Convective Outlook Valid for Today and Tomorrow

Regional Impacts

Labrador… Slight risk of weak thunderstorms over eastern areas.

Elsewhere… No thunderstorms expected today.

 

Convective Discussion

Dynamics look somewhat favourable for the development of weak thunderstorms early this afternoon for eastern Labrador, however the conditions become less favourable later this afternoon so the conditions will not likely build through the day. If thunderstorms do develop the will likely not persist very long and be fairly quick moving. No significant rain nor severe weather is expected with these storms should they develop.

 

For tomorrow potential area of thunderstorm activity will likely expand but the likelihood is still quite low with a relatively dry airmass that will make convection difficult to get going. It is possible that some coastal convergence could be sufficient to get enough lift to initiate thunderstorms. However with weak updraft potential no significant convection is expected.

 

ML

 

Thunderstorm Outlook for Day 1

 

 

Thunderstorm Outlook for Day 2

Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Today

 

Regional Impacts

Isolated thunderstorms across parts of the Atlantic provinces today. Some of these storms could become more robust over northern NF and SE Lab.. the main threat are strong gusts possibly exceeding 70 km/h and heavier showers at a rate of 10-15mm/h.

 

Convective Discussion

At 12z the 500mb low was located over the mid-coast of Labrador with a thermal trough extending to the St. Lawrence Valley. This feature will slowly slide eastward today and along with a surface trough will become the focus for isolated pulse type thunderstorms during the afternoon especially over N portions of NF. All soundings across the region (except NS) were indicating a convective temperature ranging from 21 to 25 which should be reached fairly easily despite the limited sunshine.. with a couple of moisture axis maintaining Td’s above 16.. the result is MLCAPE between 500 to 800 J/kg. Under these conditions widespread Cu/TCU field is expected to grow during the afternoon and some of these cumuliform clouds should reach the next stage and evolve into CB’s with tops extending to 9 km, well below the tropopause which is lowering. Precipitable water analysis is showing 25-30 mm throughout the area, and as much as 35-40 over NS where stratiform cloud and embedded TCU’s are exiting.

 

 

Thunderstorm Outlook for Sunday

 

 

Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Today

 

Regional Impacts

Potentially robust thunderstorms approaching severe limits over northernmost NB.. main treat is localised damaging wind gusts and some hail

Isolated elevated CB/ACB’s giving brief heavier showers over eastern Gulf of St. Lawrence, western NF/Lab

 

Convective Discussion

A frontal wave near Gaspé will continue to move NEwd giving widespread rain from eastern NS to Labrador, some elevated convection is associated with this feature and it should continue throughout the day. CLDN did indicate a few strikes over Nrn NS earlier and it continues over the Lower Quebec North Shore.

The main forecast problem today will be what happens in the wake of this system.. convective initiation is expected from the Beauce region to northern Maine.. a slightly cyclonic jet core is approaching from the Eastern Townships and is providing some extra support on the left-side exit which sits over northern NB/Chaleur region. Satellite imagery is showing the airmass transition currently occurring over northern Maine and western NB, although this new brand of air is more dry it has been historically quite buoyant. Convective temperature around 25 or 26 C, combined with dewpoints of 15 to 17 is enough to push SBCAPE above 500 or 600 J/kg. The drying in the mid-levels will certainly increase the downburst potential with modelled DCAPE values exceeding 700 J/kg. Some of the longer-lived storms could organize into a squall line but the deep layer shears are fairly high (45kt).

 

 

 

Thunderstorm Outlook for Tonight

 

Decaying thunderstorms over the Gulf of St. Lawrence region

 

 

 

Thunderstorm Outlook for Saturday

 

Surface / upper trough extending south from Labrador and a somewhat unstable airmass over Atlantic Canada

 

 

ECCC Convective Outlook Valid for THURS - THURS NIGHT - FRI

Thunderstorm Outlook valid for JULY 28^th:

 

Regional Impacts

Isolated non-severe thundershowers are possible across portions of NB today as an advancing feature approaches out of the Great Lakes basin.

 

Convective Discussion

The forcing for the weather today stems back across Ontario and Michigan. A northern branch of a jet streak is pushing into the Montreal area this afternoon, and a southern branch near New York City. Ahead of this system, the atmosphere is slowly destabilizing. Over most of the Maritimes, a weak thermal cap at 700mb still exists, and a significant dry layer from 700-500mb. This is the delineating feature of the day. A low pressure system on the Grand banks continues to produce strong thunderstorms over those marine areas today, near the surface trof. TS risk shifts further east in the overnight hours tonight with showers.

 

Thunderstorm Outlook for Day 1

 

Thunderstorm Outlook for Night 1

 

Thunderstorm Outlook valid for JULY 29^th:

 

Forecast for Friday is widespread showers/fog/drizzle/and risk of TS embedded for NS and PEI along advancing frontal feature. Sfc moisture is expected to converge well ahead of the trof’s arrival. With proper jet support, storms in central NB may become severe. Gusty winds can be expected as the storm mode seems to favour squalls/multi-cell dynamics. However, the catch is that shear may actually be too high. Values near 50kTs could rip storms apart before they can grow to mature heights. This will be monitored extensively in next 24hrs. 0-6k shear values near Montreal at 18z today will be important forecaster information.

 

Thunderstorm Outlook for Day 2

 

Forecaster: TIRONE

ECCC Convective Outlook Valid for Today, and Tomorrow

Thunderstorm Outlook valid for JULY 27^th:

 

Regional Impacts

Isolated non-severe thunderstorms along an advancing frontal feature across the Avalon early today. Additional isolated non-severe thundershowers are possible in the interior of Nfld as air mass modifies slowly.

 

Convective Discussion

The main forcing is the broadly sweeping cold front that continues to trundle eastwards. Directly behind the front remains slightly unstable so in clear skies a pop up shower is possible later this afternoon. Dynamics are not favourable for any significant hazards other than lightning. Across Labrador, there is a strong thermal cap at 700mb and it is quite dry in mi-levels. Low-cloud will also create quite a hindrance. Across the Maritimes, this 700mb cap is even stronger as can be easily deciphered on Caribou and Yarmouth’s soundings this AM. Stable, sunny, relatively dry conditions are the Wednesday forecast here. No TS risk tonight.

 

Thunderstorm Outlook for Day 1

 

Thunderstorm Outlook for Night 1

 

Thunderstorm Outlook valid for JULY 28^th:

 

Northern tier of New Brunswick, largely terrain driven, will de-stabilize slightly adding the risk of late afternoon pop-up showers and thunder. Severe hazard criteria is not expected to be met by these single-cell storms. Skinny CAPE values at best are near 300J/kg, with minimal shear in the background environment.

 

Thunderstorm Outlook for Day 2

 

Forecaster: TIRONE

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

 

NL: isolated thunderstorms with locally heavy downpours and strong winds

Labrador: isolated to scattered thunderstorms with locally heavy downpours and small hail.

Southern and eastern marine regions: strong winds and heavy downpours

 

Convective Discussion

 

A low pressure system over western Labrador will slowly move eastward today and weaken, while a cold front that moved off of Nova Scotia this morning will continue eastward across the marine slope waters and north across Newfoundland today. This front is currently being maintained  over the slope waters by favourable upper dynamics the assist of a strong 250 mb jet axis over Nova Scotia and strong bulk shear of 45KT. The upper levels beyond 500 mb are warm based on the Stephenville sounding but that should degrade some with a cold trough this afternoon depending on breaks in cloud cover to increase surface based heating to further destabilize the air mass. Thunderstorms currently over southern portions of Newfoundland could continue or reignite this afternoon.

 

Some convection is expected for southern Labrador south along a elongated trough axis where the thickness ridge will move to the northeast. Some clearing this morning will also help to increase instability in the area where CAPE values are indicating near 1000J/kg. Storm are expected to be non-severe multi-cell type but with little bulk shear, there is the possibility of heavy downpours and small hail given lowering freezing levels.

 

Thunderstorm Outlook for Day 1

 

 

Thunderstorm Outlook for Day 1 Night

 

Thunderstorm Outlook for Day 2

 

Weak short wave trough moves into Newfoundland. Any surface based heating over inland areas could trigger some non-severe convection that will move to the northeast during the day. Although precipitable water will be lower than today, with values still near 30 mm and CAPE values near 500 J/kg, there could be some local heavy downpours and brief wind gusts.

 

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

 

NB: scattered strong to severe storms capable of producing strong winds, hail, heavy downpours and a possible funnel cloud or tornado

PEI: isolated to scattered strong storms capable of producing strong winds, hail and heavy downpours

NS: isolated thunderstorms giving heavy downpours

NL: isolated non-severe thunderstorms over western regions

LAB: isolated non-severe thunderstorms over southwestern regions

 

Convective Discussion

 

Active weather is expected for most of the Maritimes today and tonight. An upper low pressure system over central Quebec slowly pushes eastward today while a trailing cold front pushes from southern Quebec into New England. The front then moves into New Brunswick this afternoon and into Prince Edward Island and Nova Scotia in the overnight period.

 

Most of New Brunswick remains in cloud this morning with some showers moving through this morning but some breaks in the clouds are now occurring over eastern regions. Temperatures in central to southern New Brunswick are expected to be in the low 30s and dewpoints near 20C. A cyclonic 250mb jet will track slowly southeast into New Brunswick with a strong southwesterly jet of 35KT at 850 mb. With MUCAPE values around 2000 J/kg and strong southwesterly 0-6km shear of 40KT combined with low level shear (SRH around 100) and upper divergence, storms that develop will be able to be maintained this afternoon and possibly continue into the evening as elevated convection over PEI and Nova Scotia. The main storm motion will initially be supercells with a mean motion of storm to the northeast at 35KT A possible tornado cannot be ruled out, mainly over central to eastern New Brunswick given similar dynamics to yesterday which saw some splitting supercells over northwestern New Brunswick with generally an eastward motion. Supercell composities for this afternoon are indicating values of 2 to 3 with significant tornado parameters of 1 to 2. Towards the late afternoon, squall or bowlines with strong wind gusts will likely be the main storm threat as storms begin to lose energy but elevated convection may continue into the overnight period with heavy rainfall.  

 

Over Newfoundland, a warm frontal features continues to track northward and convection that occurred early this morning will weaken. Isolated convection this afternoon from the trough over central Quebec will move into southwestern Labrador this afternoon and weaken by this evening.

 

 

Thunderstorm Outlook for Day 1

 

Thunderstorm Outlook for Day 1 Night

 

Thunderstorm Outlook for Day 2

 

Upper low moves into Labrador for Tuesday where area of southern Labrador will see scattered showers and thundershowers. The cold front over the Maritime waters will continue to weaken but there could be some isolated thundershowers remaining through the Slope waters, Grand Banks and eastern Newfoundland. A warm cap at 700 mb may inhibit surfaced based convection.

 

 

 

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

 

SE Labrador/NE Newfoundland: Scattered strong to severe thunderstorms expected this afternoon and evening for central and eastern Newfoundland, and southeastern Labrador. Main hazards will be lightning, gusty winds, hail and locally heavy downpours.

 

New Brunswick: Scattered strong to severe thunderstorms possible late this afternoon and evening for Northwestern New Brunswick. Main hazards will be lightning, gusty winds, hail and locally heavy downpours.

 

 

Convective Discussion

 

Several areas of concern for this afternoon/evening for the Atlantic region with particular focus for eastern Newfoundland, Labrador and northwestern New Brunswick where a very hot and humid air mass resides over the region.

 

For Newfoundland and Labrador, a strong short wave tracking into eastern Labrador extending into Newfoundland will help enhance convection today. Interior parts of central to eastern Newfoundland will see high temperatures near 30C and dewpoints between 17-19C. MUCAPE values near 2000 J/kg, 0-6k shear at 35kts and precipitable water above 30 mm combined with increasingly favourable upper dynamics will help maintain strong storms that develop. Strong multicell type storms are most likely but there could be the risk of supercells.  A funnel cloud or short lived tornado cannot be completely ruled out, however the probability of that remains very low at this time. Storms will weaken in the evening as they head out over much cooler ocean waters and become de-coupled from the surface. There is a bit of a low-level capping inversion to break based on the 12Z Goose Bay sounding, limiting surface based convection over southeastern Labrador, however, a 500mb cold trough over the southeastern regions could kick off some elevated convection this afternoon. Dynamics are a bit weaker but heavy rain is possible.

 

For New Brunswick, an approaching trough currently over SW Ontario will move eastward into southern Quebec today and to the Maine/New Brunswick border this evening/overnight. 12Z KCAR sounding suggest ample energy given temperatures near 30C and high dewpoints near 19C, MUCAPE values reaching 2000 J/kg and strong 0-6km shear near 40KT. There is also the enhancement of being in the left exit region of a 100KT 250mb jet. This will promote severe limits on convection especially over Maine this afternoon which will move northeastward into parts of western New Brunswick later this afternoon into this evening. With a dryer 500-700mb, strong winds associated with organized multicell or bowlines will be the biggest threat.  

 

Thunderstorm Outlook for Today (Sunday July 24^th)

 

Thunderstorm Outlook for Day 1 night (Monday July 25^th)

 

 

For Monday, isolated thunderstorms are expected for western Labrador, parts of Newfoundland and possible storm to severe storms for New Brunswick/Prince Edward Island. A cold front will move through New Brunswick in the afternoon. With ample energy still in place over much of the region, the risk of severe thunderstorms continues further into New Brunswick then into Nova Scotia in the evening/overnight.

 

Thunderstorm Outlook for Day 2 (Monday July 25^th)

ECCC Convective Outlook Valid for Today, and Tomorrow

Thunderstorm Outlook for SATURDAY:

 

Regional Impacts

Isolated non-severe thunderstorms possible this afternoon in many different areas of the Atlantic provinces, due to various weak forcing features. An approaching trof in northern Quebec may produce a marginally severe thunderstorm this afternoon in extreme western Labrador – greatest hazards being heavy rain and lightning.

 

Convective Discussion

Various features will create weak and short-lived thunderstorms today. A decaying trof over northern Nfld, a weakening low centre with associated occluded fronts near James Bay, and a weak sea breeze convergence zone over interior NS are the easiest to pick out from this morning’s air mass analysis. The ongoing heat wave across the Maritimes is keeping mid levels quite dry. Surface dew points are over 19 already, bringing Humidex values near 40 in Cape Breton this morning. Across NS/NB/PEI the expected weak thermal trof-ing at 850 to 500 is also occurring. Hence a shower that struggles to build will do just that, struggle.

 

Thunderstorm Outlook for Day 1 - JULY 23, 2022

 

Thunderstorm Outlook for SUNDAY:

 

Regional Impacts

Scattered non-severe thunderstorms possible tomorrow afternoon in parts of New Brunswick and Labrador. Isolated severe thunderstorms are possible in central Newfoundland including Gander and vicinity. Main hazards will be gusty winds, small hail, and frequent lightning. Rainfall rates could exceed 30mm/h in local pockets of heaviest downpours.

 

Convective Discussion

The focus of this discussion will be central Newfoundland. A strong short wave setup will destabilize a very hot and humid air mass currently established over the interior mid-day Sunday. As such, MU CAPE values are very high at over 2000J/kg, and ML CAPE is near 1300. ML CAPE is the most important here as we need the dew points to remain over 16 to have heights climb to severe levels. 0-6k shear is at 40kts. Storm type will be Supercell in this environment, and storm motion will be Bunkers RM. This has the potential to become a complex weather situation if the ingredients all line up at the right time of day. A funnel cloud or short lived tornado cannot be completely ruled out, however the probability of that remains very low at this time. Hail and strong winds have been included on the Day2 graphic in Area B to express the severe weather risk to the public. This weather threat may be upgraded to HIGH in future forecast issues. Storms will weaken in the evening as they head out over much cooler ocean waters and become de-coupled from the surface. Elevated lightning (from 700mb and above) could continue along the coast late into the evening.

 

Thunderstorm Outlook for Day 2 - JULY 24, 2022

 

Forecaster: TIRONE.

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

 

Today

Southern LAB/western NL: scattered elevated thunderstorms possible.

NS: slight risk of an isolated thunderstorm for eastern mainland.

 

Tonight

Southeastern LAB/NL: isolated thunderstorms possible

 

Saturday

Western LAB/northern NB/northeastern NL: isolated thunderstorms possible.

 

Convective Discussion

A much quieter day compared to the severe weather in NW NB yesterday. Some ongoing elevated thunderstorms associated with the upper trough moving over the GLFSTLAWR will likely be on and off this afternoon and into tonight as it slopwly progresses eastward over southern LAB and NL. Only some locally heavy downpours are expected but could be some gusty winds as well in some of the stronger cells. That same trough will likely give some isolated stuff overnight and into Saturday morning for parts of Newfoundland. And a slight risk of a thunderstorm this afternoon for eastern mainland NS close to that 500mb trough.

 

On Saturday a new 500 mb trough/short wave will approach from Quebec increasing the chance for thunderstorms across western LAB and far northwestern NB. Also a slight chance for an isolated cell for northeastern NL close to that first departing trough.

 

Thunderstorm Outlook for Day 1 afternoon/evening

 

Thunderstorm Outlook for Day 1 night/Day 2 morning

 

Thunderstorm Outlook for Day 2 afternoon/evening

 

Jeremy

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

 

Today

NB: scattered strong to severe thunderstorms expected this afternoon and into the evening across NW portions of the province.

 

Tonight/Friday morning

NB/Western NS/PEI: isolated thunderstorms possible.

Central LAB: isolated thundershowers possible.

 

Friday afternoon/evening

MRTMS/central LAB/western NL: isolated to scattered thunderstorms possible. Some of the cells could be strong.

 

Convective Discussion

It appears prime for possible strong to severe thunderstorms across northwestern NB this afternoon and evening. From top down: an approaching 250 jet maxima (right quadrant) and associated divergence by mid to late afternoon approaching northern ME and NW NB; an approaching 500mb trough currently over QC and a strong 50-50 knot jet just ahead of it; good dry air in the mid levels as is currently evident in conventional SAT PIX; Very moist air from 850mb to the surface and a strong LLJ of around 30 knots (~925mb) which was seen upstream in the 12Z Albany sounding. The really interesting area that would have been nice to have a sample from was missed, but adjusting the Grey and Albany soundings produces 1000-2000 j/kg SBCAPE, with 0-6 km effective westerly shear up around 50 knots and decent 0-3 km srh helicty of just shy of 200. That area will be advecting northeastward coinciding with the approaching trough (both at the surface and 500 mb), which in most circumstances spells trouble. Given the observed data and higher resolution model support we expect winds to be the main issue, however owning to the strong updrafts in the deeper cells hail is also a potential. PWAT is around 40, but storms should be moving fast enough to not produce a significant amount of rain (unless there is slight back-building or training of storms). In line with the Storm Prediction Center there is also a slight risk of seeing a tornadic supercell.

 

In summary: Strong to severe storms producing wind gusts of 60-100 km/h and hail up to 2 cm for northwestern counties in NB possible this afternoon and evening.

 

Thunderstorm Outlook for Day 1

 

Thunderstorm Outlook for tonight and Friday morning

 

Thunderstorm Outlook for Day 2 afternoon and evening

 

Jeremy

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

 

Today

NL: isolated thundershowers giving locally heavy downpours.

 

Tonight

No thunderstorms forecast.

 

Thursday

NB: scattered thundershowers with risk of lightning, heavy rain and strong winds.

 

Convective Discussion

An upper trough with a cut-off surface low pressure system will slowly weaken as it tracks northeastward over Newfoundland today. Any remaining convection today will be near the low centre where cooling aloft along with surface based heating will help provide instability for isolated thundershowers. With low CAPE values of 200-400 J/kg and not much bulk shear, the main threat will be enhancement to rainfall where precipitable water remains in the low 30s, however, low level winds will maintain quick movement of anything that develops.  

 

An approaching hot and humid air mass moves into the Maritimes on Thursday. Ahead of an upper trough that will be moving through southern Quebec/New England during the day will trigger organized convection that will likely move into extreme northwestern New Brunswick later in the day. There looks to be ample energy with forecasted CAPE values of over 1000 J/kg with sufficient 0-6km shear as well as low level shear to support organized bowlines and possible supercells ahead of the trough. The uncertainty at the moment is the timing of this feature as it progresses into New Brunswick as instability will diminish into the evening/overnight period.

 

Thunderstorm Outlook for Day 1

 

Thunderstorm Outlook for Day 1 night/Day 2 morning

 

Thunderstorm Outlook for Day 2

 

 

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

 

Today

NL/NS/PEI: isolated thundershowers giving locally heavy downpours.

Labrador: isolated to scattered thunderstorms possibly giving strong winds and small hail in the west.

NB: scattered thunderstorms possibly giving strong winds, hail and heavy rainfall.

 

Tonight

NL: isolated thundershowers giving locally heavy downpours

 

Wednesday

NL: isolated thundershowers.

 

Convective Discussion

None of the upstream TEPHIs are going to give the air mass moving into western NB any justice since the prime location is east of Maniwaki and north of Grey ME. But a fairly sharp and digging upper trough (and associated surface front) is evident in WV imagery this morning over Quebec and is already initiating some storms. The 12Z KCAR profile shows about 40 knots of westerly shear but is moist given the precipitation at the time of the launch. Things dry rapidly in the mid-levels not far upstream and, combined with MLCAPE up around 1000 J/Kg will generate some strong to possibly severe cells this afternoon and into the evening. Freezing levels are pretty high but will be lowering and since the CAPE is fairly “fat” some of the stronger updrafts could support some 1-2 cm hail. PWATs are high with ample low level moisture and TDs around 20 will give a threat to torrential rainfall as well. A thickness ridge currently moving across the MRTMS will enter NL this afternoon with perhaps an isolated embedded thundershower associated with it. There could be an isolated strong to possibly severe cell that may impact the Churchill Falls and Lab West/Wabush areas this afternoon giving strong winds and small hail. There is already convection upstream over Quebec so will also have to keep an eye on things up in the Big Land.

 

Thunderstorm Outlook for Day 1

 

Thunderstorm Outlook for Day 1 night/Day 2 morning

 

Thunderstorm Outlook for Day 2 afternoon

 

Jeremy

Convective Outlook Valid for Today and Tomorrow

Regional Impacts:

 

Today

NL: Wind gusts 70-90 km/h, Hail ~1 cm, rainfall 5-15mm, scattered lightning.

Labrador: Hail 0-1 and scattered to frequent lightning

NS: isolated lightning

 

Tonight

NB: rainfall 15-25mm, isolated lightning.

PEI: rainfall 15-25mm, isolated lightning.

NS: rainfall 15-25mm, isolated lightning.

Labrador: isolated lightning.

 

Tuesday

Labrador: wind gusts 70-90 km/h, Hail 1-2cm, scattered lightning.

NB: wind gusts ~ 70 km/h, Hail 0-1 cm, scattered lightning.

NS: isolated lightning.

PEI: isolated lightning.

NL: isolated lightning.

 

Convective Discussion:

Cold upper low over Labrador with a broad upper trough extending southeastwards towards central Newfoundland will provide the focus for the majority todays thunderstorms. Instability over central to eastern Labrador is quiet plentiful with MLCAPES generally in the range of 400-600 J/kg. Cold temperatures aloft will allow from plenty of lift through the IC zone enabling charge separation giving rise to frequent to scattered lightning, these same temperature profiles will support small hail, however it will be size limited given the skinny nature of the CAPE seen in the profiles. Bulk shears are fairly weak on  the order of 10-20kts, which given the cold vertically stacked low may allow for  funnel clouds. In NL instabilities are much anticipated to be more robust this afternoon with T/Td of 25/14 yielding approximately 1000 j/kg of CAPE, bulk shears are also higher given the proximity to a mid tropospheric jet (20-35 kts). Hence cells may be able to sustain themselves in a more organized manner, any supercells should they develop will deviate to the southeast of the mean wind with a speed of ~20kts. The primary hazard with these cells would be strong wind gusts. In the Maritimes a  lack of a good trigger beyond daytime heating and capping at ~5000ft will be hard to overcome, the best chance for some isolated lightning appears to be inland in mainland NS.

 

Tonight: Heavy showers with elevated convection will spread across the region as a low moves northeastward from New England. Primary hazard will be high rainfall rates as deep moistures is adverted northward with this system rom the southern states… PWATs are expected to approach 50mm by daybreak in southern NB.

 

Tomorrow: General instability and lightning looks to continue near and along the track of the low as it moves towards NL. Behind this system enough clearing may take place to allow for decent instability to rebuild in western NB later in the afternoon, strong linear shear and fast storm motion would present a wind gust hazard should storms develop. In Western Labrador a vigorous shortwave near James bay should trigger convection fairly early in the afternoon, given MLCAPES in excess of 1000 J/kg possible strong wind gusts and hail look possible with storms here, despite lower than ideal bulk shears (15-25kts) .

 

Thunderstorm outlook for today:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Thunderstorm outlook for tonight

 

 

Thunderstorm outlook for Tuesday:

 

Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Today

 

Regional Impacts

Isolated thunderstorms are possible for NB, western and northern NS – some of these storms could approach severe limits,

Scattered thunderstorms western NF, central and eastern Labrador – some of these storms could approach severe limits over the lower Churchill valley.

 

Convective Discussion

The main feature this morning is a surface low pressure system over the Smallwood reservoir with a trough extending southward to the Gulf of St. Lawrence. Both Stephenville and Goose Bay soundings support energy in the order of about 500 J/kg off the surface, and there is plenty of energy in the hail growth zone for small hail withing some of the stronger clusters. A weak zonal upper jet from Maine to the east coast of NF will provide some extra support for stronger cells , the caribou soundings hints at deep layer shear values in excess of 35kt and the possibility of longer-lasting cells with cape values in excess of 1000 J/kg which could produce 2+cm hail and damaging wind gusts. Over NS the upper winds are somewhat lighter but the airmass is much more buoyant with CB tops to 8-9 km. The airmass is becoming more rich with moisture content with CB cloud top possibly exploding to 12-14 km.

 

 

 

Thunderstorm Outlook for Monday

Increasingly humid airmass advancing from New England late in the day.

Convective Outlook valid for Today, and Tomorrow

ECCC Thunderstorm Outlook valid for July 16^th, 2022.

 

Regional Impacts

Isolated non-severe thundershowers are possible in northern NB, and western Labrador as a disturbance in Quebec affects the region.

 

Convective Discussion

With a warm frontal approach, a few showers may spark lightning across the northern tier of New Brunswick and western Labrador this afternoon. Moisture in this airmass is far less than yesterday across the Maritimes, and ML CAPE at best is only near 300 J/kg. Storms do not have good upper dynamics so they are expected to be short lived in nature. With the return of the Maniwaki sounding, confidence in model initialization has increased.

 

Thunderstorm Outlook for Day 1 - SATURDAY

 

Thunderstorm Outlook for Day 2 - SUNDAY

*broad risk of thunderstorms across most areas as an upper trof can trigger convection in a growingly humid airmass. If heat warning criteria is reached, a few cells in the Annapolis valley could push severe limits briefly.  

 

Forecaster: TIRONE

Convective Outlook valid for Today, and Tomorrow

ECCC Thunderstorm Outlook valid for July 15^th, 2022.

 

Regional Impacts

Broadly, scattered non-severe thunderstorms are possible over many regions of Atlantic Canada this afternoon and evening. Additionally, isolated severe thunderstorms are possible in areas of Nova Scotia and eastern portions of New Brunswick.

 

Convective Discussion

As sticky humidity continues across the Maritimes today, the risk for thunderstorms follows suit. With dew points expected to remain near 17C, and some good pockets of direct solar heating, things should fire off this afternoon. Upper features are in place to sustain storms today especially near Truro and Bathurst to severe limits. Hail, gusty winds, and heavy rainfall can all be expected under a strong cell. Lapse rates of 500-700mb are similar to yesterday across Maine and NB (16-18). ML CAPE values are a bit better than yesterday near 1200J/kg, and 0-6k shear is 35-40Kts. Development of storms will be monitored closely and watches may be required. Storm motion today is expected to be E-ly at 15kts. A supercell will head SE at similar speeds should it develop. Additionally, the sweeping cold trof from the decaying Labrador low will spark a few thundershowers in marine waters and some areas of Newfoundland. The dynamics at play in these regions are much weaker.

 

Thunderstorm Outlook for Day 1

 

Thunderstorm Outlook for Day 2

*slight risk of thundershowers across northern tier of NB, and extreme western Labrador as upper trof continues to affect central Quebec.

 

Forecaster: TIRONE

Convective Outlook valid for Today, and Tomorrow

Thunderstorm Outlook valid for July 14^th, 2022.

 

Regional Impacts

Isolated non-severe thunderstorms are forecast today for areas in Labrador, western New Brunswick, and offshore over the slope waters.

 

Convective Discussion

Thundershowers are possible near the low centre in the Labrador sea and over the Big Land. In NB, thundershowers are also possible north of Fredericton this afternoon in an area of clearing already apparent on satellite. Dew points are moist enough to trigger surface convection, with CAPE values 500-700J/kg. The second part of the story is tonight as a shortwave trof swings into the humid airmass from the west near midnight. This is the dynamic feature that will cause nocturnal thunderstorms over the province, and parts of PEI. Pwats are near 30mm, and 0-6k shear values near 30kTs. The biggest hazard is pockets of heavy rain and lightning.

 

Thunderstorm Outlook for Day 1

 

Thunderstorm Outlook for Night 1

 

Thunderstorm Outlook for Day 2

*Thundershowers still possible along broad frontal feature stemming from Labrador low.

 

Forecaster: TIRONE

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

For Nova Scotia… there is a low likelihood that thunderstorms will occur however thunderstorms that do develop have the potential to produce small hail, heavy downpours and strong wind gusts. Primarily over central and eastern parts of the province.

For Labrador… some embedded thunderstorms are possible.

 

Convective Discussion

 

Once again the favourable dynamics will be the primary driver of organised thunderstorm activity today. Overall Cape will be modest with values between 500 and 1000 j/kg but wind shear values are fairly significant with over 50 knots of deep shear. The initiation of thunderstorms will depend largely on the timing of the cooling at 850 and depth of the moisture available near the surface. Thunderstorms are most likely to develop along the spine of NS and track northeastward, affecting areas of central through to eastern and possibly northern NS. These storms, should they develop are likely produce small to moderate hail and heavy downpours. Given the dry mid levels and significant DCAPES there is a good chance for strong surface wind gusts with these thunderstorms. Watches may be issued if some convective initiation triggers deep convection.

 

ML

 

Thunderstorm Outlook for Day 1

 

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

For Labrador… some embedded thunderstorms could lead to locally heavier rainfall this evening.

For New Brunswick… potentially severe thunderstorms could affect northern New Brunswick late this afternoon. Small hail with strong wind gusts and potentially heavy downpours can be expected.

 

Convective Discussion

We are looking at very favourable dynamics for the development of severe thunderstorms later this afternoon. Aloft the 250 mb jet will be in a good position for enhanced vertical motion later today with the exit region over northern New Brunswick. The windshear through to mid-levels is favourable for the development of supercells or possibly bow echoes, but it is still possible that a QLCS( Quasi Linear Convective System) could form west and move over New Brunswick later today. One remaining concern if the amount of available low level moisture and CAPE, but with the approaching upper trough the atmosphere will destabilize at some point today. Needless to say a large variety of possible outcomes, but in all likelihood severe winds will be the main concern should thunderstorms develop. Watches may be issued a little later today once we have some stronger indication of the clouds dissipating and more insolation occurring upstream of our area of concern.

 

ML

 

 

Thunderstorm Outlook for Day 1

 

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for Day 2