Heavy Rain, Heat and a Possible Tropical System Ahead for Newfoundland
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A very warm and humid stretch of weather is underway across Newfoundland, but the bigger concern over the next couple of days will be the potential for significant rainfall in parts of the province.
The highest confidence for heavy rain remains along the South Coast, where a widespread 50 to 75+ mm is possible through Wednesday. Some areas could see even more, with up to 90 mm possible in the Burgeo area.
Farther east, the forecast becomes a little more complicated.
A tropical wave currently east of Bermuda could develop into a tropical depression or tropical storm as it moves north-northeastward. If it becomes a named storm, it would be called Dolly.
The system itself is not expected to bring damaging winds to Newfoundland. The concern is the very deep tropical moisture associated with it and how much of that moisture gets pulled northward toward eastern Newfoundland Tuesday night into Wednesday morning.
Current guidance suggests a narrow band of very heavy rain could develop from parts of Placentia and Trinity bays across the Avalon Peninsula. Rainfall forecasts currently show roughly 30 to 40 mm in some eastern areas, but locally higher totals are possible if that narrow band of tropical moisture remains over one area for several hours.
There is still uncertainty. A relatively small shift in the track or timing could push some of the heaviest rainfall offshore, while a shift in the other direction could result in substantially higher totals across parts of eastern Newfoundland.
Before that happens, Tuesday will be very warm across much of Newfoundland.
The Avalon should see at least some sunshine, with temperatures in the mid to upper 20s around the St. John's metro area. Humidex values could climb into the mid-30s, and if we get more sunshine than currently expected, Tuesday could end up being one of the warmest days of the summer.
Showers and thunderstorms will also remain possible across parts of western and southwestern Newfoundland overnight before the rain threat gradually shifts toward the Burin Peninsula, Central and eastern Newfoundland during Tuesday.
The heavier tropical moisture should begin moving across eastern Newfoundland Tuesday night, with the greatest potential for heavy rainfall occurring overnight into early Wednesday morning. The system should then move offshore by around midday Wednesday.
Once we get through Wednesday morning, the weather looks much quieter. Much of Newfoundland is expected to see temperatures in the 20s through the remainder of the week, with a very summer-like finish to August.
I'll continue to watch the track of the tropical wave and the placement of the heaviest rainfall closely as the forecast becomes clearer.
The next forecast update will be tomorrow morning! Check back for updates!
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