Convective Outlook Valid for Today and Tomorrow

Regional Impacts:

 

Today

NB/NS/PEI: None

NL/Labrador: Isolated lightning and locally heavy downpours

 

Tonight

NS/NB/PEI/Labrador: None

NL: Isolated lightning and locally heavy downpours

 

Thursday

NB/NS/PEI/Labrador: None

NB/NS/PEI: Isolated lightning

 

Convective Discussion:

 

A slow moving trough of low pressure extending from a low over northern Quebec will advance eastward across Newfoundland and Labrador today and tonight. Ahead of the trough embedded lightning and downpours are occurring. Precipitable water values are in the mid 40s and rainfall warnings are in effect for the southern Newfoundland coast. Over western Labrador there is a risk of surface based lightning in the wake of the trough this afternoon. The CAPE and shear values are quite low so only small hail or wind gusts are likely there.

 

As the trough continues eastward on Friday there is a risk of thundershowers for eastern Newfoundland and associated waters.

 

Thunderstorm outlook for today:

 

 

Thunderstorm outlook for tonight:

 

Thunderstorm outlook for Friday:

 

 

 

 

 

 

 

 

 

Convective Outlook Valid for Today and Tomorrow

Regional Impacts:

 

Today

NB/NS/PEI: isolated lightning and locally heavy downpours

NL/Labrador: None

 

Tonight

Labrador/PEI/NS: isolated lightning and locally heavy downpours

NB/NL: None

 

Thursday

Labrador/NL: isolated lightning and locally heavy downpours

NB/NS/PEI: None

 

Convective Discussion:

 

A slow moving trough of low pressure extending from a low over central Quebec will advance eastward across the Atlantic region today into Thursday. This trough is pulling in a lot of moisture from the Gulf Stream, reaching far into northern Labrador with precipitable water values in the mid 40s. Convection is expected to remain isolated in nature as the air mass is quite warm at 500 mb over the Maritimes today and reaching further north and east towards Labrador and Newfoundland overnight and into Thursday, enhancing rainfall amounts. The western Maritime waters lie along the right entrance of a 120KT 250mb jet so the convection may remain mostly over the marine waters but an isolated strike cannot be ruled out further north.

 

As the trough continues eastward on Thursday, another short wave trough will move through western and central Labrador. CAPE values near 700 J/kg and some cooling aloft will prompt some convection in the afternoon. Effective shear will be too high (near 60Kt) to maintain any organized convection but anything that does develop could have some small hail.

 

Thunderstorm outlook for today:

 

Thunderstorm outlook for tonight:

 

Thunderstorm outlook for Thursday:

Convective Outlook Valid for Today and Tomorrow

Regional Impacts:

 

Today

Northwestern NB: isolated lightning, locally heavy downpours and gusty winds

PEI/NS/NL/Labrador: None

 

Tonight

Western NB/NS: Isolated lighting and locally heavy downpours

 

Tuesday

NB/NS: isolated lightning and locally heavy downpours

PEI/NL/Labrador: None

 

Convective Discussion:

 

A low pressure system will advance northeastward over Hudson Bay with a trough extending southward into New England today. There is a risk for convection over northwestern New Brunswick ahead of the trough and will continue eastward into the evening. The limiting factor is a warm nose at 850 mb and 500 mb as seen on the 12Z KCAR sounding. However, should daytime surface temperatures reach 30 degrees, along with the thermal trough at 500 mb pushing eastward, it should be enough to initiate convection over central Maine this afternoon. With increasing 0-6km shear and precipitable water above 40 mm, more organized lines that develop could maintain into New Brunswick into the evening.

 

An isolated TCU is possible over northeastern New Brunswick as well but there may be too much warming aloft to initiate any CBs.

 

As the trough continues to approach overnight and into Wednesday, convection will be more elevated and isolated in nature. A short wave will develop south of Long Island this evening and get wrapped into the main trough as it tracks through the Maritimes. This moisture will get drawn northeastward towards western Nova Scotia early Wednesday morning and continue through the Maritimes and towards southern Labrador by Thursday morning. The main threat will be locally heavy downpours with precipitable water values near 50 mm along the Atlantic coast of Nova Scotia.

 

Thunderstorm outlook for today:

 

Thunderstorm outlook for tonight:

 

Thunderstorm outlook for Wednesday:

Convective Outlook Valid for Today and Tomorrow

Regional Impacts:

 

Today

Labrador: Isolated lightning and locally heavy downpours

NB/PEI/NS/NL: None

 

Tonight

None

 

Tuesday

NB: Isolated lightning and locally heavy downpours over northern sections

PEI/NS/NL/Labrador: None

 

Convective Discussion:

 

An elongated quasi-stationary front rides from Hudson Bay across central/northern Quebec and across central Labrador. Convection will be isolated and embedded in nature along this feature as the atmospheric profiles are moist adiabatic, but with some slight cooling at 700 mb and lower level jets at 850 mb and 700 mb to help provide lift over the higher terrain. With CAPE values of 200-300 J/kg, weak to moderate effective shear and precipitable water in the 30 to 40 mm range, locally heavy downpours will be the biggest impact.

 

A low pressure system will advance northeastward over Hudson Bay with a trough extending southward into New England on Tuesday. There is a risk for convection over northwestern New Brunswick for tomorrow ahead of the trough. A sea-breeze set up combined with surface-based heating over the Acadian Peninsula may also provide enough lift to push past a warm nose between 700 and 500 mb in order to produce isolated convection in the afternoon.

 

Thunderstorm outlook for today:

 

Thunderstorm outlook for tonight:

 

Thunderstorm outlook for Tuesday:

 

Convective Outlook Valid for Today and Tomorrow

Regional Impacts:

 

Today

NS: isolated lightning

NB: none

PEI: none

Labrador: none

NL: isolated lightning

 

Tonight

None

 

Sunday:

NS: none.

NB: none.

PEI: none.

Labrador: isolated lightning

NL: none.

 

Convective Discussion:

A decaying cold front could act as a trigger for a few isolated CBs later today, especially where surface convergence will be enhanced by S-SW flow off the Atlantic. Instability appears sufficient with MLCAPEs ranging from 300-500 J/kg, however skinny CAPE profiles and dry entrainment above 650 mb could act to limit updraft strengths in the IC growth zone for sufficient charge separation. A similar scenario appears likely in eastern NL however it appears dry air entrainment does not appear to be as much of a limiting factor, despite skinny CAPE profiles. Effective shears of 20-30 kts in NL appear more reasonable given the instability as opposed to NS where shear might be too strong for the available instability (effective shears of 30-40 kts).

 

Tomorrow appears rather quiet, western Labrador may see some elevated convection with as a shortwave from northern MB moves eastward along a zonal Baroclinic zone.

 

Thunderstorm outlook for today:

 

 

Thunderstorm outlook for Sunday: