Convective Outlook Valid for June 30th, 2019

 

Convective Discussion

 

Today we are looking at a few different areas of convective activity, an area of low pressure slowly moving south of Nova Scotia and surface based convection for this afternoon over interior areas of Newfoundland and Labrador.

 

An upper level low over southern Quebec will be slowly drifting southeastward today and align with a surface low pressure system which is developing southwest of Nova Scotia and will drift eastward this afternoon. Elevated thunderstorms have already been firing up over southern Maine and have slowly drifted towards the western marine areas and western Nova Scotia. There has also been quite a bit of convection over the extreme southern slope waters of the Maritime marine district associated with the low’s warm front. That general area of convection is expected to round up the eastern and northern side of the low affecting parts of eastern Nova Scotia this evening and overnight. The main threat with this convection today and overnight will be heavy downpours. There is not much wind shear aloft to drive convection along that develops and precipitable water values are ranging from 30-35mm. There could be some localized areas of 30-50 mm mainly over extreme western Nova Scotia and parts of Cape Breton. There is also some upper level support being on the left exit of a strong 250 mb jet and a cold pool at 500mb over central Quebec tracking to the southeast. Some late afternoon convection is also possible over northwestern New Brunswick associated with the upper level low, especially if they get some clearing this afternoon.

 

For Newfoundland and Labrador, the main trigger for thunderstorms this afternoon will be daytime heating as well as slight cooling in the upper levels enhancing instability. Goose Bay sounding required a convective temperature of 20C with 300 J/kg of CAPE. There is very little shear however so only non-severe pulse type storms are expected west of Goose Bay giving brief gusts and locally heavy downpours. Similarly over Newfoundland, the main risk for any convection will be over interior areas where maximum daytime heating is likely with temperatures expected to reach 23C, combined with slight troughing in the upper levels.

 

Regional Impacts

 

Maritimes…

Locally heavy downpours over western Nova Scotia and Cape Breton. Isolated downpours and brief gusts over northwestern New Brunswick.

 

Newfoundland and Labrador…

Risk of locally heavy downpours and brief gusts over central Newfoundland and central/western Labrador.

 

 

 

Roberta McArthur

 

Convective Outlook Valid for June 29th, 2019

Convective Discussion

Modifying the 12Z Caribou sounding to the convective temperature of 24 deg gives 830 J/kg of CAPE. There is 35 knots of 0-6 km shear. The shear is unidirectional and is all above 3 km. At Caribou, the shear from 0-3 km is very low so based on this sounding, squall lines are unlikely. There is a strong 80 knot jet in the upper levels over the southern Maritimes as indicated by the 12Z sounding at Yarmouth. However, over NS and PEI, CAPEs are low so severity is not expected. The prog sounding for 18Z over western Labrador indicates that with daytime heating to the forecast high of 19 deg, convective initiation would give up to 800 J/kg of CAPE. Shear over western Labrador is low, so only pulse storms are expected if they form.


 As is often the case, the challenge today is the amount of sunshine this afternoon to trigger the convection. At 11 am there is still a lot of cloud cover over the areas outlined as potential for convection. For NB where there is a slight risk of conditions approaching or meeting severity, the most likely scenario is for strong storms to form over srn QC and then advecting late this afternoon or this evening over the province.

Regional Impacts

 

Maritimes…

Risk of thundershowers over most of NB, mainland NS, slight risk PEI. Possible wind gusts and small hail over NB

Newfoundland and Labrador…

Risk western Labrador.

 

Stephen Hatt
Forecaster
ASPC 

Convective Outlook Valid for June 28th, 2019

Convective Discussion

Convection today will be surface based with generally low CAPE’s. Highest CAPE will be northwestern New Brunswick this afternoon where up 700 J/kg is possible. Elsewhere CAPEs are in the 200-400 J/kg range. The dew points are generally in the 12-16 deg range and upstream dew points are similar. 0-6 km shear is low and in the 20-25 knot range. There is a strong 250 mb jet (60-80 knots) extending from southwestern Quebec to southwestern Nova Scotia. Otherwise mid and upper level winds are quite light over Atlantic Canada (30 knots or less). 500 mb temperatures are fairly uniform across eastern Canada at about -15 deg, so little change in stability aloft is expected.

Regional Impacts
Maritimes…
Risk of thundershowers over most of NB and western NS.

Newfoundland and Labrador…
Slight risk extreme western Labrador.

Stephen Hatt
Forecaster
ASPC

Convective Outlook Valid for June 28th, 2019 Day 2 Outlook

Convective Discussion for Friday, June 28, Day 2 Outlook

The upper trough that is digging over Quebec will move eastward tonight and will over the Maritimes on Friday. Mid level temperatures on Friday will drop a few degrees and more insolation is expected. In addition, an upper level jet over southern Ontario will move eastward over the western Maritimes on Friday. Heavy downpours of rain, small hail and wind gusts are possible

Regional Impacts

Maritimes…

New Brunswick, western Nova Scotia.

Newfoundland and Labrador…

None expected.

Stephen Hatt

Forecaster

ASPC

Convective Outlook Valid for June 27th, 2019

Convective Discussion

Conditions are generally unfavourable for convection over Atlanta Canada today. However, there is lots of instability and dynamics over the St. Lawrence River this morning that will slowly advect eastward. Over this region, there is a moist tongue of dew points in excess of 16 deg and warm temperatures of 20 deg or higher. There is an east-west 250 jet over southern Ontario and a north-south 250 jet extending from western Maine into eastern Quebec. There is also a digging 500 mb trough with diffluence ahead of it. There is a possibility that some cells with high precipitable water could creep into extreme northwestern New Brunswick later today giving heavy downpours.

Regional Impacts

Maritimes…
Western New Brunswick.

Newfoundland and Labrador…
Slight risk western Labrador.

Stephen Hatt

Forecaster

ASPC

Convective Outlook Valid for June 26, 2019

Convective discussion

Basically there is a risk of non-severe thundershowers for the western Maritimes. Currently there is a nearly stationary low near James Bay with a frontal trough extending from it southeast over Maine. This trough is nearly stationary with little dynamic upper support. There is also very little moisture west of the main feature. There is some weak detstabilisation in the mid levels, with a 500 mb thermal trough well east of the 700 mb trough thisch continues down to 850 mb. There is also some moisture near and below 850, with a moist tongue over northern Maine extending toward  Northwest New Brunswick, and mid level clouds are moving away to the east. If and when the stratus breaks up there may be enough heating to produce some thundershowers.

In the Gulf of Maine a nearly stationary broad weak low is triggering some  embedded which  moving towards southwestern  Nova Scotia. There cellc should not go much east of the tri-county area.

For Thursday, indications are for a slow progression into Labrador and across the western Maritimes.

Regional Impacts

Nova Scotia: Slight risk for this afternoon into this evening and overnight for non-severe thundershowers.

New Brunswick: Slight risk for evening and overnight for non-severe thundershowers.

Newfoundland, Labrador, and Prince Edward Island: None for today and tonight. Overnight into early Thursday morning there is a slight risk for western Labrador.

Doug Mercer

Convective Outlook Valid for June 25th, 2019

Convective Discussion

A quasi-stationary low pressure system just off the coast of Labrador will continue to weaken today. Clouds and scattered showers will persist over Newfoundland/Labrador. Very low dew points in the wake of this system will continue to suppress any possible convection.

Regional Impacts

Maritimes…

None.

Newfoundland and Labrador…

None.

Andy Firth

Convective Outlook Valid for June 24th, 2019

Convective Discussion

A quasi-stationary low pressure system just off the coast of Labrador will gradually weaken over the next two days. Clouds and showers are expected over Newfoundland/Labrador. Very low dew points in the wake of this system will suppress any possible convection.

Regional Impacts

Maritimes…

None.

Newfoundland and Labrador…

None.

Andy Firth

Convective Outlook for Atlantic Canada Valid for June 23rd, 2019

Convective Discussion

 

The Atlantic Region is still under the influence of what is now a nearly vertically stacked low pressure system over Northern Newfoundland. In terms of the thunderstorm activity there is still a chance of embedded thunderstorms near the main band of heavier rain wrapping around the low. These are will be more pronounced in the trough ahead of this system, which will be near the Labrador coast today. Any thunderstorms triggered here will initiate well aloft and could generate some locally heavier downpours.

 

Across the Maritimes dry air and weak dynamics greatly reduce the potential for any severe weather. However, there is a very slight chance that weak thundershowers could develop over central and northern Nova Scotia as a weak trough passes through picking up a bit of moisture from the Northumberland Strait. No significant impacts are expected although there is a chance of a heavier shower likely with 10-15mm of rain with pea sized hail.

 

 

 

Convective Outlook for Atlantic Canada Valid for Saturday June 22nd 2019

Convective Discussion

 

There is a low probability that thunderstorms could develop over three main areas today, which are  extreme western Labrador, southwestern New Brunswick and Newfoundland.

Over Newfoundland the heaviest area of Total Precipitable Water (TPW) has swung past the Island and weakened somewhat. With TPW values in the mid 30mm range heavier rainfall in embedded convection is possible but the heaviest rainfall will likely be just north of the Island or possible over the Northern Peninsula.

 

For extreme western Labrador a band of showers could impact the area this evening as a weak through moves through. Updrafts with this feature will be very weak, however there may be just enough depth to these storms to produce some lightning.

 

Finally across western New Brunswick we are looking at TCU’s and CB’s forming early this afternoon, the  more intense  cells will likely remain over Maine.  However,  some could impact SW New Brunswick as well. CAPE values will generally be as high as 500 J/kg and locally heavier downpours are possible in the 15mm to 20mm range should they affect NB. Some stronger gusty winds and small hail could be generated as well.  However,  warning level criteria are not expected.

 

 

 

 

Mel Lemmon

Convective Outlook Valid for June 21, 2019

 

Convective Discussion

 

The main feature today is an intensifying low pressure system southwest of Nova Scotia which is expected to  track just south along the Atlantic coast of Nova Scotia today and stall east of Cape Breton Island Saturday morning. Heavy rain with embedded thunderstorms has moved and are continuing to affect parts of southern Nova Scotia this morning as the warm front continues to push eastward. Embedded thunderstorms are expected to continue mainly for Nova Scotia and southern marine waters for today and overnight, leading to locally heavier rainfall amounts (Kejimkujik has already received over 50 mm since rain began early this morning). The Yarmouth sounding verifies this with precipitable water values of 45 mm. Rainfall warnings are in effect for Southern New Brunswick, most of mainland Nova Scotia, and Prince Edward Island where 50 to 75 mm is forecast. These rainfall warnings also extend into western and central Newfoundland as heavy rain fills in for them this evening. Convection however, is expected to remain offshore south of Newfoundland.  

 

There is also an area of instability associated with an upper level low spinning over western Labrador. Convection has already initiated south of Churchill Falls where areas remained more cloud free this morning. An area over northwestern Labrador where some positive vorticity advection will help to trigger some afternoon convection.

 

 

Regional Impacts

 

Nova Scotia: Embedded thunderstorms will give lightning and periods of enhanced heavy rainfall today.

 

New Brunswick and Prince Edward Island: Mainly heavy downpours today for southern New Brunswick and Prince Edward Island.

 

Newfoundland and Labrador: Lightning and brief downpours for parts of western Labrador. Heavy downpours for marine areas south of Newfoundland overnight and into Saturday morning.

 

 

Roberta McArthur

 

Convective Outlook Valid for June 20th, 2019

 

 

Convective Discussion

 

For today, we have a broad trough extending from the Great Lakes northeastward toward central Labrador.  Within this trough there are a couple of upper level features over central Quebec and central Labrador. Convective temperatures are not expected to be reached, especially given the amount of cloud cover currently in the region but there will be a decrease in temperatures aloft, leading to further instability along with the upper level features as a trigger to initiate some non-severe convection this afternoon and evening. Areas south of Labrador City to Goose Bay over southern Labrador into North Shore Quebec could see CAPE values close to 500 J/kg and with 0-6km shear values nearing 40 kts, some thunderstorms may organize further into lines or weak bow echos where  locally heavy downpours and brief gusts are possible.

 

Meanwhile, a low pressure system south of the Great Lakes will progress northeastward over New England today. The system is then expected to intensify offshore near Cape Cod overnight into Friday morning and track over Nova Scotia Friday afternoon. This system will likely have embedded convection overnight along the warm front which will push into New Brunswick this evening and into Friday morning for Prince Edward Island and western Nova Scotia. Heavy rainfall will be the biggest threat with this system as it taps into tropical moisture streaming northward from the southern Gulf stream. Rainfall warnings have been issued for southern New Brunswick and northern Nova Scotia and will likely be extended eastward this afternoon.

 

 

Regional Impacts

 

Newfoundland and Labrador: Lightning, locally heavy downpours and brief gusts for parts of central and western Labrador.

 

 

Maritimes: Embedded thunderstorms will give lightning and enhanced heavy rainfall beginning late this afternoon and evening over northern New Brunswick and overnight and into Friday morning for western Nova Scotia and Prince Edward Island.

 

 

Roberta McArthur

 

Convective Outlook Valid for June 19th, 2019

 

Convective Discussion

A strong upper level zonal flow exists today over Atlantic Canada south of an upper low over Labrador. There is very little vorticity advection or thermal advection today. 0-6 km shear is moderate at 30 to 35 knots over NB and NF. There is lack of low level moisture which should keep convection in the non-severe category.

 

Regional Impacts

Maritimes…

Scattered T-shwrs over northern and central NB likely

 

Newfoundland and Labrador…

Risk of non-severe thundershowers over central NF and SW Lab.

 

Steve

 

Convective Outlook Valid for June 18th, 2019

Convective Discussion

An upper low is anchored over Labrador this afternoon. System cloud exists over coastal and western Labrador. In the relative cloud free area in between, daytime heating to 18 degrees will give TCU and a possible CB.

Regional Impacts

Maritimes…

None.

Newfoundland and Labrador…

Risk of non-severe thundershowers over central Labrador this afternoon.

Andy Firth

Convective Outlook Valid for June 17th, 2019

Convective Discussion

Clearing skies are expected today in the wake of a low pressure system exiting Nova Scotia. Dew points will remain in the mid teens this afternoon over areas of Nova Scotia and eastern Prince Edward Island. This combined with some local convergence and afternoon temperatures near 25 could lead to a risk of non-severe thundershowers. Dry bulb temperature of 25 and a dew point temperature of 15 will break the cap and give CAPE values near 200 J/kg.  So the necessary values required to break the cap are also at the maximum of the range of temperatures expected for today. Over Labrador a risk of thundershowers are expected south of the forecast areas.

Regional Impacts

Maritimes…

Risk of non-severe thundershowers over northern and eastern Nova Scotia. Also for eastern Prince Edward Island.

Newfoundland and Labrador…

Risk of non-severe thundershowers over extreme southwestern Labrador.

Andy Firth

Convective Outlook Valid for June 16th, 2019

Convective Discussion

There are two features over Atlantic Canada today/tonight. An approaching low pressure system over central Quebec will give a risk of surface based thundershowers over extreme western Labrador this afternoon/evening. There is currently some relatively cloud free skies ahead of the low which will aid in the convection. The second feature is a warm front which will track just south of western Nova Scotia tonight. A risk of elevated thundershowers are possible over marine areas south of Nova Scotia.

 

Regional Impacts

Maritimes…

None.

 

Newfoundland and Labrador…

A risk of thundershowers over extreme western Labrador this afternoon/evening.

 

 

 

Andy Firth

Lead Meteorologist

Atlantic Storm Prediction Centre, MSC
Environment Canada / Government of Canada

3rd Floor, 45 Alderney Drive

Dartmouth NS B2Y 2N6

andrew.firth@canada.ca / Tel: 902-426-7779 / Fax: 902-426-4873

 

Andy Firth

Premier Météorologue

Le Centre de prévision des intempéries de l'Atlantique, SMC
Environnement Canada / Gouvernement du Canada
3e étage, 45 Alderney Drive

Dartmouth NS B2Y 2N6

andrew.firth@canada.ca / Tél: 902-426-7779 / Télécopieur: 902-426-4873

 

Convective Outlook Valid for June 15th, 2019

Convective Discussion

There are two features over Atlantic Canada today. An approaching low pressure system over central Quebec will give a risk of surface based thundershowers over extreme western Labrador this afternoon. There is currently some relatively cloud free skies well ahead of the low which will aid in the convection. The second feature is an elevated area of warm air (TROWL)  which is moving across western Newfoundland. A very slight risk of thundershowers are possible there. It is such a slight risk that it is not noted in the graphic below.

 

Regional Impacts

Maritimes…

None.

 

Newfoundland and Labrador…

A very slight risk of elevated thundershowers over southwestern Newfoundland this afternoon/evening.

A risk of thundershowers over extreme western Labrador this afternoon.

 

 

 

Andy Firth

Lead Meteorologist

Atlantic Storm Prediction Centre, MSC
Environment Canada / Government of Canada

3rd Floor, 45 Alderney Drive

Dartmouth NS B2Y 2N6

andrew.firth@canada.ca / Tel: 902-426-7779 / Fax: 902-426-4873

 

Andy Firth

Premier Météorologue

Le Centre de prévision des intempéries de l'Atlantique, SMC
Environnement Canada / Gouvernement du Canada
3e étage, 45 Alderney Drive

Dartmouth NS B2Y 2N6

andrew.firth@canada.ca / Tél: 902-426-7779 / Télécopieur: 902-426-4873

 

Convective Outlook Valid for June 14th, 2019

Convective Discussion

A low pressure system over the southern Maritimes will continue to produce rain over western NF&Lab today. The inversion along  the frontal boundary will generate severe wind gusts to the lee of  the Cape Breton Highlands and the mountain range on the west coast of Newfoundland.

Further west, a surface cold front extending southward from a low over western Quebec will reach the lower St. Lawrence/Maine/New Brunswick later today. A 30 kt southwesterly low-level jet ahead of this feature is pushing enough moisture over northern NB to sustain some instability this afternoon once the low cloud/fog dissipates. This will take a few more hours since the lowest 5 000 feet is saturated (CAR sounding is showing this). However once the cloud cover breaks, instability will increase and a number of ingredients will be coming together to support the development of strong pulse Storms. The deep layer shears calculated from this mornings upper wind soundings are probably too strong to support long-lived bowing lines, however the presentation of the CAR hodograph suggests veering winds with heights, and if this pattern was maintained after convective initiation this afternoon formation of a tornado might not be out of the question. Having said this, as the air mass becomes depleted of the higher water content in the mid-levels - downdraft CAPE values between 400 to 600 J/kg will evolve, at that point the Storms could potentially produce damaging wind gusts in excess of 90 km/h. This appear to be the main threat for today.

Regional Impacts

New Brunswick: Over Northern regions this afternoon, strong pulse type thunderstorms capable of producing brief downpours, small hail and damaging winds. Storm motion will be eastward at 50+ km/h. Hourly rainfall rates of 15-25mm/h are also likely during brief downpours.

Isolated thunderstorms from central Maine may propagate over the mid and lower Saint John River Valley this evening.

Elsewhere across the rest of the Atlantic provinces, no thunderstorms are expected.

Jean-Marc

Convective Outlook Valid for Thursday June 13th, 2019

Convective Discussion

A large low pressure system currently over the Great Lakes will move eastward today and tonight. A strong southwesterly jet will spread a very moist air mass with embedded thundershowers over the Maritimes tonight. The area of rain will spread northward to reach Western Labrador on Friday. Over the rest of Newfoundland and Labrador tranquil conditions are expected.

A cold front will approach Northern New Brunswick Friday giving a risk of afternoon thunderstorms.

Regional Impacts

Nova Scotia: Hourly rainfall rates of 15mm/h producing enhanced runoff over western region. Rainfall amounts of 20 to 40mm with the highest amounts along the South Shore.

New Brunswick: Hourly rainfall rates of 20mm/h or more producing enhanced runoff over the Fundy Region. Rainfall amounts of 20 to 40mm with the highest amounts over Grand Manan Island.

Jean-Marc Couturier

Convective Outlook Valid for June 11, 2019

 

 

Convective Discussion: There is a deep dry ridge over the Maritimes and Labrador moving east today. Behind it there is a deep trough extending from east of Hudson Bay south to New England, with an embedded weak low south of Long Island, New York. The only areas with a chance of convection are western Nova Scotia and New Brunswick, and it should be non-severe, except for the possibility of training.

 

The weak low will move just south of Nova Scotia this evening, giving some extra moisture.  There will also be midlevel destabilisation, partially due to cooling  aloft in the wake of the 500 mb thermal ridge currently over western Nova Scotia and New Brunswick moving out ahead of the 850-700mb thermal ridge just west of the Maritimes.. The moisture will mainly help Nova Scotia and southern New Brunswick get enough energy for possible thundershowers this afternoon into this evening.. For west to northwest New Brunswick, moisture will be less, but the deep upper trough, a weak left entrance region from an associated jet approaching the northwest of the province, and some PVA and indications of lift from 700 mb upwards, again gives a possibility of thundershowers.

 

 

Regional Impacts:

 

Newfoundland and Labrador: No significant convective weather expected.

 

Prince Edward Island: No significant convective weather expected.

 

New Brunswick: A chance of thundershowers this afternoon into this evening over western parts of the province. If they happen, expects local heavy rain, and gusty winds.

 

Nova Scotia: A chance of thundershowers this afternoon over parts of the southwestern mainland.. If they happen, expects local heavy rain, with a lesser risk of  gusty winds.

 

Marine Areas: Non-severe thundershowers this afternoon into this evening over southwestern Maritimes waters.

 

Doug Mercer

Lead Meteorologist

Atlantic Storm Prediction Centre

Meteorological Service of Canada

45 Alderney Drive, Dartmouth

Nova Scotia, B2Y 2N6

Doug.mercer@canada.ca

Office: (902) 426-9200

 

Premier Météorologue
Centre de prévision des intempéries de la région de l'atlantique

Service météorologique du Canada

45 promenade Alderney, Dartmouth

Nouvelle-Écosse, B2Y 2N6

Doug.mercer@canada.ca

Bureau: (902) 426-9200

Cell: (902) 403-7951

 

Convective Outlook for Atlantic Canada Valid for June 10th, 2019

 

Convective Discussion

 

Another quiet day across the region as we remain on the cold side of a large ridge of high pressure. The atmosphere is stable through a significant layer and with the very limited low level moisture no deep convection is expected.

 

Regional Impacts

 

None expected

 

 

Mel Lemmon

 

 

 

Convective Outlook Valid for June 9th, 2019

Convective Discussion:

Upper low at 500mb will continue to move eastward to the Grand Banks later today. The St John’s west sounding is indicating some mid-level instability which is producing weak shower activity over eastern portions of the island. In the cold pool, the weakening available energy is extending to 500mb where temperatures are around -25 to -30. Given these conditions,  there is a slight risk of an isolated CB/ACB east of the island during the next few hours.  

An upper ridge over western Quebec will continue to build over the rest of the Atlantic provinces maintaining fair weather conditions through Monday.  

Regional Impacts:

Newfoundland and  Labrador: No thunderstorms expected.

Prince Edward Island: No thunderstorms expected.

Nova Scotia: No thunderstorms expected.

New Brunswick: No thunderstorms expected.

Jean-Marc

Convective Outlook Valid for June 8th, 2019

Convective Discussion:

The focus for surface-based convection will be over eastern Newfoundland this afternoon…

A convergence line at the surface currently advancing over central parts of the island will be the main forcing mechanism. The airmass ahead of the line is moisture limited (dewpoint values below 10 and precip. Water around 15mm), however modifying the Stephenville sounding for a worst-case scenario (20,9) gives surface-based CAPE in the order of 400-450 J/kg. This would be enough for isolated thunderstorms to form. The freezing level is down to 7 000 ft, and the distribution of the area of CAPE above it indicates the possibility of hail - the size of pellets. The storm motion for any isolated cells that form would be eastward at 40 km/h, these fast moving storm would limit the amount of rain produced over a locality, and finally  the gust potential is 70 km/h.       

For offshore waters,  isolated thunderstorms are possible over the southern Grand Banks, upper support include a 100+ kt southwesterly jet, PVA and cold air advection along a surface front.

Regional Impacts:

Newfoundland and  Labrador: Isolated non-severe thunderstorms over eastern areas.

Prince Edward Island: No thunderstorms expected.

Nova Scotia: No thunderstorms expected.

New Brunswick: No thunderstorms expected.

Jean-Marc Couturier

Convective Outlook Valid for June 7, 2019

 

Convective Discussion:

 

A broad upper trough over Quebec is rotating down towards New Brunswick this afternoon. This may cause weak thundershowers, as there is some upper dynamic support However, the  lower airmass is very dry, with 850 mb dewpoints near or below zero, and surface dewpoints generally less than 5 C over New Brunswick, Maine, and northwest towards the trough.  For Nova Scotia, moisture levels are higher, with dewpoints near 10-13 C, and with afternoon highs into the low 20’s inland. There will also be some midlevel destatbilisation from cold advection ahead of the upper trough.

 

For offshore waters especially for the southeaster grand Banks, upper support and  PVA ahead of an approaching cold front should give a few elevated thundershowers.  thundershowers

 

Regional Impacts:

 

Newfoundland and  Labrador: No significant chance for  thundershowers.

Prince Edward Island: No significant chance for  thundershowers.

Nova Scotia: Chance of non-severe thundershowers this afternoon into early this evening.

New Brunswick: Slight chance of non-severe thundershowers this afternoon into  this evening.

Marine regions: Chance of non-severe thundershowers.

 

 

Doug Mercer

Lead Meteorologist

Atlantic Storm Prediction Centre

Meteorological Service of Canada

45 Alderney Drive, Dartmouth

Nova Scotia, B2Y 2N6

Doug.mercer@canada.ca

Office: (902) 426-9200

 

Premier Météorologue
Centre de prévision des intempéries de la région de l'atlantique

Service météorologique du Canada

45 promenade Alderney, Dartmouth

Nouvelle-Écosse, B2Y 2N6

Doug.mercer@canada.ca

Bureau: (902) 426-9200

Cell: (902) 403-7951

 

Convective Outlook Valid for June 6th, 2019

Convective Discussion

A weak low pressure system with an associated tropical moisture feed will move across Nova Scotia today. Rain at times heavy is occurring ahead of this feature. Cloudiness will limit daytime and any severe weather threat.

 

Regional Impacts

Maritimes…

A risk of non-severe thunderstorms over southwestern sections. Synoptic rainfall warnings of 50 mm in 24 hours are in place for parts of Nova Scotia. Severe rainfall warning criteria of 25 mm in 1 hour is not expected to be met.

 

Newfoundland and Labrador…

Significant rainfall but no warnings currently in place.

 

 

 

Andy Firth

Lead Meteorologist

Atlantic Storm Prediction Centre, MSC
Environment Canada / Government of Canada

3rd Floor, 45 Alderney Drive

Dartmouth NS B2Y 2N6

andrew.firth@canada.ca / Tel: 902-426-7779 / Fax: 902-426-4873

 

Andy Firth

Premier Météorologue

Le Centre de prévision des intempéries de l'Atlantique, SMC
Environnement Canada / Gouvernement du Canada
3e étage, 45 Alderney Drive

Dartmouth NS B2Y 2N6

andrew.firth@canada.ca / Tél: 902-426-7779 / Télécopieur: 902-426-4873

 

Convective Outlook Valid for June 5th, 2019

Convective Discussion

Satellite images are showing multiple bands of convective clouds ahead of an advancing upper low located just west of Labrador. The instability is limited to the low and mid levels for the time being. A cyclonic southwesterly upper level jet over western Newfoundland is supporting isolated TCU/CB’s east of Stephenville, and with the advancing cold air aloft the mid-level lapse rates are expected to favorable for continued development of isolated cells over central and eastern NF. The moisture available in this airmass is limited so rainfall amounts should remain low.

 

 

Regional Impacts

Newfoundland and Labrador…

Isolated non-severe thunderstorms are expected this afternoon over much of Newfoundland and Southeastern Labrador

The main threat ahead of these isolated clusters would be gusts of around 70 km/h.

 

Maritimes…

No thunderstorms expected

 

 

Jean-Marc Couturier

 

Forecaster / Meteorological Service of Canada

Environment and Climate Change Canada / Government of Canada

Jeanmarc.couturier@canada.ca

 

Prévisionniste / Service météorologique du Canada

Environnement et Changement climatique Canada / Gouvernement du Canada

Jeanmarc.couturier@canada.ca

 

Convective Outlook Valid for June 4th, 2019

 

Convective Discussion

 

Not much on the go today. A weakening frontal trough affecting some offshore waters and NL will give rise to a slight risk of an embedded TSRA today. OTWZ a weak upper trough will give some ISOL TCU to NB this afternoon. KCAR has a freezing level of 4,300 ft…so would not be surprised if there are some IP mixed in with some of the heavier showers.

 

Regional Impacts

 

Newfoundland: slight risk of an embedded TSRA across the SE.

Elsewhere: nil

 

Jeremy

Convective Outlook Valid for June 3 2019

 

 

 

Convective Discussion

A cold front associated with a deep low over southern Quebec will move into New Brunswick this afternoon, and an associated trough moving into  Nova Scotia will cross the province by overnight tonight. As the associated  trough approaches Newfoundland, it  may re-initiate convection over southwestern Newfoundland later today into tonight. Meanwhile a warm front moving north over Newfoundland today has triggered a few thundershowers along the South Coast, which should end this afternoon.

 

For the Maritimes the moisture is low, with surface dewpoints in the 5-10 C range, and a strong dry intrusion is approaching from the southwest along the front towards New Brunswick. The 0-6 km shear near the frontal jet is about 90 kt, and the 0-3 km shear is near 50 kts, which given the low moisture may shear off any convection. Over Nova Scotia the moisture is a little better, and CAPE’s may approach 300 J/kg if the inversion breaks, but the fast upper flow is moving things along fast enough to reduce local rainfall rates. For Newfoundland moisture is higher, with precipitable  water amounts near 30 mm, which may go higher later today. 0-6 km shear is in the 40-50 kt range, but will diminish from west to east as a southerly jet moves east along the south coast. As the trough moving across Nova Scotia approaches, there may be a second bout, again with high shear, but with a bit more moisture than for the Maritimes. In general, rainfall amounts should remain below warning levels unless there is training, and wind gusts should stay below warning levels due to relatively low CAPEs.

 

Regional Impacts

 

Newfoundland: A few non-severe thundershowers in the east tapering off this afternoon. In the west a second batch of thundershowers beginning late this afternoon into this evening and persisting into the overnight period.

Labrador: no impacts expected.

New Brunswick: Non-severe thunderstorms this afternoon into this evening.

Nova Scotia: Non-severe thunderstorms mainly along the Atlantic coast. These thunderstorms will move east across the province, and will pass east of the mainland this evening and for Cape Breton by Wednesday morning.

Prince Edward Island: Nothing severe expected.

 

Doug Mercer

Lead Meteorologist

Atlantic Storm Prediction Centre

Meteorological Service of Canada

45 Alderney Drive, Dartmouth

Nova Scotia, B2Y 2N6

Doug.mercer@canada.ca

Office: (902) 426-9200

 

Premier Météorologue
Centre de prévision des intempéries de la région de l'atlantique

Service météorologique du Canada

45 promenade Alderney, Dartmouth

Nouvelle-Écosse, B2Y 2N6

Doug.mercer@canada.ca

Bureau: (902) 426-9200

Cell: (902) 403-7951