A Peak Into The Fall Season

Baltimore,MD - Ahh the fall season!  Pumpkin spice, pumpkin drinks, college football, cool nights and warm days, and the return to dark evenings!  Fall is my favorite season of the year! However, fall can be a very challenging time of the year to forecast weather in Maryland.  

In an age of evolving technology and a better understanding of the dynamics behind our weather; we are able to look into the future to see what the long range forecast may hold. The Japanese, Canadians, Europeans, and America's all run special forecast models to sniff out patterns that may unfold going into the next 30 -60 days.  Some models can actually show trends going 90 days into the future.  While the accuracy range between 40% to a meager 5%, the general idea of long range forecasts make for interesting reads!

In this blog I will introduce you to the CFS model, a forecast run by the National Oceanic Atmospheric Administration. The CFS model samples all the interactions between Earth's oceans, land, and atmosphere. The accuracy of this model preformed rather poorly last year when it predicted an average year of temperatures and snow while the end result was well above normal temperatures and NO SNOW! 

While a forecast model should not be taken as gospel to a forecaster, the guidance and trends is something we can work from in order to generate a long range forecast.

The CFS model going into September paints a very interesting picture in respect to overall trends segueing from this month into September.  Since August 1st, our pattern has flipped from brutal heat and humidity to more of a trough over the eastern third of the nation.  Our temperatures have been running near normal while rainfall has come back closer to normal (for the month).  What this says to me is a pattern change is in play and the high heat continues to manifest itself over the south central portion of the country where it may stay.

The CFS says this pattern looks to continue as we head into September.  (See Picture on top left).  The North Atlantic Oscillation or commonly referred to as "NAO" ( a pattern we look at that directly influences our daily temperatures) continues to stay negative where it presently resides.  This indicates to me a trough or area of low pressure will settle over the eastern third, keeping the high heat to the west of us! The CFS has picked up on this idea and has modeled this through much of the month of September into October.

In situations like this we will have to watch the tropics very closely. While the high heat of the oceans remain, cooler air and storms moving south like to interact with the high ocean heat content allowing for "home grown" storms to form (storms close to the coast). On the flip side, a trough over the east will BLOCK any western moving storms through the western Atlantic recurving them well offshore! 

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