Updating the Hurricane Season Forecasts

Back in the March/April time frame, the major institutions that produce hurricane season forecasts released their initial forecasts, most of them calling for a mild season.  While Weatherbell Analytics is a company that I think tends to get forecasts right, they're a subscription service and pricing seems to be aimed more at the companies who need an accurate forecast to stay in business than it is aimed at interested people in the general public.  Still, their chief forecaster, Joe Bastardi - who's also an author whose book I've bought - issued his preliminary forecast, too, and published it in a place where I could read and download it.  

Bottom line, Joe seemed most concerned with the red "Above Normal" area off the east coast of the US and especially that area from the NC coast up through Massachusetts.  He said he was concerned that the above-normal sea surface temperatures that are being seen in the Atlantic might lead to storms that form rapidly and come onshore with minimal preparation time.  When I look at a graphic like this, my interpretation is that anything that doesn't say Above or Below normal is probably looking at a plain old normal forecast.

Most forecasts were expecting this to be relatively quiet year.  They seemed to nod to the developing El Nino half of the Southern Oscillation cycle, which tends to keep Atlantic storms from organizing or strengthening.  Not all, but the "consensus of the science" was not a very active season.  The Barcelona Supercomputing Center and Colorado State University post this summary chart at SeasonalHurricanePredictions.org, which is a bit busy but understandable with a bit of explanation.  (There is much more information at that link and many ways to look at this data)

The horizontal scale contains the names of the various organizations making predictions.  The color code at the top explains, for example, the light green is a University's prediction, the light blue is a Government agency's and the fabulous pink is a private entity's prediction.  The distinction between long lines, shorter lines and dots show if the prediction includes a (wider or narrower) range or a single number.  The horizontal dashed lines are the low, normal and high numbers of storms.

For example, kind of in the middle horizontally is a group of three blue bars; left to right those are NOAA, SMN (I don't know who that is) and the UK Meteorology Office.  NOAA, for example seems to be predicting 5-9 storms, SMN is predicting 3-7 and the UK Met is predicting 8-14.  The yellow dot on the Y-axis, at 7, is the average prediction.  In this version of the plot these are the numbers of only hurricanes, not named storms.  Weatherbell, by the way, over on the far right, was predicting 5-7. 

As mentioned the other day, the season is off to a quick start, with TS Brett and Tropical Depression #4 currently active (the A storm was much earlier in the year - I think it was well out of the season, months ago).  Bret and #4 are MDR storms, which usually doesn't become active until late July or August.  The University of Arizona Department of Hydrologic and Atmospheric Sciences, the leftmost green bar, came out with their June update, and it's a doozy, joining the UK Met Office and Skyfora in calling for an extremely active 2023. (It's already in this graphic).  For the record, the UA has one of the better seasonal forecasting track records.

So what does this all mean? To be honest, I'm trying to understand it all, too, but it looks like the unusually high sea surface temperatures are overriding the tendency of the El Nino to suppress the Atlantic Hurricanes.  The El Nino charts on Watts Up With That don't show this to be particularly strong but we're also early into the El Nino phase of this ENSO (El Nino Southern Oscillation).  It looks like the deciding factor is going to be the relative strength of the effects of the El Nino versus the over 3 standard deviations high sea surface temperatures.