Convective Outlook Valid for Today, Tonight and Tomorrow

Regional Impacts

TODAY

NS+NB+PEI: Widespread thunderstorms and synoptic rain is advancing from west to east early in the day as forecast. Hazards – lightning, and heavy rain has been observed. A local rainfall warning and SWS remain in effect at this time.

Annapolis Valley of NS: Repeated rounds of convection continuing this afternoon. Hazards – torrential rain possible. Watches may be required if atmosphere destabilizes further.

 

TOMORROW

Gulf waters and Nfld: Thunderstorms with high mid-level moisture leading to persistent heavy rain. Hazards – heavy rain.

 

 

Convective Discussion

Ongoing convective rain is spreading across the Maritimes as the trof moves east. The jet axis placement is a very important feature today. Heaviest rain is falling just north of it. And a second round of convection is forecast to develop south of it. This axis at 10am lies across the Bay of Fundy. Rain in NB will end from west to east this afternoon. Rain in PEI will continue for much of today. Northern and central NB will see convection bubble up again under a partial clearing this afternoon. LL helicity in the Keji area of NS will play into the strength of possible squall line this afternoon that the HRRR depicts, if it can hold together. LL moisture is ambient, and mid-level moisture is also over 40. These dynamics drift over Gulf of St Lawrence waters tonight and into Nfld tomorrow morning. Heavy rain is the expected hazard on day 2. Isolated waterspout formation across eastern maritime marine areas is also likely this evening and tonight. A watch may be issued this afternoon for marine interests.

 

Thunderstorm Outlook for Today

 

Thunderstorm Outlook for Tonight

 

Thunderstorm Outlook for SATURDAY

 

Forecaster: TIRONE

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