Name_____________________________Date__________________Period_________________

The Superstorm of 1993

Background

Although the Nor’easter of March 12-15, 1993 was not the biggest snow producer orcoldest storm in history, it has gone down as one of the largest and most destructive winterstorms in US history. Its beginnings quiet and its end only five short days later, the storm affectedfully half of the United States’ population and caused over 500 deaths and three billion dollars indamage. Since it represents the closest version to “perfection” an extra-tropical (mid latitude)cyclone can achieve and historical data is limited on other storms of the same type from earlieryears (especially in terms of satellite data), the ‘93 Superstorm represents a goldmine ofmeteorological data and forms the basis for most current research into extra-tropical cyclones. For this lab, you will combine information already presented in class with meteorological mapreading and satellite imagery to analyze the Storm of the Century.

Internet Sources

For most of this lab, the Weather World 2010 Project will be used as the primary sourcefor satellite and surface data. This project is an outreach of the University of Illinois (known forits strong meteorology department) and contains archived data about many of the greatestmeteorological events of the late 20 century including hurricanes and tornado outbreaks. Toth

begin, go to the main page for the Superstorm of 1993 at http://ww2010.atmos.uiuc.edu/(Gh)/arch/cases/930312/home.rxml

General Instructions

Part 1: General Information

Using the Introduction and Storm History sections of theWW2010 archive, record the requested data on your lab sheet. Notethat the included links and a few independent web searches of othersources will be needed to obtain some of the data since it is not directlyrelated to SS93 (SuperStorm of 1993).

Part 2: Surface Data/Station Models

The second part of this lab focuses on reading meteorologicalsurface data. Since so much incoming data is used in each and everyweather report, scientists reduce it to a series of related symbols whichare then plotted on a map for analysis. Called station models, thesesymbols can be easily interpreted and used to formulate weatherforecasts.

Part 2: Surface Data/Station Models (cont.)

When you have advanced to the screen that starts with “surface Images,” look at the smallmap below the title. Although they are too small to read, each set of symbols on the maprepresent a separate set of weather data observed at the site where the symbols are located. Inaddition, the light blue lines are isobars which you have already been introduced to. Click on“surface observations” and review how station models are constructed if you need a refresher.

Now, pick a city along the East Coast that was obviously affected by the passingsuperstorm and consistently shows station models throughout the Nor’easter event. You mightneed an atlas/map to name the city. Redraw five separate station models for the same location onyour lab sheet that are as evenly spread out through the event as possible. The goal is to producean overall impression of how the weather at the station you chose was affected by the stormbefore and after it passed. The best locations to choose for this will be along the coast fromGeorgia to New England.

Finally, remember the images are shown in Zulu time and must be translated into localtime for accurate analysis. It is also important to note that along the bottom of the surfaceanalysis maps, the surface pressure interval is given along with the highest and lowest pressureson the map (although the key does not tell you exactly where that pressure reading wasmeasured).

Part 3: Satellite Imagery

United States meteorological satellites basically provide three types of imagery. Usingdevices already introduced earlier in the course, these satellites provide visible light, infrared andwater vapor images. Not surprisingly, each resolves different types of information better than theothers so all three are vital components of weather prediction and forecasting. You will also notethat the infrared images have been colorized for better viewing. However, unlike the usual colorscheme you might expect where reds and yellows are the warmest locations and blues are thecoolest, remember the reverse is true in weather imagery. As you know, the higher into theatmosphere a cloud is forced to rise, the colder its top becomes. Since a satellite will pick up onlythe tops of the clouds, meteorologists use their approximate temperature to determine theirvertical development. Thunderstorms are immensely high clouds capable of reaching to the top ofthe troposphere, their tops tend to stand out among the warmer air around them making themeasy to identify (as you will see). If you have not done so already, read the GOES Meteorologysection of the AGS 371 Remote Sensing Lab before completing this section in order to familiarizeyourself with how the GOES satellites operate and what services they can provide. Thisinformation can be found at http://geochief.org/Course_Materials/Remote_Sensing/sensing2.htm

Go back to the storm history page and look beneath the color image to locate a table titled “Satellite Images.” This table will be your major jump point to the satellite databases. For somequestions, multiple images may be needed.

Name_____________________________Date__________________Period_________________

The Superstorm of 1993Lab Sheet

Part 1: General Information

1. In what geographic area did the SS93 first appear at the surface?

2. Using Figure 1.2, what Florida city represented “ground zero” when the center of the cyclone made landfall?

3. Franklin County, Florida recorded the highest wind speeds of anywhere in the Gulf States. Had the storm been a hurricane, what classification would it have received? (You willneed to look up the classification system for hurricanes. Try www.nhc.noaa.gov forstarters.)

4. During the storm, Philadelphia observed a record low barometric pressure. Find theminimum recorded pressure for the following listed events as a comparison and note thedifferences.

Event Minimum Pressure (mb)

SS93 (Philadelphia)

Lowest Phila. reading in past24 hours*

Hurricane Andrew** (1992)

Hurricane Floyd** (1999)

Blizzard of ‘96

Hurricane Wilma** (2005)

*Go to http://weather.unisys.com/surface/meteogram/ and find the meteogram for Philadelphia(KPHL). Then use the online information to determine the barometer reading.

**The Tropical Prediction Center (National Hurricane Center) keeps detailed archives for everyhurricane/tropical storm in their Seasons Archive section which can be accessed from the mainNHC page.

Part 2: Surface Data/Station Models

Station Models

Selected City________________________

Date/Z-Time

Station Model Analysis of two important trends or information directlyrelated to SS93*

* Your task here is to examine the impact of the SS93 on local conditions, not explain what is in the model...it is assumed you already know

how to read them. For instance, do not report “...the winds were coming from the NE...” Instead, report “...the winds showed a noticeable

shift to the NE from the past model as the center of the low pressure approached the region and a CCW spin started to be created around

it...”

Part 2: (Continued)

1. Using the available surface data plots, determine the greatest national pressure gradient inthe United States throughout the storm’s lifespan. In other words, a normal nationalpressure gradient on any given day is about 15-20mb from the highest high to the lowestlow. Look at what impact the SS93 had on the gradient!

Date/Time_________________ Highest Pressure___________Lowest Pressure________

2. At what local date and time (you must convert Z time...use EST) did the storm reach itsgreatest strength and where was its center located at that time?

3. Choose 12 evenly spaced (approximate) times throughout the storm’s life and record thewind direction as recorded in Philadelphia. Using what you have already learned aboutpressure and wind, explain what the significance of the wind direction has on determiningthe actual location of the storm for someone who might be caught outdoors throughout thestorm’s duration. (In other words, if you were outside but understood the nature of winds,how could you “track” the storm?)

Date/Time

V*

*V = Wind Vector

Explanation:

4. Locate Orlando, Florida using the computeror an atlas. Your goal is to determine atwhat date/time the strong cold front thatdropped south from the storm center passedthe area. How do you do that?

There are actually a few important indicators. The first is that isobars often“kink” towards higher pressure where afront crosses them. Bearing that in mind,look at the diagram at the right and fill in thewind directions for the included stationmodels using what you already know about PGF, CE, etc. You should notice a trend in winddirection that can help you locate the front (I have spoken about it before).

5. Remember that you are looking for a cold front. What temperature and precipitationpatterns should be present to help identify the front’s location? (Do NOT simply say “coldtemperatures”...that is not enough. How can you find the actual front?)

6. At what date and time did the SS93's destructive cold front pass through central Florida? Support your answer with specific data from any sources used (there are multiple strategiesand sources of data that can be used to answer this question.)

Part 3: Satellite Imagery

1. Choose a date/time (use daylight hours so visible imagery will be available) where imagesexist for all three types of sensors and examine each photo. Since this data is being receivedfrom satellites, it will periodically contain data errors so discount these photos as well if theerrors are large enough to obscure the storm. For each type of information below, indicatewhich type of photo would be the most useful for examining that particular data. This is notsimply an opinion question...in certain cases especially, one type of image or another is muchmore useful than the others. There may be multiple answers for certain types of desired data.

Desired Data Best Image Type/Explanation

Overall Storm Structure

Cloud Types and Organization

Storm Intensity

Location of Jet Stream

Center of the Storm

Front Boundaries

Station Model Refresher

Below is a diagram illustrating all of the possible information contained in a station model. Although all of this information is rarely available a the same time, it must nevertheless be accountedfor. In addition, the possible symbols used for current weather conditions, clouds, etc. are quitenumerous and have been included on the back of this page for your use.

Here is a “worst case scenario” station model that shows where to put all possible weatherinformation.

Now, here’s an example of what such a station model might look like...