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.

 

Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Day 1

 

Regional Impacts

Isolated thunderstorms with heavier showers throughout NS, PEI, and Les Iles-de-la-Madeleine this afternoon and this evening. This activity will continue into the night for areas adjacent to the Gulf of St. Lawrence.

 

Some daytime convection might develop over southern Lab during the afternoon – an isolated/non-severe thunderstorm.

 

There is a slight chance of a thunderstorm along with brief heavier showers over southern areas of NF tonight.

 

Convective Discussion

Frontal wave at the surface approaching Yarmouth county at 12z. The associated low will travel northeasterward and reach the Northern Peninsula of NF Saturday. The airmass around this system is fairly moist with overcast layers of cloud extending from the low levels to 7-8 km, and embedded CB’s to about 9 km. Precipitable water from the area soundings are showing values of 30-25mm. Deterministic models are suggesting synoptic rainfall of 15 to 30 mm over the region, with the EU is hinting at areas of 40-50mm. Rainfall rates of 10mm/hr reported along the Atlantic coast west of Halifax this morning would support the idea of locally higher amounts.

 

 

 

Thunderstorm Outlook for Day 2 – Saturday

 

Late day thunderstorms with heavy showers are possible especially for areas adjacent to the Gulf of St. Lawrence.

 

ATL Thunderstorm Outlook for Today and Tomorrow

Convective Outlook for Today – THURS July 29^th

 

Regional Impacts

Non-severe thundershowers are possible over offshore waters from a frontal passage. Isolated, non-severe thundershowers are also possible over eastern Labrador.

 

Convective Discussion

The main forcing for today’s weather is a sweeping trough that is well east of the Maritimes. The rest of the region is dominated by a ridge of high pressure and strongly capped at 700mb. Nova Scotia in particular is quite dry at the surface. If a cell does manage to bubble up in Labrador, it will be short lived and single cell pulse in nature.

 

 

Convective Outlook for Tomorrow – FRI July 30^th

 

Regional Impacts

Embedded non-severe thunderstorms are possible in parts of the Maritimes with a developing low pressure system. Heavy synoptic rain is the main hazard, in New Brunswick.

 

Convective Discussion

The limiting factor for any storms to develop will simply be the battle with cloud cover. If the low does not have clear slots to facilitate daytime heating, it will be difficult to create strong lift and cloud tops cold enough to cause any lightning. Nevertheless, a rainy/windy day in store for many parts of Atlantic Canada.

 

 

Convective Outlook for Day 3 – SAT July 31^st

 

Regional Impacts

The start of the long weekend does not look to be very stormy in regards to thunderstorms. No deep shear or strong CAPE is being resolved by the models at this time. No forcing of concern is expected on Saturday specifically.

 

Convective Discussion

There does not appear to be a signal for severe convective weather for PEI at this time. Check future forecasts from Environment Canada for updates.