Weather Explinations

Weatherpersons Day

Today is National Weatherperson’s Day

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We’ve already celebrated one weather related holiday, Groundhog day where we wait with bated breath for a large rodent to tell us what the rest of the winter holds. Today, February 5th is National Weatherman’s Day where we celebrate real people, meteorologist and weatherpersons, who work hard to try and accurately predict the often fickle weather. Despite major technological advances and supercomputers, forecasting the weather is still a tricky, and ever changing business.

Sometimes the criticism is more challenging than the forecast. We get used to it. Weather is not an exact science and no matter how much we are right and sometimes wrong there will always be someone who isn’t happy with the forecast or the weather.

According to the Air Force News, Weatherman’s Day “commemorates the birth of John Jeffries, one of America’s first weathermen”. Jeffries was born on Feb 5, 1745. He kept weather records from 1774 to 1816.

But Jeffries was more than a weather observer or “weatherman” he was a Boston physician, and you can read some interesting history about the man in the link provided, if you like. Dr. John Jeffries: physician, Loyalist, aeronaut.

So lets try to keep the criticism to a minimum today and be nice to your local weather person and meteorologist. From my experience most of you are very kind and have good sense of humor so I want to thank you.

Today would also be a good day to appreciate those who observe the weather and I want to thank those that take time to be part of local SkyWarn, Storm Chasers, and Weather Watchers. Thank You…

usadvisories

Major Winter Storm Impacts a Large Part of the United States

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Winter Storm warnings stretch from Texas, through Oklahoma, Missouri, Illinois, Indiana, Ohio, Pennsylvania, New York to Vermont with Winter Storm Watches stretching into Maine and Blizzard warnings for Missouri and Illinois. This storm will impact a large area of the United States. It is not only for snow but many locations will also see ice.

In my professional opinion of all the winter types of precipitation ice is the worst of them all. Ice can cause massive power outages. It only takes a glaze of about a quarter of an inch of ice to weigh down power lines causing them to sag and break. Not to mention the glaze of ice it puts down on area roadways. When it comes to an “Icy Mix” there are two types, sleet and freezing rain. Sleet is not as bad and doesn’t coat power lines. Sleet is more of an ice pellet. Freezing rain on the other hand is what we all think of when it comes to an ice storm. Freezing rain actually falls through the atmosphere as a liquid only to go through a very shallow layer of air at or below freezing. This layer is so shallow and so thin the water doesn’t have time to refreeze until it makes contact with items in this below freezing layer like cars, houses roads and power lines. This is a major concern for those in Oklahoma, Missouri, Southern Illinois, into Indiana, Ohio and Pennsylvania including the cities of Oklahoma City, St Louis, Indianapolis, Cincinnati, Columbus and Pittsburgh. Everything else to the north looks to be in the form of snow.

Of course winter weather is not the only concern with this storm, but also a threat of severe storms in the south and into the southeast. This storm as you can see will have a wide range of impact and if you are under any of these advisories, watches or warnings please listen to local media outlets for the latest weather information specific for your area. I will pass along any and all interesting weather I find but I can not forecast and update every location. Especially since I will be working a lot since here in western NY we could see anywhere from 10 to 15 inches of snow if not more.

TALLADEGA WEATHER: Look at Friday Night Storms

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Click here for the Latest Forecast

Conditions at Talladega Municipal Airport:
Current Weather Conditions | Look at Doppler Radar | Mobile Friendly Site | Mobile Radar

Other Alabama Weather Links:
AlabamaWX.com | ABC33/40 |

As I watch Twitter post this evening there seems to be a lot of confusions about the storms most of central, northern and eastern Alabama are seeing Friday night. These are NOT the storms & severe weather been advertised for Saturday. This is just activity out ahead of the main feature that will produce the round of severe weather Saturday afternoon & evening at and around Talladega. These are what we call elevated convection since most of the activity is taking place well above the surface. These kind of storms don’t usually produce severe weather. Also the best dynamics for severe weather is located to the west into Mississippi where there’s Tornado Watch box and severe weather warnings. From the reports I am getting the lightning is very vivid. This may cause a few people to go out and watch but know, if you can hear thunder you can get struck by lightning.

CURRENT WATCHES, WARNINGS & ADVISORIES IN ALABAMA: Warning Map | Mobile Warning Map

All of this activity will move east during the day Saturday. There could be some morning storms and showers through central Alabama but as the NWS, Talladega officials and NASCAR mentioned in Friday afternoon there could be time of some sunshine but I don’t think it will be enough to dry a track or get the Nationwide race in during the afternoon.

The afternoon/evening is the main focus for severe weather for Talladega. Super cell storms are very likely. These storms will have strong damaging winds, large hail and possibility of forming tornadoes. If you are at the track please monitor local weather outlets like radio or weather radio. On FM Radio Thunder 92.7 WDTR on Twitter at Thunder927. Also many race scanners have the capability of accessing the NOAA All-Hazards Weather Radio Frequencies. I’d check on the local ones in the area in set those on your scanner. local WX frequency for Anniston Alabama is 162.475 You can also find your frequency here – NWR Stations Listing for Alabama

The following are definitions of severe weather situations:

A Tornado Watch is issued when conditions are favorable for tornado development. People located in and around the watch area should keep an eye to the sky and listen to their NOAA Weather Radio all hazards or tune to local broadcast media for further weather information. The watch is intended information. The watch is intended to review safety rules.

A Tornado Warning is issued when a developing tornado has been detected by National Weather Service Doppler radar or a reliable report of a tornado has been reported. A Tornado Warning is usually issued for portions of one or two counties… for an hour or less. The storm could also produce large hail and destructive straight line winds. If the Tornado Warning includes your neighborhood or work place… you should seek safe shelter immediately.

(Same is true for Severe Thunderstorm Watches or Warning except replace Tornado with large hail (Inch or greater) & damaging winds (58 mph or greater)

NWS Special Weather Statement for Central Alabama for Saturday

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I am not one to over hype the weather. I have 10 years of severe weather forecast and 8.5 of those years have been spent on TV. I am posting this because with Talladega being such a large wide open place with a lot of fans around either attending activities or camping I want to keep people informed and safe. This is not the time to take the “Meteorologist or Weatherman is always wrong” approach. This is a very clear cut forecast. Bottom line I expect storms late in the day around Talladega, some could arrive towards midday. Because of the conditions in place across the state this is not the kind of forecast to take lightly. Even if there are no severe warnings for Talladega tomorrow it is better you prepared and planned as if there will be cause I think there will be.

Here is a Special Weather Statement from the NWS in Birmingham concerning the potential for Tornadoes Saturday afternoon across Central Alabama:

Tornadoes are possible across central Alabama on Saturday and Saturday night

(more…)

Explaining Percent Chance of Probability of Precipitation

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Many of you have sent me forecasts from other sources through my Twitter account that say “Weather.com is calling for 50% or the NWS is saying 40% chance of rain” but do you really know what that means? I’ve asked this question before of people and here are some of the answers:

“it means that 40% of the area where I live will see rain”
“40% chance means that it will rain/snow for 40% of the day”
“say there is a 40% chance of rain that they are saying that over the recorded history of the date that it rained 40 times out of 100 on that day.”

Actually, actually all three of those are wrong. The way I was taught in school was that a 40% PoP (probability of precipitation) means that forecasters have calculated that in a 100 similar weather situations, rain has fallen 40 times in the forecast area. POP is for any point in your forecast area, not the whole area. So, for instance, a PoP of 90% for rain means that 9 times out of 10 when this weather situation is predicted, you ought to get rain somewhere in the forecast area, example at your home, school or at the airport.

Apparently that’s not how the National Weather Service figures out the PoP. Personally their explanation seems very confusing and very misleading. Here is what I discovered from the National Weather Service office in Peachtree City GA:

What does this “40 percent” mean? …will it rain 40 percent of of the time? …will it rain over 40 percent of the area?

The “Probability of Precipitation” (PoP) describes the chance of precipitation occurring at any point you select in the area.

How do forecasters arrive at this value?

Mathematically, PoP is defined as follows:

PoP = C x A where “C” = the confidence that precipitation will occur somewhere in the forecast area, and where “A” = the percent of the area that will receive measureable precipitation, if it occurs at all.

So… in the case of the forecast above, if the forecaster knows precipitation is sure to occur ( confidence is 100% ), he/she is expressing how much of the area will receive measurable rain. ( PoP = “C” x “A” or “1″ times “.4″ which equals .4 or 40%.)

But, most of the time, the forecaster is expressing a combination of degree of confidence and areal coverage. If the forecaster is only 50% sure that precipitation will occur, and expects that, if it does occur, it will produce measurable rain over about 80 percent of the area, the PoP (chance of rain) is 40%. ( PoP = .5 x .8 which equals .4 or 40%. )

In either event, the correct way to interpret the forecast is: there is a 40 percent chance that rain will occur at any given point in the area.

To me this could be confusing to some especially if the forecaster is 100% confident that IT WILL Rain or Snow but thinks only a percentage of the area sees measurable rain or snow then that percentage becomes the PoP for the forecast.

When I do a weather forecast I do not use a percent chance, I don’t like them and I think because everyone has a different idea of what percent chance means like if it is 40% chance of rain it is 60% chance of sun. That’s not what it means and I don’t want to add tot he confusiong

Here are common terms I use and what I mean by them:

Scattered Showers mean showers will be around but not everywhere will see rain. Kind of like spilling a jar of marbles. They are scattered across the floor.

Isolated Showers: I will use this if I think most of the area will be dry but with one or 2 spotty showers possible. This can happen in the summer were a shower or storm will pop up and be very isolated in one spot when the rest of the area is seeing no rain at all.

I will say occasional or periodic showers if I think there will be rain but not sure on the timing or the timing is just impossible to figure out. Like a day that see rain most of the day with the brief break between periods of rain.

I hope that helps clear up some things. Feel free to ask me any kind of weather question you may have. I’d be more than happy to answer it.

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