Case Study 016"Moberly,
Missouri Tornado"
04 July 1995
This case focuses on the tonado which occurred in Moberly Missouri on 04 July 1995. The data were presented as a laboratory exercise during the Satellite Mesoscale Meteorology residence course held at COMET.
In most years, upper flow over the central U.S. becomes relatively weak by the beginning of summer. In fact, by late June the jet stream has typically migrated far to the north, and is found situated over the northern U.S., or southern Canada. However, the morning of 04 July 1995 found an unusually intense synoptic scale trough located over the central and south central U.S. - - potentially strong upper level dynamics at a time of year when daytime temperatures were nearing their yearly peak, and moisture across the central and southern plains was abundant.
You will be playing the part of a forecaster at Pleasant Hill (EAX), located within Cass County in NW Missouri (40 miles SE of Kansas City airport, MKC), with an area of forecast responsibility as shown in the attached figures. You will be simulating the entire forecast process, from the issuance of morning outlooks to afternoon nowcast updates, as well as severe weather warnings -- when and if appropriate.
OVERVIEW OF CASE
SYNOPTIC SITUATION --
Start GARP for the case study of 04 July 1995
Task I. The time is 1600 UTC. Using GARP, look at the upper air analyses and other data available up to 1600 UTC, familiarize yourself with the current situation. In particular, load hourly satellite imagery for the WV (6.7 ) and IR4 (10.7) channels (prior to 16 UTC). Prepare a discussion summarizing the current weather and how it evolved.
What effects did the Mesoscale Convective System (MCS) have on the observed conditions and the 12Z model forecast? Was there more than one MCS of interest in the area? Which model data did you use?
MORNING FORECAST --
Task II. The time is 1800 UTC. Using what you found in Task 1, you should now begin the process of making the morning convective outlook for the forecast area. This outlook is due by 1830 UTC at your station, valid for the next 18 hours. Use the 4 km VIS, WV and IR satellite data prior to 18 UTC. Sketch the boundary features of interest (fronts, outflow, etc), using the 12 UTC surface analysis and the updated satellite imagery. The 15 UTC surface analysis is also provided for time continuity.
Look at the Surface RUC and RUC fields up to 18 UTC. (Note: theta-e is available only in RUC.)
Evaluate the spatial distribution in the equivalent potential temperature field at 1800 UTC. Are any significant features observable ?
Using a new GARP, compare the topography image (under Options, Topographic Maps, Midwest; use the 'roygbv' color enhancement option) with the satellite image animation. Do you think any topographic features could have influenced the propagation of the outflow boundaries over Missouri?
AFTERNOON UPDATES --
Task III. The time is 2015 UTC. There has been no severe weather reported up to this time in your area. Prepare an update to the severe weather outlook valid at 2030 UTC, using the available 1 km VIS satellite imagery prior to 2000 UTC, and other satellite and EAX radar data available before this time. You can use the GARP Options to overlay the NEXRAD sites and radar range rings on the first frame of your satellite loop. You may also wish to use the GARP cursor zoom with the 1km VIS imagery to focus in on the area of interest.
Also, be sure to review the RUC/Surface RUC fields up to 2000 UTC.
Task IV. The time is 2155 UTC. A report of a brief tornado touchdown was called in at 2035 UTC. The tornado touched down in Doniphan County, Kansas. Otherwise, the only severe reports have been hail (3/4") in eastern Kansas. Prepare an update to the severe weather outlook at 2200 UTC. Load an animation sequence of 15-minute interval, 1 km VIS satellite imagery; for example the rapid scan sequences 2035-2045 and 2135-2145 UTC.
Also utilize the RUC/Surface RUC analyses and evaluate the NIDS radar data for EAX and LSX prior to 2200 UTC.
FURTHER WARNINGS --
TASK 5 The time is 2315 UTC. New reports include 1" hail in Buchanan County, MO, with wind gusts to 60 mph. A tornado has been reported near St. Joseph in Buchanan County within the past 20 minutes, but there are no other details available as yet. First look at the Rapid Scan satellite time sequence ending just prior to 2315 UTC, as well as radar data prior to 2315 UTC. Which storm do you think produced the tornado and what is your reasoning? Use the surface RUC and RUC data. Use the cursor zoom function to examine details of the satellite imagery. On the base map, sketch the location of convective features which threaten your Warning Area. What are their formation mechanisms? Will these features intensify, remain the same or weaken?
Issue severe weather warnings in the EAX County Warning Area as appropriate. Evaluate which thunderstorms within this Area warrant the issuance of a severe or tornado warning, and be prepared to justify this issuance. Look for storm scale features. Do these features represent the threat of severe weather ? If so, how do you incorporate this information into your warning ?
FOLLOW-UP DISCUSSION: Summary of case and discussion of verification.