Why Forecasting Rainfall Is So Difficult

By -
Rainfall amounts, especially from thunderstorms, can vary widely in time and space. Meteorologists have been hopeful that a very new technique called "mesoscale modeling" will eventually be of great assistance.

Yesterday, we had an example of the promise and peril of mesoscale modeling.

The Forecast
This is a view of south central Kansas with the 4.5 (inches) over Wichita. The darker brown are forecast amounts of 5.5 to 6.1 inches. The forecast was made from the 7pm data yesterday evening and applied to the overnight hours.

The Actual Rainfall 
In terms of the amount of rain, the forecast was remarkably good. Amounts in excess of five inches are highlighted. The issue is that the real-world heavy rain was roughly 15-20 miles farther west and south than forecast. For example, at Wichita's Eisenhower National Airport (the official reporting site) had .75  inches versus a forecast of 4.50 inches. A huge difference.

I certainly see this as a "glass three-quarters full" situation. The amounts of rain were quite accurate and the locations were close enough to be useful -- but, the human meteorologist was required in this situation to monitor the radar and place any flood forecasts (with the drought, little flooding expected).

So, while this is an excellent start, we still have a ways to go before these forecasts are good enough to be used on their own.

Comments

Post a Comment

Popular posts from this blog

The East Coast Severe Weather Threat is Over

By -
Image
Midnight: The East Coast Threat for Tornadoes and Severe  Thunderstorms Has Ended 3:50pm. Tornado watch for the Middle Atlantic Region. 2:30pm Tornadoes are also forecast in the South. 2:20pm. A couple of tornadoes, hail and wind gusts to 65 mph are possible with these storms. This includes NYC and Philadelphia.  1:05pm. The tornado risk has been extended northward into New York. The brown area has a significant risk of tornadoes. Remember: if a tornado warning is issued, go to your basement and get under heavy furniture like a pool table. Of, if your basement is finished, get into the bathroom. Go ahead an put a couple of water bottles and, if appropriate, diapers in your shelter area. Wear shoes.  If you don't have a basement or safe room, go to the lowest floor and get into a bath or closet in the middle of your home. Children should be put in the bathtub.  I'll update later today. 
Read more

Today's Tornado and Severe Thunderstorm Outlook - 9:30pm

By -
Image
After 65 mph winds went through Wichita, we have been without power for 35 minutes. So, I am going to have to end coverage for the night (using backup systems to write this). Scroll down for the forecast of tornadoes and severe thunderstorms for Sunday and Sunday night.  Please read down for the latest forecasts regarding this dangerous tornado and damaging wind situation! 5:40pm, a new "regular" tornado watch has been issued for north central Kansas.  Note that wind gusts to 80 mph are likely in this storm in addition to tornadoes and giant hail. Please make sure friends and relatives in the area are aware of the danger in the area outlined in red below plus the red area outlined at 2:50pm  In addition to "several strong tornadoes," hail to 4.8" in diameter is forecast along with wind gusts to 80 mph. Now is the time for persons living in mobile homes, manufactured homes and those with mobility issues should be making plans!!  Do not wait until a tornado warn
Read more

Updated Freezing Rain and Heavy Rain Forecast

By -
Image
Note: An Updated Forecast is Available HERE Freezing Rain The National Weather Service has now issued winter weather advisories, two warnings and a watch. It may be a bit too large but, when it comes to freezing rain and slick roads, caution is usually the better course of action.  Here's a color code: Deep purple is an ice storm warning; serious condition where power outages are possible. Pink is a winter storm warning for significant icing. Deep green is a winter storm watch. I don't know why this is still a watch. If I were on the forecast desk I would have a winter storm warning for icing.  Dark blue is a winter weather advisory, a lesser condition, for icing.  Here is a view of the entire watch/warning/advisory area. The small area of green in Illinois is for flooding and, in Nebraska, for snow.  Here is a forecast of freezing rain amounts; totals to 6am Tuesday.  Color codes: Yellow is 0.25 to 0.50 inches. Power outages may occur in this areas. Deep blue is 0.1 to .25 inc
Read more