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.

 

 

Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Day 1 – Monday Aug 2

 

Regional Impacts

Isolated non-severe thunderstorms over northern NB this afternoon and evening. There is a non zero chance that a TCU in Labrador could have a lightning strike this afternoon.

 

Convective Discussion

Generally not a great set up for thunderstorms across the region today with a lack of surface moisture and weakly capped above 700mb. However as the upper trough and associated PVA pass through northern NB this afternoon it could kick up some isolated, non severe thunderstorms.

 

 

Thunderstorm Outlook for Day 2 – Tuesday Aug 3

 

Regional Impacts

New Brunswick: slight risk of non severe thunderstorms late in the afternoon.

Labrador: risk of non severe thunderstorms early in the afternoon in the west to in evening farther east. Potential for some gusty winds and small hail.

 

Convective Discussion

Greater risk for Labrador than for northern NB for thunderstorms tomorrow along the approaching front. If thunderstorms do develop in Labrador the biggest threat would be wind given the dry midlevels but there is a lot working against them. There will still be a lack of surface moisture and still some weak capping above 700 mb. This low is also dragging quite a bit of smoke aloft with it and currently there is little to no TS activity on it as it passes through extreme northern ON. Something to look into again tomorrow morning.

 

Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Day 1 - Sunday

 

Regional Impacts

Isolated non-severe thunderstorms over Central NF and southeastern Labrador this afternoon.

 

Convective Discussion

The upper air analysis from this morning shows an upper cold low over northern Labrador with the upper trough extending from the low to Georgian Bay. The cold pool aloft extends to the Gaspe and Central NF where limited daytime heating might be enough to trigger some isolated CB’s with tops to 7-8 km. The energy is not great but given the cold air aloft small hail is not out of the question.

At the surface there is a weak frontal band which stretches from southeastern Labrador along the St. Lawrence Valley to Lake Ontario. An associated wave over Lake Ontario will push cloud an moisture over the Maine late today and into Maritimes Monday. Some of the guidance is suggesting some instability over northern NB on Monday, but it appears to be weak at this time. A second wave forming near the US mid-Atlantic coast will travel south of NS on Monday. Embedded Thunderstorms will likely stay offshore, but one or two thunderstorms could brush the Atlantic coast of NS.

 

 

Thunderstorm Outlook for Day 2 – Monday

 

Slight risk of thunderstorms for central Labrador and northwestern NB.

 

 

Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Day 1 - Saturday

 

Regional Impacts

There is a slight risk of non-severe thunderstorms for northeastern NB, northern PEI, Iles-de-la-Madeleine, and northern Cape Breton.

Isolated thunderstorms are likely over central NF and southeastern Lab.

 

Convective Discussion

Extensive cloud cover over southern Labrador and much of the Gulf of St. Lawrence due to the presence of a mature surface low pressure system near Blanc Sablon. A couple of cold fronts trailing behind could provide enough lift for convective cloud growth over the Atlantic provinces. For the Maritimes, the convective temperature for this afternoon is about 22 degrees which might be reached in areas of eastern NB where solar insolation will be greater. T/Td of 22/10 will yield CAPE values slightly above 200 J/kg. Similar conditions are expected over central NF with the advancing airmass. While the surface temperature required for initiation is similar, the moisture content of the airmass is higher over NF – this will contribute to somewhat higher energy from the surface and mixed-layer CAPE above 300 J/kg. Brief heavier showers is the main threat.

 

 

Thunderstorm Outlook for Day 2 – Sunday

 

Some lingering daytime instability over parts of NF giving a slight risk of thunderstorm.