High temperatures today are expected to soar into the low 70s for much of Iowa. The calendar does now say November, so one may expected the staying power of such warm temperatures to be fleeting. The featured chart presents the frequency of having a day above 70 followed by another day over 70 by each day of the year. As shown by the chart, the chances for early November are not good. Indeed, temperatures will fall back into the 40s tomorrow as the warm up will be brief!

After high temperatures soared into the 70s on Tuesday, they will struggle to do any raising at all today with some locations expected to set their daily high temperature at midnight this morning. The featured chart looks at the frequency of having the warmest temperature of the day occur during the midnight hour for Des Moines. For November, these frequencies equate to roughly 4-5 days per year.

Iowa got a preview of winter yesterday with some locations picking up their first measurable snowfall of the season. This was thanks to a process of cooling the air from having snow fall into warmer air near the surface and cooling it from phase change into rain. The more intense precipitation will lead to the strongest cooling rates and best chances of snow in these situations. The featured chart presents a comparison of average afternoon temperature against a composite of RADAR reflectivity. In general, the coolest temperatures are associated with the higher rates of precipitation.

The sham that is daylight saving time ends this weekend and so to encourage those who wear tin foil hats, the featured chart is presented comparing two periods of the day computed in CST and CDT. For the work day, the difference is computed between the 8 hour average temperature computed over the 8 AM to 4 PM period based in CST and CDT year-round. The "CDT effect" is for a slightly cooler 8 hour work day as compared to the same period if it was CST all summer. This effect remains the same in the winter time, but lo and behold our clocks go back to CST to reverse the effect. From an energy perspective, the result is potentially favorable for businesses to save a bit on cooling in the summertime and heating in the winter time. It is a conspiracy! Of course, when we are at home, the effect is reversed, so we have slightly warmer sleeping periods in the summer with CDT and cooler sleeping periods in the winter with CST. Your head is probably spinning trying to follow the logic presented, but think how CDT shifts the work day into earlier in the day to leave more light at night and time for lawyers to golf after work (net cooler, less cooling bill). In the winter, the shift is for more light in the morning (so that kids have light to go to school, whatever) which puts more of the work day into hours with sunlight (net warmer, less heating bill). Enjoy the extra hour of sleep :)

The featured chart presents the frequency of having a high temperature above average and observed precipitation by day of the week so far this year for Ames. Sunday has seen the highest percentage of days with precipitation with Saturday having the least. Of course, over a long enough time period, this plot evens out as there is not a physical process that depends on day of the week. Precipitation is in the forecast this week along with chances of measurable snow for the northern parts of Iowa.

A winter storm watch was in effect for portions of Iowa this evening and tomorrow for an approaching winter storm. The watch was upgraded to a winter weather advisory with a few inches of snow expected. The featured map presents the frequency of winter storm watches for the past six years. Most of the state is shown in the 4-8 watches per year.

Our first major winter storm of the season is dumping wet snow over most of the central portion of the state. Slushy snowfall totals have been reported over 6 inches to the southwest of Des Moines so far this morning. The featured map is of Iowa State Patrol road conditions showing roads in southeast Iowa just wet with the snow covered roads to the west in the central part of the state. This snow will have a tough time sticking around as ground temperatures are still warm and air temperatures are expected to be well above freezing during the daytime.

The first winter storm of the season is in the books dumping very wet snow over swath of Iowa including most of Des Moines. The featured map is a crude analysis of snowfall reports from the storm with the highest totals around 6 inches. We'll produce maps like this after every storm this winter season and you can find these maps later by clicking on "Winter Storms of 2011-2012" link underneath "Most Popular Links" on the homepage. Last year, we had 16 such maps, so we have plenty of winter to go this year!

Having clear skies after a new snowfall always makes for pretty pictures from space like the one featured today. The new snow cover also makes for interesting local weather effects as can be seen by afternoon high temperatures on Thursday. The snow reflects much of the sun's energy back out into space which keeps air temperatures cooler than neighboring snow free areas. This snow patch should continue to decrease in size with more above freezing temperatures expected.

Outside of a very warm day for the first day this month, temperatures have been to stay above average. High temperatures this past weekend warmed nicely into the 50s, but cooler weather back in the 40s is expected for most of this coming week. Highs in the 40s are about average for this time of year, so it could certainly be much worse!

The featured chart presents an analysis of minimum reported temperature so far this fall season. It would appear that practically all portions of the state have seen a freezing temperature so far this fall season. Some of the coldest weather so far this season is expected to arrive in the state this evening with lows in the 20s and highs on Wednesday barely breaking 40.

The past few days have seen bouts of severe weather over various parts of the country. The Storm Prediction Center issues tornado and severe thunderstorm watches in advance of these storms. The featured chart presents the year to date totals of watches issued for Iowa and Texas since 1997. Last year was the only year Iowa has beaten Texas in total watches. The bottom chart shows the percentage of total watches issued that covered a portion of Iowa. This year's percentage is the second lowest behind 1997.

The precipitation total for this November has already exceeded the total for all of October for Ames. The featured chart presents the difference in precipitation between October and November each year for Ames. 37 of the total 119 years have seen a wetter November than October, so having this happen is about an one in three years chance. There are only small rainfall chances in the forecast.

Thursday morning saw our coldest temperatures of the season with lows approaching zero degrees in far northwest Iowa. The featured chart presents the average first date of occurrence for a given temperature for four sites in Iowa. It is interesting to see how much closer Ames is to Sioux City than Des Moines. Davenport's climatology is about two weeks later than Ames, so for example Ames hits its first sub freezing around mid October and Davenport is toward the end of October.

After two very windy days on Friday and Saturday, Sunday was a bit calmer as shown by the featured chart of daily average and peak wind speeds from the Des Moines Airport sensor. November has yet to see a day with wind speeds below 10 mph for the entire day. This is not uncommon as November is a battle ground month for air masses, which drive the windy conditions.

You may have remembered it like yesterday, but back on the 7th of July the three cities of Burlington, IA , Miami, FL, and Fairbanks, AK had a high temperature within two degrees of each other around 80 degrees. Fast forward a bit more than 4 months and a much different tale is to be told. While Fairbanks struggled to breach -30 degrees, Miami enjoyed a warm 85 and Burlington was stuck somewhere the middle around 40 degrees. This graph makes the directional choice for Iowans going on vacation in the winter easy.

The featured chart presents the range in forecasted morning lows and afternoon highs from the "NAM" weather model output statistics (MOS) and actual observations for the Des Moines Airport. The forecast for Thanksgiving has high temperatures around 60 degrees, which is around 20 degrees warmer than average for this time of year! The warm weather will be fleeting with rain chances for your trip home from grandmother's house.

Temperatures have warmed nicely on Thanksgiving with 50s and 60s reported in Iowa. For Ames, today is the warmest day since the first of the month (23 days). The featured chart presents the number of days prior to Thanksgiving that were cooler than the high temperature on Thanksgiving. This year's total is the second longest on record! Reality will set back in with highs back below average by next week.

Since setting record high temperatures on Thanksgiving, our weather has been on the windy side with wind gusts measured above 30 mph each day since somewhere in the state. The featured chart presents the climatology of having one or more hours of wind observations at or above 30 mph for each day of the year. The annual signal is clear with these events more limited in the summer and peaking during the transition seasons of spring and fall. There are some localized peaks due to peaks in thunderstorms and strong winter storms.

Snow was reported yesterday over locations well to our southeast in Tennessee and Alabama. Not all in Iowa have yet to see their first snowfall of the year! The featured chart presents the NWS Cooperative Observer reports of 1+ inches of snowfall so far this year. Just a swipe of snow from the 9 November storm is about all Iowa has to show this year. There are chances of snow in the forecast for this coming weekend.

The airport weather sensors for Des Moines and Ames are typically called 'ASOS' sensors and lumped into the same data pile as they both have similar sensors and maintenance standards. The featured chart presents a summary of reported sky conditions at 6 AM each morning this year. While these sites are only separated by 30 some miles, there are some large differences in the number of clear mornings reported. The difference here is that the Des Moines sensor has augmentors that report cloud ceilings higher (to 25,000 feet) in the sky than the Ames sensor can (to 12,000 feet). This is just one of the data quirks that keeps life fun and various people employed to keep track of this all!