METR 361 Spring, 2016
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 12):
1. We are using the Dell laptops because
BUFKIT won’t run with Linux or Mac. Your
professor will have BUFKIT running on the machines when you arrive for lab.
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 Science
and Operations Officer (SOO) at NWS-OKX has set up Oneonta BUFKIT profiles for
us. He lists them as EON. Other 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.