Flash Flooding Rains and Tropical Storm Force Wind Gusts With Near-Record High Temperatures to Roll in the Month of December
/Issued: December 1st, 2020 @ 4:30 AM
Updated: December 1st, 2020 @ 4:30 AM
Forecaster: James Follett
Good mild morning on this 1st December day! Wow, can you believe it, already in December, seems time went fast, but it sure doesn’t feel like it, we didn’t have much of a fall so far.
It may be the first of December, but we are on storm watch as a large slow-moving storm is going to unleash Widespread flooding rains and Tropical Storm force wind gusts.
So far this morning, wind gusts have reached over 90 km/h, in Brier Island at 91 km/h. Yarmouth and many other areas have already climbed to 78 km/h. These winds will continue to rise as the day and night go on.
It will be Wednesday morning by the time we start to see some clearing, and even then we’re going to see more showers and periods of rain arrive Wednesday Night into Thursday. By the time it is all said and done, many areas of the South coast can see as much as 140 mm of rainfall. Elsewhere in the province, there are amounts of 30-50mm and as much as 75mm closer to Halifax.
We will get to the Forecast rainfall in just a little bit, but first, we will go through the power outages.
High winds this morning have been disrupting powerline wires and bringing some trees down. as of this morning at 4:30 AM, there are 6 active power outages with 4,275 customers without power this morning.
There are fewer than 5 customers in the dark this morning near Kemptville. Clarence East has also fewer than 5 customers in the dark. The number of customers without power goes much higher as we get towards Kentville, where over 4,220 customers are without power this morning and in Seabright this morning, there are 52 customers without power. ETA times for everyone are set for 8 AM as of right now, and all are caused by high winds.
We already have power outages in the province this morning, but lets look at the probability of them! Yarmouth, Digby, Bridgewater, Liverpool all have possible outages, which of course is already occurring, but this is for Today and tonight and through Thursday.
From Greenwood to Antigonish, there is a slight chance for more of a isolated outages. We already have large power outages in near Kentville this morning.
The reason for power outages is due to high winds and very heavy rainfall.
Speaking of rainfall, let’s get to the timing of this system!
For this morning, we are looking at very heavy rainfall for Yarmouth through Digby, this is where the rainfall rates at times can exceed 15-20mm/hr! From Shelburne to Truro and near Amherst, heavy rain will slowly move in and some moderate to light rain for remainder of the province.
As we get towards the Afternoon hours through the evening hours, this is when we see the very heavy extreme rainfall that will create some flooding problems and flash floods. Rainfall rates at times will exceed 30mm/hr. Heavy rain spreads as far as Halifax, Light to Moderate rain continues for Northern parts of the province.
even through the overnight hours we will continue to see flooding extreme rainfall amounts. as much as 25 to 45 mm/hr rain rates are possible leading to a high threat for flash flooding and rising water levels in the rivers.
By Wednesday morning, we will have seen the heaviest rain move out, however Heavy rain will continue to fall in the southern sections. and light to moderate for much of the rest of the province.
As the system slowly moves away, we’ll see clearing conditions for the late day hours in the south, some light rain and drizzle sticking around. all that heavy rain moves north impacting Halifax to Amherst and Truro. Moderate rain towards Antigonish and still light rain over Cape Breton.
By Evening and overnight Wednesday, another round of rain, mostly moderate will swing back in the southern portions of the province from Greenwood to Yarmouth. and some remaining left over showers over Northern and Cape Breton.
So how much rainfall can we expect?
This is one of the Canadian models we use, the RGEM, goes out towards 4 days. This model suggests that as much as 140mm will fall in Yarmouth with up to 100 mm in Digby and rest of the south shores. 40 to 80 mm from Halifax North and South. Then once we get towards northern portions of the province, we see rainfall amounts of 15 to 30 mm.
This is our North American Model, or “NAM” The Nam model shows that by Thursday evening, upwards of 80-90 mm can fall. with Northern parts of the province seeing only 10-20mm, except for Cape Breton where 20 to 30 mm still would fall.
One of the Ensemble weather models the ARW models, shows that up to 80 mm by Thursday evening, and up to 25 mm for Central then a lot for Cape Breton with as much as near 50 mm.
WRF ARW model ensemble showing 70-90 mm with up to 50 for central, and 20 to 40 mm over Northern and Cape Breton.
The king of models the ECMWF is suggesting also a good 60-80mm of rainfall. and much lesser amounts North.
then we have the GFS, Global Forecast System. The GFS has over 100 mm of rainfall
Lastly we have the ICON model, this shows a good 100+ mm for the south. So basically the models are split on decision of rainfall forecast.
Up to 140+mm of rain is possible!! otherwise looking at a wide swath of 75 to 125 mm! or 3-5”, could see some areas maybe getting 6” of rain! For Greenwood, Kentville, Halifax, Truro, and Amherst… look for 40 to 75 mm of rainfall by Thursday. Elsewhere in province, look for 15 to 30 mm.
Most of the highest rainfall projections are likely cause of the probability of thunderstorms!!! Risk of thunderstorms through Thursday, A light Isolated risk of severe risk thunderstorms in Yarmouth where some strong wind gusts, and pea size hail and very torrential flash flooding rains can be expected in those storms. Otherwise, a non-severe risk of storms all the way up towards Amherst.
Along with the rain is also the very high winds. because of the center of the low, the highest winds will be on the coast from Yarmouth to Digby where winds could occasionally gusts up to 105 km/h. We already seen gusts up to 91 km/h this morning in Brier Island. For everyone else, winds gusting of 70 to 80 km/h is expected.
For the month of December on the first day, it sure does not feel like it! in fact as of right now, we have temperatures as warm as 15 degrees this early morning.
Temperatures will be in the 15 to 20 range, and I do think some folks MAYBE will flirt with 20-degrees! If it does happen, it will be inland mainland areas near Kentville and Greenwood. Highs there nearing 17 or 18 is very likely.
For Cape Breton, southern parts will see up to 15 degrees, while the north stays cool with highs near 10.
Let’s take a look at the Southern Regional Forecast!
For Yarmouth, looking at some very heavy rain and embedded thunderstorms, warm! 15 degrees, still mild tomorrow with more rain and showers, some clearing in the afternoon. cooler but mild! highs of 9, cloudy, drizzly and misty and cool! on Thursday highs only getting up to 6, which is only 1 degree above average. 9 on Friday under sun & clouds and 8 on Saturday with more showers! So staying fairly mild for 1st week of December! and also very wet.
For Digby, Flooding rain and thunderstorms today, 15 degrees, 9 tomorrow with sun and clouds, chance of showers on Thursday and chilly with highs of 5. 8 Saturday with sun and clouds and 6 on for Saturday with a chance of showers returning.
For Shelburne, Heavy flooding rains and embedded storms today, highs of 14. Cloudy and misty tomorrow and Thursday. highs of 9 tomorrow and 6 on Thursday. 10 on Friday with sun and cloud and 8 on Saturday with more showers.
And lastly for Queens! 13 today under heavy rainfall and gusty winds. showers tomorrow, and Thursday. 9 tomorrow, 6 on Thursday. back up to 10 Friday with sun and clouds, return to misty conditions on Saturday and 8-degrees.
Here is your Halifax 7-day Forecast!
Temperature wise…. for the first week of December it is not so bad! but it is going to be very wet and unsettled this week.
Rain today at times heavy and Gusty winds of up to 80 km/h. rainfall amounts as much as 75 mm by Thursday evening. Highs of 15
Tomorrow, still mild! 14 with more rain and wind.
we cool down on Thursday with more showers and sprinkles, remaining breezy. Highs only at 7
10 on Friday with sunny breaks returning.
Saturday is showery and mild. 8-degrees
Sunday is at 13! with another storm system possibly!! this one will need to be watched as the track is a bit close, and will be tapping into cold air, so we could be seeing a messy winter storm or a rain storm. but as of now, a chance of heavy rain and gusty winds.
Monday, Rain turns to snow! windy and turning MUCH colder! we go from 13 on Sunday to -2 on Monday, start the day at near freezing then temperatures will fall during the day. plan on wind chills into the -5’s to -10’s!
