Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

Slight risk of an afternoon thunderstorm over parts of Labrador: northwest of Wabush-Churchill Falls today; and then over western and central regions Tuesday.

 

Convective Discussion

Another round of thunderstorm activity is expected today in a warm and somewhat unstable airmass supported by a light to moderate southerly flow over northern Quebec. An upper trough over Hudson’s Bay extending SEward and a 60kt southerly upper-level jet will serve as the main trigger mechanism. Forecast guidance is suggesting surface-based CAPE values between 200-500 J/kg in an elongated area from Ungava to near Schefferville, lifted indices 0 to -2.

There has NOT been any lightning detected since Sunday evening near the upper low centre currently located over Laurentian Fan. That system produced a large rain band which affected most of the Maritimes yesterday and last night as it travelled westward, it now extends from northern NB to Lurcher and is weakening.

 

Thunderstorm Outlook for Today

 

 

 

Thunderstorm Outlook for Tonight

 

 

 

Thunderstorm Outlook for Tomorrow

 

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

Just a slight risk of a thunderstorm this afternoon (and Monday afternoon) north of the YWK area.

 

Convective Discussion

A short wave will move across northern QC today giving some scattered thunderstorms, which will likely drift into western LAB this afternoon and evening…but should remain north of the YWK and Lab City area. Looks like the possibility of another isolated TSRA again Monday afternoon, though the support is much less for that to happen. OTWZ nil sig wx to talk about due in part to that retrograding low south of NF.

 

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for Tomorrow

 

Jeremy

Convective Outlook Valid for Today , Tonight and Tomorrow

Regional Impacts

Slight risk of a TSRA Sunday afternoon and evening north of the Wabush/Lab City area.

 

Convective Discussion

Quiet weekend in store across the region today as we deal with a developing cut off low that will lurk south of NF likely for the next 5 to 7 days or so. A plume of moisture currently streaming northward into NF today and tonight could produce a very isolated embedded flash or 2 but that would be about it. Aside from that there will be a short wave trough pushing across northern QC on Sunday that could lead to an isolated TS drifting into western LAB, but that would be north of the Wabush/Lab City area.

 

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

 

Thunderstorm Outlook for Tomorrow

 

Jeremy

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

 

NS/NB/PEI/NL… None

 

Convective Discussion

 

As an upper trough stalls over the Maritimes today, cold dry air will usher in from northern Quebec dropping dewpoints to the low to mid single digits. Dry low levels in conjunction with minimal wind shear will likely inhibit any thunderstorm development today across the Maritimes. A warm nose above 600 mb will inhibit much vertical development over central NS, however some isolated TCU are still possible. Extreme western New Brunswick may also see some isolated TCU this afternoon, but extremely dry low levels will likely prevent any development. The only area that is likely to see any lightning will be well offshore, closer to the 500 mb jet southeast of Nova Scotia.

 

Similar dry conditions are expected again tomorrow under the stalled upper low, with no thunderstorm development expected.

 

Thunderstorm Outlook for Today

 

 

Thunderstorm Outlook for Tomorrow

 

 

Copp

Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

 

Nova Scotia… Slight risk of an isolated thunderstorm over southwestern Nova Scotia early this afternoon, with the main risk being heavy downpours of 15 mm/h.

 

Convective Discussion

 

A small shortwave moving over New England this morning will cross the Maritimes this afternoon. This feature, in conjunction with a 55 knot 500 mb jet south of Nova Scotia will provide ample lift for some isolated convection over portions of southwestern Nova Scotia early this afternoon. Models have been under-forecasting dewpoints in this part of the province this morning by about 5 degrees, so MUCAPE values may exceed the 500 J/kg that the models are currently forecasting, increasing the likelihood that convection may occur. One of the limiting factors will be bulk shear values increasing to over 60 knots by late this afternoon, which may shear apart any convection that does fire earlier in the day. Any storms that do develop are likely to be short lived, with heavy downpours of 15 to 20 mm/h being the main hazard.

 

A colder airmass over northern Quebec will move south tonight, cooling the mid to upper levels. Provided ample clearing tomorrow morning, a lightning strike or two cannot be ruled out over central Nova Scotia, where there is more wind shear to work with. Thus said, the risk remains very low.

 

Thunderstorm Outlook for Today

 

 

Copp