Convective Outlook for Today, and Tomorrow

Thunderstorm Outlook for TODAY – Monday, Aug 9, 2021

Regional Impacts

Isolated non-severe thundershowers are possible this afternoon and early evening over extreme NW New Brunswick.

 

Convective Discussion

A weak approaching boundary from Quebec may be enough to trigger just enough lift to excite a TCU or 2 this afternoon in the northern terrain. Only hazard with a cell if it can form would be lightning. With dew points of only 11, this airmass is not muggy enough to see any impactful rainfall.

 

 

 

Thunderstorm Outlook for TOMORROW – Tuesday, Aug 10, 2021

 

Regional Impacts

Isolated severe thunderstorms are possible across the northern tier of New Brunswick with heavy downpours and gusty winds being the main threats. Elsewhere, isolated non-severe cells may spark up if we get partial clearing of the cloud deck/fog/mist.

 

Convective Discussion

Shear depicted in the RDPS is enough to get multi-cell training storms, as well as profiles look elevated enough to cause gusty winds to near 90km/h. Heavy rain will be the biggest concern if a storm lacks forward motion (25-50mm/h). This thunderstorm risk will be re-assessed by the ASPC on Tues AM.

 

Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for today – Friday August 6

 

Regional Impacts

Isolated thunderstorms with brief downpours over Eastern NS and NF. A slight risk of hail over west-central NB. Non-severe storms over sourthern Lab.

 

Convective Discussion

A moisture laden air mass continues to prevail over southern NB, NS and NF, precipitable water estimates from this morning sounding range from 40 to 50 mm. At the surface the frontal band extends from South Shore of NS to PEI to central NF. Embedded ACC/ACB continue to produce isolated pockets of heavier showers. Some surface based convection is beginning to develop with the help of daytime heating, and some upper support (upper SWly jet from NB to southern Lab). 500 mb heights have been falling in the past 12 hours by about 3 or 4 dam which indicates cooler temperatures advancing aloft. Tephigram modification suggest cape values of about 500 J/kg and EL between 250-330. Good enough for pulse storms in the shaded area of the map. The Gagetown sounding is slightly more interesting, with moderate deep layer shear values, and surface-based cape values between 700-900 J/kg. Equilibrium level would still be well below the tropopause (below 380-420).

 

 

Thunderstorm Outlook for tomorrow - Saturday August 7^th

 

There is a risk of non-severe afternoon thunderstorms over portion of the region.

 

Thunderstorm outlook for today

 

Thunderstorm Outlook for Day 1 – Thursday Aug 5

 

Regional Impacts

Rain at times heavy with embedded thundershowers expected today and tonight over southern NB and western and central NS.

 

Convective Discussion

Elevated convection with initiation from between 900 and 850 mb is likely today and tonight over these regions. This convection is embedded within a broad area of rain. There is a lot of low level moisture within this airmass to support ongoing isolated embedded thundershowers. The risk in this situation is heavy rainfall, not necessarily directly due to thundershower activity. Strong winds and hail are not a threat.

 

 

 

Thunderstorm Outlook for Day 2 – Friday, Aug 6.

 

Regional Impacts

Most of New Brunswick and Labrador.

 

Convective Discussion

Labrador: Low level moisture is sufficient, with model temps being low to mid 20s and dew points around 15. There is cooling aloft, sufficient to give CAPEs around 1000 J/kg. Shear values are near 30 knots. Heavy downpours, small hail and gusty winds are possible.

 

New Brunswick: Isolated single cell pulse thundershowers are possible. However, there will be cap between 750 and 700 mb that may be difficult to break. Shear is forecast to be low (0-6 km shear only 20 knots.). Brief downpours are possible. No severe convection expected.

 

 

Thunderstorm outlook for today

Thunderstorm Outlook for Day 1 – Wednesday Aug 4

 

Regional Impacts

Isolated non-severe thunderstorms over central NB this afternoon and evening.

 

Convective Discussion

Generally not a great set up for thunderstorms across the Region. Over NB, there is descent shear, about 35-40 knots, but the sounding is weakly capped above 700 mb. If lift goes above the cap, the upper level buoyancy is very weak. Most of the CAPE would be below 700 mb. Elsewhere, throughout Atlantic Canada, the soundings are very stable and dry. No thundershower activity is expected.

 

 

Thunderstorm Outlook for Day 2 – Thursday Aug 5

 

Regional Impacts

Nova Scotia: slight risk of non severe thunderstorms in western Nova Scotia.

 

Convective Discussion

A warm front will move into the southern Maritimes on Thursday morning and will continue moving northeastward. Instability associated with the front and saturation with low level dew points of 15 to 20 deg could give convective initiation

from around 850 mb. A warm, moist airmass behind the front Thursday afternoon and evening could continue to give isolated thundershowers. The area currently shown for convection may be expanded north and east with the next convective outlook.

 

 

Convective Outlook Valid for Today

Thunderstorm Outlook for today – Tuesday Aug 3

 

Regional Impacts

New Brunswick: Slight risk of non severe thunderstorms late this afternoon.

Labrador: Risk of non severe thunderstorms this afternoon. Potential for some small hail.

 

Convective Discussion

Greater risk for Labrador than for northern NB for thunderstorms today along an approaching trough. If thunderstorms do develop in Labrador the biggest threat would be small hail but there is a lot working against that including an abundance of cloud to inhibit convection. In both areas, Cape values are quite low due to a lack of surface moisture.