THURSDAY AM RADAR – FAST EAST LOADING RADAR
The Thursday morning radar shows very little activity over any portion of the Plains …the Midwest or the Deep South. There is a cluster of storms over southeast Iowa and there is a band of moderate rain over the northwest half of North Dakota into southeastern Montana and into the far northwest corner of Wyoming. Some of this rain is falling as snow over the highest elevations.
RAINFALL LAST 24 HRS ending 0700 cdt 21 SEPTEMBER
The only significant rain that fell was heavy rain over the southeast 25% of Iowa. Here the rainfall amounts are quite impressive with general rainfall of 1-5″/ 25-125mm but there were locally heavier amounts over places such as Ottawa which reported 9.5″/ 235mm. Keep in mind that in some locations in southeast Iowa it is still raining past 7:00 AM cdt. Additional light to moderate rains 1-4″/ 25-100mm inches fell over 60 to 70% of southeast Wisconsin.
MAX TEMPS MONDAY
Max temperatures continue to run unseasonally warm over much of the ECB as well as the Deep South and the central and lower Plains. This is not unexpected given the overall pattern and the recent forecasts but it is fairly impressive. 60s were common over eastern MT, western ND … 70s over rest of ND, SD, eastern WY, eastern COL, NEB, MN … 80s over WI, IA, KS, northern IND, MI, OH, KY … 90s over TN, GA, AL, MS, LA, ARK, MO, OK, TX with some 100+ readings over sw TX.
1-5 DAY = There are not big changes in the forecast but there are some moderate ones with regard to which areas are going to see the best rains over the next 5 days and in the 6-10 day. The models generally show a wide band of 1-6″/ 25-150mm rains covering most of Minnesota … central and eastern portions of South Dakota … central and eastern Nebraska with lighter amounts over western Kansas and into the Oklahoma and Texas panhandle as well as eastern Colorado. The GFS model is a little faster with the rain in terms of progressing it to the east than the European. And the GFS model has the best rains of 5-7″/ 125-175mm over northeast Nebraska … southeast portions of South Dakota into southwest Minnesota. The coverage in this wide band of rain on both models is a least 70% and in some areas it could be a little higher. Areas east of the band are completely dry all the next 5 days and this includes all of central and eastern Kansas …Missouri …Iowa …most of Wisconsin …all of Illinois …Indiana …Kentucky …Ohio …Arkansas and Tennessee.
6-10 DAY = The model agreement here is not good at all. The GFS advances the front on the north rapidly through the Midwest so that the eastern portions of the WCB and all of the ECB regions do not see widespread significant rain. The GFS shows 40 to 50% coverage in these areas of only 0.25-1.0″/ 6-25mm. The southern end of the front on the GFS model stalls over Oklahoma and Texas and that results in a widespread 2 -8″/ 50-200mm rain over 75% of Texas and Oklahoma and 1-3″/ 25-75mm rains over Arkansas and southern Missouri.
The European model is significantly slower with the front and given the overall pattern this makes sense. As a result the European has additional 1 -2″/ 25-50mm rains over central and eastern Minnesota …northwest Wisconsin …all of Iowa …the far eastern third Nebraska …central and eastern Kansas and 1-3″/ 25-75mm rains over central Oklahoma and much of central Texas including the eastern portions of the TX Panhandle.
With this sort of significant model disagreement the best thing to do would be of course to move to the GFS and European ensembles. But in this case that doesn’t help a lot. Both models agree that in the 6-10D the best rains will clearly fall over south central Kansas …western and central Oklahoma …and all of western and central Texas. The GFS ensemble mean shows a large area of 2-5″/ 50-125mm rains with 80% coverage over these areas.
The European model is similar but the rainfall amounts are not nearly as heavy ranging from 1 -4″/ 25-100mm but also with 70 to 80% coverage. In addition the European model still as 0.5-1.5″/ 12-38mm rains over portions of eastern Nebraska …all of Iowa …Minnesota and all of Wisconsin. The GFS model only has scattered showers in these areas. Again due to the overall pattern …the Delta region and all of the ECB stays completely dry in the 6-10D.
11-15 DAY = Starting day 8-9… a major trough will move through the Midwest and drive towards the East Coast. This will put some rain into the ECB but the rapid movement of this powerful trough will ensure that the rainfall amounts over the ECB will be fairly light. The front will reach the East Coast by September 29. Behind the front temperatures will turn chilly for several mornings on the 30th as well as October 1 -3 over most of the Midwest. The model data does show readings into the mid and upper 30s over portions of Minnesota, Iowa, Wisconsin and Michigan …and upper 30s and low 40s over portions of Illinois, Indiana and Ohio. It is possible that these temperatures may be cold enough to bring about the first significant frost in some areas. However this is still a long way off and the model data is having a lot of difficulty nailing the temperatures down — which is pretty typical in dealing with temperature forecast beyond day 10. During the weekend and early next week we shovel much better idea of how chilly temperatures will be during the first couple days of October.