Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

TODAY

Interior of NFLD: Chance of isolated thundershowers in the triple point of an advancing low. Hazard – lightning.

Western NB: Chance of isolated thunderstorms later today as a ridge destabilizes with daytime heating. Hazard – lightning.

 

TOMORROW

NS+NB+PEI: Widespread thunderstorms are expected to advance from west to east early in the day. Hazards – lightning, and heavy rain likely.

Annapolis Valley of NS: Repeated rounds of convection beginning in the overnight and continuing Friday. Hazards – torrential rain possible.

 

 

Convective Discussion

The chance of thunderstorms in western NB this evening and overnight is the precursor to the more widespread heavy rainfall event. Rainfall rates this evening are only forecast to be near 5mm per hour. The HRRR has the main system timed thru mid-morning for central Nova Scotia, and out to Cape Breton by Friday afternoon. Very high dew points and mid-level advected moisture will bring high rainfall rates. Pwats in the RDPS are near 35mm. Uncertainty still remains in the highest rates and totals. The location could shift slightly south into NS over slightly north into coastal NB. Parts of the Maritimes are vulnerable due to repeated high rainfall events in the last 2 weeks. This is being kept in mind by forecasters as this event nears.

 

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for FRIDAY

 

Forecaster: TIRONE

Recall: Convective Outlook Valid for Today , Tonight and Tomorrow

Lemmon,Mel (ECCC) would like to recall the message, "Convective Outlook Valid for Today , Tonight and Tomorrow".

Convective Outlook Valid for Today , Tonight and Tomorrow

Correction for a typo…

 

Regional Impacts

Today…

NS, PEI and NB… Thunderstorms giving locally 25mm today. Gusts to 70 km/hr.

Southwest NS… Possibly heavy downpours this afternoon in thunderstorms, 25 to 50mm.

 

Convective Discussion

 

There are two main areas of convection today, the first area of thunderstorms is the embedded convective activity with the front that is already over eastern NS. The intensity of the convection has diminished from the overnight period where heavy rain impacted western and central areas and is not expected to re-intensify today. It is however still possible to get some heavier embedded showers and gusts in thunderstorms to 70 km/hr or slightly higher.

 

A second weak trough currently tracking towards the western NS will be the potential trigger for afternoon thunderstorms. High precipitable water and most unstable CAPE values over 1000 J/kg could bring some potential for heavy downpours. The wind shear will not be significant in terms of prolonged severe thunderstorms but could be sufficient to allow the initiation of back building thunderstorms. Watches are not likely to be required but may be sent out if the potential for heavy rainfall develops.

 

 

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…

NS, PEI and NB… Thunderstorms giving locally 25mm today. Gusts to

Southwest NS… Possibly heavy downpours this afternoon in thunderstorms, 25 to 50mm.

 

Convective Discussion

 

There are two main areas of convection today, the first area of thunderstorms is the embedded convective activity with the front that is already over eastern NS. The intensity of the convection has diminished from the overnight period where heavy rain impacted western and central areas and is not expected to re-intensify today. It is however still possible to get some heavier embedded showers and gusts in thunderstorms to 70 km/hr or slightly higher.

 

A second weak trough currently tracking towards the western NS will be the potential trigger for afternoon thunderstorms. High precipitable water and most unstable CAPE values over 1000 J/kg could bring some potential for heavy downpours. The wind shear will not be significant in terms of prolonged severe thunderstorms but could be sufficient to allow the initiation of back building thunderstorms. Watches are not likely to be required but may be sent out if the potential for heavy rainfall develops.

 

 

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

NB/NS/PEI/NL/Labrador: None

 

Tonight

NS/NB: Thundershowers giving local downpours.

PEI/NL/Labrador: None.

 

Wednesday

NS/NB/PEI/NL: Thundershowers giving local downpours.

Labrador: None

 

Convective Discussion:

A low approaching from the Great Lakes area will track across the region on Wednesday. There are already rainfall warnings in effect for areas of New Brunswick and they will be expanded to the southwest and issued for areas of central and western Nova Scotia. No surface based convection is expected however the mid level instability ahead of the low is quite significant and is represented in very low Showalter indices.  Gusty winds up to 60 km/h are possible. PWAT values of 40-50 mm enhance the downpour threat and that is evident in observations currently coming out of areas of New England where 25 mm/hr or higher have been reported.

 

Thunderstorm outlook for today:

 

Thunderstorm Outlook for Tonight:

 

Thunderstorm Outlook for Tomorrow: