again over New Brunswick with CAPE values above 1500 J/kg, dynamics are not as favourable as they were yesterday over New Brunswick but the precipitable water remains high and any convection that develops will be slow moving with weak 0-6km shear.

 

Convection over central Labrador will continue eastward under an upper level low today. The 12Z Goose Bay sounding indicated a strong capping inversion around 900mb but with a weak 850mb jet along with topographic lift and approaching 500mb thermal trough, some organization of storms is possible. With weak shear and high precipitable water near 40 mm, the main risk will be heavy downpours.  There is a slight risk for a pop-up thundershower over the southwestern interior of Newfoundland this afternoon if daytime heating can break a capping inversion near 850mb.  

 

For Sunday, an approaching short wave trough over central Quebec will track northward with instability increasing over western Labrador and northwestern New Brunswick.

 

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for Sunday

 

Forecaster: McArthur

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

 

Today

New Brunswick: Isolated to scattered severe thunderstorms possible giving torrential downpours (25 to 50 mm per hour rates), small hail and gusty winds in central to northern regions.

Labrador: Isolated non-severe thunderstorms possible in the afternoon giving heavy downpours and gusty winds.

 

Tonight

New Brunswick: Isolated non-severe thunderstorms giving locally heavy downpours and gusty winds.

 

Saturday

New Brunswick: Isolated severe thunderstorms possible giving locally heavy downpours and gusty winds.

Newfoundland and Labrador: Isolated non-severe thunderstorms possible giving locally heavy downpours.

 

Convective Discussion

 

An approaching trough from central Quebec combined with daytime heating will trigger convection into Labrador and New Brunswick this afternoon and evening. The air mass continues to be hot and humid (20-22C dewpoints this morning over New Brunswick and 19C into southwestern Labrador) and surface based CAPE values are expected to exceed 1500 J/kg in New Brunswick. There will be further destabilization in the upper levels as a 500 mb thermal ridge currently over the Maritimes tracks further east but there is only weak to moderate 0-6km shear of 20 to 30 kts. Therefore, there is the threat of slow moving severe pulse or multicell storms for central to northern New Brunswick with torrential downpours being the main threat with 25 to 50 mm per hour rates likely, although strong wind gusts and small hail are also possible. This could especially be a concern for areas of northwestern New Brunswick that received substantial rainfall from last week.

 

Early morning elevated thundershowers over Prince Edward Island and northern and eastern Nova Scotia may continue into early this afternoon. Upper level troughing over eastern Newfoundland will keep the environment cool and unstable but some elevated convection may persist in the waters east of Newfoundland.

 

For Saturday, the main threat of showers and thunderstorms will be over New Brunswick under a hot and humid air mass and central Labrador as the trough slowly progresses eastward. Isolated convection under an upper trough in central Newfoundland is also possible.  

 

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for Saturday

 

Forecaster: McArthur

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

 

Today

Labrador: Isolated thunderstorms possible giving locally heavy downpours and gusty winds.

New Brunswick: Isolated thunderstorms possible giving locally heavy downpours.

 

Tonight

None.

 

Friday

Labrador: Isolated thunderstorms possible in the afternoon giving heavy downpours and gusty winds.

New Brunswick: Isolated severe thunderstorms possible giving locally heavy downpours, small hail and gusty winds.

 

Convective Discussion

 

A slow moving upper low will remain over Newfoundland today, while an approaching trough moves eastward into western Labrador this afternoon. There may be some remnant early afternoon convection under the upper low over the Avalon Peninsula and marine areas east of Newfoundland. Dynamics are more favourable over western Labrador with the approach on a trough in central Quebec giving diffluence aloft and a weak 500 mb thermal trough.  With a fairly decent temperature and dew point spread, there is the threat of convective gusts.

 

Over the Maritimes, a weak ridge of high pressure and increased warming in the mid to upper levels should cap any convection. However, convective temperatures are expected to be reached over northern Maine and western New Brunswick. With only weak to moderate wind shear over the area, there should not be much organization of cells that develop. Therefore, locally heavy downpours are the main threat with these. There is an incoming 700mb thermal ridge which should prevent convection in Nova Scotia, but some inland TCUs may develop in the sea breeze in western Nova Scotia and give some locally heavy downpours.

 

For Friday, a approaching trough from Quebec will trigger convection into Labrador and New Brunswick. With an increasingly hot and humid flow, surface based CAPE values are reaching over 1500 J/kg in New Brunswick but 0-6km shear appears to remain weak to moderate. There is the threat of severe pulse storm are possible for northwestern New Brunswick with heavy downpours being the main threat but strong wind gusts and small hail are also possible.  Some inland showers may develop again in the sea breeze in Nova Scotia.

 

 

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for Friday

 

Forecaster: McArthur