Tuesday, October 11, 2016

If Hurricane Matthew Rain Was Snow, How Much Snow Would You Have?

13.6 trillion gallons of water fell on the 5 state region (Florida, Georgia, North/South Carolina and Virginia) from Hurricane Matthew. This amounts to only 1% of the total rainfall across the continental United States this year. Hat tip: Ryan Maue

Rainfall through early October
It's very hard to wrap our minds around what a trillion gallons of anything looks like. But what if this water was lake effect snow?  How much would it amount to?  How much snow would cover the entire state of Ohio?

Here is how you would calculate this:

Ohio covers 44,852 square miles. This is roughly 1,250,400,000,000 square feet

Convert 14 trillion gallons of water to cubic feet gives us 1,818,055,555,556 cubic feet

Divide the two and convert to inches yields roughly 17 inches of water over the entire state of Ohio.

In order to convert the water to snowfall, we need the snow ratio.  That is the amount of snow per one inch of liquid. The problem is lake effect snow can have a ratio from 20 to 1 to almost 40 to 1 depending a variety of factors.  So let's take the lower conservative end:  20 to 1.

This gives us......drum roll please...

28 feet of lake effect snow over the the entire state of Ohio

Thursday, October 06, 2016

Hurricane Matthew: VERY Strong Statement from the NWS

I haven't seen a National Weather Service discussion with language this strong since Hurricane Katrina 11 years ago:

Statement from the National Weather Service office in New Orleans before Hurricane Katrina:

Tuesday, October 04, 2016

PART II - Northern Ohio Summer Recap

Summer Recap - PART II

Summer of 2016-17 was the warmest on record in Cleveland and at many recording stations across northern Ohio.

Graphic Courtesy NWS Cleveland

Regarding how you define summer (see Part I in previous post), it was the warmest ever!
Summer temperatures versus average over the last 10 years. 2010 and 2012 were the closest to this past summer.

The top 10 warmest summers for historical perspective show five of the top ten warmest summers have occurred since 2000.

We typically remember past weather for its extremes not averages. Although we didn't break many daily records, the warmth was steady both day and night.

 Second most number of days at or above 85 degrees ever!

Very warm overnight lows.

Humidity levels measured by dew point wasn't as high as most thought. 2010 and 2011 featured more higher humidity days.

Relative cooler days were few and far between...

Our rainfall was well below normal for the first time since 2012, driest since 2002. Four of the last six summers have had above normal rainfall.

Many use the drought year of 1988 as the standard for which we measure very dry summers. Interestingly, this summer's rainfall was nearly identically to 1988.  Yet 2016 and 1988 didn't crack the top 10 driest.

Summer rainfall varied from place to place. Only Mansfield made it into the top ten driest on record. Cleveland 26th and Akron 35th.

The storm track took the majority of the rain and storms through the heart of the corn belt.

Purple colors indicate above normal rainfall

We forget that 2002 and 1991 were consistently drier than 1988 and 2016 even into the fall. This year, the rainfall deficit has improved with recent late September rainfall.

In my next post, I'll talk about how the above average Lake Erie water temperatures this summer compare to warm summers of the recent past and how that might impact lake effect snowfall.



Thursday, September 29, 2016

Part I - The Most Complete Summer Recap You'll Find Anywhere!

The autumnal equinox has come and gone. Summer is now officially over.  So it's time for the ANNUAL SUMMER RECAP.

First, how do we define summer?  There are three definitions of summer I believe cover it. Meteorological Summer which stretches from June 1st through August 31st. Meteorologists and climatologists use this three month period to keep historical data consistent. Astronomical Summer is defined as the period from the summer solstice (around June 21st) to the Autumnal Equinox (around September 2nd). This is what you see on the calendar.  Rarely does it correspond to the actual weather conditions. The third definition of summer is one that is closer to home for most us.  I like to call it Sensible Weather.  It's defined as our perception on when summer begins and ends usually marked by a holiday or big event, sometimes weather related.

In order to keep my summary consistent with National Climate Data Center standards, I used Meteorological Summer weather data between June 1st and August 31st.


First the National Recap...

Our initial outlook was for temperatures to stay above normal this summer. The temperature analogs taking into account ONLY summers after strong or super El Ninos with a weak El Nino state in late spring yielded this result. Warmer colors indicate above normal temperatures.

In reality, the result was a bit different especially across the west and New England:
  • Per the NCDC (National Climate Data Center) recap: Every state across the contiguous U.S. had a statewide temperature that was above average June through August. 

  • California, Connecticut and Rhode Island each had their warmest summer on record. 
  • Alaska observed its second warmest summer in its 92-year record. The contiguous U.S. average maximum (daytime) temperature was the 10th warmest on record.  The contiguous U.S. average minimum (nighttime) temperature was the warmest on record. 
  • Ohio had a record warm summer minimum temperature at 63.2°F, Almost 4°F above average surpassing the previous record of 63.1°F in 2010
  • Based on NOAA's Residential Energy Demand Temperature Index (REDTI), the contiguous U.S. temperature-related energy demand during summer was 147 percent above average and the third highest value on record, driven in large part to warm temperatures across the densely populated Northeast.

Alaska had only 2 days with below normal temperatures this year based on 25 stations. The second occurred on September 25th.

A quick look at the last five summer temperatures vs normal shows a large part of the central US has had at or below normal temperatures over the last 3 summers. 2012 was warmer overall.

Early summer heat in 2016 was confined to the western US. 

Notice the below normal temperatures in the corn belt in July which ran coincident with above normal rainfall (more on that shortly).

The core of the heat in August settled into the eastern US especially the Ohio Valley and New England.

I compiled the temperature departures nationally for each day of the summer. The waves of heat and cool are very evident.
Surface Temperature Anomalies from June 1 to August 31st
The 500mB heights and the jet stream position was north through the central US and Great Lakes in June. Tornadoes this month were well below average since 2007. Yet the tornado coverage was mainly along the jet stream across the northern Great Plains and Ohio Valley.

The jet stream shifted further south in July as the western ridge was pushed south. Notice the Bermuda High establishing itself over the southeast.
The southeast ridge expanded. The jet stream shifted north which boosted temperatures across the eastern US and dropped temperatures in the Rocky Mountain west. Tornado numbers surged compared to recent years.

The active jet configuration created conditions favorable for severe weather and above normal rainfall in the central US.

The corn belt warmth was tempered by the above normal rainfall. Summer temperatures didn't crack the top 10 (data from the late 1940s).

Extreme drought conditions prevailed in California and the Rocky Mountain west, the deep south--Georgia and South Carolina and from eastern Ohio into New England.

In my next post--Part II Summer Recap--I will focus on northern Ohio specifically...

Wednesday, September 21, 2016

What is Snowfall in Cleveland like AFTER Summers with Many 90 Degree Days?

Many ask me if there is a connection between summers with many 90 degree days and snowfall in the winter ahead.  According to this chart, maybe there is something to this.

I caution anyone who uses JUST ONE piece of data in drawing a conclusion about any upcoming season as there are MANY components in determining seasonal outlooks.

Friday, August 12, 2016

What Are Shelf Clouds?

Thursday, August 11, 2016 several strong thunderstorms passed over the Cleveland suburbs. Many viewers submitted photos of stranger cloud formations with some speculating that there tornadoes. What are these clouds?  Are they a rare phenomena?  Not really. These are called shelf clouds or Arcus Clouds. They are fairly common around thunderstorms even in northern Ohio. I blogged about shelf clouds over 10 years ago!

What are shelf clouds? The National Weather Service has a great description.
Shelf clouds are typically seen at the leading edge of a thunderstorm or squall line of thunderstorms. Remember, shelf clouds are not tornadoes or wall clouds. These are formed when rain-chilled air descends in a thunderstorm's downdraft, then spreads laterally when reaching Earth's surface. Warmer, more moist air is lifted at the leading edge, or gust front, of this rain-cooled air. When this warm, moist air condenses, you see the shelf cloud. 
Normally, you will feel a burst of cooler wind followed by rain and maybe hail. The higher gusts occur on the back edge which can cause downed trees and power outages. So when the next storm develops, look for the Arcus Cloud. Remember that tornadoes normally don't accompany these cloud formations just gusty winds, rain/hail then the highest winds toward the back end.