METR 361 Spring, 2015

BUFKIT

A radiosonde sounding can be a very valuable tool in many situations. As sounding analyses can be time-consuming and difficult, especially under the deadline of putting out forecasts and warnings, a computerized sounding analysis package would be helpful. Fortunately, forecasters at the Buffalo Weather Service Office have designed such a program, mainly for analysis of lake effect situations. BUFKIT, as the program is called, is also very useful during synoptic snowstorms and severe weather situations. It has been adopted by the NWS and is available free at the Warning Decision Training Branch (http://wdtb.noaa.gov/tools/BUFKIT/ ).

Lab assignment (due Friday, Feb 13):

1. We are using the Dell laptops because BUFKIT won’t run with Linux or Mac. First, access the appropriate web drive as follows: Right-click on the “This PC” computer icon on the desktop. Click Map Network Drive. The Drive letter must be W: In the folder line, type \\employees.oneonta.edu\employees$\blechmjb exactly like that, especially the slashes. Uncheck the Reconnect at sign-in box. Click Finish. You will need a password. When you have the drive open, double-click the BUFKIT – Shortcut icon. In the BUFKIT folder you will find the icon for BUFKIT. It looks like a brown riveted angle iron with paper and a hammer. Run the program.

2. Familiarize yourself with the BUFKIT screens in lab before continuing. The main window is a sounding which is generated by a computer forecast, perhaps NAM or GFS. BUFKIT supports many model types, like RAP, SREF, NAMm and, of course NAM and GFS (listed as nam and GFS3). For practice today, we have a NAM profile on the screen. What you see is the model’s forecast of the vertical properties of the atmosphere at one location. You can choose that location, given that you have the BUFKIT profile for that place. So, for example, in the top left box, you could click on the green namm link and two different cities show up next to the model box (KJFK and KPHX). If you click the RAP model, you get a message that there are no RAP profiles since none have been downloaded for you. Click the nam link again and switch to the EON nam profile. EON is Oneonta. An alumnus who is now the SOO at NWS-OKX has set up Oneonta BUFKIT profiles for us. He lists them as EON. BUFKIT profiles can be found at http://www.meteo.psu.edu/bufkit/CONUS_NAM_00.html, http://www.erh.noaa.gov/okx/bufkit.html, and many others on the web.

3. Click the slider bar above the sounding to move from time to time manually. The time and date are located at the bottom. You may need to move the entire program window up to see it. Once you have clicked in the slider bar, you can also advance the times using the keyboard left and right arrow keys. NOTE: for some reason, time advances to the left, unlike most other applications.

4. Click the “Map” button to change the left-hand display. Notice there are several other choices (Data, Indices, Precip type, Lapse rates, etc). Try them to see what you get. Each display shows a different aspect of the forecast sounding.

5. The sounding is drawn on a skew T – log P diagram. You can add or subtract features after clicking the Overlays button. Try Dry Adiabats or click Clouds. The sounding display will change. Click again to remove.

6. Add a display of vertical motion, i.e., Omega, also from Overlays. It’s a thin white curved line. Negative values show upward vertical motion (do you know why?).

7. Click some of the other boxes and notice what happens to the sounding. In general, all buttons and boxes are toggles which allow you to design a sounding which makes you comfortable with the information displayed.

Questions 8, 9, and 10 are the graded part of this lab. Type your answers to a text file. Put your name at the top and send it to Jerome.Blechman@oneonta.edu

8. Based on the NAM BUFKIT forecast for New York (KJFK), initialized at 00Z Sunday, February 1, 2015, answer the following (Note, first check the box for Bourgouin Precip Type):

a. During what hour (UTC) and on what date is precipitation forecast to begin?

b. What is the type of precipitation at the beginning, and when does it change at which times to the end of the forecast period? Be sure to note from what precipitation type to what other precipitation type.

c. From the class website, download a text file of observed conditions at KJFK. Time increases from bottom to top in this list. Contrast the predicted precipitation type and intensity to the observed values. Remember, one dot means intermittent precipitation, two dots mean light, three dots mean moderate, four dots mean heavy. What can you say about the BUFKIT predictions?

d. Turn on Omega at 12 UTC on Feb 2. What does that display tell you about what’s going on in the atmosphere at that time? Be quantitative in your answer. Include units.

e. A key meteorological event that you could see on a MSLP map of temperature, fronts, etc. (if you had one) happens between 13 UTC and 15 UTC on Feb 2. What is that event and what happens on the profile sounding to tell you what it is? Cite two sounding features that are useful in identifying that synoptic event.

f. The precipitation type changes and BUFKIT tells you very plainly what type is expected. How did BUFKIT decide on the precipitation types? To answer, click the Precip Type button. If the button says Energy, click that, too.

g. Just from the BUFKIT profiles, how much snow will fall and what is the total liquid equivalent of the entire event? Hint: you may have noticed this number in a previous screen. For snow, use an appropriate snow:liquid ratio to estimate how many inches and document the ratio you used.

9. Use the NAM forecast for Grand Forks, ND (KGFK) to answer the following questions. KGFK experienced a cold frontal passage and strong cold air advection, starting around 12Z on Feb 28, 2014. When professors explain cold fronts to freshmen, we tell them the dense, cold air is pushing under the light, warm air. The KGFK BUFKIT forecast soundings, starting from 12Z Feb 28 show something different.

a. How do both temperature and dew point soundings contradict the simple idea that cold air pushes underneath the warm air when this cold front passed Grand Forks?

b. The temperature at the lowest level should be the surface temperature. On Saturday, March 1, BUFKIT projected the minimum surface temperature to be -35.4°C which is -31.7°F. What kind of synoptic weather situation was necessary for such a very cold minimum temperature?

c. The actual reported minimum was -26°F. What conditions are shown on the 13Z BUFKIT forecast sounding that could explain why the morning minimum was almost 6 degrees warmer than -31.7°F? You don’t have to be certain that’s what happened but some BUFKIT forecast conditions were not consistent with such a spectacularly cold morning and your answer to part b. Although -26°F is quite cold, BUFKIT forecast it to be worse. The human forecaster could have improved that by seeing what?

10. One of the great advantages to BUFKIT is that data may be generated for any point in the model, not just upper air stations like KBUF, KOKX, and KALB. With the NAM model selected, pick Oneonta, which is EON. It’s from today’s 12Z NAM.

Analyze the situation for the next 84 hours (12Z today through 00Z Sunday) for Oneonta. You may also use the 12Z NAM forecasts at the usual NCEP site using a browser (http://mag.ncep.noaa.gov/). Do NOT use any guidance other than the 12Z NAM and BUFKIT profile. Analyze the corresponding BUFKIT forecast from the perspective of the vertical atmospheric temperature, dew point, and wind structure. You must report why and how much (liquid equivalent) precipitation is forecast to fall at Oneonta during the 84 hour period. Also, use the BUFKIT forecast soundings to discuss the coming Arctic air incursion in central New York.