Severe Weather/Heavy
Precipitation Forecasting Exercise
The purpose of this exercise is to prepare heavy precipitation forecasts and
issue severe weather outlooks (and watches as needed) for three consecutive
12-h periods beginning at 0000 UTC tonight. For this exercise, the class
will be split into one team of three students, and two teams of four students
with all three teams presenting their forecasts each day. Additionally,
the team that goes first on a given day will give a brief forecast discussion
beginning at 4:45 pm (see presentation mechanics section below).
1. Forecasts to be issued:
a. National 12-h quantitative precipitation forecasts (QPFs)
for 0000-1200 UTC (overnight), 1200-0000 UTC (tomorrow), and 0000-1200 UTC
(tomorrow night) for precipitation amount thresholds of 0.25'', 0.50'', 1.00'',
2.00'', etc.
b. National severe weather outlooks for the same periods as the QPF forecasts
and modeled after the Storm Prediction Center (SPC) outlooks that are routinely
disseminated. Watch boxes may be issued as appropriate.
2. Methods:
a. Work as a team.
b. Use any available maproom and internet products.
c. Try to prepare some of YOUR OWN analysis products, such as surface mesoanalyses.
d. Pay
special attention to surface boundaries of all kinds. Make liberal use of
our departmental surface potential temperature and mixing ratio maps.
e. Use satellite and radar imagery and precipitable
water charts to help locate moisture axes. Consider computing surface and
upper-air moisture convergence using GEMPAK from NCEP model analysis and
forecast grids, available in the directory /data1/gempak/hds/.
f. Monitor stability changes through model gridded datasets and/or the low-tech
alternative of preparing simple 850-700 hPa and 700-500 hPa temperature
difference maps.
g. Consider the presence or absence of severe weather ingredients (i.e., lift,
instability, moisture, and boundaries).
h.
Summarize your dynamical and thermodynamical
reasoning by preparing composite charts that illustrate the juxtaposition of
key ingredients (moisture axes, jet corridors, boundaries, thermal ridges,
ascent zones, etc.), as in this
example from
Maddox and Crisp (1999).
i. Generate all your severe weather forecast
and QPF electronically using the graphics program of your choice (e.g.,
PowerPoint).
3. Verification:
Prior to the map discussion and forecast
presentations, one of the teams not giving the forecast discussion/first
forecast presentation will provide a precipitation and severe weather forecast
verification. Since there are six classes devoted to this exercise, each
team will perform the verification twice. Verification data can be found
at the SPC Storm Reports page, the NOAA-NWS
Precipitation Analysis, and the National
Precipitation Verification Unit.
4. Presentation Mechanics:
After the verification is presented, the lead team
will provide a 15 to 20 minute map discussion, followed by a presentation of
their forecasts. Each team will lead twice.
The job of the other two teams is, first, to CHALLENGE AND QUESTION the
arguments of the lead team, and, second, to present their own forecasts.
The other presentations should be significantly shorter than the lead
presentation, and should highlight points of disagreement with the other
forecasts, accompanied by supporting evidence.
5. Potentially Useful Severe
Weather-Related Links:
Atm 401/501
Severe Weather Overview Presentation (pdf)
Storm Prediction Center Forecast
Tools webpage
Meteorology
Education and Training COMET Modules
The following modules
are particularly applicable to severe weather:
a. A Convective Storm Matrix: Buoyancy/Shear Dependencies
b. An MCS Matrix
c. Mesoscale Convective systems: Squall Lines and Bow Echoes
d. Severe Convection II: Mesoscale Convective systems
e. Principles of Convection I: Buoyancy and CAPE
f. Principles of Convection II: Using Hodographs
g. Principles of Convection III: Shear and Convective Storms
h. Quantitative Precipitation Forecasting Overview
University of Illinois Severe and
Hazardous Weather Page: An excellent resource for learning about storm
structure and climatology
HPC
Development and Training: QPF and winter weather
HPC Model
Diagnostics: Model verification and d(prog)/dt
Mike Bodner's real-time standardized anomaly page at NCEP/HPC
