The map above shows the paths of hurricanes and tropical storms in the North Atlantic so far this season. Each storm’s location is plotted at 6-hour intervals. The dots and small triangles show the intensity of the storm at that location, with red dots being the strongest and blue triangles the weakest.
We expected an above average number of hurricanes and tropical storms in the North Atlantic this year and the season is playing out as we thought it would. While the peak of the hurricane season is Sept. 10, there is still plenty of time for more tropical storm activity in October and even in (mainly early) November.
Here’s a list of the hurricanes and tropical storms of 2021 so far. The links to each tropical storm can be found here. We are down to the letter “V” with “Victor” in the Central Atlantic. Keep in mind we’re naming some storms that would not have been named in previous decades (before satellites). “Larry” was a tropical storm for 10 1/2 days, but “Danny”, “Julian” and Teresa for only 12 hours.
Check out the ACE Index (far right column). The ACE Index is a measure of the strength and duration of each storm. There’s a BIG difference from “Danny” at 0.2 ACE to long-lived “Larry” at 32.8 ACE. High winds are often a secondary factor in hurricane/tropical storm damage. “Sam” has been a big hurricane, but has stayed out in the Atlantic. Ida peaked as it came onshore in Louisiana. It’s been more than a month since Ida hit SE Louisiana and this early morning (9/30) there are STILL 5,022 customers without power in Louisiana. Sometimes a minimal tropical storm can stall and produce severe flooding and sometimes significant flooding can occur long after the storm has moved inland (Ida in New Jersey).
Here’s a summary of global tropical storm/hurricane activity in 2021 compared to (average). First, the number of storms in the S. Hemisphere is zero. That’s not surprising since it’s been winter in the S. Hemisphere.
While Accumulated Cyclone Energy (ACE Index) is above average in the North Atlantic (102.6 compared to an average ACE to date of 79.4), the Earth as a whole has a below average ACE Index (340.4 compared to an average-to-date or 383.0. Tropical storm activity in the North Atlantic represents only 20.7% of the total tropical storm activity in the N. Hemisphere. The NE Pacific (storms that form off the west coast of Mexico and generally dissipate before reaching land) represents 28.2% of total tropical storm activity in the N Hemisphere. The NW. Pacific represents 48.9% of N. Hemisphere tropical storm activity. This year the NW Pacific has an ACE-to-date of 140.9, compared to an average ACE-to-date of 187.2 – or 75.3% of average.
Meteorologists/Climatologists (inc. yours truly) were very confident in forecast these numbers (above average number of storms in the N. Atlantic and below average in the Pacific largely due to the continuing La Nina:
Here’s current sea-surface water temperatures compared to average. Blue is cooler than average, yellow to red is warmer than average. You can see the warm water off the Northeast Coast of the U.S. and the relatively cool water along the Equator west of S. America (that’s the La Nina – which is continuing for the 2nd year in a row. The warm water off the East Coast should continue to give the Northeast (and Great Lakes) warmer than average temperatures thru at least the first half of October (and probably the 2nd half of the month as well. The recent cold air coming off of Alaska has cooled the water just south of that state.
 Active Storms | Marine Forecasts 2-Day Graphical Tropical Weather Outlook | 5-Day Graphical Tropical Weather Outlook |
Hurricane Sam is a major storm. Fortunately the storm is missing land, just producing some heavy surf in the Leeward Islands and Puerto Rico. Sam should miss Bermuda to the east and stay over the Central Atlantic as two new tropical storms form and move west with the potential cause some trouble.
 Active Storms | Marine Forecasts 2-Day Graphical Tropical Weather Outlook | 5-Day Graphical Tropical Weather Outlook |
The NE Pacific remains unusually quiet as does the Central Pacific.
Here’s a satellite image of the NW Pacific showing typhoon (a typhoon is the same as a hurricane) “Mindulle” and depression 91W to the east.
Here’s the forecast path of typhoon “Mindulle”. This is a static image – if you want the latest track of the storm go here. “Mindulle” looks to stay far enough east of Japan/Tokyo to prevent any significant damage there.
Keep in mind that a recurving typhoon like this often leads to a cooler pattern for the eastern U.S. around 10-14 days down the road. It doesn’t always happen, but it’s certainly a forecasting rule and once in a while a rule like this catches a pattern before the weather computer models do.
The latest 8-14 day temperature forecast from the Climate Prediction Center continues to show warmer than average weather for much of the U.S. including all of the Great Lakes. I’m on record forecasting overall warmer than average weather in October. Sometime in Nov. we should flip to a more average or cooler than average pattern, which should usher in a cooler and probably snowier pattern for early winter. You can also see the cool weather for the Pacific NW (ties in with the cooler-than-average water temperatures off the NW Coast) and also for Alaska – where it’s been cold and relatively snowy this last week of September.
The 8-14 Day Rainfall Forecast from the Climate Prediction Center continues to give drier than average weather for the Great Lakes for Oct. 5-11.
In the meantime…(mostly) sunny and dry for Tuesday – Thursday with clear, cool nights. Showers are possible next weekend with a little cooler pattern for next week.
