Case Study 006HEAVY RAIN FORECASTING EXERCISE
17-19 July 1996
By Jim Moore and Ron Przybylinski
This exercise will focus on forecasting a heavy rain event in the upper Midwest. In the first part of this exercise, you are asked to:
1) Diagnose the pre-convective environment for 1200 UTC July 17 over the upper Midwest. Specifically, you should
- Locate surface boundaries.
- Identify upper (lower) level jet streaks over the region.
- Diagnose the moisture available to the system (e.g. mean RH, 850 mb dew points, theta-e)
- Location of shortwave troughs at mid-levels
-Analyze relevant Skew-T's to diagnose the depth of the moisture, CAPE, and low-level shear.
-Examine satellite imagery (IR/WV) and radar imagery (NOWRAD or individual sites) for the period 0600 - 1200 UTC July 17.
(Complete this part of the exercise within 30 minutes.)
2) Using your analysis, discuss the atmospheric setting for 1200 UTC 17 July.
3) You are working at the famous NWS forecast office at Romeoville Illinois (CHI). Your task will be to forecast the type of weather for the period 1800 UTC 17 July through 0600 UTC 18 July. Do you expect any severe weather to occur over the state of Illinois during this period? If so, where, and what type of severe weather do you expect. Try to estimate the Corfidi vectors. Along with model data, you can now view the surface, satellite and radar imagery up to 1800 UTC.
4) Make a 24 hour QPF forecast from 1200 UTC 17 July to 1200 UTC 18 July for the state of Illinois (Not Basin Average). Highlight your area of heavy rain in inches.
Summarize your findings.