Convective Outlook Valid for Today and Tomorrow

Regional Impacts

 

NS/NB/PEI: None

NFLD: A chance of severe wind gusts and downpours this afternoon.

Labrador: Elevated convection giving downpours.

 

Convective Discussion

 

Elevated convection giving downpours is possible in Labrador. Precipital water is 30 mm there and it is in the region of the left exit of a 100 kt jet which is giving it support. Over eastern regions of Newfoundland surface based convection will initiate this afternoon. Precipital water is 40 mm and dry mid layers will allow possible wind gusts to 80 km/hr. A high freezing level of 13,000 feet will limit possible hail size. The sheer is a relatively low 20 kts or less so storms will be mostly pulse in variety.

 

Thunderstorm Outlook for Day 1

 

 

Thunderstorm Outlook for Day 2

 

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

There is a slight risk of an isolated severe thunderstorm or 2 across central areas of New Brunswick this afternoon into this evening giving torrential rainfall and strong winds. Small hail is also a possible in the stronger cells.

Scattered thundershowers are likely for southeastern Labrador and western Newfoundland today and into tonight. This is mostly elevated precipitation so just some heavy downpours are expected.

There is a slight risk of a thundershower this afternoon and early this evening across the valley and northern Nova Scotia.

Lastly isolated thundershowers are possible for western Labrador later today.

 

Convective Discussion

The same front that produced some severe weather in Quebec yesterday is now situated across central areas of New Brunswick (though in a somewhat weakened state). The 12Z KCAR profile does support MLCAPE of 800-1000 j/kg, PWAT around 44 mm and good shear at around 40 knots. And also good low level instability. There are 2 warm noses that could prevent things from firing. However given enough buoyant energy, a diffluent flow at 500 mb observed at 12Z and a jet streak at 250 mb placing the region in the left exit region, isolated severe storms are a possibility.

 

An upper level feature will give some scattered thundershowers to SE LAB and WRN NL but all non-severe.

 

For the valley and northern NS there is a slight risk of a thundershower this afternoon and evening…but the limiting factor will be the upstream cloud cover now entering the region and lack of any trigger. Expect mostly TCU giving locally heavy downpours.

 

An approaching upper-level trough over north-central Quebec will give some isolated non-severe cells to western LAB later today.

 

Thunderstorm Outlook for Day 1

 

Thunderstorm Outlook for Day 2

 

Jeremy

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

There is a risk of thundershowers this afternoon and evening across western and central Labrador. These could advect eastward affecting portions of the LAB coast tonight as well. Brief heavy downpours and gusty winds are possible.

There is a slight risk for a severe thunderstorm across the far northwest of NB. The main threat would be torrential rainfall…however strong wind gusts are also a possibility.

Lastly, there is a risk of isolated thundershowers this afternoon across the valley and northern NS. Torrential rainfall is the main threat.

 

Convective Discussion

The main focus today will be to see what forms upstream across southern Quebec and northern Maine. What will be a moot point today is a trigger. The KCAR tephi has ~ 25 knots of shear, PWAT of around 40 and MLCAPE of 1000-1200 j/kg. There is a moist tongue near the surface which would add to the buoyancy as the day progresses. The deep layer trough at 500 mb is further upstream at 12Z, but that should propagate eastward today, resulting in an increase in wind shear across NW NB. If cells do make it to the region, torrential downpours and gusts to 70-80 km/h would be expected. Will have to monitor the upstream development this afternoon and the evolution of movement.

 

For Labrador, where shear is 40-45 knots, and closer to the surface and upper trough, scattered cells are likely. Then only issue would be warm air aloft…however given the dynamics that would be broken fairly easily. Brief heavy downpours and gusty winds are possible with the storms.

 

There is a risk of isolated non-severe thunderstorms across the valley and northern NS this afternoon. There is very little shear (YQI and GYX showing 20 knots), but the PWAT is 40+. CAPE looks to be in the 500-1000 range. Locally torrential downpours will be the threat.

 

Thunderstorm Outlook for Day 1

 

Thunderstorm Outlook for Day 2

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

 

NB/NS/PEI/Labrador:  No significant impacts expected.

 

Newfoundland: Slight risk of short lived thunderstorms over central and eastern Newfoundland.  Main threat is local heavier showers and gusty winds. 

 

Convective Discussion

 

An area of PVA is currently bringing some showers and thundershowers just southwest of Newfoundland.  This area of PVA along with cooler upper atmosphere temperatures and high insolation will bring some thundershower activity to parts of Newfoundland today.  Wind shear is low so long lived severe thunderstorms is not expected.  Precipitable water is low as well so torrential downpours are not expected.  Still, there is a low potential for short lived severe storms bringing localised heavy rainfall and gusty winds mainly over eastern Newfoundland.  Prog tephis over eastern Newfoundland showing between 500 to 1000 J/kg with low shear and low precipitatble water.

 

Thunderstorm Outlook for Day 1

 

Thunderstorm Outlook for Day 2

 

 

Barrie MacKinnon

 

 

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

 

For Labrador.. Small hail and gusty winds in thunderstorms this afternoon and this evening. Heavy downpours may occur.

 

For New Brunswick.. Isolated thunderstorms possible over norther New Brunswick this afternoon. No Severe Weather expected. Small Hail possible.

 

Convective Discussion

 

Labrador continues to be a main threat area today with an upper trough progressing eastward through northern Quebec. Aloft at 250 there isn’t strong support but the dynamics are somewhat more favourable as you move down through the atmosphere. Good low level shear below 500 mb could favour the development of organised thunderstorms this afternoon, possible affecting western Labrador late this afternoon and early in the evening.

 

Not much is expected southward in New Brunswick with somewhat dry, relatively speaking,  lower levels and upper lapse rate that are not overly conducive to deep convection. However an upper trough may act to destabilize the atmosphere allowing for daytime heating and surface convergence near the northern coastlines to trigger some convection.

 

Thunderstorm Outlook for Day 1

 

 

Thunderstorm Outlook for Day 2