Convective Outlook Valid for Today

Thunderstorm Outlook for Today

 

Regional Impacts

Isolated thunderstorms today over NB and western Labrador. Over eastern NS and southwestern NFLD, locally heavy showers are possible.  20 mm/hr or more is not out of the question.

 

Convective Discussion

A favourable left exit of a jet over weak surface troughing supported heavy rain over portions of Nova Scotia and PEI this morning. 25 mm or more in an hour was reported in the Bridgewater area. The embedded line of convection has moved east and watches are in place in areas of most concern this afternoon. The PWAT values of 35-40 mm persist in this area and that is the same airmass that gave flooding to areas of King County Nova Scotia yesterday. Southwestern Newfoundland will need to be monitored for potential significant rainfall this afternoon. Over NB and western Labrador, surface heating this afternoon will give isolated thundershowers and low freezing levels which will support small hail formation. Cape values of less than 500 J/kg and shear less than 20 knots are expected in these areas.

 

Convective Outlook Valid for Today

Thunderstorm Outlook for Today

 

Regional Impacts

Isolated thunderstorms today over NS and southern NB with locally heavy showers possible.  20 mm or more is not out of the question.

 

Convective Discussion

Dynamics are not great today for severe thunderstorms, however the risk is still there but likely low.  There is not much support in the upper level dynamics with no significant jet stream over the area and a lot of moisture at 700 mb.  A lot of cloud over most of the area will inhibit solar insolation.  Wind shear values between 20 to 30 kts will likely not be enough to help maintain long lived cells.  However, there is a lot of low level moisture over the area and a marginally unstable atmosphere (500 J/kg ) associated with a broad and nearly stationary trough over the region. Any storms have a low chance of becoming severe however they could still bring quite significant rain due to the abundance of moisture (PWAT near 35 mm) and the fact that the cells will likely be slow moving. 

 

 

Convective Outlook Valid for July 20th and July 21st

Thunderstorm Outlook for Day 1 – July 20^th, 2021

 

Regional Impacts

Scattered thunderstorms today over NFLD, PEI, NS and southeastern NB with locally heavy showers possible especially over southeastern NB.  10 to 20 mm but higher not out of the question.

 

Convective Discussion

Dynamics are not great today for severe thunderstorms, however the risk is still there but likely low.  There is not much support in the upper level dynamics with no significant jet stream over the area and a lot of moisture at the 700.  A lot of smoke and cloud over the area will inhibit solar insolation.  Wind shear values of between 20 to 30 kts will likely not be enough to help maintain long lived cells.  However, there is a lot of low level moisture over the area and marginally unstable atmosphere ahead of a trough currently located over NB.  This trough will track southeastward through the day and will likely kick off some tstorms.  These storms have a low chance of becoming severe due to all the inhibiting ingredients mentioned above, however they could still bring down quite a bit of rain due to the abundance of moisture and the fact that the cells will likely be slow moving.  10 to 20 mm expected with higher possible.

 

 

 

 

 

Thunderstorm Outlook for Day 2 – July 21^st, 2021

 

Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Day 1- July 19^th, 2021

 

 

Regional Impacts

 

Nova Scotia and Prince Edward Island…Isolated risk today and this evening. Locally heavy downpours and gusty winds are possible.

 

New Brunswick…Isolated risk mainly for central regions with heavy downpours possible today and this evening.

 

Labrador…Isolated risk for southern regions near this afternoon and evening.

 

Maritime waters…Isolated thunderstorms continue today and overnight, possibly reaching southern Newfoundland early tomorrow morning.

 

Convective Discussion

 

A surface trough lies to the west extending from southern Labrador toward southern Quebec and into the New England. The main threat of organized convection remains closer to the trough north of the St. Lawrence River and extended northeast towards extreme southern Labrador today where heavy downpours and small hail is possible. The Maritimes remain in a moist southwesterly flow today ahead of this trough. Precipitation moved through the region yesterday evening and is now moving into southern Newfoundland today. Isolated thundershowers continue this morning south of Nova Scotia and may make their way inland along the Atlantic coast of Nova Scotia today bringing heavy downpours. Although most of the Maritimes remains cloudy this morning, some scattering of the cloud mainly over the Annapolis Valley and northern Nova Scotia could help the area reach their convective temperature. Dew points this morning are near 20C. There is also the aid of an 850mb low-level jet, weak 0-6km shear of near 20 kts, some cooling in the upper levels, and precipitable water values near 40 mm. Thunderstorms should be short-lived but would likely produce heavy downpours that will drift to the northeast into eastern Prince Edward Island or western Cape Breton this evening.

 

 

Thunderstorm Outlook for Day 2- July 20^th, 2021

 

This trough today will continue to slide further east tomorrow. Some enhanced risk is possible over much of New Brunswick, Nova Scotia and Prince Edward Island.

 

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

 

Labrador… Today isolated non-severe thunderstorms possible. Tomorrow an increased potential for more intense thunderstorms with

gusty winds.

 

Nova Scotia… Today a chance of thunderstorms with locally heavy amounts for southwest areas late this afternoon and this evening. Tomorrow an enhanced chance of thunderstorms with locally heavy downpours and gusty  winds expected.

 

New Brunswick and PEI… Tomorrow a chance of thunderstorms with locally heavy downpours.

 

Convective Discussion

 

Overall moisture will remain high for the next couple days in a general southwest flow over the region. Surface troughing will act to enhance the chance of thunderstorms tomorrow for most of the Atlantic region. Moderate wind shear will remain as well over Nova Scotia and Labrador giving a slightly higher chance of organised convection tomorrow.

 

Thunderstorm Outlook for Day 1

 

 

Thunderstorm Outlook for Day 2