Past Features
This page lists out the IEM Daily Features for a month at a time. Features have been posted on most days since February 2002. List all feature titles.
Fri Nov 01, 2024
Difference One Rainfall Makes
01 Nov 2024 05:30 AM
A stretch of very dry weather during September and October came to an abrupt end on Wednesday into Thursday with a significant rainfall event averaging over 1.30 inches for the state. This event sort of "spoiled" a number of potential records for driest October and/or driest stretch of days on record for a number of sites. That aside, the featured two maps present the large difference one rainfall event can make for monthly precipitation metrics. The two maps present climate district precipitation ranks for the 1-30 Oct period (top panel) and 1-31 Oct period (bottom panel). The difference in rank improved between 24 to 64 positions just with one event! For south central Iowa, the change was from a top 10 driest to a value that was above average for the month! Such is often the case for precipitation metrics as single events can dramatically change the result.
Voting: Good - 21 Bad - 0
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01 Nov 2024 05:30 AM
A stretch of very dry weather during September and October came to an abrupt end on Wednesday into Thursday with a significant rainfall event averaging over 1.30 inches for the state. This event sort of "spoiled" a number of potential records for driest October and/or driest stretch of days on record for a number of sites. That aside, the featured two maps present the large difference one rainfall event can make for monthly precipitation metrics. The two maps present climate district precipitation ranks for the 1-30 Oct period (top panel) and 1-31 Oct period (bottom panel). The difference in rank improved between 24 to 64 positions just with one event! For south central Iowa, the change was from a top 10 driest to a value that was above average for the month! Such is often the case for precipitation metrics as single events can dramatically change the result.
Voting: Good - 21 Bad - 0
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Mon Nov 04, 2024
Recent Drought Busting
04 Nov 2024 05:30 AM
The dryness of September and practically all of October is being made up for in rapid fashion. The featured chart presents trailing 31, 91, and 365 day precipitation departures for Ames. The analyzed US Drought Monitor category is underlain. The significant rains over the past week have really put a dent in the drought that rapidly degraded this fall. More rainfall is in the forecast for early this week.
Voting: Good - 13 Bad - 0
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04 Nov 2024 05:30 AM
The dryness of September and practically all of October is being made up for in rapid fashion. The featured chart presents trailing 31, 91, and 365 day precipitation departures for Ames. The analyzed US Drought Monitor category is underlain. The significant rains over the past week have really put a dent in the drought that rapidly degraded this fall. More rainfall is in the forecast for early this week.
Voting: Good - 13 Bad - 0
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Tue Nov 05, 2024
2024 Soil Moisture
05 Nov 2024 05:30 AM
The recent rainfall is certainly very welcome as deficits from the early fall season are being erased. Sometimes big rainfall events can come too quickly and water is "lost" (with respect to soil moisture) to runoff. So it is a good time to check in on soil moisture observations from the ISU Soil Moisture Network. The featured chart presents daily soil moisture observations at a twelve inch depth. This year's value is plotted along with the period of record climatology. The chart is a bit noisy due to having just 12 years of data, but tells a good story of the 2024 year. We came into this growing season with good soil moisture reserves and timely rains throughout much of the season kept levels above average. The drying that occurred during October has quickly been reversed with current values above the 75th percentile.
Voting: Good - 16 Bad - 16
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05 Nov 2024 05:30 AM
The recent rainfall is certainly very welcome as deficits from the early fall season are being erased. Sometimes big rainfall events can come too quickly and water is "lost" (with respect to soil moisture) to runoff. So it is a good time to check in on soil moisture observations from the ISU Soil Moisture Network. The featured chart presents daily soil moisture observations at a twelve inch depth. This year's value is plotted along with the period of record climatology. The chart is a bit noisy due to having just 12 years of data, but tells a good story of the 2024 year. We came into this growing season with good soil moisture reserves and timely rains throughout much of the season kept levels above average. The drying that occurred during October has quickly been reversed with current values above the 75th percentile.
Voting: Good - 16 Bad - 16
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Wed Nov 06, 2024
Another Blue/Red Map
06 Nov 2024 05:30 AM
In case you are not sick of seeing blue and red state maps yet, today's IEM Daily Feature adds another to the pile. The map presents an IEM computed rank for year to date tornado warnings by state. A value of "1" indicates the lowest total over the period since 2002. A value of "23" would be the highest. There are certainly some interesting contrasts shown over the country a clear deficit shown over the "Dixie Alley" states of Mississippi and Alabama. The states of New York, Ohio, Oklahoma, and Florida are indicated as having the most for this period.
Voting: Good - 12 Bad - 4
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06 Nov 2024 05:30 AM
In case you are not sick of seeing blue and red state maps yet, today's IEM Daily Feature adds another to the pile. The map presents an IEM computed rank for year to date tornado warnings by state. A value of "1" indicates the lowest total over the period since 2002. A value of "23" would be the highest. There are certainly some interesting contrasts shown over the country a clear deficit shown over the "Dixie Alley" states of Mississippi and Alabama. The states of New York, Ohio, Oklahoma, and Florida are indicated as having the most for this period.
Voting: Good - 12 Bad - 4
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Thu Nov 07, 2024
SPS Graphics
07 Nov 2024 05:30 AM
The National Weather Service issues Special Weather Statements (SPS) to cover a wide variety situations whereby they wish to alert the public to something notable. Recently, these statements have covered overnight fog that was not being handled by a Dense Fog Advisory for some counties. The featured map is an info-graphic that the IEM produces that attempts to visually show the highlighted geography along with the narrative text found within the SPS. If you are looking for archives of these plots, the most approachable means is to navigate the NWS Text Archives interface. If the SPS product contained a polygon, you can use the point search tool to find the alert and then click the "view text" link to retrieve the plot as well.
Voting: Good - 10 Bad - 0
Tags: sps
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07 Nov 2024 05:30 AM
The National Weather Service issues Special Weather Statements (SPS) to cover a wide variety situations whereby they wish to alert the public to something notable. Recently, these statements have covered overnight fog that was not being handled by a Dense Fog Advisory for some counties. The featured map is an info-graphic that the IEM produces that attempts to visually show the highlighted geography along with the narrative text found within the SPS. If you are looking for archives of these plots, the most approachable means is to navigate the NWS Text Archives interface. If the SPS product contained a polygon, you can use the point search tool to find the alert and then click the "view text" link to retrieve the plot as well.
Voting: Good - 10 Bad - 0
Tags: sps
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Fri Nov 08, 2024
Making Up For Dry Months
08 Nov 2024 05:30 AM
The featured chart presents daily statewide precipitation estimates for Iowa made by the IEM. Note that the plotted values are valid at 7 AM, so they aren't true calendar day values. That aside, the last eight days have certainly put a dent in the deficits accumulated over the past two months. Two of the largest values found since 1 August have occurred over the past eight days! Outside of a bit of snow that fell over far northwestern Iowa, this has all fallen as much needed rainfall and at rates that should have promoted good infiltration.
Voting: Good - 17 Bad - 1
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08 Nov 2024 05:30 AM
The featured chart presents daily statewide precipitation estimates for Iowa made by the IEM. Note that the plotted values are valid at 7 AM, so they aren't true calendar day values. That aside, the last eight days have certainly put a dent in the deficits accumulated over the past two months. Two of the largest values found since 1 August have occurred over the past eight days! Outside of a bit of snow that fell over far northwestern Iowa, this has all fallen as much needed rainfall and at rates that should have promoted good infiltration.
Voting: Good - 17 Bad - 1
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Mon Nov 11, 2024
Mississippi River Warmth
11 Nov 2024 05:17 AM
The featured map presents the minimum low temperature since the first of October from long term climate sites tracked by the IEM. Very cold air for this time of year has been limited thus far with only a few sites dipping down into the teens. Of particular interest to today's plot are the warmest plotted values shown along the Mississippi River valley. Places like Dubuque at 33, Davenport at 33, and Burlington at 34 nicely show the warming effect of being next to a significant amount of water. Water does not cool as rapidly as soil, so near surface air temperatures will be warmer next to water than soil.
Voting: Good - 8 Bad - 0
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11 Nov 2024 05:17 AM
The featured map presents the minimum low temperature since the first of October from long term climate sites tracked by the IEM. Very cold air for this time of year has been limited thus far with only a few sites dipping down into the teens. Of particular interest to today's plot are the warmest plotted values shown along the Mississippi River valley. Places like Dubuque at 33, Davenport at 33, and Burlington at 34 nicely show the warming effect of being next to a significant amount of water. Water does not cool as rapidly as soil, so near surface air temperatures will be warmer next to water than soil.
Voting: Good - 8 Bad - 0
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Tue Nov 12, 2024
Fall Winds Aloft
12 Nov 2024 05:30 AM
The featured chart presents fall season averaged wind speeds at the 500 hPa pressure surface based on the evening soundings from Omaha. This level is approximately half way through the troposphere and is often a good proxy to how energetic the atmosphere is. The 2024 value is shown at the bottom of the range of values from the site since 1960, but a strong caveat is that climatology favors stronger winds into November, so there is still time for the 2024 value to increase. That aside, the low value certainly tells a story to how few storms there have been over the region since the start of September. This value being another proxy to how generally dry it has been for the fall season, outside of the very recently wet pattern.
Voting: Good - 9 Bad - 2
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12 Nov 2024 05:30 AM
The featured chart presents fall season averaged wind speeds at the 500 hPa pressure surface based on the evening soundings from Omaha. This level is approximately half way through the troposphere and is often a good proxy to how energetic the atmosphere is. The 2024 value is shown at the bottom of the range of values from the site since 1960, but a strong caveat is that climatology favors stronger winds into November, so there is still time for the 2024 value to increase. That aside, the low value certainly tells a story to how few storms there have been over the region since the start of September. This value being another proxy to how generally dry it has been for the fall season, outside of the very recently wet pattern.
Voting: Good - 9 Bad - 2
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Wed Nov 13, 2024
Above Average Again
13 Nov 2024 05:30 AM
The featured chart presents year to date accumulated precipitation for Ames. The tan area represents the envelope of observed data, with the maximum year (1993), minimum year (1910), climatology (dashed line), this year and last year's data also plotted. This year's line of travel is rather remarkable with a good chunk of spring spent at levels above the wettest year of 1993 and well above average. The fortunes reversed by July into August with the mostly flat line from September into October. Then the deluge happened over the past two weeks and the year to date total is again above average. We'd only need another half inch for the rest of the year to finish above average for the year.
Voting: Good - 18 Bad - 0
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13 Nov 2024 05:30 AM
The featured chart presents year to date accumulated precipitation for Ames. The tan area represents the envelope of observed data, with the maximum year (1993), minimum year (1910), climatology (dashed line), this year and last year's data also plotted. This year's line of travel is rather remarkable with a good chunk of spring spent at levels above the wettest year of 1993 and well above average. The fortunes reversed by July into August with the mostly flat line from September into October. Then the deluge happened over the past two weeks and the year to date total is again above average. We'd only need another half inch for the rest of the year to finish above average for the year.
Voting: Good - 18 Bad - 0
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Thu Nov 14, 2024
November wetter than
14 Nov 2024 05:30 AM
For much of the state, this November has been wetter than the previous months of October, September, and even August for not quite as many locations. For Ames, the November total has eclipsed those three months already. The featured chart looks into the frequency of one month having a higher precipitation total than another month for the same calendar year for Ames. The three highlighted boxes are relevant for today's featured topic. It shows that the individual month comparison situation is not necessarily all that rare. While not shown on this chart, a manual database check indicates that having November wetter than all the previous three months almost happened just recently in 2022 with the November total tying August.
Voting: Good - 9 Bad - 1
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14 Nov 2024 05:30 AM
For much of the state, this November has been wetter than the previous months of October, September, and even August for not quite as many locations. For Ames, the November total has eclipsed those three months already. The featured chart looks into the frequency of one month having a higher precipitation total than another month for the same calendar year for Ames. The three highlighted boxes are relevant for today's featured topic. It shows that the individual month comparison situation is not necessarily all that rare. While not shown on this chart, a manual database check indicates that having November wetter than all the previous three months almost happened just recently in 2022 with the November total tying August.
Voting: Good - 9 Bad - 1
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Fri Nov 15, 2024
Nov 15 Snow Season Split
15 Nov 2024 05:30 AM
Today marks the mid point of November and thus far, one a single winter storm has clipped far northwestern Iowa. So does a season to date snowfall total of zero portend anything for snow for the rest of the season? The featured chart presents the combination of total snow prior to and after 15 November. Not much for a relationship is to be seen between the two. On average, we are only about 3% (1 inch out of 33 total) of the way through the winter season for snow by this date. So is there any snow in the immediate term forecast? Not really, but late next week does seem to hold the possibility of such a storm according to forecast models.
Voting: Good - 10 Bad - 0
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15 Nov 2024 05:30 AM
Today marks the mid point of November and thus far, one a single winter storm has clipped far northwestern Iowa. So does a season to date snowfall total of zero portend anything for snow for the rest of the season? The featured chart presents the combination of total snow prior to and after 15 November. Not much for a relationship is to be seen between the two. On average, we are only about 3% (1 inch out of 33 total) of the way through the winter season for snow by this date. So is there any snow in the immediate term forecast? Not really, but late next week does seem to hold the possibility of such a storm according to forecast models.
Voting: Good - 10 Bad - 0
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Mon Nov 18, 2024
Only 44
18 Nov 2024 05:30 AM
There has not been much to speak of for seasonally cold weather so far this fall, nor for snowfall. The combination of the two has resulted in a mild season with the featured chart presenting the yearly minimum daily high temperature for Ames for the season to date. The 2024 value of only 44 degrees comes in a tie for sixth place warmest and the warmest such value since the record of 48 degrees set back in 2016. This week will start off mild before a mid week storm ushers much colder temperatures into the state. It certainly appears that a colder fall season minimum high temperature will be established on at least Thursday.
Voting: Good - 12 Bad - 0
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18 Nov 2024 05:30 AM
There has not been much to speak of for seasonally cold weather so far this fall, nor for snowfall. The combination of the two has resulted in a mild season with the featured chart presenting the yearly minimum daily high temperature for Ames for the season to date. The 2024 value of only 44 degrees comes in a tie for sixth place warmest and the warmest such value since the record of 48 degrees set back in 2016. This week will start off mild before a mid week storm ushers much colder temperatures into the state. It certainly appears that a colder fall season minimum high temperature will be established on at least Thursday.
Voting: Good - 12 Bad - 0
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Tue Nov 19, 2024
November Snow Climo
19 Nov 2024 05:30 AM
Snowfall climatology is difficult due to all kinds of reasons including difficulties of measurement, limited periods of record, and season totals being dominated by isolated / large events. NCEI does produce a heavily smoothed out climatology, so the featured map attempts to provide a month of November accumulation climatology map! While the map shows some fine scale details, those should generally be ignored with a focus on more broad scale features shown over the state. In general, amounts vary from about an inch over far southeastern Iowa to about five inches of northwestern Iowa. While there was some forecast optimism that measurable snow was coming mid week, that scenario doesn't seem all that likely at the moment.
Voting: Good - 15 Bad - 0
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19 Nov 2024 05:30 AM
Snowfall climatology is difficult due to all kinds of reasons including difficulties of measurement, limited periods of record, and season totals being dominated by isolated / large events. NCEI does produce a heavily smoothed out climatology, so the featured map attempts to provide a month of November accumulation climatology map! While the map shows some fine scale details, those should generally be ignored with a focus on more broad scale features shown over the state. In general, amounts vary from about an inch over far southeastern Iowa to about five inches of northwestern Iowa. While there was some forecast optimism that measurable snow was coming mid week, that scenario doesn't seem all that likely at the moment.
Voting: Good - 15 Bad - 0
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Wed Nov 20, 2024
Wind Advisory Timing
20 Nov 2024 05:30 AM
The National Weather Service in Sioux Falls, SD issued a Wind Advisory Tuesday afternoon till Wednesday evening for a few counties in far northwestern Iowa. The featured chart looks into the time of day timing for when such events are in effect. The plot is effectively for Sioux County and shows the percentage of all 203 events on record for the site active during a given minute of the day. The diurnal signal is clear with the largest frequencies found during mid afternoon hours. This coincides with the strongest solar heating and mixing of the lower atmosphere, this mixing transfers higher momentum air to the surface, increasing wind speeds! The overnight frequencies are rather constant and are those events associated with strong surface pressure gradients between high and low pressure systems.
Voting: Good - 10 Bad - 3
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20 Nov 2024 05:30 AM
The National Weather Service in Sioux Falls, SD issued a Wind Advisory Tuesday afternoon till Wednesday evening for a few counties in far northwestern Iowa. The featured chart looks into the time of day timing for when such events are in effect. The plot is effectively for Sioux County and shows the percentage of all 203 events on record for the site active during a given minute of the day. The diurnal signal is clear with the largest frequencies found during mid afternoon hours. This coincides with the strongest solar heating and mixing of the lower atmosphere, this mixing transfers higher momentum air to the surface, increasing wind speeds! The overnight frequencies are rather constant and are those events associated with strong surface pressure gradients between high and low pressure systems.
Voting: Good - 10 Bad - 3
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Thu Nov 21, 2024
Season's First Trace
21 Nov 2024 05:30 AM
Much of Iowa got its first taste of winter on Wednesday with a cold wind and plenty of snow flurries with some brief bursts of visibility reducing snowfall. For Des Moines, a trace of snow was reported for the first time this season. The featured chart looks into the first fall season occurrence of snowfall for the site. The left side presents the first trace or higher snowfall amount and the number of subsequent days with snow reported on the ground (how long did the snow stick around). The right hand plot looks at the trend of this first date over the period of record. With ground temperatures still well above freezing, light snowfall events do not stand much chance at accumulating nor sticking around very long if some accumulation happens. Having the first trace of snow on 20 November comes in at about the 80th percentile, so four out of five years were earlier than this year.
Voting: Good - 9 Bad - 1
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21 Nov 2024 05:30 AM
Much of Iowa got its first taste of winter on Wednesday with a cold wind and plenty of snow flurries with some brief bursts of visibility reducing snowfall. For Des Moines, a trace of snow was reported for the first time this season. The featured chart looks into the first fall season occurrence of snowfall for the site. The left side presents the first trace or higher snowfall amount and the number of subsequent days with snow reported on the ground (how long did the snow stick around). The right hand plot looks at the trend of this first date over the period of record. With ground temperatures still well above freezing, light snowfall events do not stand much chance at accumulating nor sticking around very long if some accumulation happens. Having the first trace of snow on 20 November comes in at about the 80th percentile, so four out of five years were earlier than this year.
Voting: Good - 9 Bad - 1
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Fri Nov 22, 2024
Sub 20°F Wind Chills
22 Nov 2024 05:30 AM
The past two days have been a stark reminder of the long winter season to come with a brisk and cold wind blowing through the state. It has been the first time this season that wind chill temperatures have been of concern. The featured chart presents the daily feels like temperature range as computed from available hourly reports from the Ames Airport. Any days with a value at or below 20°F is highlighted red. So it has been since the end of March with as cold as wind chill temperatures we have experienced these past two days. The chart nicely shows the large range of feels like temperatures for the year ranging between -45°F and 111°F!
Voting: Good - 13 Bad - 1
Tags: feelslike windchill
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22 Nov 2024 05:30 AM
The past two days have been a stark reminder of the long winter season to come with a brisk and cold wind blowing through the state. It has been the first time this season that wind chill temperatures have been of concern. The featured chart presents the daily feels like temperature range as computed from available hourly reports from the Ames Airport. Any days with a value at or below 20°F is highlighted red. So it has been since the end of March with as cold as wind chill temperatures we have experienced these past two days. The chart nicely shows the large range of feels like temperatures for the year ranging between -45°F and 111°F!
Voting: Good - 13 Bad - 1
Tags: feelslike windchill
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Mon Nov 25, 2024
Late mid-20s Cold
25 Nov 2024 05:30 AM
For many sites in the state, the coldest air temperatures of the season so far arrived over the weekend with lows into the mid 20s on Saturday. The featured chart presents the climatology of season to date minimum temperature for Ames. The blue line is the season to date value and the most recent values are at the warm end of the range of values for the day of the season. Afternoon temperatures this past week were very pleasant, but big changes are in store for the Thanksgiving week with temperatures expected to stay below freezing on Thanksgiving and perhaps a few days following. It is good news for those that need outdoor refrigerator space this time of year whilst entertaining family and friends!
Voting: Good - 10 Bad - 0
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25 Nov 2024 05:30 AM
For many sites in the state, the coldest air temperatures of the season so far arrived over the weekend with lows into the mid 20s on Saturday. The featured chart presents the climatology of season to date minimum temperature for Ames. The blue line is the season to date value and the most recent values are at the warm end of the range of values for the day of the season. Afternoon temperatures this past week were very pleasant, but big changes are in store for the Thanksgiving week with temperatures expected to stay below freezing on Thanksgiving and perhaps a few days following. It is good news for those that need outdoor refrigerator space this time of year whilst entertaining family and friends!
Voting: Good - 10 Bad - 0
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Tue Nov 26, 2024
Fall Freezes
26 Nov 2024 05:30 AM
Yesterday's daily feature mentioned the lack of significant cold so far this fall season with only mid to lower 20s to date as the coldest air temperature. Today's chart looks into the number of days this fall season with a low temperature below 32°F for Ames. This year's total is in to lowest ten on record, but each day in the forecast for the rest of the month is below freezing, so the total will likely be 19 days. Even so, that total would be the lowest since 2016 and about seven days below a simple long term average.
Voting: Good - 9 Bad - 0
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26 Nov 2024 05:30 AM
Yesterday's daily feature mentioned the lack of significant cold so far this fall season with only mid to lower 20s to date as the coldest air temperature. Today's chart looks into the number of days this fall season with a low temperature below 32°F for Ames. This year's total is in to lowest ten on record, but each day in the forecast for the rest of the month is below freezing, so the total will likely be 19 days. Even so, that total would be the lowest since 2016 and about seven days below a simple long term average.
Voting: Good - 9 Bad - 0
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Wed Nov 27, 2024
Few Thanksgiving Travel Worries
27 Nov 2024 05:31 AM
Since 2013, the IEM website has been archiving the main watch, warning, and advisory (wawa) map found on the National Weather Service website. The general lack of colors with the current map this Wednesday morning is a good indication of the few weather related travel worries for the busiest travel day of the year. Sometimes folks reasonably wonder what all the non-white colors on the map mean. The NWS has a help page which lists out all of the colors used and which event type they are associated with. The IEM maintains a python library with the association in a more programatic form. Anyway, hopefully you have safe travels and a good Thanksgiving.
Voting: Good - 15 Bad - 0
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27 Nov 2024 05:31 AM
Since 2013, the IEM website has been archiving the main watch, warning, and advisory (wawa) map found on the National Weather Service website. The general lack of colors with the current map this Wednesday morning is a good indication of the few weather related travel worries for the busiest travel day of the year. Sometimes folks reasonably wonder what all the non-white colors on the map mean. The NWS has a help page which lists out all of the colors used and which event type they are associated with. The IEM maintains a python library with the association in a more programatic form. Anyway, hopefully you have safe travels and a good Thanksgiving.
Voting: Good - 15 Bad - 0
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