Convective Outlook Valid for Today and Tomorrow

Thunderstorm Outlook for Today

 

Regional Impacts

Western Labrador.. Isolated thunderstorms likely producing heavy showers with rates of 10-15 mm/h

Northwestern NB.. Isolated thunderstorms giving a risk of localised heavy showers with rates of 10-20 mm/h, 1 cm hail, and strong wind gusts.

Convective Discussion

There is an upper level low centered near LG4 with a thermal trough extending southward, ahead of this feature there is thermal ridging along the Labrador coast and NF. At the surface, there is a cold front extending from west of Shefferville to southwestern Quebec. This feature will continue to be the focus for convection this afternoon. A few GLM and CLDN lightning flashes are detected and will become more widespread during the next few hours. The more robust convection will likely occur near the St. Lawrence Valley where low level moisture will combine with better upper dynamics including a 100+kt southwesterly jet and some pos pva advection. Diurnal heating will boost mixed-layer cape values to 500-800 J/kg resulting in strong enough instability to help form CB’s with tops/equilibrium level reaching the tropopause which will lower from 45hft to 35hft as the colder air advances over the region. Deep layer shears of 35 to 45 knots will help to sustain these storms longer and some will likely produce heavy showers/hail/strong wind gusts and could propagate into northern Maine/NB early this evening. Some orographic features could also contribute to the development. For Labrador, while the dynamics may not be as strong, the upper flow is somewhat diffluent and the precipitable water estimates from the morning soundings were around 25-30mm which hints at a treat of heavy showers as reported by YKL earlier.  

 

 

Thunderstorm Outlook for Friday

 

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

Western LAB for today: isolated thunderstorm possible.

 

Western and central LAB/NW NB for day 2: Isolated thunderstorms possible.

 

Southern marine waters today and Thursday: isolated embedded thunderstorms.

 

Convective Discussion

A nearly stationary frontal zone south of Atlantic Canada will give some isolated to scattered thunderstorm for the next couple of days to southern marine waters.

 

A weak short wave trough ahead of the main 500 mb upper trough may come close enough to western LAB this afternoon/evening to give an isolated thunderstorm, but likely to the northwest of Wabush/Lab City.

 

That aforementioned upper trough at 500 mb will be advancing to the east on Thursday which will act as the trigger for some isolated thunderstorms across NW NB as well as western and central LAB. Do not expect any threat of severe weather at this time.

 

Thunderstorm Outlook for Day 1

 

Thunderstorm Outlook for Day 1 night

 

Thunderstorm Outlook for Day 2

Convective Outlook Valid for Today, and Tomorrow

Thunderstorm Outlook valid for TODAY: Tuesday, Aug 9/2022.

 

Regional Impacts

Very isolated embedded convection is again possible with this slumping frontal feature advancing slowly across the Maritimes today. Pockets of heavy rain (10-15mm/hr) are occurring throughout the Maritimes.

 

Convective Discussion

Significant thunderstorms are not expected to form today (or tomorrow). Pwats are very high (50-60mm) on this morning’s weather balloons, leading to high rainfall rates and a very saturated boundary layer (up to 20,000ft at Yarmouth). 0-6k shear is near 55kts, making any storm structure be very short lived and advected quickly downstream. The grey isolated area has been overdrawn to show where isolated strikes could occur (if any). Tonight, the same lack of dynamics exist over the Avalon.

 

Thunderstorm Outlook for Day 1 - TUESDAY

 

 

Thunderstorm Outlook for Night 1 - TUESDAY OVERNIGHT

 

Embedded thundershower risk shifts slightly east in the overnight hours along frontal wave.

 

Thunderstorm Outlook for Day 2 – WEDNESDAY

 

Weak dynamics for a risk of only isolated TS in extreme western Labrador late in the day (evening) near a developing low centre in northern Quebec (Nunavik) stretching back across the Kivalliq.

 

Forecaster: TIRONE/ASPC

TS Outlook Valid for Today, and Tomorrow

Thunderstorm Outlook valid for Monday.

 

Regional Impacts

Very isolated embedded convection is possible with this slumping cold frontal feature advancing across the Maritimes today. Synoptic rain is more-so the concern over very dry ground from the recent heat wave.

 

Convective Discussion

Significant thunderstorms are not expected to form today. Scattered showers are possible, but dynamics do not support anything further. The grey isolated area has been drawn to show where isolated strikes could occur (if any) late this afternoon.

 

Thunderstorm Outlook for Day 1 - MONDAY

 

 

Thunderstorm Outlook for Day 2 - TUESDAY

 

Widespread stable conditions are expected.

 

Forecaster: TIRONE

Convective Outlook Valid for Today and Tomorrow

Regional Impacts

NB/NRN NS/WRN PEI/CNTL NL: scattered thunderstorms this afternoon and evening giving some gusty winds and torrential downpours.

NRN LAB: isolated thunderstorms giving some heavy downpours early this afternoon.

ERN mainland NS: An isolated thunderstorm is possible later this afternoon (mainly TCU).

 

Convective Discussion

A strong area of PVA has been triggering some isolated thundershowers along the north coast of Labrador this morning which will likely continue for another couple hours into the early afternoon. Further to the south we get into the hot and humid air mass that has settled into the MRTMS and central NL. An approaching frontal zone currently in the vicinity of the St. Lawrence river is sliding southeastward as too is the 500 mb upper trough. The shear will be increasing this afternoon and will be approaching 50 knots (unidirectional). Looking at the 12Z tephis does show the potential for some strong winds and torrential downpours with MLCAPE of up to 1000 j/kg. Freezing levels are pretty high so hail is not a concern. There is a load of low level moisture so torrential downpours are a pretty sure thing.

 

There are several things pointing at an active day, but the history of the front is not too impressive and the instability is not that strong. We do expect to see some scattered thunderstorms this afternoon and evening with some of them strong to possibly severe (winds and torrential rainfall). For now there was no yellow area drawn into the convective map due to the lower level of confidence in seeing an active day. It could be one of those shifts were we wait to see development on the radar and go from there with possible watches (any warnings) for some counties in NB.

 

Thunderstorm Outlook for Day 1

 

Thunderstorm Outlook for Day 1 Night

 

Thunderstorm Outlook for Day 2

 

Jeremy