Severe Weather Threat Tuesday+Return Of Summer By Weekend

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LOOKING FOR AUTUMN LIKE......

We've had some cool days here and there so far this season but REAL Autumn is nowhere to be seen. As I am sure you've noticed, foliage is way behind. See this post from last week for some of the science behind how weather impacts foliage.

TUESDAY'S THUNDERSTORM THREAT

Another warm day is on the way Tuesday and it will be more humid as well. Meanwhile, a cold front will push into the region during the afternoon. It's not the strongest front in the world but it'll be strong enough to trigger some showers and thunderstorms. Here's a high-resolution model depiction of the radar over the next 24 hours or so.The main threat appears to be between 4pm-8pm. Any storm will be capable of producing strong winds and hail.

VERY WARM WEEKEND AHEAD

By the weekend, a very strong ridge of high pressure will park over the East. In July, this kind of pattern produces highs in the mid 90s here. It's October so temperatures will climb into the 80s. Highs will be almost 20 degrees above average by Monday and Tuesday.When does the pattern break down? Maybe not until mid-month.

WE DID THIS JUST LAST YEAR

The first half of October 2017 was also very warm with lots of highs in the 70s and 80s. 

How 2018's Fall Foliage Season May Shake Out

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It's many people's favorite time of the year: football season, crisp, cool nights, pumpkin patches, hay rides and of course fall foliage. Autumn can be spectacular around here, but the quality of the foliage season can vary from year to year.

WHAT MAKES FOR A GREAT FOLIAGE SEASON?

1) A WET EARLY GROWING SEASON

If dry conditions prevail in the spring and early summer, there is an increased risk of leaves dropping before they reach peak color in the fall. This year, we DID have a pretty wet period from April-June.

2) SUNNY DAYS AND CLEAR NIGHTS LATE IN SUMMER AND EARLY IN AUTUMN

Here's where we may be in some trouble this year. September has been quite cloudy and wet across the area. In fact, it's been the wettest September on record. 

3) CALM, SUNNY DAYS IN OCTOBER

What we don't want in October is a bunch of rainy, windy days, especially later on the month. Those conditions will help pull down leaves and lead to a muted foliage season.  In the first half of the month, cool and dry days and nights would be ideal. Welp:Early October is looking pretty warm overall.

SCIENCE OF FALL FOLIAGE

Why do leaves change color? It's all about chlorophyll. That's what gives leaves their green color. But leaves have other pigments as well and as daylight decreases in the fall, chlorophyll quickly depletes. This allows those other pigments such as yellow, red, orange, etc to show up.

CURRENT FOLIAGE STATUS

We are not seeing much color yet locally. Pockets here and there but overall it seems like we already running behind schedule a bit.Colors are most noticeable in areas well north of us, mainly in the mountains.Peak colors typically occur in mid-to-late October around here. Sometimes we see a peak around October 16-23, sometimes more like October 22-31. I suspect we'll see the latter this year. 

Some Very Early Thoughts On Winter 2018-2019

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It's still (astronomical) summer and it's going to feel like it for the next handful of days with warm, humid weather in the forecast. It's WAY too early to put out an official winter forecast. But I thought I'd share a few thoughts on the upcoming winter anyway. With the important caveat:

THIS IS NOT A FORECAST.

THE OFFICIAL WINTER FORECAST WILL BE ISSUED ON AIR AND ONLINE AROUND NOVEMBER 1

Ok, now that we have that out of the way. This post will not dive into ALL the factors that I surely will be looking at when I compile the forecast in 6 weeks. I'll just touch on a couple here.

#1 The Winter Is Likely To Feature A Weak El Nino

Remember, El Nino is a phenomenon having to do with water temperatures in the Pacific Ocean and how they compare to average. El Nino is a warming of the waters in the eastern Pacific, near the equator. What does this have to do with our weather?? Well, the oceans and the atmosphere are one big system and what happens in the oceans can influence how the atmosphere behaves.Right now odds favor an El Nino this winter although the odds of it being a "neutral" winter are not negligible (at 31%).  The strength of an El Nino is important. Weak El Ninos tend to result in more "surprises" and more variance than strong ones. In other words, the range of outcomes is greater than during a winter featuring a strong El Nino.The location of the warmest water (compared to average) is also important. A "standard" El Nino sees the warmest water banked up against South America. But there is a special flavor of El Nino called "modoki", which sees the warmest water farther west.These 2 flavors of El Nino often produce winters over the US that are quiet different.   Odds favor a "modoki" this winter.Modiki: 

#2 The "QBO" Or Quasi-biennial Oscillation Is Going From VERY Negative (Easterly) To Near Neutral

Say what? The QBO refers to the oscillation of river of air at very high altitudes in the atmosphere. It switches directions at regular intervals and has been shown to have an impact on weather patterns in the northern hemisphere winter.  It was very "negative" or easterly last winter through this summer but is trending back toward neutral.Again, so what?

Winter Outlooks Are Largely Based On Looking At The Past

Making a seasonal forecast is tough but thankfully we have lots of data to look at., including detailed records of the past. So, we look for years with similar setups and see what happened. For the purposes of this post, I'll just look at past years with weak modoki El Ninos and a QBO trend similar to this fall. When I do the "real" forecast, I will be looking at much more than this.Temperatures (averaged together) during winters with weak modoki El Ninos:Finding years with a weak modoki El Nino AND a QBO trending from very negative back toward neutral is tough. Only found a few. Average them and you get this:Precipitation anomalies: Using these factors alone, the winter of 1968-1969 is the best overall match. Temperatures that winter:Pretty cold winter. Snow was nothing to write home about. A bit below our average in the lower/mid 60s actually.Again, the forecast will come out sometime around November 1. This just gave you a little peek behind the curtain. I love the challenge of the winter forecast and look forward to trying to beat the atmosphere this year!   

Review of Summer 2018

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Meteorological summer will end as September arrives Saturday morning. This summer will go into the record books as a hot one with highly variable amounts of precipitation. Let's look at the numbers.At the YNG airport, rain totals will finish between 3/4" and 1" below average. Temperatures will be a little more than 3 degrees above average.2018 was the warmest summer since 1995, just edging out 2016 and 2005.Rain totals will end up below average at the airport but some places had a lot more rain. That rainy spot in southeastern Mahoning County is of course due to the deluge that occurred over the course of a few hours a couple of weeks ago.Notice how northern Trumbull and Mercer look wet? Much of that was earlier in the season. It's been dry in those locations lately.In fact that zone is in the "abnormally dry" category on the latest drought monitor.2018 was the 2nd consecutive summer with below-average rain. This follows a streak of 5 straight wet summers.Meteorological summer may be ending but I think September will bring a continuation of the very warm pattern. 90 degree temperatures will be possible next week.