Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

 

Today:

NB: Near-severe thunderstorms possible over western and northern regions this afternoon and evening giving strong wind gusts (70 to 90 km/h), small hail and heavy downpours (20-40mm per hour rates).

NS/PEI/NL&LAB: None

 

Tonight:

NB: Thunderstorms possible overnight giving heavy downpours.

NL&LAB: Thunderstorms possible over southwestern Newfoundland and southwestern Labrador.

 

Saturday:

NB: Thunderstorms over central and southern regions this afternoon and evening giving heavy downpours.

NL: Thunderstorms over central to northern giving heavy downpours.

NS/PEI/LAB: None

 

 

Convective Discussion

 

An upper level trough extends from the Great Lakes northeast into the St. Lawrence River Valley with a surface low pressure developing this afternoon over central Quebec. Ahead of the trough over the Maritimes lies a warm and humid air mass with dewpoints remaining near 20C today over central to northern New Brunswick and precipitable water near 40 mm. Should there be sufficient clearing this afternoon, this may also provide additional surface based heat with temperatures into the high 20s with possible MUCAPE (upwards of 2000 J/kg) over central to northern New Brunswick. Caribou’s 12Z sounding indicates a capping inversion near 850mb but there is decent instability above.  With a 40KT 700mb jet and weak to moderate deep layer shear near 25KT, multicell development will likely occur over the higher terrain in north and central Maine (already ongoing this morning) and northwestern New Brunswick this afternoon. Cells may form into more organized lines as they track northeastward this afternoon and into the overnight. Given general northeast orientation of storm movement, there is the threat training and locally heavy downpours over the same locations. With sufficient mid-level instability, downdraft wind gusts and small hail with the more intense storms are also possible.

 

For Saturday, the trough inches slowly southeastward. The threat for severe thunderstorm development has decreased, but areas of central and southern New Brunswick could see heavy downpours in the afternoon and evening as well as northern Newfoundland.

 

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for Saturday

 

Forecaster: McArthur

 

Convective Outlook Valid for Today , Tonight and Tomorrow

***This will be the final scheduled outlook for the season.****

 

Regional Impacts

Today…

Eastern Labrador.. Slight risk of thunderstorms, some lightning possible.

Offshore Atlantic Marine areas and southeastern Newfoundland.. embedded thunderstorms possible.

 

Tomorrow… Slight chance of embedded thunderstorms.

 

Convective Discussion

It continues to be an interesting summer with most of the Atlantic region wedged between the remnants of Idalia and building ridge of high pressure. In terms of thunderstorm potential this will not be a very strong set up, however a weak upper trough could trigger some thunderstorms over eastern Labrador and west of the Maritimes in Quebec and Maine. As the moisture associated with Idalia creeps slowly northeastward there will be slight risk of a thunderstorm near the low. It is likely that most of the heavy precipitation will remain south of Nova Scotia, but there is a slight chance with higher PWAT value coming onshore over southeast Newfoundland that a few heavier showers could happen tonight and tomorrow. Tomorrow over Nova Scotia there will be a slightly enhanced chance of convection near the vicinity of the low pressure system, but the probability will remain quite low for heavier showers or thunderstorms.

 

Thunderstorm Outlook for Today

 

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for Tomorrow

 

Mel Lemmon

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

 

Today:

Labrador: risk of a thunderstorm north of Labrador City/Wabush to Esker to Schefferville

 

Monday: None

 

Convective Discussion

An upper trough over Hudson’s Bay and an associated active cold front will move across northern Quebec today. A strong southwesterly low-level-jet is feeding moisture ahead of the surface feature. Precipitable water levels are currently between 30-35 mm. The cold front will reach western Labrador this evening. However, with the loss of daytime heating, forecast guidance is suggesting a weakening area of instability over the fp17hx area.

 

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

 

Thunderstorm Outlook for Tomorrow

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

None

 

Convective Discussion

The base of a cold upper trough in conjunction with the warm waters off western NL produced a few strikes and convective showers earlier this morning. However the upper trough is expected to continue progressing eastward with heights rising in its wake yielding stable conditions across all of Atlantic Canada. As such no thunderstorms are anticipated for the next 2 days.

 

Thunderstorm Outlook for Today

 

 

Thunderstorm Outlook for Tonight

 

 

Thunderstorm Outlook for Tomorrow

 

 

Allen

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

 

Today

NL/NS/NB/PEI/LAB: None

Southeastern Marine waters: Lightning and reduced visibility in heavy downpours.

 

Tonight

NL/NS/NB/PEI/LAB: None

Southeastern Marine waters: Lightning and reduced visibility in heavy downpours.

 

Friday

None

 

Convective Discussion

 

The UA at YYT this morning revealed the same tropical air mass that was in place across the Maritimes yesterday, with PWATs near 50mm. Instability exists aloft at ~850 mb but MUCAPE is limited (~150 J/Kg or less) due to some thermal ridging at the 500mb pressure level. This is also noted through the limited delta T between the 700 and 500mb levels of ~11-12 C, indicative of very little mid level instability. For this reason the no lightning is expected of land areas of eastern NL, however across the marine areas to the south and east of the Avalon higher MUCAPEs upwards of 500 J/Kg exist, and this should allow sufficient buoyancy and charge separation to produce isolated to scattered lightning today and tonight. Primary hazard for these mariners will be sharply reduced visibility in downpours.

 

By Friday this air mass is expected to move well to the east of the region and associated marine waters, with a much drier and stable air mass in its wake.  Stable conditions across Atlantic Canada are expected to last through Saturday at this time with no thunderstorms activity.

 

Thunderstorm outlook for today:

 

 

Thunderstorm outlook for tonight:

 

 

Thunderstorm outlook for Friday:

 

 

Allen