Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

Today: Severe thunderstorms are likely in the vicinity of Goose Bay, Labrador. There is the potential of supercells and a history of hail, wind, and rain with this front. Severe thunderstorms are also possible in the far NW corner of NB through the Edmundston valley with the same frontal passage. Gusty winds, hail, and rain are the main hazards here as well. However, some tornadic rotation is possible later this afternoon and early evening.

Tonight: Decaying thunderstorms continue for many areas in NB and Labrador. There will also be offshore convection south of NS and Nfld tonight.

Tomorrow: Risk of isolated non-severe thundershowers across much of NB, parts of western Nfld along the de-stabilized trof. Capping ridge is starting to enter the lower Maritimes – preventing widespread deep convection.

Convective Discussion

A very strong low pressure system anchored over the Kavallik region of northern Quebec is bringing a sweeping front from the Labrador Sea down to the Ohio River Valley. This broad feature is driving deep convection, with enhanced spin out ahead of it. It is has a 3-day history of impactful weather as it tracked thru much of eastern Canada. Cape values in central Lab are near 1500+ today, and Effective Helicity is heightened. Sig tor flags supercell development late day near Goose Bay. Sig tor 2 also flags the same area. NW NB is non-zero as well near 00z tonight. However, there is a CIN factor to contend with. Dewpoints of 20 need to advect further east this afternoon, and there is a lot of other cloud cover in the vicinity. Difficult to get discrete cells without a partial clearing. Svr TS watches are going to be issued for areas directly downstream of this trigger – E. Townships of Quebec, Edmundston, Goose Bay. Dynamics are weaker night 1 and day 2 across the Maritimes, with high heat building into the region for much of the week ahead. Isolated higher based windy storms are forecast for Tuesday.

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:

LAB: Risk of thunderstorms late this afternoon with locally heavy downpours and strong wind gusts.

Maritimes/NL: None

Tonight:

LAB/NB: Risk near-severe embedded thunderstorms this evening giving locally heavy downpours and strong wing gusts.

PEI/NS/NL: None

Tomorrow:

LAB: Risk of near-severe thunderstorms with heavy downpours, small hail and strong wind gusts.

NB: Risk of a thunderstorms giving locally heavy downpours and strong wind gusts.

PEI /NS /NL: None

Convective Discussion

A low pressure system over James Bay this morning has a trailing cold front stretching from central Quebec into the eastern USA. Thunderstorms along and ahead of the front may reach western Labrador and northwestern New Brunswick by early evening with the threat continuing into the evening. This front will continue to stream in precipitable water into the 40-50 mm range even as far as northern Labrador over the next few days. However, some smoke notes aloft over the region may work to inhibit full daytime heating potential. The highest risk of severe thunderstorms remains over southern to central Quebec where with cooler air aloft, and a strong 850mb jet. Regardless, heavy downpours and strong wind gusts may continue into the overnight for western New Brunswick and western to central Labrador.  

Tomorrow, the front will continue to track eastward further north over Labrador. With CAPE potentially reaching 1000 and moderate effective shear reaching 35-40KT, lines may organize into lines in the afternoon ahead of the cold front over central and eastern Labrador. Behind the front, a shortwave is expected to quickly track across central Quebec and into western Labrador by the evening. With this, there could be further multicell convection with strong wind gusts being the main threat with a drier air mass.

Meanwhile further south, a slow moving low pressure system and ridge over the southern marine waters will keep the threat of convection mainly over north and western New Brunswick. Locally heavy rain and strong wind gusts would be the main threat with convection that can continue from northern Maine.

 

Thunderstorm Outlook for TODAY

Thunderstorm Outlook for TONIGHT

Thunderstorm Outlook for TOMORROW

 

Roberta McArthur

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

Today:

LAB: Risk of thundershowers with heavy downpours and gusty winds in northern Labrador.

NB: Slight risk of a thundershower giving a brief heavy downpour and gusty winds.

PEI/NS/NL: None

Tonight:

None

Tomorrow:

LAB: Risk of thundershowers with heavy downpours and strong wind gusts.

Maritimes/NL: None

Convective Discussion

A low pressure system is slowly moving southeastward across the Grand Banks today. There has been the odd embedded thunderstorm north of the low over the Avalon Peninsula this morning and the threat of heavy downpours continues further east, mainly affecting the northern and southeastern Grand Banks today.

A weak trough will move into northern Labrador today from northern Quebec. While upper dynamics are limited, sea breeze convergence, terrain influence and warm surface temperatures could aid in the development of thundershowers this afternoon.

Although there is a ridge over the Maritimes keeping most of the area capped for any strong convection, the convective temperatures may be realised over parts of central and western New Brunswick this afternoon with high temperatures reaching 28C. Based off the 12Z Caribou sounding and not much change expected in the mid-upper levels,  isolated showers with a slight risk of a thundershower giving a brief heavy downpour are possible.

Tomorrow, a relatively deep low pressure system will track into James Bay, with a trailing cold front stretching from central Quebec into the eastern USA. Thunderstorms along and ahead of the front may reach western Labrador by afternoon before convection diminishes in the evening.

Thunderstorm Outlook for TODAY

Thunderstorm Outlook for TONIGHT

Thunderstorm Outlook for TOMORROW

 

 

Roberta McArthur

 

 

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

 

Today

NB: isolated thunderstorms this afternoon/early evening giving some gusty winds, heavy downpours, and possibly small hail. Do not expect any cells to become severe.

NS and southeastern NL: risk of an elevated thunderstorm today and into this evening giving locally heavy downpours.

 

Tonight

Southeastern NL: continuing with the risk of an elevated thunderstorm through the overnight and into Saturday morning giving locally heavy downpours.

 

Saturday

Lab: slight risk of an afternoon thunderstorm.

 

Convective Discussion

 

A couple features of interest today: one is a frontal trough passing south of NS and the other a 500 mb trough entering NB. There has been some history of activity with both features, more notably the upper trough. The instability doesn’t appear as deep as it was yesterday when the trough was upstream in Quebec, and the feature itself is showing some signs of weakening. There should be some isolated storms in Maine that will drift across inro western NB through the afternoon giving some gusty winds, locally heavy downpours and small hail. The 12Z tephi out of caribou has pretty weak shear but the FZLVL is just above 10,000 ft so the chance for small hail seems legit.

 

The trough currently passing south of NS and approaching southeastern NF will produce some isolated thunderstorms offshore with a slight chance it could touch the Burin and southern Avalon tonight and into Saturday morning. The instability is pretty good but quite high so we shall see if anything does materialize. Locally heavy downpours would be the only threat.

 

Lastly a weak surface trough could be enough to trigger an isolated thunderstorm or 2 across parts of the Big Land on Saturday.

 

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for Tomorrow

 

Jeremy

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

Today:

NB: Risk of thundershowers with heavy downpours and strong wind gusts.

NS/southwestern marine waters: Risk of embedded thundershowers.

Tonight:

NB: Risk of thundershowers with heavy downpours.

NS/southern marine waters: Risk of embedded thundershowers.

Tomorrow:

NB: Risk of thundershowers with heavy downpours, small hail and strong wind gusts.

NS/PEI/southern marine waters: Risk of embedded thundershowers.

Convective Discussion

A slow moving trough over southern Quebec along with daytime heating and increasing shear will aid in the development of thunderstorms for southern Quebec and Maine this afternoon and this area will slowly move into northwestern New Brunswick tonight and tomorrow. Ahead of the trough, daytime heating will aid in destabilization with mainly non-severe pop-up thundershowers in north central New Brunswick and southwestern Labrador this afternoon. The main threat this evening and overnight will be heavy downpours if cells redevelops over one area with moderate precipitable water with this air mass. Meanwhile, embedded thundershowers are possible along a boundary off New England that will move into the southern Maritime marine waters and across southwestern Nova Scotia this evening and overnight into tomorrow. With precipitable water increasing over southwestern Nova Scotia into the 40s overnight and early tomorrow morning, there is a risk of heavy downpours.

For Friday, the trough will lie over New Brunswick and there is a possibility of moderate rain, small hail and strong wind gusts and the upper levels cool and freezing levels lower. With CAPE values above 500 J/kg and increasing shear towards 35 kts into the afternoon, some storms could form into lines or possible supercells.  A low pressure system that develops south of Nova Scotia will aid in thundershower development across central and eastern Nova Scotia and eastern Prince Edward Island towards southern Newfoundland by the evening.

Thunderstorm Outlook for TODAY

Thunderstorm Outlook for TONIGHT

Thunderstorm Outlook for TOMORROW

 

Roberta McArthur