meteorology unit 4

Weather Forecasting

Predicting how the present state of the atmosphere will change over a period of time

Folklore Forecasting

A traditional method of predicting weather based on observations of natural phenomena, such as animal behavior and plant growth.

Persistence Forecasting

A forecasting method that assumes past weather patterns will continue into the future, relying on current conditions to predict short-term weather outcomes. (what happened yesterday will likely happen today)

Climatology Forecasting

The study and analysis of long-term weather patterns and trends to make predictions about future climate conditions, often using historical data.

Short-term (trend) Method

Assumes that the speed and direction of weather systems will not change.

Analogue Method

A forecasting technique that uses past weather patterns and conditions to predict future weather by comparing current patterns to similar ones from the past.

Numerical Method

A forecasting approach that uses mathematical models and computer simulations to predict weather by solving complex atmospheric equations, allowing for detailed and quantitative analyses.

Spaghetti Model Plots

Graphs that depict various forecast outcomes by using multiple computer models to visualize potential paths of a weather system, helping to assess uncertainty in predictions.

Ensemble Forecast

Different iterations of one model adjusted for different scenarios/equations.

Model Output Statistics (MOS)

A statistical technique used in meteorology that refines the output of numerical weather prediction models by incorporating observational data to improve forecast accuracy.

Observations

First step in the forecasting process: look at current weather conditions.

Analysis

Second step in the forecasting process: assessing and interpreting data to understand weather patterns.

Prediction

The third step in the forecasting process: estimating future weather conditions based on analysis and models.

Post-Processing

Final step in the forecasting process: reflect on how your forecast was and how accurate it was.

Station Model Plots

a “cluster” of current weather data for one particular weather reporting site.

Thunderstorms must contain

thunder and lightning, strong and gusty winds, hail, and precipitation (may contain tornadoes)

Ordinary Thunderstorms

Typically form in warm, moist air and are characterized by weak vertical wind shear, resulting in short-lived storms with light to moderate rainfall.

Growth Stage of a Thunderstorm

The phase in thunderstorm development where strong updrafts cause the storm to grow vertically, leading to the formation of cumulonimbus clouds.

Mature Stage of a Thunderstorm

The phase in which a thunderstorm reaches its peak intensity, characterized by heavy rainfall, strong winds, and the presence of downdrafts alongside updrafts, often producing severe weather phenomena.

Decaying Stage of a Thunderstorm

The final phase in thunderstorm development is where rainfall decreases as downdrafts dominate, leading to the dissipation of the storm.

Multicell Thunderstorm

A cluster of thunderstorms that form in different growth stages in one area and are characterized by stronger winds, often resulting in a longer duration of severe weather.

Squall-Line Thunderstorm

A type of thunderstorm that forms in a line, often producing severe weather such as heavy rain, strong winds, and sometimes tornadoes, typically associated with a cold front.

Bow Echo

A portion of the leading edge jumps out ahead of the rest of the line and will likely produce damaging winds.

Supercell Thunderstorm

A highly organized thunderstorm characterized with a rotating updraft that can produce severe weather including tornadoes, large hail, and damaging winds.

Mesocyclone

a rotating updraft

Mesoscale Convective System (MCS)

A large grouping of multiple storms that move together and last for hours.

Circular MCS

covers many states and can produce severe weather and heavy rain

Linear MCS

has very strong winds, isolated and quick tornadoes

Gust fronts

The leading edge of cold air coming from a large, severe thunderstorm; the “exhaling” air from a thunderstorm.

Microbursts

A very localized column of sinking air, producing damaging and straight-line winds at the surface.

Derechos

A widespread and long-lived, violent wind storm that is associated with a fast-moving band of severe thunderstorms usually takes the form of a bow echo.

Lightning

a discharge of electricity in a mature thunderstorm

Thunder

Heating and expansion of the air create a shock wave as a result of lightning.

How lightning works

A charge separation occurs in the cloud; Negative charges are found near cloud base and positive charges are higher up in the cloud and at the ground

Stepped Leader

initial “spark” of lightning that leaves the cloud base

Flanking Line

Updraft/food supply for mesocyclone

Rear-Flank Downdraft

The rear portion of the mesocyclone’s downdraft

Inflow

“Suck zone,” influx of moisture rich air into mesocyclone

Return Stroke

The upward flow of the current that we see (as lightning)

Tornado

A rapidly rotating column of air whose rotation reaches the ground

Waterspouts

Similar to tornadoes, only over water and with much slower speeds

Landspout

Similar to tornadoes, but they form from the ground up from low-level circulation

Funnel Cloud

A funnel-shaped cloud of condensed water droplets, associated with a rotating column of air and do not reach the ground

Dust-Whirl Stage of Tornado

Dust swirling upward from the ground grows towards the funnel cloud in the sky with minimal damage

Organizing Stage of Tornado

Downward extension of the funnel and “connection” with dust-whirl on the ground with light damage.

Mature Stage of Tornado

A tornado is on the ground with strong winds and a “whistling howl” noise that is produced by violent winds with most severe damage.

Decaying Stage of Tornado

Tornado starts to end-rotation slows and stops, stretches into a thin funnel shape rope, becomes greatly contorted, and “stretched”

When do tornadoes occur?

Most occur in the late afternoon because of daytime heating, and the atmosphere is more unstable but can occur anytime of the year

How do tornadoes form?

Need strong winds that turn with height, strong winds blowing in different directions, unstable atmosphere, and strong updrafts

Suction vortices

stronger winds than the overall tornado that produces significant damage

Doppler Radar

A specialized weather radar that “sees” wind (velocity) and precipitation (reflectivity)

Measuring the strength of tornadoes

Meteorologists examine the damage done by tornadoes, and the winds are estimated based on the damage produced

Tornado Direction and Duration

Most tornadoes travel from Southwest to Northeast, but some change direction and path.

Warning signs of a tornado

Strong, persistent rotation in clouds, circulating dust and debris, hail and then rapid quiet, and a very loud roar with heavy rain

How to be prepared for a tornado

Stay alert with local media and seek shelter.

After the tornado

Listen to instructions from emergency personnel, stay together, help the injured, stay away from damaged buildings, and dont use matches or lighters.