Convective Outlook Valid for Today, Tonight, and Tomorrow

Regional Impacts

NS: Isolated thundershowers possible this afternoon across mainland NS, locally heavy downpours of 10-20 mm. Chance of an isolated thunderstorm over the Cape Breton Highlands early this afternoon; 1-2 cm hail, 70-90 km/h wind gusts, and locally heavy downpours of 25-50 mm.

NB: Isolated thundershowers possible today, locally heavy downpours of 10-20 mm.

PEI: Isolated thunderstorm possible over eastern PEI early this afternoon; 1-2 cm hail, 70-90 km/h wind gusts, and locally heavy downpours of 25-50 mm.

NL: Scattered thunderstorms possible through west-central NFLD today; 1-2 cm hail, 70-90 km/h wind gusts, and locally heavy downpours of 25-50 mm.

 

Convective Discussion…

A small but intense shortwave trough moving through the Maritimes this morning brings the chance for sever weather across the eastern gulf of St. Lawrence and west-central NFLD today. Models have been struggling to resolve the intensity of this trough, with some strong storms having already moved through PEI and Iles-de-la-Madeleine this morning. These storms have weakened slightly as they moved over cooler gulf waters, but may re-intensify as they approach Cape Breton and the western shores of NFLD early this afternoon. Upper dynamics will allow for sustained convection over west-central NFLD, with a 110 kt 250 mb jet over the region. Bulk shear of 30-40 kts and SBCAPE values in excess of 1000 J/kg provide an ample environment for severe weather potential with the incoming shortwave trough acting as the main trigger. These storms will move northeast into north-central NFLD by this evening. The main threats with these storms will be pea to dime size hail, strong wind gusts reaching 70-90 km/h, and locally heavy downpours of 25-30 mm per hour.

 

In addition, isolated pop-up thundershowers are possible across the Maritimes this afternoon. Due to a lack of upper support however, these storms are expected to have short life spans, with the main threat being brief heavy downpours.

 

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for Tomorrow

 

Copp

Convective Outlook Valid for Today, Tonight, and Tomorrow

Regional Impacts

NS: None.

NB: A few thunderstorms possible over western and northern NB this afternoon; 1-2 cm hail, 70-90 km/h wind gusts, and locally heavy downpours of 25-50 mm.

PEI: Slight chance for an isolated thundershower over western PEI this evening, locally heavy downpours of 15 mm possible.

NL: A few thunderstorms possible between Goose Bay and Labrador City this afternoon; 1 cm hail, 70 km/h wind gusts, and locally heavy downpours of 20-40 mm.

 

Convective Discussion…

A small shortwave moving through eastern Quebec this morning will bring the risk for severe weather across parts of northwestern NB and central Labrador today. In NB, SBCAPE values are expected to climb upwards of 1500 J/kg this afternoon. This, in combination with bulk shear values of 30-40 kts will provide an ample environment for the development of severe weather. Dew points in parts of New Brunswick have been observed to be slightly higher than models have forecast this morning, as such SBCAPE values may be slightly higher than models are currently predicting. The main threat with these cells will be small hail of 1-2 cm, strong wind gusts of 70-90 km/h, and locally heavy downpours upwards of 25 mm per hour.

 

In central Labrador, SBCAPE values will be similar to those in NW NB, 1500-2000 J/kg between Labrador City and Goose Bay. Bulk shear here is slightly weaker however, in the 20-30 kt range, nonetheless a 40 kt 500 mb jet over the region will aid in sustaining organized convection this afternoon and into this evening. There is a chance these storms make it to Goose Bay by late this evening, however the main threat area is to the west of here. The hazards associated with these storms will be 1 cm hail, 70 km/h wind gusts, and locally heavy downpours of 20-40 mm.

 

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for Tomorrow

 

Copp

RE: Convective Outlook Valid for Today , Tonight and Tomorrow

*** Updated Thunderstorm Outlook for Tuesday. See image below ***

 

Regional Impacts

NB NS PEI: none.

NF: Scattered thunderstorms, possibly strong later this afternoon, localized downpours of 15 mm, small hail, and gusty winds near thunderstorms.

 

Convective Discussion…

The plume of tropical moisture has now moved east of NF. At 500mb, a trough extends from the James Bay region to the Gulf of St. Lawrence, leaving NF in a fairly unstable airmass. Precip. Water calculated from the area soundings are ranging from 30 to 50 mm, except for AYT (55 mm) which has some residual tropical moisture. VIL of the day guidance is showing values of 35-50 kg/m^2 - fairly strong updrafts and large CAPE values are in store in today’s environment which may lead to some small hail.  

A 90kt southwesterly upper jet extending from NS to the Avalon will add some dynamic for some stronger surface-based convection over the region. Moderate unidirectional deep layer sheers will also provide an opportunity for some clusters of thunderstorms to semi-organize.  

Tomorrow, the environment found over QC/NE US will advance over NB and Lab.

 

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for Tomorrow

 

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

NB NS PEI: none.

NF: Scattered thunderstorms, possibly strong later this afternoon, localized downpours of 15 mm, small hail, and gusty winds near thunderstorms.

 

Convective Discussion…

The plume of tropical moisture has now moved east of NF. At 500mb, a trough extends from the James Bay region to the Gulf of St. Lawrence, leaving NF in a fairly unstable airmass. Precip. Water calculated from the area soundings are ranging from 30 to 50 mm, except for AYT (55 mm) which has some residual tropical moisture. VIL of the day guidance is showing values of 35-50 kg/m^2 - fairly strong updrafts and large CAPE values are in store in today’s environment which may lead to some small hail.  

A 90kt southwesterly upper jet extending from NS to the Avalon will add some dynamic for some stronger surface-based convection over the region. Moderate unidirectional deep layer sheers will also provide an opportunity for some clusters of thunderstorms to semi-organize.  

Tomorrow, the environment found over QC/NE US will advance over NB and Lab.

 

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for Tomorrow

 

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

NB NS PEI: Isolated thunderstorms, giving localized downpours.

NF: Scattered embedded thunderstorms over western sections, torrential rain with 30-60 mm with the highest amounts in the southwest.

Lab: Scattered thunderstorms, possibly strong later this afternoon, localized downpours of up to 20 mm, small hail, and gusty winds near thunderstorms.

 

Convective Discussion…

Satellite imagery shows the tropical moisture feed over western Newfoundland. Precip. Water calculated from the area sounding are ranging from 40 to 45 mm, VIL of the day guidance is showing values of 40-60 kg/m^2.  While convective inhibition is still fairly high over eastern parts of NF, in the west where the 500mb thermal through lies, embedded convection will continue to support moderate to heavy rain. A slightly cyclonic southwesterly 90kt upper jet will add some dynamic support for some stronger surface-based convection over Labrador. Moderate to strong deep layer sheers will also provide an opportunity for some clusters of thunderstorms to semi-organize.  

A 500mb through extends from Hudson’s Bay to the Gulf of Maine. This feature along with the upper jet and some limited insolation may provide enough energy/support for the development of isolated CB’s in the still very moist environment found over the Maritimes. Convective temperature is running around 28 for most of the areas – for areas with less cloud cover CAPE values will be approaching or even surpass 500J/kg at the peak of insulation later this afternoon. Tomorrow, the stronger convective activity will shift over eastern portions of the island of NF.

 

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for Tomorrow