June 17, 2015 Lab Exercise Objective: To become comfortable with: Interpreting heavy rainfall forecast products and ingredients before an event (Part 1) Monitoring key heavy rainfall products during an event (Part 2) Instructions: Get into groups (no more than 6) and identify a person to write down your answers. Work together as a team to answer the questions in the lab in the space provided. You are welcome to use any materials from class to help you complete the exercise. In the final portion of the lab you will need to use RadarFirst so be sure to have a computer at the ready. Your Role and Area of Responsibility: Take on the role of a decision maker in one of the blue shaded counties in southern Oklahoma. Each group should pick one role and stick to it for the duration of the lab. Consider roles such as the following: County emergency manager City mayor First responder Safety officer at a hospital Facility manager at a casino State trooper 1
Additional Map: 2
Part 1: Interpreting Heavy Rainfall Forecast Products and Ingredients Before an Event Question 1. What role is your group playing for this exercise? Include your area of responsibility. On Sunday, June 14, 2015 you hear on the news about Oklahoma receiving the remnants of a tropical storm Wednesday to Thursday of the upcoming work week. You pull up the following 5-day rainfall forecast map from the NWS Weather Prediction Center to prepare for your week. Question 2. Where is the heaviest precipitation forecast to be in Oklahoma? Approximately how much rain is your area of responsibility expected to get in the next week? Question 3. What (if any) actions would you be taking at this point? 3
It is now Tuesday, June 16, 2015 the day before the remnants of the storm are expected to enter Oklahoma. You see this 3-day rainfall map from the NWS Weather Prediction Center. Question 4. Describe how the forecast has changed since the one you saw on Sunday. What is the predicted rainfall (approximate) for your area of responsibility now? Question 5. The tropical system is forecast to enter Oklahoma tomorrow. What actions would you be taking at this juncture? 4
Question 6. What are the four weather ingredients needed for heavy rainfall events? It is the evening before the remnants of the storm are expected to move into Oklahoma. The below map shows a regional look at dew point temperatures (in degrees Fahrenheit) and winds (in miles per hour) at 7PM on Tuesday, June 16, 2015. Question 7. What critical dew point value (and above) is needed for heavy rainfall? On the above regional map draw a line separating areas that are meeting this requirement from areas that are below it. What parts of Oklahoma are at or above this critical dew point value? Question 8. The tropical storm is currently down in Texas. Based on the wind information, mark where the center of the circulation is on the above regional map with an L. 5
It is still the evening before the storm remnants are expected to impact Oklahoma. The following 500 millibar map shows winds (in knots) and other conditions at 7PM on Tuesday, June 16, 2015. Winds at this level (approximately 18,000 feet up) are important because they give a rough estimate of storm motion and speed. Question 9. Wind speeds of knots or less at 500 millibars lead to very slow moving storms that could produce flooding conditions. Please indicate that speed below. Where are these conditions being met in the south central U.S.? Question 10. If storms were occurring in southern Oklahoma at this point, what would their approximate speed be? 6
Part 2: Monitoring Key Heavy Rainfall Products During an Event For this second part of the lab we will transition our focus to monitoring radar as well as Mesonet data. Open up the RadarFirst software. At the top of RadarFirst, go to Edit à Date... Change the date to 6/17/2015 and change the time to 12PM. View the data in 1-pane mode (View à One Pane). Make sure cities are visible on the map (Edit à Options à Show Cities). Question 11. Play a 3-hour animation (9AM-12PM) of BREF1 from the KTLX (Oklahoma City) radar. What direction is the entire tropical system moving? What direction are individual storms moving? Question 12. Go to Edit à Date and change your time to 6PM. View a 3-hour animation (3-6PM) of BREF1 from KTLX. Describe what you are seeing on radar in southern Oklahoma. We would say that the radar echoes are. (Fill in the blank) At 6PM you also view the following 3-hour Mesonet rainfall map. Question 13. Given the radar trends you have observed and the above 3-hour Mesonet rainfall map, what actions would you be taking in your jurisdiction at this time? 7
Go to Edit à Date and change your time to 9PM. Switch to 2 panel mode (View à Two Panes). In the left window load RAINS (storm total rainfall) and in the right window load BREF1. View a 3-hour animation from KTLX. Question 14. What time period is the RAINS (storm total rainfall) product showing right now? How many hours is that? In your left window move your mouse cursor over the colors. What are highest rain totals you can find? Question 15. Focusing only on the 5 southern Oklahoma counties identified on page 1 compare the radarestimated rainfall totals you were just seeing to the below Mesonet rainfall map for the same time period. How much different are they? Which one has the higher values? Question 16. On Mesonet rainfall maps what do the colors represent? What is the source of that information? What do the numbers represent? 8