Thunderstorms – METAR TS with a – for light and for heavy
Out of all of the specific weather hazards thunderstorms are perhaps the greatest threat to pilots because they can be your one-stop-shop for danger. When talking about thunderstorms lightening and turbulence are not your only enemy. They can create anything from significant hail to tornadoes and microbursts all of which is often lethal.
Not all thunderstorms exude these occasions three ailments need to be current- medium to high moisture content material any amount of air instability and some lifting action. The lifting motion could be brought on by changes in terrain elevation frontal modifications or temperature increases and decreases.
You will discover two kinds of thunderstorms – airmass thunderstorms and severe thunderstorms. Airmass thunderstorms are probably the most prevalent. They have a tendency to pop up on summer afternoons or throughout coastal evenings can be short in length and are normally scattered. Serious thunderstorms as are additional violent and produce wind gusts beginning at fifty knots or higher generate hail inches in diameter or bigger and can also turn out tornadoes. Metar by pasconation
Thunderstorms have three phases or perhaps a daily life routine – the cumulus stage mature stage and dissipating stage. These 3 stages are seen in each and every thunderstorm formation. The cumulus stage has continuous updrafts as fantastic as three000 feet per moment Abbott Kailey 2004. The storm matures when the cloud becomes too dense to be supported by the drafts of your previous phase.
When you picture a fully-formed thunderstorm cloud you are thinking of this probably the most violent phase on the storm. 1 side with the storm still has warm updrafts while the leading edge from the storm has cool precipitation. Also at the leading edge are strong winds. Inside the dissipating stage the cloud ceiling rises at least 10000 ft and the updraft is found exclusively within the cloud. The entire cloud now sheds rain and accompanying down drafts.
A thunderstorm can present itself as single-cell super-cell or multi-cell. Weve all noticed pictures with the updraft of a thunderstorm. They start out rather flatly at a low altitude and vertical updrafts cause the storm to billow up beyond 30000 ft. A single-cell thunderstorm isnt anything to sniff at and lasts under an hour. Super-cell thunderstorms are quite severe and can last up to two hours.
Multi-cell storms are condensed groups of thunderstorms in different levels of the lifestyle routine. This grouping causes the storms to interact with every other and therefore last considerably longer. Sometimes these groupings cause whats known as squall lines. 1 misconception is that quall lines are always equated having a front. While this is often the case these squalls can happen anywhere. When they may be indeed frontal thunderstorms they develop fifty to 300 miles in front of a fast-moving cold front. Abbott Kailey 2004
Thunderstorm-specific hazards-
Lightening – Reports submitted by PIREPs and Climate offices with live lightening trackers.
Lightening almost goes without saying. Lightening can be categorized as in-cloud cloud-to-cloud cloud to ground and between cloud and clear air although rare. No matter which type lightnings voltage is about 300000 volts per foot and is an astounding fifty000F. Abbott Kailey 2004 This heat causes the surrounding air to expand and a corresponding shock wave that we know as thunder.
Lightening strikes can cause external damage to the aircraft but rarely causes catastrophic damage to airplane or crew. It can temporarily blind pilots at night and it can effect the aircrafts navigational equipment.
Turbulence – METAR not applicable. Reports are submitted as a PIREP.
While turbulence isnt exclusive to thunderstorms it is an expected and predictable phenomenon unlike unexpected clear-air turbulence. The Thunderstorm-related turbulence occurs right where the updrafts and down drafts combine in. Anyone who as flown through turbulence can relate to the jerky up and down sensation can relate to this.
Turbulence nicknamed chop may be light moderate or extreme. When reporting turbulence to air traffic control from the air there are actually no set rules in determining the severity. Pilots leave it up to prevalent sense and previous experience when reporting light or moderate chop although experts would say moderate chop is usually felt when the updraftdowndraft gusts are around 30 knots. Extreme isnt often experience by pilots without their Instrument Flight Rating unless they experience clear-air turbulence as they stay away from storms and clouds in general. IFR flights are typically channeled away from reported extreme turbulence by air traffic control.
Microburst – no METAR code reported by PIREPS and can be put in the remarks section of speci sic climate reports
Microbursts are maybe one of one of the most feared climate occurrences out there. Theyre low in altitude and can occur in an area of 1 nautical mile or less horizontally and 1000 ft vertically Abbott Kailey 2004. Aircraft landing or taking off or low-flying aircraft are most likely to run into this phenomenon.
Microbursts are lethal for the reason that the winds can increase upwards of 100 knots but the real hazard lies inside the downbursts of up to 6000 feet per minute. Many commercial flights over the years have crashed due to microbursts such as Delta Air Lines Flight 191 in 1985 and USAir Flight 1016 in 1994 – both happened while on approach to their respective runways.
Hail – METAR GR Small hail is GS along with snow pellets
Hail is caused by rain drops being picked up by the updrafts of a thunderstorm which are then frozen at substantial altitudes. Once they become too heavy to be supported by the updrafts the chunks of hail anywhere from the size of a raindrop to a baseball or larger depending on how many friends it gathered on the way up fall to the ground at a large velocity over 100 MPH. Three-quarters of an inch or more is all the girth thats needed to cause structural damage to an airplane Abbott Kailey 2004.
Tornadoes – METAR FC for funnel clouds tornadoes or water spouts
Tornadoes or funnel clouds is often predicted and spotted by local weather offices using Doppler Radar. The weather information is then sent to local air traffic control facilities and ARTCCs. The controllers will then do their best to control aircraft away from these violent storms. Low-flying unaware VFR aircraft would be in most hazard as tornadoes are formed at cloud bases and VFR flights are usually not always speaking to a tower or arrivalapproach facility though pilots without an IFR rating wouldnt be allowed in areas with climate bad enough anyway. Tornadoes are brought on by the rotation brought on by thunderstorms. Funnel clouds are called tornadoes once they touch the ground. The wind speeds within a tornado can exceed 200 knots.
Serious weather can be avoided by obtaining a thorough and current climate report from an airports weather office 1-800-WX-BRIEF or an AFSS before taking off. Climate ailments are updated at least every hour on the airport ATIS. Air traffic controllers will advise all IFR flights of any changes as theyre reported.
Source-
Mike Abbott Liz Kailey et al. 2004. Colorado- Jeppesen-Sanderson. Metar by pasconation