Clouds Wednesday Evening

November 15, 2017

Here is another great look from the GOES 16 showing where the clouds are this evening. Using this channel of the satellite works well at night showing low stratus clouds and areas of fog which are made up of small water droplets.

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Posted under Clouds, GOES-16, GOES16

This post was written by Schnack
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New Polar Orbiting Satellite

November 15, 2017

 

 

 

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Posted under NASA, NOAA

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La Niña Advisory

November 15, 2017

The Climate Prediction Center (CPC) issued a La Niña Advisory in early November. There is a 65-75% chance of La Niña conditions this winter in the Northern Hemisphere.

So…what is La Niña?

La Niña occurs when surface temperatures near the equator, in the Pacific Ocean, become cooler than normal.

 

Sea surface temperature anomaly (difference from normal temperatures) for the week centered on November 1, 2017

 

The deeper blue shades near the equator in the photo above indicate cooler than normal temperatures.

Sea surface temperatures fluctuate from year to year in a natural cycle, with some years cooler and some warmer. This year, CPC expects a weak La Niña to influence the North American weather pattern.

In general, a La Niña pattern brings cooler and wetter conditions to northern parts of the United States. This winter’s La Niña is forecast to continue through early 2018.

For the current sea surface temperatures in the Pacific, click here.

For NOAA’s winter outlook, click here.

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Posted under Climate, NOAA

This post was written by Rachael Peart
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Windy Wednesday

November 15, 2017

You might have woken up this morning to a little bit of a breeze. Winds strengthened early this morning as a system tracks away from the area. Strong winds stick with us through the day. In a previous blog, we discussed the basics of what causes the wind to blow (click here for the Wind FAQ post).

In the two photos below, the thick black lines represent the isobars – lines of equal pressure. Note how many isobars there are over the state of Iowa versus Arkansas or Alabama. More isobars means stronger winds over an area. Isobars in the next two photos are plotted every 2 millibars. Click on a photo to enlarge it.

National analysis of sea level pressure and winds. 9AM CST November 15, 2017

 

Zoomed analysis of sea level pressure and winds. 9AM CST November 15, 2017

The graphic below shows the isobars in blue as well as the station models across Iowa. A station model plots multiple weather variables in a compact package. Winds on a station model are noted by a single line extending from each small circle. If there is no wind, there will only be a circle.

Each of the station model plots below feature the main line as well as smaller barbs extending from it. The barbs depict different wind speeds in knots (kts). Long barbs represent 10 kts and short barbs represent 5 kts. The direction of the main line shows the direction from which the wind is coming.

Isobars are the blue lines below and are plotted for every millibar.

Iowa analysis of sea level pressure and station models. 9AM CST November 15, 2017 (Iowa Mesonet)

More strong winds move in later this week.

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Posted under Forecast Discussion, Windy

This post was written by Rachael Peart
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Thanksgiving Week Outlook

November 15, 2017

Thanksgiving is next week and that means the cool season holidays are officially here. Many will be traveling over the next couple weeks. The Climate Prediction Center (CPC) calls for near normal temperatures from November 20-24 (Monday through Friday) for much of the Mississippi River Valley.

CPC Temperature Forecast for November 20-24, 2017

The precipitation outlook favors drier than normal conditions for most of eastern Iowa.

CPC Precipitation Forecast for November 20-24, 2017

Continue to check our weather page as the forecast is fine tuned in the coming days.

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Posted under Forecast Discussion, Holiday

This post was written by Rachael Peart
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Gravity Waves

November 14, 2017

A variety of gravity waves propagate through the stratocumulus deck off South America. Click on the image below to play the movie.

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Posted under Clouds, NOAA

This post was written by Schnack
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Foggy Days

November 14, 2017

It has been a foggy start to the week with areas of dense fog both Monday and Tuesday. Here is what the fog looked like in Dubuque earlier on Tuesday.

 

A DENSE FOG ADVISORY is in effect for northeast Iowa until midnight tonight. In the advisory area, visibility will be reduced to a quarter of a mile or less.

 

The charts below show the amount of days, in 2017 (red), fog was reported at Waterloo, Dubuque, Cedar Rapids and Iowa City. These numbers are compared the average number of days (blue) each month fog is reported. December is typically the month with the most days fog is reported.

Click on the image below to enlarge.

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This post was written by Schnack
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Daylight Changes

November 14, 2017

The days have been getting shorter everyday with the nights getting longer since late June. Between the summer solstice in June and the winter solstice in December, more and more daylight is gradually lost.

We are now more than halfway between the summer and winter solstices. Eastern Iowa will lose more than six hours of daylight within the six month period. However, once we reach and pass the winter solstice (also known as the first day of winter), the days slowly become longer and nights shorter.

If you think nine hours of daylight is bad, imagine living in Barrow, Alaska. The northern most point in the U.S. will see the sunset on November 18, 2017 and the sunrise on January 22, 2018. That is over two months of darkness known as “polar night”.

2017 Sunrise and Sunset in Barrow, Alaska. Orange shades show days where sun never rises above the horizon through the end of the year

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Posted under Miscellaneous, Weather Trivia

This post was written by Rachael Peart
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Air Quality

November 14, 2017

Yellow (moderate) air quality index conditions are across Iowa this afternoon.

 

Here is the complete Air Quality Index (AQI).

 

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This post was written by Schnack
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A Clear View of the Clouds

November 13, 2017

Here is a look at where the clouds are this evening (blue shaded areas). East central and southeast Iowa under a clear sky. The clouds will spread back over this area tonight.

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Posted under GOES-16, GOES16

This post was written by Schnack
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