Tuesday, July 19, 2011

H-O-T

Hello everyone, and welcome again! As if we needed any reminder, it's Summertime! Of course, with Summer we expect the heat and humidity levels to rise accordingly. Depending on where you live in the country...or the world, you've likely become accustomed to a certain level of Summer heat. Here in Upstate New York and New England, high 80s and low 90s generally serve as the threshold for what many residents would consider hot. Throw in a healthy dose of humidity, and things become uncomfortable fast. By contrast, head to parts of Texas, Arizona, New Mexico, and even the central Plains, and most people probably wouldn't bat an eyebrow at a day near 100°.

But, every now and again Mother Nature decides to crank the heater to the max and walk away for a while. It may start as something isolated, like a heat wave over southern Texas or the desert Southwest. A stretch of 95°+ degree days in Phoenix or Albuquerque or a few 100°+ days in Houston and Dallas. Initially, it may look like the pattern will break and the heat will die down. But then, seemingly overnight, the isolated pocket of blistering air becomes a surging torrid leviathan that envelopes two-thirds or more of the nation in dangerously hot and humid air. This has been exactly the case for the better part of the last 2 months here in the U.S.

Now, the monstrous mass of heat and humidity is beginning to make its move. A ridge of high pressure over the southern Plains is gaining strength and beginning its push toward the north and east. In most cases, a ridge of high pressure is something we'd celebrate to an extent. It means fair weather, and at other times of the year, a comfortable moderation in temperatures. This time, however, it's a torrent of dangerous heat that's set to cook us for days on end.

Here are some of the highlights from this unrelenting heat wave so far:

Excessive Heat Watches/Warnings and/or Heat Advisories have been posted for 30 states at the same time, with that number expected to rise to near 40.

As of 7/17/2011, Oklahoma City had seen 27 days with temperatures above 100°. That puts the city on pace to tie or break the record of 50 days set in 1980.

As of 7/10/2011, Witchita Fall, Texas had seen 36 or 38 days will temperatures above 95°.
Knoxville, Iowa recorded a heat index of 131° on 7/18/2011.

Minneapolis, Minnesota broke unofficial the record for the highest dew point temperature ever recorded there. The dew point reached 82 degrees between 3:00 and 4:00 PM on 7/19/2011, breaking the previous record of 81.

National high temperatures on 07/19/2011
All of that is just the tip of the iceberg (or inferno, I guess...) as far as records and notable statistics from this year's heat wave. Now that it's coming our way, it's important to be prepared, and to know what to do to keep yourself safe during an extreme heat wave. The fact of the matter is, heat is one of the biggest weather-related killers, and no one is immune to its dangers.

Here are some important heat safety tips, plus a breakdown of heat-related advisories and warnings:

Heat Advisory: High heat and humidity are expected to result in a heat index of 100°-105° during the daytime, or overnight lows above 80° are expected for 2 consecutive days or more.

Excessive Heat Watch: Issued by the National Weather Service when heat indices in excess of 105ºF during the day combined with nighttime low temperatures of 80ºF or higher are forecast to occur for two consecutive days.

Excessive Heat Warning: Issued when heat index values over 105° are expected for more than 3 hours per day for two days or more, or if heat index values over 115° are expected at all.

What you Should Do:
    -  Limit time spent outdoors.
    -  If you must conduct activities outdoors, limit them to either the early morning or evening.
    -  STAY HYDRATED! Drink plenty of cool water.
    -  Have a cool place to relax, preferably an air-conditioned one.
    -  Brings pets indoors and keep them out of the heat. Take them on short walks only.

Be safe over the next few days, everyone! Until next time!

Thursday, July 7, 2011

2011 Tornadoes: Another Revisiting

Welcome everyone! We all know that it has been an absolutely unforgiving and unrelenting year for tornadoes and extreme weather in general. One could spend weeks retelling and accounting it all, from the unprecedented onslaught of tornadoes in April, to the record floods along the Mississippi River and here in the Northeast in May, and back to tornadoes again in May and June. Extreme heat and drought have even made their presence known across a large expanse of the country in the Plains and parts of the Southwest. As promised though, one more time, we revisit the realm of powerful and deadly tornadoes.

The severe weather had seemed to be showing some mercy during the month of May. That of course came to a screeching halt on May 22, when an EF5 tornado tore through Joplin, Missouri killing over 150 people. But the tornadoes would not stop there that week. Just two days later, the same storm system would spark yet another outbreak of destructive twisters across the nation's heartland in Texas, Oklahoma, Kansas and Arkansas. Goldsby, Oklahoma would catch particular attention on the afternoon of May 24, 2011 as an EF3 tornado tore through parts of the town. Houses were wiped clean off of their foundations, leaving little more than a concrete slab behind. The twister itself was captured on video by KFOR's Chopper 4 as it tore across the countryside. The pilot even briefly set the chopper down near a demolished house to check on the survivors stepping out from their storm cellar. Despite the destruction seen across the town, no one was killed by this tornado.


Still, the picutres speak for themselves...


Above is an SRV (Storm Relative Velocity) radar image out of Norman, Oklahoma from the evening of May 24, 2011. The image shows wind speed and direction across the radar's field of view. Red colors note winds blowing away from the radar, while green colors denote winds that are blowing toward the radar. The circled area shows what is called a "couplet" and indicates an area where the winds within a storm are rotating and where a tornado may possibly be located. This particular image shows a strong tornado rolling through the western suburbs of Oklahoma City. Tornadoes are not usually this easy to spot on radar.

We here in the Northeast weren't spared from this year's tornado rampage. A strong cold front barreling across upstate New York and western New England brought the severe weather here to our neck of the woods, getting the month of June off to a destructive start. Shortly after noon on June 1, 2011 showers and strong thunderstorms began to develop in an unseasonably hot and humid air mass. Parts of Saratoga, Washington, and Rensselaer Counties in NY were bombarded with torrential downpours and enormous hail. The storms continued east into southern Vermont and western Massachusetts, dropping hail over 3" in diameter in some areas. The greater Albany area dodged a thunderstorm that just nicked the south side of the city, but this particular storm would make a name for itself before the day was over.

The cold front continued into central New England, taking the storms with it. However, on this day, central Massachusetts, southern Vermont, and southern New Hampshire was a simmering pressure cooker just waiting to pop. High heat and humidity coupled with favorable wind shear and a strong trigger along the cold front provided more than enough fuel to support strong, rotating thunderstorms. For as strong as the initial storms had been in eastern New York, they were only precursors to some absolutely explosive storms that would fire in central New England. By about 4:00 PM that afternoon, rotating supercell thunderstorms were exploding to life as they rolled downslope of the Bekshires. Severe thunderstorm and tornado warnings were alreay being issued, including one tornado warning that was issued around the Brattleboro/Keene area of VT and NH. Also around this time, the same cell that just missed Albany earlier in the day had now grown into a full-fledged supercell just to the west of Springfield, Massachusetts. The storm continued to strengthen as it began to bear down on the city. The greater Springfield area was placed under a tornado warning around 4:30 PM, and tower cameras in the city were about to catch video that would soon go viral in the coming hours. A powerful tornado swept in across the Connecticut River, plowing right into the city of Springfield. The twister damaged homes and businesses, destroyed countless vehicles, and even flipped a tractor trailer right in the middle of the evening rush hour. The tornado, later determined to be an EF3, was responsible for 3 deaths in the greater Springfield area.

Here is a shot taken from a tower camera in Springfield, MA as the tornado crossed the Connecticut River into the city.

One of many streets with demolished buildings following the tornado.

Another view of the tornado as it tore across the city of Springfield. The twister would continue as far east as Sturbridge, MA destroying several homes in the process.

It's been said time after time this year, but I'll say it one more time. All of these accounts of tornadoes serve as reminders of what an intensely active year it has been. Tornado activity has trailed off in recent weeks, and statistically we are beginning to head into the quieter time of the year. The year of extremes has survived in other ways, however. Record heat, more flooding in the northern Plains, and measurable snow over Colorado as late as the beginning of June keep giving up things to talk about, and keep weather in the news headlines. Now a month into hurricane season, we've had only one named storm in the Atlantic. Will this year of extremes expand its influence into a record year of hurricanes? Only time will tell.

Until next time!