Dewpoints in IA/MN

[Josh Richardson]

Anybody see the dewpoints surging northward through IA? Already hitting 78 and higher in some places and its only 11 am. LOL, nice 6500 Cape Values over me already here....definitely a muggy day out there.

[Adam Lucio]

Evaportranspiration. Its that time of the year, I hate to see so many of these days go to waste under muggy sunshine and a field of fail-cu that cant amount to anything. If only we could get these dews in April or May.

[Michael O'Keeffe]

Yea it is always a shame to see these big moisture, extreme CAPE events go to waste but the once in a blue moon time they do happen can lead to some violent events. A few include August 28, 1990 Plainfield, IL F5 Tornado, where the dews were in the low 80s and CAPE soared to 8000+ j/kg, July 18, 1996 the Wisconsin F5, and Iowa has also had their share but I can't remember the name. I guess as long as you can get enough CAPE (at least 6500 j/kg) shear doesn't matter much.

[Jeff Duda]

A recent ob from the AWOS at Algona: 90/86 with a heat index of 126! Wow.

You can check obs over Iowa easily every hour at http://mesonet.agron.iastate.edu/data/mesonet.gif

[Josh Richardson]

A recent ob from the AWOS at Algona: 90/86 with a heat index of 126! Wow.

You can check obs over Iowa easily every hour at http://mesonet.agron.iastate.edu/data/mesonet.gif

Yeah, I was actually going to bring up KAXA but that station always reads way higher than surrounding stations so I just kind of dont pay any attention to it.

We already have 89/79 here for a heat index of 105.

[Steve Conley]

Location: Newton, IA
Temp: ~91F
Dew Point: 80F
Heat Index: 110

It's like walking into a freaking wet sock...I don't even want to go out for lunch :)

[Scott Weberpal]

Yea it is always a shame to see these big moisture, extreme CAPE events go to waste but the once in a blue moon time they do happen can lead to some violent events. A few include August 28, 1990 Plainfield, IL F5 Tornado, where the dews were in the low 80s and CAPE soared to 8000+ j/kg, July 18, 1996 the Wisconsin F5, and Iowa has also had their share but I can't remember the name. I guess as long as you can get enough CAPE (at least 6500 j/kg) shear doesn't matter much.

Both of those days were high shear events as well.

[Josh Murfield]

Last night at 10:00 here in Lincoln, NE it was 89/80, with all the windows on our house fogging up a bit on the outside. Not sure I've ever seen it quite this muggy here in NE!

[Justin Wiley]

Newton, IA 1:15pm CDT:

Temp: 93 F
Dewpoint: 84 F
Heat Index: 120 F

I seriously cannot imagine what that kind of oppressive humidity feels like. Wow.

[Steve Conley]

Just keeps climbing:

Location: Newton, IA
Temp: ~93F
Dew Point: 86F
Heat Index: !125!

Thinking I'm going to skip watching the baseball game in town tonight...

[Darren Addy]

Shenandoah, IA
Temp: 97
DP: 85
Heat Index: 150.2
at 3 PM

[Jeff Snyder]

2000 UTC METARS:
CITY SKY/WX TMP DP RH WIND PRES REMARKS
ATLANTIC * SUNNY 95 81 63 SW9 29.87S HX 115
COUNCIL BLFS * N/A 95 82 66 S9 29.85F HX 119
CRESTON * SUNNY 95 79 59 S14 29.88R HX 112
HARLAN * MOSUNNY 91 75 59 S3 29.88F HX 102
LAMONI SUNNY 94 76 55 S12 29.87F HX 106
RED OAK * SUNNY 97 82 63 S10 29.85S HX 121
SHENANDOAH * N/A 97 86 71 SW8 29.86S HX 130

Do some of these sites (like Shenandoah and Newton, which I've heard mentioned a few times as "wow, look at this ob") have a normal high bias? I know that some METAR sites in Oklahoma are biased high (e.g. Ardmore and Watonga come to mind right away). 97/85 is absolutely ridiculous if it's an accurate ob! Looking at nearby obs, though, I suspect it may be a few F high.

[Jeff Duda]

The Shenandoah site is planted in the middle of a corn field. Its dewpoint always reads a few degrees too high.

[J. Murman]

Is there a record high dew point maintained for areas in the United States?

[Josh Murfield]

The Shenandoah site is planted in the middle of a corn field. Its dewpoint always reads a few degrees too high.


Dewpoint in Nebraska City is in the lower 70's, with mid to upper 70's in areas of southwestern Iowa near Shenandoah.

[Steve Conley]

I believe Newton's is at the airport, and based on my boss's station at home, and my truck (ok, not the most accurate device <grin>), it seems to be pretty accurate.

[Rob Wadsworth]

The evapotranspiration rate of corn/soybeans in Iowa is in an extreme point of their growth phase. I'm sure these numbers also translate into the nearby towns.

Sounds like the kind of day where people shut everything off - except for their air conditioners and de-humidifiers. A cool basement would also be a proper place to be - so long as a de-humidifier is working. I've been in IA when temps were similar to these.
Yeow!

[Josh Richardson]

I think this thread gets brought up every year but since someone asked about record dewpoints...the highest I've seen around here was 101/87 over at Onawa. Like Jeff mentioned earlier though there are many of these stations planted in corn fields and its pretty easy to determine which numbers are skewed and which aren't. I would say with confidence though that the average dews around here were still near 80, maybe 78 or 79. So heat indices have been hovering near the 105 mark in many places. I did notice Creston IA earlier was up to 95/79, 113 heat index.

[Jeff Duda]

This linear MCS moving through is a blessing. The temperature in Ames dropped from about 94 to about 70 when the gust front moved through. The dewpoint only went down to about 68 though :p.

http://mesonet.agron.iastate.edu/plotting/iemcc/

[Steve Conley]

Agree with the blessing, 76 in Newton now.

[cstrunk]

I have had to work outside yesterday and today. I immediately started sweating whenever I stepped outside. Agreed about the squall line, much nicer outside now!

We have been kind of lucky in terms of nice weather (bad in terms of storm chaser weather!!) with temps in the 60's and 70's for quite a while. Now we're paying for it with the heat!

[mikegeukes]

I usually like to compare the ASOS stations to AWOS stations.
Often the ASOS dewpoints are a tad lower than the AWOS Stations
in situations during June and July when evapotranspiration is occurring.

Iowa ASOS Stations:
Ames, Burlington, Cedar Rapids, Davenport, Des Moines, Dubuque,
Estherville, Iowa City, Lamoni, Marsalltown, Mason City, Ottumwa,
Sioux City, Spencer, Waterloo.

Mike

[Joel Wright]

With the hybrid corn/soybeans nowadays it seems as if the evapotranspiration is worse. Corn seems to grow taller every season around here. Kind of makes you wonder lol. Either way, living in the cornbelt is an interesting experience this time of year. If you've ever been near a cornfield on a day like today you'll understand how the dewpoints can get so high. It's amazing how much moisture those plants release into the surrounding air. It's damn near suffocating.

[Mike Hollingshead]

Earlier today while chasing in nw IA I noticed several stations reporting mid-80 dews. Kind of doubt they are all way off. Top I saw was 96/86. I did see that 101/87 at Onawa mentioned, a few years ago. You have hilly terrain, corn, and that time recent rain and a left over boundary nearby.

TWC mentioned one in Saudi or some desert over there the other day. Some record or something. 108/93 I think. Temp was 108, I forget the TD might have been over 93.

[Dustin Wilcox]

When the corn is silking it uses approximately .30" of water a day...

[GlennMartin]

You are right about the corn. June-August on calm nights you can often see thick ground fog pool around the cornfields, I first noticed this as a young man driving through the cornfields of northern Ohio and Indiana sometimes the eerie fog was suddenly so thick you had to slow to a crawl.

[John Wetter]

We're still 3-4 weeks from peak transpiration from the corn... Silking in IA/MN is usually mid-July, later as you go north. Sweet corn is of course a bit earlier, but there isn't as much.

It's always hard this time of year to do CAPE numbers because you can't just use the surface ob because that really soupy air is a fairly shallow layer, so it isn't all realized by a storm. As far as the people though, yeah, it's miserable. You can sit next to a corn field and feel the moisture flowing out on a calm evening.

[Jason McKittrick]

Highest dewpoints, I looked this one up a couple of years ago. The worlds highest was 96 recorded in the Amazon. I have seen 90's on a few occasions in the Persian Gulf since then. I do not remember the highest US dewpoint seems like it was 92. I did however see, during the July heat wave in 1995 Appleton, Wisconsin reach 103/90. That is the highest dew I have ever seen in the US. The highest dew I have experienced hear in Omaha was on July 15, 1988, the day of the Council Bluffs tornado. The airport hear had an observation of 92/84 just prior to that event.

It is funny to watch the mets on the weather channel try and talk about dewpoints in the cornbelt. The think they live in a humid place and they have never seen 80 degree dewpoints down there in Atlanta, or at least it is very rare. Yesterday they were talking about how humid it was in the cornbelt with "dewpoints in the upper 60's and lower 70's". Dewpoints at that time were actually in the upper 70's and lower 80's most places. Guess they didn't believe there eyes. Anyone who lives in the cornbelt can tell you that the gulf coast is not nearly as humid as a cornfield in July.