I was bored this morning and thought I’d post a discussion of today’s weather to provide a heads up to ARES members…
The Storm Prediction Center in Norman, Oklahoma has forecast a moderate risk for severe thunderstorms over portions of Central Indiana today. The Lafayette area is under a slight risk for severe weather. The severe probabilities are 5% tornado, 30% hail, 30% wind. These percentages are the probability of the stated event occurring within 25 miles of a point. For more information see http://www.spc.noaa.gov/products/outlook/day1otlk.html
A strong low-level jet ahead of an approaching cold front will provide for a probability of strong-to-severe thunderstorms this afternoon. The threat will be mitigated by a lack of surface heating (due to cloud cover) and shallow lapse rates. This combined with low surface dew points/high LCLs should preclude widespread tornadic activity. However, small, brief tornadoes cannot be ruled out given the high ambient storm-relative helicity.
Low freezing levels and strong mid-level winds (87 knt at 500mb) will provide for the possibility of hail and damaging winds with storms that approach along and ahead of the cold front. Given the weak instability, very large hail (greater than 2″) is not expected, and wind gusts will likely not exceed 75 mph.
It appears the most likely time for severe weather in Tippecanoe County will be the early afternoon, specifically from 2pm until 6pm. Non-severe thunderstorms will likely occur prior to this time frame, but all storms should have passed by sundown.
In addition to the severe weather threat today, flooding will be a concern over the next several days. The forecast for the Wabash River at Lafayette is that flood stage (11.0 feet) will be reached late tonight. The crest is forecast to be 18.4 feet Tuesday morning. At 18 feet, extensive flooding is in progress. Flooding covers many acres of agricultural land. River cabins become isolated. Indiana 225 closed by high water. River Road, the western approach to Granville Bridge and higher county roads begin to flood. High water affects river cabins near Fort Ouiatenon area. County Road 775 East near Americus in Northeast Tippecanoe County begins to flood. All parks in the West Lafayette and Lafayette areas are flooded. McAllister Park Golf Course begins to flood.
Note that the flood forecast is based on current and expected conditions at Lafayette and upstream. Heavier rain than expected could amplify and/or extend the duration of the flood.