WINTER WEATHER TERMS(wikipedia/dictionary/noaa source)

Evaporative cooling- A process in which an evaporting liquid cools a object or liquid that comes in contact with it. The diff between dry bulb and wet bulb temparture determines the pot. of Evaporative cooling.

Wetbulbing- Wetblub is what the temperture would be if the atmosphere was completly saturated. It takes Evaporative Cooling for this process to take place It takes 100% relative humidtiy to take full effect. "I believe you take 1/3 of the dew point depression and subtract it from the current temp." From Clay MTWC on TN Weather Zone"

That is right good link about wetbulbing here. http://www.ktbb.com/news/View.php?ArticleID=12354

The Dew Point Depression is temp - dew point with 70 Temp and 60 DP the Dew Point Depression is 10.

Example problem: Temp 35 and the Dew Point is 17. Dew Point Depression is 35-17=18. You take 1/3 of 18. Which is 6. You subtract 6 from the current temp of 35. To get the Wetbulb temp. of 29 if the atmosphere was 100% saturated.

Warm Air Advection- Transport of Warm Air by horizontal winds.

Dynamic Cooling- Cooling that results from decreasing pressure also called Adiabetic Cooling

Dynamic Warming- Warming that results from increasing pressure also called Adiabetic Warming

Wind Chill Factor- What the temparture fells like when an increased wind is felt on exposed skin. In West KY wind Chill values below -10 are Wind Chill Advisory range, and Wind Chill -25 are warning and life threating range.

Snow- Ice Crystals that fall to the surface. Fall as soft mutiple flakes all of different shapes and sizes. http://en.wikipedia.org/wiki/Snow

METAR- An international code (Aviation Routine Weather Report) used for reporting, recording and transmitting weather observations from NOAA

Sleet- Falling Ice Pellets and bounce when they hit the ground but dont freeze as a mass unless mixed with freezing rain. Occurs as snowfalkes melt or partially melt as they enter the warm layer of mid atmosphere to freeze again closer to the surface: link http://en.wikipedia.org/wiki/Ice_pellets

SN- METAR code for Snow

FZRA- METAR code Freezing Rain

PL- METAR code for ice pellets also known as sleet

Freezing Rain- Snow that melts in warm layer in most of the lower and mid layers of atmosphere. Than despite falling as rain refreezing on surfaces when they are 32 degrees or below at the surface. Can cause very damaging ice acculmations that can make travel impossible, knock out power to thousands and cause tremendous tree and wildlife damage, and cause serious injury and death due to slips, falls, and traffic accidents. Considered the worst type of winter precip.

Freezing Point- In F it is 32F degrees. In C it is 0C degrees. In Kelvin it is 273.15K Degrees

Nor Easter- A nor'easter (also northeaster; see below) is a macro-scale storm along the East Coast of the United States "From Wikipedia"

Applachin Runner- A strong low pressure system that runs up the Applachin Mountain Chain. Sometimes these in very rare cases might be almost as strong as Nor Easters.

Lakes Cutter- These are systems that form in the midwest but take a strong negative tilt towards the Great Lakes this are ideal Midwest storms, but can lead to warmth and rain in Eastern US

Alberta Clipper- An Alberta clipper (also known as a Canadian Clipper) is a fast moving low pressure area "from Wikipedia" Mostly effects Canada and Upper midwest rarely KY and TN but it does happen.

Manitoba Maulers and Saskatchewan Screamers are same as Clippers except they come from thier respected Canadian provinces

QBO- (WIKIPEDIA DEFINATION) Quasi-Biennial is a quasi-periodic oscillation of the equatorial zonal wind between easterlies and westerlies in the tropical stratosphere with a mean period of 28 to 29 months. The alternating wind regimes develop at the top of the lower stratosphere and propagate downwards at about 1 km per month until they are dissipated at the tropical tropopause. Downward motion of the easterlies is usually more irregular than that of the westerlies. The amplitude of the easterly phase is about twice as strong as that of the westerly phase. At the top of the vertical QBO domain, easterlies dominate, while at the bottom, westerlies are more likely to be found.

PDO- Pacific Decadal Oscillation is a pattern of Pacfic climate varibity that shifts about 20 to 30 years. A warm or postive phase the West Pacific cools and East Warms. In a cool or negative phase the East Pacific Cools and West Pacific warms. The interdecadal Oscillation effects the north and south Pacific slimar to ENSo except in 20 to 30 year patterns.

ENSO- Also known as El Nino warming in the East Pacfic which means in Spanish Christ Child or Little Boy. La Nina is cooling of Pacfic. El Nino can if strong enough effect the whole Oscillation cycle and is being directly linked to several events. Linking one event to El Nino or La Nina isn't neccasary an accurate conculsion.

AO- Arctic Oscillation (WIKIPEDIA DEFINATION) is the dominant pattern of non-seasonal sea-level pressure (SLP) variations north of 20N, and it is characterized by SLP anomalies of one sign in the Arctic and anomalies of opposite sign centered about 37-45N. The North Atlantic oscillation (NAO) is a close relative of the AO and there exist arguments about whether one or the other is more fundamentally representative of the atmosphere's dynamics
NAO- North Atlantic Oscillation(WIKIPEDIA DEFINATION) is a climatic phenomenon in the North Atlantic Ocean of fluctuations in the difference of sea-level pressure between the Icelandic Low and the Azores high. Through east-west rocking motions of the Icelandic Low and the Azores high, it controls the strength and direction of westerly winds and storm tracks across the North Atlantic. It is highly correlated with the Arctic oscillation, as it is a part of it.

MJO- Madden-Julian Oscillation (WIKIPEDIA DEFINATION) is an equatorial traveling pattern of anomalous rainfall that is planetary in scale

Blizzard- the National Weather Service defines a blizzard as sustained 35 mph (56 km/h) winds which leads to blowing snow and causes visibilities of ¼ mile or less, lasting for at least 3 hours.

Severe Blizzard- The National Weather Service defines a "severe blizzard" as a storm with winds of 45 miles per hour or greater; a great density of falling or blowing snow; and temperatures of 10 degrees or less.

Ice Storm- In Kentucky and Tennessee the defintion of a ice storm is 1/4 inch or more of ice glaze from one storm

Wintry Mix- Anytime more than one form of wintry precipation falls in one storm or round


Winter Storm- NWS Defination This term may refer to a combination of winter precipitation, including snow, sleet, freezing rain, etc.

Heavy Snow- (Kentucky and TN defination both diff.) The definition of heavy snow in Kentucky is 4" or more in 12 hours, or 6" or more in 24 hours. In TN the definition of heavy snow is 3" or more in 12 hours, or 5" or more in 24 hours.

Overrunning Pattern- Usually when a layer of warm air trys to ride retrating cold air. Or when a relativly warm air mass rides over a denser air mass at the surface

Arctic Front- Seprates Arctic from Polar Air masses and is coldest air mass.

Polar Front- Seprates Polar air masses from Temparture. Sometimes by mistake these can be called arctic fronts.

Snow to Rain ratio- How much rainwater can be taken from the fallen snowcover. One inch of rain is

Snow Cover- How much snow has fallen and accumalated to cover the ground.

Blowing/Drifting Snow- Snow that gets blown around by the wind. Sometimes in snowstorms when strong wind acts on snow it can blow it into a mound called a snowdrift. This usually occurs on the windward side of the object. In extreme cases this can cause a whiteout in which ground,air,line of sight is all a big white mass due to blowing intense snow in a blizzard.

Wind Chill Formula- Wind Chill(F) = 35.74 + 0.6215T- 35.75(V^0.16)+ 0.4275T(V^0.16) ^exponent

F and C Formula- F = C × 9⁄5 + 32 - From Celsius C = (F− 32) × 5⁄9 - TO Celsius

Black Ice- Frozen Ice with limited air particles trapped in it making it transparent. A sig. hazard to drivers, pedristians, and sailors.

Degree Day- Encarta Defination "Degree-Day, unit used in estimating heat requirements in buildings and fuel costs. The degree-day is based on the Fahrenheit temperature scale and is essentially a measurement of the difference between a standard indoor temperature and the (lower) outside temperature. One degree-day corresponds to a difference of 1° F between the outside mean temperature and a given reference temperature, which is taken as 65° F for heating calculations. Hence, one winter day with a minimum temperature of 30° F and a maximum temperature of 50° F, or a mean temperature of 40° F, would count as 25 degree-days." MSN Encarta

Frost- This is frozen dew on surface of grass. Grass and Car surfaces are cooler than water and collect ice above freezing. Frost can occur in temps as high as 37 and 38. If a freeze isnt likely but temps hover at 32-37 range a Frost Advisory might need to be issued.

Freeze- When the low temp is expected to hit 32 or below. Freeze Warnings are issued at the end of growing season or for freezes during growing season. Average Freeze in KY and TN runs from Oct 10th-30th depending on elevation and how far north or south you are.

Hard Freeze- By NWS defination 4 or more hours of temps 26 or below signals the end of growing season.

Winter Weather Advisory (includes snow adviosrys, freezing rain advisory, and winter weather, snow and blowing snow, and blowing snow advisorys) NWS DEF: Issued for winter precipitation that is not expected to produce significant risks to life and/or property, but that could still impact travel or other activities. Advisories are issued for a variety of winter weather conditions.

Winter Storm Watch- NWS DEF: Issued when significant winter precipitation is possible in the 24 to 48 hours. Again, a watch does not mean its a sure thing, but is designed to alert you to the fact that hazardous winter weather could occur. Watches are issued for winter storms, heavy snow or blizzards

Winter Storm Warning ( inculdes ice storm, heavy snow, winter storm warnings)- NWS DEF: Issued when winter precipitation that could lead to a threat to life or property is expected. A warning is the most serious of the winter weather messages and indicates that action should be taken immediately to get ready for the storm. Warnings are issued for winter storms, ice storms, heavy snow, blizzards and heavy sleet.

Blizzard Warning- See Blizzard. Very rare warning for KY and TN when blizzard conditions are expected with near 100% confidence.

Polar Jet- The Jet that exists in the Polar Region. When it dips down into the US strong storms and Arctic Cold/Polar Fronts can form bringing arctic outbreaks, winter storms, damaging wind and tornado outbreaks.

Subtropical Jet- The jet that typically moves across the Deep SOuth and Gulf. Responisible for GUlf Storms that during winter can produce winter storms.

NOAA's SNow Terms

Snow Flurries
Snow flurries are an intermittent light snowfall of short duration (generally light snow showers) with no measurable accumulation (trace category).


Snow Shower
A snow shower is a short duration of moderate snowfall. Some accumulation is possible.

Snow Squall
A snow squall is an intense, but limited duration, period of moderate to heavy snowfall, accompanied by strong, gusty surface winds and possibly lightning (generally moderate to heavy snow showers). Snow accumulation may be significant.