Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

 

Today:

NB: Scattered thunderstorms possible this evening over southern regions giving lightning, locally heavy downpours of 10-20 mm.

NS: Scattered thunderstorms possible this evening for western regions giving lightning, locally heavy downpours of 25-50 mm, small hail and 70-90 km/h wind gusts .

NL and LAB: Scattered thunderstorms possible through Labrador and parts of central NFLD today giving lightning, 1-2 cm hail, 70km/h wind gusts, and locally heavy downpours of 20-30 mm.

 

Tonight:

NB/PEI/NS: Scattered thunderstorms possible tonight giving locally heavy downpours of 20-30 mm.

LAB: Isolated thunderstorms for eastern area giving locally heavy downpours.

 

Friday:

NB: Scattered thunderstorms giving lightning, locally heavy downpours, small hail, and strong wind gusts.

LAB: Isolated thunderstorms giving lightning, locally heavy downpours, small hail, and strong wind gusts.

 

Convective Discussion

There are a couple of different features to track of interest today. An intense short wave trough that affected southern Ontario yesterday is moving over New England today and eastward towards the Maritimes tonight. Ahead of this trough, afternoon instability will increase along with moisture over southern New Brunswick and Nova Scotia. Although the main threat of severe weather remains west over New England given the dynamics and the timing of this feature, convection could persist into the overnight hours. An approaching 30KT 850mb jet, moderate 0-6km shear, and cloud top cooling will also aid in continued risk of convection overnight, giving the risk of lightning and heavy downpours into Friday morning as the trough axis exits east of Cape Breton.

 

An upper low over northern Quebec will shift southeastward across Labrador today and out over the Labrador Sea tonight with a trough extending southward into Newfoundland. Convection occurring this morning east of the low centre will persist into this afternoon. An area of concern lies in central to southeastern Labrador (left exit of a 250mb jet, an approaching 500mb cold trough, increasing moderate shear and MLCAPE values above 1500 J/kg) such that convection that develops this afternoon with daytime heating could organize into multicell lines. Freezing levels are also lower which could increases the hail potential as well. There is also the possibility of embedded convection over Newfoundland from an area of moisture moving in from the Gulf of St. Lawrence this morning.

 

For Friday, the short wave trough exiting Cape Breton will affect portions of the marine waters south of Newfoundland. Meanwhile, the next short wave over central Quebec will be quickly tracking eastward towards New Brunswick and the Gulf of St. Lawrence by Friday night. Ahead of this trough in the afternoon, scattered thunderstorms are possible over northern New Brunswick and southwestern Labrador.

 

 

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for Friday

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