Convective Outlook Valid for Today and Tomorrow

Regional Impacts

For Labrador today… Isolated thunderstorms giving 15-20mm locally.

NB, PEI and NS today… Low probability of near severe thunderstorms.

 

Convective Discussion

 

There is a low probability that severe or near severe thunderstorms could develop today over the gulf waters and Northumberland Straight. The dynamics are good with plenty of deep shear and weak convergence along a surface trough. It may be a struggle to break through a stable layer above 700mb until later today when it weakens however daytime heating will also be weakening. For now no severe thunderstorm alerts are expected however should longer lived cells develop they may be issued. The warmer waters this time of year may also help to feed the thunderstorms and should they develop could pose a risk to marine waters.

 

 

Thunderstorm Outlook for Day 1

 

 

Thunderstorm Outlook for Day 2

 

 

Mel Lemmon

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

 

New Brunswick…Isolated thunderstorms giving locally heavy downpours.

PEI… Chance of isolated thunderstorms late today.

Nova Scotia… A few thunderstorms are expected tonight with locally heavy downpours.

 

Convective Discussion

Despite the cloudiness, favourable dynamics and high moisture are expected to keep thunderstorms progressing though the day in NB and into NS and PEI this evening and tonight. Locally heavy downpours, exceeding 25mm are possible for some areas today and tonight.

 

Tomorrow the upper level jet and increasing wind shear may offset the weaker instability especially over the warmer Gulf and Northumberland Straight waters where there is a chance of thunderstorms.

 

Thunderstorm Outlook for Day 1

 

 

 

Thunderstorm Outlook for Day 2

 

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

Today.. No thunderstorms expected

Tomorrow.. Isolated thunderstorms with locally heavy downpours.

 

Convective Discussion

 

Not much expected today however the dynamics will improve tomorrow as the upper ridge moves away ahead of the approaching cold front. With respect to the moisture we are looking at high precipitable water values and high surface moisture. Vertical velocity could be somewhat limited but most unstable capes could be in the 500-1000 J/kg range, with low level shear above 30 knots some longer lived cells could be a concern, possible producing gusty winds and heavy downpours with local amounts exceeding 25mm/hr.

 

Thunderstorm Outlook for Day 1

 

 

Thunderstorm Outlook for Day 2

 

Convective Outlook for Weekend of Aug 28-29th

Thunderstorm Outlook for TODAY – Saturday, August 28, 2021

 

Regional Impacts

None expected at this time.

 

Convective Discussion

A strong ridge is building in from the west today, and with it is increasing atmospheric stability. Additionally, a northerly flow last night over much of the region dried out the muggy airmass. The cold front is exiting Newfoundland’s marine waters this afternoon, and there are no other forcings at play today.

 

 

 

Thunderstorm Outlook for TOMORROW – Sunday, August 29, 2021

 

Regional Impacts

None forecast.

 

Convective Discussion

Ridge still keeping atmosphere stable and dry in lower and mid levels. Invading high cloud also a deterrent.

 

 

*Forecaster: TIRONE

 

end/ASPC

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

 

Maritimes:  None today and Saturday.

NFLD/Labrador: A risk of thundershowers this afternoon and evening over central/eastern Newfoundland and southern Labrador. None on Saturday.

 

Convective Discussion

 

Just a chance of embedded thundershowers in Newfoundland today. Over southern Labrador, a few surface based thundershowers are possible this afternoon but the shear is very low so they will be short lived.

 

Thunderstorm Outlook for Day 1

 

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

 

New Brunswick:  Isolated to scattered thundershowers this afternoon and evening.  Potential severe thundershowers giving downpours, gusty winds and hail.

NS/PEI/ NFLD/Labrador: A risk of thundershowers this afternoon and evening.

 

Convective Discussion

 

A cold front will approach northern New Brunswick this afternoon. ML cape values near 1000 J/kg are expected and wind shear near 30 kts.  Freezing levels are high but decent cape exists in the hail growth zone. Dry mid layers will allow for gusty conditions. PWAT values will be near 40 mm so rainfall is a concern. The upper dynamics are supportive as well this afternoon as a strengthening diffluent trough approaches ahead of the main 250 mb jet. There is also possible rotation as the helicity values will be over 100.

 

Thunderstorm Outlook for Day 1

 

 

 

Thunderstorm Outlook for Day 2

 

 

 

Convective Outlook Valid for Today and Tomorrow

Regional Impacts (Day 1)

 

None

 

Convective Discussion (Day 1)

 

None

 

Thunderstorm Outlook for Day 1

 

 

Regional Impacts (Day 2)

 

New Brunswick:  Isolated to scattered thundershowers tomorrow afternoon and evening.  Potential severe thundershowers giving downpours, gusty winds and hail.

NS/PEI/Labrador: A risk of thundershowers tomorrow afternoon and evening.

NFLD: Nil.

 

Convective Discussion (Day 2)

 

A cold front will cross northern New Brunswick tomorrow afternoon and evening. ML cape values near 1000 J/kg are expected and wind shear near 30 kts.  Freezing levels are high but decent cape exists in the hail growth zone. Dry mid layers will allow for gusty conditions. PWAT values will be near 40 mm so rainfall is a concern. The upper dynamics are supportive as well.

 

Thunderstorm Outlook for Day 2

Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Day 1

Slight chance of thunderstorms, except some local downpours for southwest Labradors, and some possibly significant rainfall and gusty winds for western New Brunswick.

 

Convective Discussion

N-S ridge over eastern Newfoundland with a nearly vertically stacked deep trough from western Labrador to New Brunswick then extending towards Cheasapeake Bay. There are embedded lows for Labrador, New Brunswick, and near Cape Cod. As with yesterday, many of the profiles are moist adiabatic and tropical, with 40-50 mm PWATs and ample surface moisture, with surface dew points near 21 C. Shears are about 25 kts near the trough increasing to 40 for central Nova Scotia then dropping back to 24 for eastern regions.

 

For Labrador the low has a frontal trough extending east towards Mary’s Harbour, and the low will move steadily east.  There is some Cuing up near and west of the low, and some isolated thundershowers are possible. Ahead of the front there should be TCu’s possibly with a strike or two, but with some heavy downpours being the main factor.  PWATs are about 40 mm and Capes may approach 500 J/kg, but the capping inversion may have some trouble breaking.

 

For New Brunswick, especially in the west the story is similar, but with more energy and surface moisture, with energy peaking late in the afternoon  near 500-1000 J/kg, with surface dewpoints near 20 C and the main moisture axis through the center of the province. The shear is low at about 25 kts, so supercells probably won’t be an issue. The impacts will be airmass cells with heavy downpours and some gusty winds.

 

 

 

Thunderstorm Outlook for Day 2

 

Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Day 1

Rain with heavier convective downpours for the Atlantic Coast of Nova Scotia, with isolated lightning and some gusty winds. A weak area of convergence may spark up some cells for southwestern Labrador.

 

 

Convective Discussion

The main threat for today, and especially for tomorrow, is due to the influence of the remnants of Henri as it approaches and then moves through the Maritimes. Henri is a vertically stacked system up to 250 mb, within a vertically stacked trough, again up to 250 mb. There’s a frontal trough extending south then southwest of the low, and it is approaching the western Maritimes today. Moisture is good with near 22 mm dewpoints at the surface extending above 850 mb. PWATs are up to 50 mm. Also, east of the system there is a fre-frontal band  with a  low level jet extending up to 500 mb. The tephis show a roughly moist adiabatic profile ahead of the system, so not a lot of CAPE (~ 300-600 j/kg), with deep layer shear less than 25 kts. So basically local heavy downpours, some gusty winds, and maybe some lightning.

 

Highest rainfall amounts are likely for tonight into tomorrow. Late today into this evening it will start over the Atlantic Coast of Nova Scotia,  then spread north.

 

Thunderstorm Outlook for Day 2

 

Basically the same story with the rainfall propagation east. The main system will be moving into New Brunswick, with some likelihood for isolated  cells for the Long Range Mountains of Newfoundland.

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

 

Labrador…Risk of thundershowers this evening over western sections.

 

Convective Discussion

 

A trough moves in from central Quebec tonight into western Labrador, extending from a low pressure system over Hudson Bay. This trough is expected to bring in showers and a risk of thundershowers over central Quebec which may continue into this evening into western Labrador as the area is under the influence of moderate 0-6km shear and PWATs near 30 mm.

 

Tropical Storm Henri will soon be making landfall in New England or eastern Long Island, and weaken into a depression then a post-tropical storm on Monday. Outer rain bands well north and east of the centre with heavy rainfall possible will move over the Maritime southwestern marine district today and tomorrow.

 

 

Thunderstorm Outlook for Day 1 – August 22, 2021

 

 

Thunderstorm Outlook for Day 2 – August 23, 2021

 

Convective Outlook Valid for August 21st and 22nd

Thunderstorm Outlook for Day 1

 

Regional Impacts

None

 

Convective Discussion

With a ridge of high pressure dominating the area, there is no risk of severe thunderstorms today.  A trough moves in from the west Sunday night over western Labrador bringing a risk of thundershowers.

 

 

Thunderstorm Outlook for Day 2

Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Day 1

 

Some heavy downpours and local gusty winds with isolated thunderstorms, mainly  for New Brunswick  and southern Newfoundland. Otherwise noting significant expected for today and tomorrow.

 

Convective Discussion

 

The main area of interest is southern Newfoundland and New Brunswick. To the north there is too much shear (~40-60 kts)  and not enough moisture (PWATs 20 mm or less), combined with  a ridge building in from the west.

 

Currently there is a trough extending east over Newfoundland and southwest over the Maritimes from a developing weak low over the Gulf. The low will track over southern Newfoundland today and tonight. For New Brunswick there are currently some stable layers that will destabilise somewhat with the trough and daytime heating, combined with surface dewpoints between 18-22 and PWATs fairly healthy in the 35-55 mm range. There is little shear (~12-22 kts) arguing for airmass pop-ups. Farther north there is less upper support but more daytime heating. For both cases CAPEs on the order of 500 J/kg are possibly. The low shear and good moisture argue for airmass pop-ups with local heavy downpours and brief gusty winds.

 

For Newfoundland the stability this morning was higher, with the developing low hopefully destabilising aloft and giving some lift from convergence below. The moisture is a bit less with PWATS near 35 mm, but the dewpoints are only a couple of degrees cooler than the Maritimes. So the impacts should be similar, but possibly with the training along the trough-low-topography combination.

 

 

 

 

 

 

Thunderstorm Outlook for Day 2

 

Good news.

 

Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Day 1

A chance for occasional heavy showers and some wind gusts for southwestern New Brunswick. Chance of isolated thundershowers for northeastern Newfoundland.

 

Convective Discussion

Basically there is a low in the Labrador Sea with a couple of troughs extending southwest into the Maritimes. Most of Atlantic Canada is under an inversion preventing any significant lift, with the exception of New Brunswick. There is a shallow inversion combined with some afternoon destabilisation. There’s also half decent moisture, with PWATs in excess of 30 mm, and dew points in excess of 20 C for southwestern New Brunswick. Afternoon surface CAPES may be around 400-800 J/kg. However, with shear being  12-25 kts for most regions, air mass pop-ups will probably be the rule for today.

 

For Newfoundland there is a chance of a thundershower or two this afternoon, if the daytime heating is high enough.

 

 

Thunderstorm Outlook for Day 2

 

 

 

 

 

Convective Outlook Valid for August 18th and 19th

Thunderstorm Outlook for Day 1

 

Regional Impacts - Risk of isolated thunderstorms over NB bringing local heavy showers of 10 -15mm.  Risk as well over interior Labrador and interior

 

Convective Discussion

As high pressure begins to move away and higher surface moisture moves in, conditions become a bit better for thunderstorm activity today.  The atmosphere becomes a bit more unstable as a jet stream tracks into the area from the north.  CAPE values of around 500 J/kg are currently expected.  However, mid level moisture is high and wind shear values are low at around 25kts so long lived storms are not currently expected.  Local heavy showers of up to 10-15 mm is possible for parts of  New Brunswick in isolated thunderstorms especially over clear skies.  Risk of isolated non severe thundershowers as well for interior Labrador and interior Newfoundland. 

 

 

Thunderstorm Outlook for Day 2

Convective Outlook Valid for August 17th and 18th

Thunderstorm Outlook for Day 1

 

Regional Impacts - None

 

Convective Discussion

High pressure continues to dominate much of the area today bringing unfavourable conditions for thunderstorm formation.

 

 

Thunderstorm Outlook for Day 2

Regional Impacts – Risk of thundershowers for New Brunswick, western PEI and interior Labrador.  Local heavy showers of up to 10 mm possible.

 

Convective Discussion

As the high pressure begins to move away, conditions become a bit better for thunderstorm activity.  Higher moisture levels begin to move into New Brunswick and the atmosphere becomes a bit more unstable as a jet stream tracks into the area.  CAPE values of 500 J/kg are currently expected.  Wind shear values are low at around 25kts so long lived storms are not currently expected.  Local heavy showers of up to 10 mm is possible for parts of  New Brunswick.  Risk of non severe thundershowers as well for interior Labrador.

 

Convective Outlook Valid for August 16th and 17th

Thunderstorm Outlook for Day 1

 

Regional Impacts

Western Labrador: isolated thundershowers possible giving 5 - 10 mm.

 

Convective Discussion

Much of the area is under high pressure today  with relatively dry conditions so no thunderstorm activity is expected except over western Labrador where a trough will move into the area this afternoon possibly bringing a few thundershowers with 5-10 mm possible.  Severe thunderstorms not expected as the trough will be weakening as it moves over the area.

 

Thunderstorm Outlook for Day 2

 

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

For Labrador…isolated thunderstorms possible locally 20mm possible.

For Newfoundland…Scattered thunderstorms possible with heavy downpours and gusty winds.

 

Convective Discussion

 

The focus has moved from the Maritimes to Newfoundland today with precipitable water values near 50mm and most unstable cape values ~1000 j/kg. Thunderstorm structure should be similar to what New Brunswick saw yesterday with several reports of nearly 25mm in less than an hour although unreported amounts were likely higher. There is some potential for cluster or multicell storms to form giving decent gusts, however it may be a challenge to trigger the stronger storms but it does seem that the cloud is breaking up over the island and solar insolation could increase through the afternoon.

 

 

 

 

Mel Lemmon

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

New Brunswick…Isolated or possibly organised thunderstorms with potentially heavy downpours and strong wind gusts.

 

Nova Scotia and PEI… Isolated thunderstorms with potentially heavy downpours.

 

Newfoundland and Labrador… Isolated thunderstorms with potentially heavy downpours and gusty winds for southwest Labrador.

 

Convective Discussion

We will begin to see some movement on the very warm air mass that has bee situated over the region for the last several days as a cold front slowly moved over Quebec today. A broad area of showers and thunderstorms will slowly move over New Brunswick and Labrador today, making its way over Nova Scotia and Newfoundland tonight. The dynamics for severe weather should be better today than it has been for the last few days  with about 30 knots of deep shear over New Brunswick and Labrador making the likelihood of longer lived thunderstorms much higher. Convergence should be sufficient today near the trough line to initiate thunderstorms which are already occurring in Maine and Quebec. Severe Thunderstorm watches could potentially be issued this afternoon should some deeper convection begin to form over the area.

 

Thunderstorm Outlook for Day 1

 

 

Thunderstorm Outlook for Day 2

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

 

New Brunswick…Heavy downpours possible this afternoon and evening over eastern coastal regions.

Nova Scotia… Heavy downpours possible this afternoon and evening.

Prince Edward Island… An isolated thundershower is possible this afternoon.

Labrador… Heavy downpours possible this afternoon and evening over south/central sections.

Newfoundland…Heavy downpours are possible early this afternoon and evening over southeastern sections. An isolated thundershower is possible as well this afternoon over western sections.

 

Convective Discussion

 

A very warm and humid air mass continues over the Atlantic region today as a trough of low pressure over southern Quebec extending into New England slowly makes its way further east. A weak trough moved through overnight and is still providing some elevated convection this morning over the Gulf of St. Lawrence and eastern Maritime marine areas with heavy showers moving into the Burin Peninsula of Newfoundland. Stratus and fog over the Maritimes and western Newfoundland continues to clear this morning, making way for temperatures to rise into the low 30s for many areas this afternoon. There lacks a strong trigger as the main trough remains further west still, but some coastal convergence could provide enough lift for some single or multicellular storms to fire this afternoon. There is ample moisture with PWATs approaching 50 mm in Nova Scotia but shear remains weak and freezing levels are near 1500ft, therefore the main threat should be being lightning and heavy downpours, especially if any training occurs. Isolated thundershowers are also possible this afternoon over western Newfoundland given lift over the higher terrain, as well as in central/southern Labrador.

 

Thunderstorm Outlook for Day 1 – August 13, 2021

 

 

Thunderstorm Outlook for Day 2 – August 14, 2021

 

A sharper cold front will move into New Brunswick tomorrow afternoon. Ahead and along this front, storms are likely with the potential to be severe.

 

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

New Brunswick…Heavy downpours in thunderstorms, small hail late this afternoon.

Nova Scotia…Heavy downpours possible this afternoon.

PEI… Heavy downpours possible this afternoon.

Labrador…A chance of thunderstorms this afternoon.

 

Convective Discussion

 

Heavy Rain/downpours will be the story today and tomorrow as the moisture and instability are the main driving mechanisms. Overall the dynamics will remain rather weak… but due to the high moisture content , with precipatable water values near 50mm, even weaker updraft storms will produce decent rainfall amounts.  There is some early convection over southern New Brunswick but after that passes around noon convection may be suppressed until late this afternoon or early this evening. In general slow moving storms could produce locally 25mm but there is some potential for multicell clusters later today that could bring higher amounts and 2cm hail for central and northwestern New Brunswick.  We will be on the look out for local convergence over Nova Scotia along the spine which could cause some local enhancement, tomorrow this will almost definitely be the place to look.

 

The dynamics or shear is somewhat better over western Labrador today although the potential thunderstorms could be somewhat limited by convective inhibition at a multiple layers, however should stronger updrafts be present surface gusts will be more likely in the thunderstorms.

 

Thunderstorm Outlook for Day 1

 

 

Thunderstorm Outlook for Day 2

 

 

Mel Lemmon

Convective Outlook for Today, and Tomorrow

Thunderstorm Outlook valid for Today – WED, Aug 11, 2021

 

Regional Impacts

Isolated severe thunderstorms are possible over western portions of Labrador today. Elsewhere, non-severe thunderstorms are possible, lasting into overnight hours for areas in NS.

 

Convective Discussion

An advancing long-wave trof will trigger thunderstorms in central and northern Quebec and into adjacent Atlantic regions. These storms will mainly be rainmakers. Shear is okay at 15-20Kts, and Pwats remain near 35-45mm. Convection into tomorrow morning across SW NS is likely to be more elevated in nature producing a lot of lightning.

 

 

 

Thunderstorm Outlook valid for Tomorrow – THURS, Aug 12, 2021

 

Regional Impacts

Isolated severe thunderstorms are possible in New Brunswick. Scattered non-severe thunderstorms are also forecast across many areas of the Maritimes.

 

Convective Discussion

An invading hot and humid tropical airmass is bringing with it a lot of potential energy. With dew points above 20C and sfc temps near 29C (or higher), large amounts of CAPE can be realized from the surface. It won’t take much as a trigger to get things going…..a shortwave impulse or even a sea breeze convergence line. There is ~25Kts  of 0-6k shear, and Pwats in the RDPS are near 55mm. Model suggested 500-700mb deltT is 19 in places tomorrow. This was realized across the Ohio valley and New York State yesterday afternoon.

 

 

Convective Outlook for Today, and Tomorrow

Thunderstorm Outlook for TODAY – Tuesday, Aug 10, 2021

 

Regional Impacts

Isolated severe thunderstorms are possible over northern NB this afternoon and into this evening.

 

Convective Discussion

The limiting factor today remains to be shear. The sfc moisture is present for good buoyancy, but any storm that develops will have minimal forward motion, and unable to slant its structure significantly. And so, the biggest hazard is heavy rainfall and a downburst gust of wind.

 

 

Thunderstorm Outlook for TOMORROW – Wednesday, Aug 11, 2021

 

Regional Impacts

Isolated severe thunderstorms are possible over western portions of Labrador. Elsewhere, non-severe thunderstorms are possible.

 

Convective Discussion

An advancing trof will trigger thunderstorms in Quebec and into adjacent Atlantic regions. Greatest hazard with these storms is heavy rainfall. Shear is slightly better at 10-20Kts, and Pwats remain near 35-45mm.

 

Convective Outlook for Today, and Tomorrow

Thunderstorm Outlook for TODAY – Monday, Aug 9, 2021

Regional Impacts

Isolated non-severe thundershowers are possible this afternoon and early evening over extreme NW New Brunswick.

 

Convective Discussion

A weak approaching boundary from Quebec may be enough to trigger just enough lift to excite a TCU or 2 this afternoon in the northern terrain. Only hazard with a cell if it can form would be lightning. With dew points of only 11, this airmass is not muggy enough to see any impactful rainfall.

 

 

 

Thunderstorm Outlook for TOMORROW – Tuesday, Aug 10, 2021

 

Regional Impacts

Isolated severe thunderstorms are possible across the northern tier of New Brunswick with heavy downpours and gusty winds being the main threats. Elsewhere, isolated non-severe cells may spark up if we get partial clearing of the cloud deck/fog/mist.

 

Convective Discussion

Shear depicted in the RDPS is enough to get multi-cell training storms, as well as profiles look elevated enough to cause gusty winds to near 90km/h. Heavy rain will be the biggest concern if a storm lacks forward motion (25-50mm/h). This thunderstorm risk will be re-assessed by the ASPC on Tues AM.

 

Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for today – Friday August 6

 

Regional Impacts

Isolated thunderstorms with brief downpours over Eastern NS and NF. A slight risk of hail over west-central NB. Non-severe storms over sourthern Lab.

 

Convective Discussion

A moisture laden air mass continues to prevail over southern NB, NS and NF, precipitable water estimates from this morning sounding range from 40 to 50 mm. At the surface the frontal band extends from South Shore of NS to PEI to central NF. Embedded ACC/ACB continue to produce isolated pockets of heavier showers. Some surface based convection is beginning to develop with the help of daytime heating, and some upper support (upper SWly jet from NB to southern Lab). 500 mb heights have been falling in the past 12 hours by about 3 or 4 dam which indicates cooler temperatures advancing aloft. Tephigram modification suggest cape values of about 500 J/kg and EL between 250-330. Good enough for pulse storms in the shaded area of the map. The Gagetown sounding is slightly more interesting, with moderate deep layer shear values, and surface-based cape values between 700-900 J/kg. Equilibrium level would still be well below the tropopause (below 380-420).

 

 

Thunderstorm Outlook for tomorrow - Saturday August 7^th

 

There is a risk of non-severe afternoon thunderstorms over portion of the region.

 

Thunderstorm outlook for today

 

Thunderstorm Outlook for Day 1 – Thursday Aug 5

 

Regional Impacts

Rain at times heavy with embedded thundershowers expected today and tonight over southern NB and western and central NS.

 

Convective Discussion

Elevated convection with initiation from between 900 and 850 mb is likely today and tonight over these regions. This convection is embedded within a broad area of rain. There is a lot of low level moisture within this airmass to support ongoing isolated embedded thundershowers. The risk in this situation is heavy rainfall, not necessarily directly due to thundershower activity. Strong winds and hail are not a threat.

 

 

 

Thunderstorm Outlook for Day 2 – Friday, Aug 6.

 

Regional Impacts

Most of New Brunswick and Labrador.

 

Convective Discussion

Labrador: Low level moisture is sufficient, with model temps being low to mid 20s and dew points around 15. There is cooling aloft, sufficient to give CAPEs around 1000 J/kg. Shear values are near 30 knots. Heavy downpours, small hail and gusty winds are possible.

 

New Brunswick: Isolated single cell pulse thundershowers are possible. However, there will be cap between 750 and 700 mb that may be difficult to break. Shear is forecast to be low (0-6 km shear only 20 knots.). Brief downpours are possible. No severe convection expected.

 

 

Thunderstorm outlook for today

Thunderstorm Outlook for Day 1 – Wednesday Aug 4

 

Regional Impacts

Isolated non-severe thunderstorms over central NB this afternoon and evening.

 

Convective Discussion

Generally not a great set up for thunderstorms across the Region. Over NB, there is descent shear, about 35-40 knots, but the sounding is weakly capped above 700 mb. If lift goes above the cap, the upper level buoyancy is very weak. Most of the CAPE would be below 700 mb. Elsewhere, throughout Atlantic Canada, the soundings are very stable and dry. No thundershower activity is expected.

 

 

Thunderstorm Outlook for Day 2 – Thursday Aug 5

 

Regional Impacts

Nova Scotia: slight risk of non severe thunderstorms in western Nova Scotia.

 

Convective Discussion

A warm front will move into the southern Maritimes on Thursday morning and will continue moving northeastward. Instability associated with the front and saturation with low level dew points of 15 to 20 deg could give convective initiation

from around 850 mb. A warm, moist airmass behind the front Thursday afternoon and evening could continue to give isolated thundershowers. The area currently shown for convection may be expanded north and east with the next convective outlook.