Convective Outlook Valid for Today, and Tomorrow

Thunderstorm Forecast for TUESDAY:

 

Regional Impacts

Isolated non-severe embedded thunderstorms with 1010mb low tracking through Maritimes today. Synoptic rain and fog is the main story, but a few lightning strikes are possible ahead of the fronts.

 

Convective Discussion

There is a lot of speed shear aloft, but not much to work with in the low levels. There is, however, a plethora of low-level moisture to work with. This in turn, means Pwats of 30-40mm on the AM soundings. Skinny MLCAPE of 500-700J/kg can only produce a strike or two. Any heavy pockets of rain could be handled with a SWS or a short fused 1-hr Rainfall warning. Watches from the ASPC will not be required today.

 

Thunderstorm outlook for Today:

 

 

Thunderstorm Forecast for WEDNESDAY:

 

Thunderstorms approaching severe criteria limits of 25mm/hr rainfall rates could occur in central Nfld. Labrador and the northern tier of NB will also see some slight terrain-induced instability. NS is quite conditional on sea-breezes and a Tc of 24C in clearing. NS cells will remain down the spine of the province, and will also be good rain-makers. Data will be re-assessed on tomorrow’s 12z soundings.

 

Thunderstorm outlook for Tomorrow:

 

Forecaster: TIRONE

Convective Outlook Valid for Today and Tomorrow

Regional Impacts:

 

Today

Labrador: Isolated to scattered thunderstorms giving lightning, locally heavy downpours and gusty winds

Northwestern NB: Isolated thunderstorms

NS/PEI/NL: None

 

Tonight

NS/NB: Elevated/embedded thunderstorms

NL/PEI/Labrador: None

 

Tuesday

NS/PEI/NB: Elevated/embedded thunderstorms

NL/Labrador: None

 

Convective Discussion:

 

A trough over eastern Quebec/southern Labrador will drift southward while weakening. Ahead of the trough over southern Labrador scattered thunderstorms will develop this afternoon. Precipitable water near 25 mm and CAPE values 500-1000 J/kg are expected. Strong shear of 30-40 kts and dry mid-levels may support squall lines. Over northwestern NB, a weak shear environment and marginal cape may support pulse type storms with locally heavy downpours and brief wind gusts possible later this afternoon. Tonight and Tuesday a risk of elevated thunderstorms exists as a weak low pressure approaches.

 

 

Thunderstorm outlook for today:

 

Thunderstorm outlook for tonight:

 

Thunderstorm outlook for Tuesday:

 

 

Convective Outlook Valid for Today and Tomorrow

Regional Impacts:

 

Today

Labrador: Isolated to scattered thunderstorms giving lightning, locally heavy downpours and gusty winds

Northwestern NB: Isolated thunderstorms

 

Tonight

Labrador: Isolated thunderstorms

Northwestern NB: Isolated thunderstorms

 

Monday

Labrador: Isolated to scattered thunderstorms giving lightning, locally heavy downpours and gusty winds

Northwest NB: Isolated thunderstorms giving local heavy downpours

 

Convective Discussion:

 

An upper trough of low pressure is slowly track eastward from Hudson Bay toward central Quebec today while a ridge of high pressure stalls over southeastern Newfoundland into Monday. Ahead of the trough, an increasingly unstable air mass will aid in the formation of scattered showers and thunderstorms over western and central Labrador and into northwestern New Brunswick. Precipitable water is increasing to near 30 mm and CAPE values around 500 J/kg, however, shear will remain weak with little upper dynamics. This environment may sustain some pulse type storms with locally heavy downpours and brief strong wind gusts possible. Some TCUs in brief showers are expected along the eastern coast of New Brunswick and northern Nova Scotia today.

 

On Monday, the upper trough will track through eastern Newfoundland. With increasing vorticity, moisture and shear of 30KT, there is the possibility for more organized convection into squall lines but there will be some warming at 500 mb which may inhibit convection.

Convection Is expected along a near stationary boundary extending from southern Quebec into northwestern New Brunswick and the Gaspe Peninsula. Lighting, locally heavy rain and strong gusty winds are the main risks.

 

 

Thunderstorm outlook for today:

 

Thunderstorm outlook for tonight:

 

Thunderstorm outlook for Monday:

Convective Outlook Valid for Today and Tomorrow

Regional Impacts:

 

Today

Central-western Labrador: Isolated thundershowers

 

Tonight

None

 

Saturday

Labrador/NB: Isolated to scattered thunderstorms

 

Convective Discussion:

 

A ridge of high pressure moves through the region today while the tail end of a trough of low pressure moves southeastward over Newfoundland today. Isolated showers with the slight risk of a thunderstorm is expected over central Labrador this afternoon. Convective temperatures near 25C are expected to be reached. With CAPE values of 500 J/kg but little moisture in the low levels and weak effective shear, the main threat would be some gusty winds. Some robust TCUs are expected over central to southeastern Newfoundland this afternoon but will be fighting a thermal ridge between 700 and 500 mb. Some locally heavy downpours are possible.

 

For Sunday, a trough of low pressure will slowly track eastward over Hudson Bay toward central Quebec. Ahead of the trough, an increasingly unstable air mass will aid in the formation of scattered showers and thunderstorms over western and central Labrador and into northern and western New Brunswick. Although there is an increase in precipitable water and CAPE, shear will remain weak so pulse type storms with locally heavy downpours and strong wind gusts are possible.

 

Thunderstorm outlook for today:

 

Thunderstorm outlook for tonight:

 

 

Thunderstorm outlook for Sunday:

Convective Outlook Valid for Today and Tomorrow

Regional Impacts:

 

Today

NB/NL: Isolated thunderstorms.

NS/PEI/Labrador: None

 

Tonight

None

 

Saturday

None

 

Convective Discussion:

 

An upper low pressure system is slowly tracking northeastward over the northern Gulf of St. Lawrence and northern Newfoundland by Saturday morning. Scattered TCUs and isolated CBs were present along the frontal axis extending from the Great northern Peninsula and south over the Grand Banks earlier this morning. Some convection is possible along the northern Newfoundland coasts this afternoon if a cap at 850 mb can be broken. With precipitable water values of 30 to 40 mm, weak to moderate unidirectional wind shear, locally heavy downpours and strong wind gusts are possible. Isolated convection is also possible along the cold front which is tracking through the Grand Banks.

 

There is the possibility of isolated thunderstorms over New Brunswick today, however a capping inversion at 700mb with be the main inhibitor along with current cloud cover. KCARs 12Z sounding indicates that the RDPS is slightly overdoing this cap and with sufficient surface based heating, this cap may be able to break by this afternoon. Any showers that do develop will be slow to move given little upper flow around the upper low and with precipitable water near 30 mm, some locally heavy downpours are possible. Given more dry air in the mid level, some strong wind gusts are also possible.

 

For Saturday, a ridge of high pressure moves into the region, keeping most areas hot and dry. Some isolated TCUs are likely for Newfoundland as they remain under the influence of a trough and western Labrador as a low pressure system approaches central Quebec.

 

Thunderstorm outlook for today:

 

Thunderstorm outlook for tonight:

 

Thunderstorm outlook for Friday: