Great Weather Resource

One of the personal pet peeves I have is how uneducated people are when it comes to the weather and weather forecasting.  TV meteorologists in many markets are simply on for ratings, their skill as forecasters often leave a lot to be desired, that’s why you sometimes see a big difference in the forecast from the 6pm to 11pm news.

Now the National Weather Service, has issued a new on-line interactive glossary called Jetstream.  This resource I have found to be excellent especially for the the weather novice.

Of interest to bird watchers, is how Doppler Radar works.  Many people like to tout the power of weather radar during migration and birds certainly do show up on radar in certain modes, but so do insects, planes, smoke, hill-tops, really anything.  Just because you see a great big green blob on a clear night, doesn’t mean its all birds.

So check out Jetstream and let me know what you think in the comments section!

Weather Wednesday

We have all seen them, those slowly scrawling texts across our TV’s:

“The National Weather Service in (insert your City) has issued a (insert warning) for (insert county) until….”

Then when said thunderstorm or whatever passes through, you shrug your shoulders and wonder what all the worry was for.

What this has created is a false sense of security, people do not take National Weather Service warnings seriously and the results can be tragic.  What I hope to do here is to give you an idea of why the National Weather Service issues the warnings they do.

Flash Flood:  A Flash Flood warning means that the NWS radar has estimated that a significant amount of rain (or combination rain/snow melt) has fallen over a very short period of time, obviously if you don’t live in a flood prone area, you might not notice much (other than it is wet), but if you do live in a flood zone, then water may be rising fast, sometimes a several foot rise can occur in only a few minutes.  Also keep in mind that it is not necessary for it to be raining at your location to have a flash flood.  Flash flooding usually only lasts a couple of hours an is sometimes listed as an “Urban and Small Stream Advisory”.  The urban is for clogged storm drains and parking lots, which tend to collect water fast.

Flood Warning:  A flood warning is generally issued when flooding is expected to be a long duration event and is more widespread.  Main stem rivers may be involved, flooding is generally widespread, but may or may not be severe.  Water rises tend to be much slower than in flash flood situations and are thus more predictable.  Often a Flood watch is issued a day before the rain starts to alert people to the potential of flooding.

Severe Thunderstom Warning:  A Severe Thunderstorm Warning is issued when meteorologist, using sophisticated radar (or so they would like to think) has a thunderstorm that is producing winds of 55 mph or greater or 3/4″ inch hail or greater.  In Canada, heavy rain is also a criteria for a Severe Thunderstorm Warning.  A thunderstorm only has to exhibit these criteria once, in which case a warning is issued.  Sometimes one gust is all a storm has got, I have seen situations where the storm has dissipated prior to the Warning reaching the TV.

While many Severe Thunderstorm Warning barely if ever verify, you never know which ones will, which ones won’t.  Thus you should treat each warning seriously, that means moving to a sturdy shelter when these warnings go off and making sure your pets and children are accounted for.

Most Severe Thunderstorm warnings come after a Severe Thunderstorm Watch has been issued.  Watches are issued by the Storms Prediction Center  in Norman, Oklahoma, while warnings are issued by the individual National Weather Service offices.  However you do not need a Severe Thunderstorm Watch to have a warning.

Tornado Warning:  A Tornado Warning is issued, when either a) NWS Radar had indicated a tornado or at least, very strong rotation in the storm or b) a confirmed funnel cloud or c) a Tornado on the ground.  Like Severe Thunderstorm Warnings the vast majority never come true, but with a Tornado Warning, even if you don’t get a Tornado (and that is a good thing) you are likely to experience Severe Thunderstorm conditions with high straight-lined winds, hail and lots and lots of lightning.  If a Tornado Warning is issued for your area, you should head to your basement (if you feel awkward fold some laundry or something), if you don’t have a basement the lowest interior room of your house.  You should abandon cars and mobile homes if a tornado is spotted.  If caught in the open, lay flat in a ditch.  Its not so much the wind that will harm you, but the debris within the cloud.

There are of course other types of weather warnings, related to Winter Storms, Hurricanes and other events, but those will be discussed at a later time. 

Please take these weather warnings seriously, even though most to not do catastrophic damage, there is always that chance that the next time that warning scrolls across your screen it will.

Weather Wednesday

Those of you who know me well, know that when I was a young whipper-snapper, I originally went to college to study Meteorology.  Upon arriving at University, I discovered that the Atmospheric Science Department wanted me to take Calculus.   Thus ended my dream in a fiery blaze.

Of course I took as many weather courses as my general education credits would allow, one of my favorites was weather forecast models and analysis.  It was during that course that I learned how to do basic forecasting using computer model data.  But that isn’t the purpose of this post.

Weather Wednesday I’m hoping will be an opportunity for people to ask questions about the weather and get some sort of simple answer back.  The questions can be about anything from why does it rain to what was the jet structure of the March 1993 super-storm.  If you have a question send it to wr7681@albany.edu

To get us started this week, we will look at the difference between Hail and Sleet.

There are actually several forms of Ice which fall from the sky.  One everyone is at least aware of is Snow, but there is also, Sleet and Hail.

Hail is formed when water droplets are forced upward by violent updrafts in Thunderstorms.  These droplets are lifted above the freezing level, where they cool and crash into and join other water droplets.  Eventually these combined droplets become too heavy for the updraft to keep suspended and they fall towards earth.  The vast majority of hail, melts long before reaching the ground.  However, in the most violent of storms water droplets are forced to near the top of the troposphere if not a bit beyond and can grow quite large, up to the size of a grapefruit or softball.  No doubt some melting occurs on the way down, so these hail stones might have been even bigger in the storm!  Hail can only form in Thunderstorms.  Hail is typically found in warmer months (Which vary where you live), but can occur at anytime during the year in a Thunderstorm.

Sleet can be formed in two ways, one when snow falls it falls through a warm layer above the surface, melting the snow flake into a rain drop.  This rain drop then falls through a deep layer of below freezing temperatures and re-freeze but don’t have enough time to become snow.  Thus in winter storms you may hear the ping-ping-ping of sleet against your window.  Unlike hail, which is comprised of multiple droplets stuck together, sleet is simply a frozen rain drop.  It is clear and looks like a small pebble.  The second way sleet forms is very similar to the first, when there is lots of warm air aloft and rain then falls into a deep layer of below freezing temperatures and arrives at the surface.  Sleet can only  form from stratiform precipitation and also only occurs in colder months (wich vary depending on where you live).