Cold Weekend, Cold Winter?

COLD WEEKEND!

The weekend we just enjoyed was a cold one.

On Saturday (OCT 28) the high temperature was 41° tying the record Cold High Temperature set in 1910.

On Sunday (OCT 29) it was even colder. The high was only 39° but the record Cold High Temperature for that date is 34° set in 1925.

The last time we had a high temperature as cold as 39° was March 15, 2017 when the high was 33°.

Of course you have to have chilly air to have a high of 39° but chilly air can warm 20° with bright sunshine.

Thick Weekend Cloud Cover

The key to the weekend chill is thick cloud cover working with the chilly air. The cloud cover above us Saturday was 18,000 to 20,000 feet thick (or a bit more).  Enough sunshine gets through to brighten the night sky but not enough to warm the ground which warms the air.

Thick cloud cover  kept the air cold over the weekend.

The clouds were not as thick on Sunday, but thick enough that the weak, late October sunshine could not mix them out.

"Mixing out" means surface heating by the sun causes thermals of warm air to rise. If air rises it has to sink nearby to replace the rising air. This exchange mixes the moist air in the clouds with drier air and the cloud layer can thin or completely evaporate.

In summer clouds mix out much more easily because of the strong sunshine than in the other seasons.

COLD WINTER?

Now to answer the question from Steve Horstmeyer's What's It Mean Meme #2.

One weekend of cold weather is not evidence that an entire season will be cold.

Now if we see the pattern that caused the chilly weekend persist and cold days are becoming common it could signal a trend.

For now we have to watch the  La Niña that is strengthening in the Equatorial Pacific.

More on that and other winter trends as they develop.

-Steve Horstmeyer

Wooly Bear - or - Wooly Bull?

Does the Wooly Bear predict the severity of the coming winter?

The short answer is no!

Wooly Bear caterpillar at Otto Armleder Memorial Park October 27, 2017

FOLKLORE

Folklore tells us more black means a longer, colder snowier winter and the position of the black tells you what part of winter will be the biggest headache. The Wooly Bear in the photo is black at its head and tail-end so tradition tells us winter will have a harsh beginning and end but a  long, mild, uneventful middle.

The Wooly Bear's body has 13 segments which tradition tells us correspond to each of the 13 weeks of winter. 

FOLKLORE HISTORY

Wooly Bear folklore has a rich, long history and has it origins in Colonial America.  

The year 1938 was a banner year of the Wooly Bear myth. 

In that year Dr. Howard Curran, curator of entomology from the American Museum of Natural History, went to Bear Mountain State Park, up the Hudson River from New York City,  He counted the brown bands on 15 Wooly Bears and made the first winter prediction based on the caterpillars that eventually become Isabella Tiger Moths.  

The story was published by the New York Herald Tribune and picked up by the national press. 

NAMES

Wooly Bear - Northeast U.S.

Wooly Worm - Southeast U.S.

Hedgehog Catepillar - because it often curls up in a defensive position when touched

What's Really Going On?

The amount of black and orange-brown depends on the age and species of the Wooly Bear. If the eatin' has been good during autumn there is more black and less orange-brown.

The Wolly Bear is telling you something, but it is about the recent past not the future. Good-for-caterpillar conditions mean fat and healthy Wooly Bears and more black not a harsh winter.

Isabella Tiger Moth (Pyrrharctia isabella) - the second part of a Wooly Bear's life.