North Slope marine layer and Brook's Range Thunderstorms

Summer is moving forward up on Alaska's north slope.  The majority of the snow cover has melted, rivers and arctic lakes are opening up.  In response to some of our reader's queries about the recent warm spell affecting the 49th state I thought I'd share a little weather lore for the upper part of the state.  

The majority of Alaska is relatively warm now and will experience the warmest climatological weather in the next month or so (unless you are in the Aleutians when it comes much later).  That said the coastal areas are not as warm or lucky as the mainland.  In this article I am focusing on areas north of the Brooks however any community near large bodies of water will experience similar local microclimate effects.

Today it is bright and sunny across the majority of the North Slope.  As you can see from the infrared satellite, (courtesy of NOAA) northern Alaska has a large area of black north of the Brooks Range.  That dark color indicates warm air all the way to the ground.  Also interesting to note is the thunderstorms blossoming over the mountains.  Plenty of heat from the sun hitting the ground to allow convection along the spine of the mountains. There is additional instability support to the SW from a shortwave. Perfect recipe for storms! The coastal areas however are not near as dark as they are under the influence of the arctic marine layer.  The Arctic Ocean is still mostly frozen over and is reflecting a lot of solar radiation.  

The marine layer over the frozen ocean is cold, hanging around 32 degrees F which is a stark comparison to the landmass just to the south (60'sF).  See below picture courtesy of Ventusky.

One should note the cool greens near the coastal areas.  The winds are onshore, with a much colder marine layer invading coastal areas.  30's and 40's are spread across coastal areas while just a few miles inland its much warmer and in the 50's and 60's. Air inland from the coast being warmer and less dense is being forced to rise.  Colder, denser marine air is rushing in to replace it. Add in a little upper atmosphere instability, some low-level moisture and some elevation rise and it's the perfect recipe for thunderstorms. Here is another example of the marine layer pulled from Utqiagvik's afternoon weather sounding.  The strong June sun can't overcome the inversion caused by the marine layer.  Poor folks on the coast are still wearing winter hats while anyone to the south is in a t-shirt and shorts.

What would it take to get coastal areas to warm up and overcome the marine layer?  That would be the topic of another blog but needless to say it involves a south to north pressure gradient, with down sloping, offshore winds.  On a side note, the mosquitoes are not out yet, but I bet if I went 20 miles inland, they would be.  Thanks for reading!  Kaktovik Mike.