1.6: Alternative Text Descriptions for Investigation 1

Figure 1.1.1: Weather Conditions for the San Francisco Bay Area

This map displays real-time weather data for the San Francisco Bay Area and Central California as provided by MesoWest. Each dot represents a weather station. Numeric values next to each dot indicate the temperature in degrees Fahrenheit. Short arrows point in the direction of the wind at each station.

• Coastal cities such as San Francisco, Half Moon Bay, and Santa Cruz report cooler temperatures between 54°F and 63°F.
• San Francisco reports 61°F, while San Mateo is at 63°F.
• Inland areas are warmer:
  • San Jose area ranges from 64°F to 74°F, with some parts like east San Jose reaching 74°F.
  • Fremont reports 69°F, and Hayward shows 72°F.
  • Gilroy and Morgan Hill show values of 68°F and 68°F, respectively.
  • East Bay cities like Livermore and Concord show temperatures around 74°F and 73°F, with surrounding areas in the mid-70s to low 80s.
  • Further inland:
• Tracy: 82°F
• Stockton: 84°F
• Modesto: 84°F
• Manteca: 86°F
• Los Banos: 87°F (the warmest reading on the map)
• Wind directions vary, indicated by short arrows pointing in various directions, suggesting a mix of local wind patterns.

Figure 1.2.1: Weather Data for Continental United States

This is a synoptic surface weather map of the contiguous United States showing meteorological observations at various reporting stations, dated 22Z on June 26, 2020. Each station is represented by a standard station model symbol showing multiple weather variables.

Each station plot typically includes:

• Temperature (upper left number)
• Dew point (lower left number)
• Sea-level pressure (upper right number, usually in millibars)
• Wind barb indicating wind direction and speed
• Cloud cover (black or white circle)
• Pressure trend symbols (if present)

Several areas are highlighted with circles:

• Circle around Grand Junction, CO:
  • Temperature: 91°F
  • Dew point: 33°F
  • Pressure: 071
  • Light winds from the west
  • Mostly clear sky
• Circle around Little Rock, AR:
  • Temperature: 77°F
  • Dew point: 71°F
  • Pressure: 183
  • Moderate winds from the south
  • Partly cloudy
• Circle over San Antonio, Texas:
  • Temperature: 77°F
  • Dew point: 70°F
  • Pressure: 159
  • Wind from the southeast
  • High humidity
• Circle over Brownsville, TX shows:
  • Temperature: 86°F
  • Dew point: 78°F
  • Pressure: 151
  • Wind from the southeast
  • High humidity
• Circle around Tallahassee, FL:
  • Temperature: 81°F
  • Dew point: 79°F
  • Pressure: 203
  • High relative humidity
  • Winds from the south-southwest

Across the map:

• The western U.S. shows generally hot and dry conditions, especially in Nevada, Utah, and Arizona, with dew points often below 40°F and temperatures in the 90s to 100s.
• The eastern U.S. shows much higher humidity with dew points in the 70s and overcast or partly cloudy skies.
• Wind barbs indicate southerly to southeasterly flow in the central and eastern U.S., likely feeding moisture into the region.

Figure 1.2.2: The Station Model

This diagram is an annotated illustration of a standard station model, used by meteorologists to summarize weather observations at a particular location visually. The model consists of a central circle surrounded by several numbers and symbols, each representing a different weather parameter.

The annotations and data values shown in the diagram are as follows:

• Air Temperature (°F): Displayed in the top left corner as "71".
• Dew Point Temperature (°F): Displayed in the bottom left corner as "69".
• Barometric Pressure (in millibars): Displayed in the top right corner as "125".
• Cloud Cover: Indicated by the fill level of the central circle. A fully filled black circle represents overcast conditions (100% cloud cover).
• Precipitation: Shown as two small dots to the left of the central circle, indicating light rain or drizzle.
• Wind Direction: Represented by a line extending from the circle, pointing in the direction from which the wind is blowing. In this example, the wind is coming from the southeast.
• Wind Speed: Shown by barbs on the end of the wind direction line. Each full barb represents 10 knots, and each half barb represents 5 knots. This model shows two full barbs and one half barb, indicating a wind speed of 25 knots.

Figure 1.3.1: Precipitation 

This is a national composite radar map showing areas of precipitation across the contiguous United States, valid at 22Z (6:00 PM UTC) on June 26, 2020. The radar data represents reflectivity, a measure of the intensity of precipitation, collected from a 1-kilometer hybrid digital scan.

Key Information:

• The map covers all 48 contiguous U.S. states, as well as portions of southern Canada and northern Mexico.
• Reflectivity values are measured in dBZ (decibels of reflectivity), with values ranging from below 20 dBZ (very light rain or drizzle) to over 70 dBZ (indicative of very heavy rainfall or hail).
• The radar data is displayed as reflectivity with no base map features such as cities or terrain. Only state outlines are visible.

Areas of Notable Precipitation Activity:

• Upper Midwest (especially Wisconsin and Michigan):
  • Contains the most intense precipitation on the map, with reflectivity values exceeding 50 dBZ, indicating strong thunderstorms or heavy rain.
• Southern Plains (including Oklahoma and Texas):
  • Scattered clusters of moderate to heavy precipitation, possibly thunderstorms.
•  Central Rockies and Four Corners region:
  • Numerous small to moderate radar returns suggest widely scattered showers and embedded storms.
•  Southeast U.S.:
  • Radar echoes indicate light to moderate rainfall, especially across Alabama, Georgia, and parts of Florida.
•  Pacific Northwest and West Coast:
  • Light precipitation detected in isolated areas, primarily in western Oregon and northern California.