Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

Scattered thunderstorms this afternoon and evening across western and possibly northern LAB. Gusty winds, small hail and brief downpours are likely.

 

Isolated thunderstorms possible for central NB Friday afternoon.

 

Convective Discussion

Warm frontal trough crossing LAB today will be followed by an approaching cold which will likely give scattered thunderstorms across the west, and possibly the north coast later in the day. The LA Grande TEP has about 30-35 knots of shear, and also a fairly decent LLJ so some cells could get close to being severe. But the instability is not that great, and CAPE is nothing to write home about (in the vicinity of 500 J/KG – based on lifting from a surface temperature of 22 or so).  Lastly there are not too many breaks in the SC deck upstream so unless things break open soon it might be difficult getting deeper cells. For now, a compromise of gusts to 70 km/h or so and small hail seems to be legit.

 

On Friday a weak surface boundary and short wave trough could give some isolated afternoon storms for a portion of central NB. Locally heavy downpours seems to be the main threat.

 

A side note: there is some indication of isolated convection tonight and early Friday morning for parts of the island portion of NL associated with a weak short wave, but confidence is pretty low on that scenario.

 

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for Tomorrow

 

Jeremy

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

Slight chance of an afternoon thunderstorm for a portion of the north Labrador coast.

On Thursday a better chance for thunderstorms for western areas of Labrador.

 

Convective Discussion

The frontal trough that gave some scattered thunderstorms to a good chunk of the Big Land Tuesday is still hanging on near the coast so a slight chance for the north coast (Nain area) this afternoon. Further south there will likely be some TCUs inland from Norman Bay down to Mary’s harbour/Lodge Bay area with just the very slight chance of a rumble or 2 of thunder. Upstream TEPs have decent lapse rates in the low/mid levels but a strong cap around 600 mb will limit CAPE vales to about 200 J/KG or so.

 

Thursday afternoon has a decent potential for thunderstorms across western areas of LAB in the wake of a warm front and ahead of an advancing cold front. Strong wind gusts, small hail and brief downpours seem possible at this time.

 

Meanwhile the Island portion of the province, as well as the Maritimes, remain quiet.

 

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for Tomorrow

 

Jeremy

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

Scattered thunderstorms are expected this afternoon across portions of the Labrador interior.

Isolated embedded thundershowers possible for Slope waters and the Grand Banks today through Wednesday.

 

Convective Discussion

A surface trough will act as the catalyst for some scattered thunderstorms today across parts of the Big Land. Glancing at the upstream TEPs and the YYR sounding doesn’t indicate anything too interesting, aside from some gusty surface winds and perhaps some small hail in the deeper cells (FZLVLs are in the 8-9000 feet range). Things are fairly dry as well near the surface. No severe weather is expected.

 

A nearly stationary trough of low pressure will give copious amounts of rain to SE NL, however the sounding out of YYT is too warm aloft to support lightning today. The only real chance would be over the offshore marine waters.

 

OTWX nil sig wx xpctd.

 

Thunderstorm Outlook for Today

 

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for Tomorrow

 

Jeremy

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

NS…Chance of an embedded thunderstorm along the Atlantic coast today. Locally heavy downpours of 15 to 25 mm/h.

NB/PEI/NL… None.

 

Convective Discussion…

A slow moving trough brings the risk for a few embedded thunderstorms along the Atlantic coast of Nova Scotia today. Strong moisture flow from Cape Hatteras is aiding in high PWAT values over Nova Scotia, with the 12Z Shearwater tephi indicating 45 mm. Most of the convection will remain over slope waters, closer to the trough axis today. However a few lightning strikes are possible over eastern Nova Scotia. With limited CAPE, localized heavy rainfall remains the main threat today, with rates of 15 to 25 mm per hour possible. The risk will diminish throughout the day as the trough moves east of the Maritimes.

Tomorrow, some scattered thunderstorms are possible across Labrador with a weak incoming trough. Currently, thermodynamics and shear are weak, so the risk for organized thunderstorms is low. Brief heavy downpours will be the main hazard with these storms.

 

Thunderstorm Outlook for Today

Thunderstorm Outlook for Tonight

Thunderstorm Outlook for Tomorrow

 

Copp

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts…

 

Today

NB: Scattered thunderstorms developing, some becoming strong with potential for damaging wind gusts and 1-2 cm hail. Severe weather watch for western portions of the province for the afternoon into the evening.

NS/PEI: risk of non-severe thunderstorms

NF: A slight chance of thunderstorms south coast

Labrador: None

 

Tonight

NS and NF: A chance of embedded thunderstorms

NB/PEI/Labrador: None

 

Monday

NS and NF: A chance of embedded thunderstorms

NB/PEI/Labrador: None

 

Convective Discussion…

Low pressure near Sept-Iles with an attached frontal wave system is slowly moving eastward. In the warm sector, a 50-60kt SWly low-level-jet has been pushing very moist air northward and a large area of area of moderate-heavy rain has spread across NS earlier this morning which resulted in amounts of 10-30mm. This activity will advancing towards NF during the day.

 

To the west, an upper  trough over western Quebec will be advancing towards the Maritimes today and will be the focus severe weather (the main threat is the potential for damaging wind gusts WINDEX gusts estimates 50kt). There is not much convective inhibition ahead of this feature, and towering clouds are already noticeable north and south of the St. Lawrence valley. The main forcing will be a sharp area of convergence at the surface, emerging 30kt Wly low-level-jet, right entrance of a slightly cyclonic upper level jet, and 500mb PVA. Temperature and Dewpoint combination of 23,18 are sufficient to produce surface-based CAPE values of 1,000 J/Kg (MU 1,500) with Lifted index of -3 to -5, and deep-layer shear of 40-60kt. Under this very strong flow, hodograph is indicating straight/linear winds with storm motion of 260/35kt. Some of the storms could be long-lived especially over central Maine later this afternoon. This could produce bowing lines which could advance east of the international border.  

 

 

Thunderstorm Outlook for Today

 

 

Thunderstorm Outlook for Tonight

 

 

Thunderstorm Outlook for Tomorrow