MEA 130 Final Flashcards

The Tropics

High heat and humidity, between 23.5 degrees north and 23.5 degrees south, small seasonal changes

Tropical Cyclone (TC)

A rotating, organized storm system with a closed circulation that originates over the tropics, counterclockwise in the NH due to it being a low-pressure system

Tropical Depression

Earliest stage of TC development, sustained winds <39 mph, and disorganized

Tropical Storm

Second stage of TC development, sustained winds greater than or equal to 39 mph, organized and named

Hurricane

Organized and powerful, sustained winds greater than or equal to 74 mph, is called a typhoon or cyclone in different areas of the world

Major Hurricane

Category 3 or higher, sustained winds greater than or equal to 111 mph, and very destructive

When is the Atlantic hurricane season?

June 1st - November 30th

Eye

Clear area in the center of the storm, light winds, can be 20-40 miles wide

Eyewall

Ring of intense storms around the eye, has the strongest and fastest winds, heaviest rainfall, and can extend 18 km above the surface

Spiral Rainbands

Elongated bands of precipitating storms and clouds jutting out from the eyewall

Where is air pressure the lowest in the storm?

In the eye at the surface

TC Ingredients

Warm waters, humid air, little wind shear, and Coriolis force

Where do most TCs form?

Off the coast of Africa from tropical waves

Hot Spots for TC Development

Western Atlantic, Gulf of Mexico, and Gulf Stream

Why can’t TCs form too close to the equator?

Practically no Coriolis force at the equator, which is needed for spinning

Where can’t TCs form?

Too close to the equator?

Where are TCs at lower latitudes carried and by what?

Westward by easterly winds

The Saffir-Simpson Scale

System based on a hurricane’s wind speed, evaluated in real time, and are determined by one-minute maximum sustained winds

Saffir-Simpson Scale 1

74-95 mph, 64-82 kts, very dangerous winds, and will produce some damage

Saffir-Simpson Scale 2

96-110 mph, 83-95 kts, extremely dangerous winds, and will cause extensive damage

Saffir-Simpson Scale 3

111-129 mph, 96-112 kts, devasting damage will occur

Saffir-Simpson Scale 4

130-156 mph, 113-136 kts, catastrophic damage will occur

Saffir-Simpson Scale 5

>156 mph, >136 kts, catastrophic damage will occur

What amplifies winds?

Steering

Where are the fastest winds in the TC?

The NE quadrant

#1 Cause of Destruction and Fatalities from a TC

Storm surge

What drives storm surge?

Winds

Storm surges can be amplified by:

High tide and high rain rates

__ is more deadly than wind

Water

What determines if water flows onshore or offshore?

Wind direction

__ leads to flash flooding and landslides

Rainfall

A strong consensus that …

Major hurricanes will become more common

It is not clear that…

The number of TCs a year will change

In a TC, air is sinking in the ____

Eye

The two deadliest TC hazards are

Storm surge and freshwater flooding (rainfall)

Initially, TCs in the Atlantic track to the ____

West

Global Scale Weather Forecasting

Find out what’s happening with the westerlies, the jet stream, and air masses by checking satellite feed

Synoptic Scale Weather Forecasting

Find out what is going to impact a large portion of the country by checking large-scale models and weather maps

Mesoscale Weather Forecasting

Find out where it is going to rain, if there’s any advection, wind storms, or storm complexes by checking regional data and models

Local Scale Weather Forecasting

Find out what is going to happen in your area by checking day-to-day data, real time tools like radars, and assess the possibility of local environmental interactions

Automated Surface Stations

Automated sites that measure what is happening at the surface, almost continuous information

Radiosondes and Weather Balloons

Record atmospheric data above the surface like temperature, dewpoint, pressure, wind speed and direction

Sounding

Vertical profile of temperature, dewpoint, and wind plotted as a function of pressure

Doppler Radar

Radar reflectivity gives real-time precipitation intensity, useful for assessing the development and current status of thunderstorms, tornadoes, winds, precipitation, and updates every 5 minutes

Ocean Buoy Data

Needed for accurate marine forecasts, storm development and tracking analysis, and safety at sea

World Meteorological Organization (WMO)

Branch of the UN, responsible for the exchange of weather data globally, and assures that there are uniform data gathering methods globally

National Oceanic and Atmospheric Administration (NOAA)

A huge part of the WMO and works to better understand and predict changes to Earth’s atmosphere

National Weather Service (NWS)

122 weather forecasting offices across the country issuing weather forecasts for local/regional areas

Numerical Weather Prediction (NWP)

Forecasters using computers to simulate and predict the weather, requires the world’s most powerful supercomputers

NWP Models Struggles

Models make assumptions, not enough observations, hard to include changes to terrain, grid spacing, and chaos

Larger Grid Cells for NWP Models

Means less calculations to make → uses less processing power → less detailed predictions

Smaller Grid Cells for NWP Models

Means more detailed calculations to make → uses more processing power → very detailed predictions

Short-Term Forecasts (0-72 Hours)

Forecasts thunderstorms, tornadoes, mesoscale systems, and daily weather patterns; uses regional mesoscale models with fine grid spacing, with very high resolution

Medium Range Forecasts (3-10 Days)

Forecasts front developments, air masses, pressure systems, and the jet stream, often uses single runs of global models

Ensemble Models

Several versions of a model will be run with different starting data and setup, helps us understand the uncertainty of the situation

High model confidence is when…

Tracks are tightly clustered, showing agreement

Low model confidence is when…

Tracks are divergent, showing disagreement

Long-Term Forecasts

Forecasts temperature and precipitation outlook for a season, El Niño and La Niña probabilities, and TC seasonal outlook; uses a mixture of NWP and statistical models

AI Weather Prediction (AIWP)

Trained to learn patterns by analyzing vast amounts of historical data and use it to estimate the future state of the atmosphere

Role of a Meteorologist with Models and AI

To make sense of model predictions, knowing the characteristics of a local area, communicate risk and uncertainty to the public, and make fast decisions in real time that can have life or death consequences

Advisory

Issued for less serious hazardous conditions, generally non-threatening; examples include fog, sleet, snow, freezing rain, dust, and moderate winds

Watch

Issued when the risk of hazardous weather is possible, uncertain timing and exact location, gives people ample time to prepare

Warning

Issued when hazardous weather is imminent, severe thunderstorms, tornadoes, hurricanes, people need to seek shelter or take protective action

Precipitation Probability — 10% Chance

At any given location in a forecast area, there is a 10% chance of getting 1/100th of an inch or more of precipitation

Deterministic

“It will rain tomorrow afternoon,” is easy to understand, useful for short-term predictions, has no indication of uncertainty, and becomes less reliable the further in time it’s forecasted

Probabilistic

“There is a 30% chance of rain in Raleigh,” conveys uncertainty and risk, good for decision-making, and is more useful for long-term prediction

Why do weather forecasts become less accurate over time?

Small errors in initial conditions grow over time in a chaotic atmosphere