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

Convective Outlook Valid for Today, Tonight, and Tomorrow

Regional Impacts

NS: Embedded thunderstorms today, torrential downpours of 30-50 mm in convection.

NB: Isolated thundershowers possible this afternoon, locally heavy downpours of 10-15 mm.

PEI: Embedded thundershowers possible this afternoon, locally heavy downpours of 10-15 mm.

NL: Isolated thundershowers possible over extreme northern Labrador, locally heavy downpours.

 

Convective Discussion…

A stream of tropical moisture has made its way into southwestern NS this morning. Embedded convection is expected to continue along this stream as it slowly moves northeast over the next few days, bringing torrential rain across much of the Atlantic coast. The 12Z UA sounding from Yarmouth indicated PWAT values of 42 mm, with this forecast to increase to near 50 mm by this afternoon between Yarmouth and Halifax. Rainfall warnings have been issued along the Atlantic coast of NS for total rainfall amounts of 40 to 70 mm, with possibly higher amounts in areas of more intense convection by tomorrow night.

 

Tomorrow, an additional area of interest exists in NW NB, associated with a low pressure system that brought widespread severe weather to southern Ontario yesterday. This low is forecast to slowly track northeast along the St. Lawrence river tomorrow. Significant cooling aloft and ample moisture in NB will allow for SBCAPE values to build to 2000 J/kg tomorrow afternoon, with convective temperatures around 23 degrees, making this a suitable environment for severe weather. Bulk shear values of 30-40 kts will allow for some sustained updrafts, with the potential for 1 to 2 cm hail with these storms. Strong wind gusts to 70 km/h and locally heavy downpours of 20-40 mm are also possible.

 

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for Tomorrow

Copp