Graupel Showers

[John Farley]

We had some interesting weather in the St. Louis area today. As the sun heated the surface under very cold air aloft, convection occurred. While driving in the St. Louis area today, I encountered several bursts of frozen precipitation mixed with rain. Hard to categorize it - kind of a mix of wet snow and sleet or soft hail. Probably graupel would be the best catch-all term for it. Judging from short term forecasts issued by NWS offices, weather of this type occurred over much of Illinois and eastern Missouri today - even a few lightning strikes in the Chicago area, northwest Indiana, and southeast of St. Louis.

Kind of early for frozen precipitation in this area (other than hail from summer thunderstorms, but this was different from that).

 

[Pat Lawrence]

I've a hard time distinguishing the defintion of sleet from hail to be honest! As you said, graupel surely fits with what you observed today.

Interesting weather to say the least!

Pat

 

[Karen Politte]

I have to post about the same happening around OUN today. Around noon, the NWS posted an update on the Norman Point Forecast page saying that very sparse sleet had been reported in the area. I assume that this was the odd flake of frozen precip that hadn't managed to thaw before hitting the ground........an unusual and very interesting occurrence.

On a side note - we've just commenced watering in our front yard at 10.30pm - in a response to the Freeze Warning that has been extended down to our area for overnight tonight. Can't wait to see how low we go!!!

God I love winter!

KR

 

[Jeff Snyder]

Originally posted by Karen Rhoden
I have to post about the same happening around OUN today. Around noon, the NWS posted an update on the Norman Point Forecast page saying that very sparse sleet had been reported in the area. I assume that this was the odd flake of frozen precip that hadn't managed to thaw before hitting the ground........an unusual and very interesting occurrence.

On a side note - we've just commenced watering in our front yard at 10.30pm - in a response to the Freeze Warning that has been extended down to our area for overnight tonight. Can't wait to see how low we go!!!

God I love winter!

KR

Karen,

Good thing they did expand the Freeze Warning farther south, seeing how Norman mesonet is reporting 35F at 10pm! With dewpoints in the mid-upper 20s, I can't imagine we won't see 28-29 overnight, with the winds helping to keep the temp from completely bottoming out. You can really see the effects of calm winds by looking at the mesonet, as most of the coldest places are seeing calm winds, with warmer temps in those location that are seeing >5mph winds. This isn't surprising of course, but it's still cool to see nonetheless.

 

[Pat Lawrence]

I like winter for the first three months or so...unfortunately it lasts for another 2 months or so in the northern US

Interesting report from OK...might have been due to dry air? Can't say for certain.

Pat

 

[Anthony Silver]

Around 7 PM this evening I was up in the northern part of KC and saw some very light freezing precip. I was actually quite surprised to see it. Perhaps a sign of things to come...

 

[HAltschule]

hail and sleet are completely different and form in different ways. A google search should give you good examples and diagrams. In these situations when there is very cold air aloft and some surfaces heating, small hail is common in heavier showers.

 

[Pat Lawrence]

Originally posted by HAltschule
hail and sleet are completely different and form in different ways. A google search should give you good examples and diagrams. In these situations when there is very cold air aloft and some surfaces heating, small hail is common in heavier showers.

I see both of them as frozen rain...by definition. Which is what I was referring to. Yes the way they form is quite different, but they are both frozen rain I learned that from a fellow that taught me the difference between light and moderate drizzle...I'll not get into a discussion of the difference.

As far as what happened in OK and IL today, I haven't a clue! I wasn't there...so it may have been whatever one chooses to call a samall chunk of frozen precip. In any event, I'm off to dream land.

Pat

 

[HAltschule]

1. hail—Precipitation in the form of balls or irregular lumps of ice, always produced by convective clouds, nearly always cumulonimbus.

2. sleet or grains of ice, generally transparent, globular, solid grains of ice that have formed from the freezing of raindrops or the refreezing of largely melted snowflakes when falling through a below-freezing layer of air near the earth's surface;

 

[Pat Lawrence]

Originally posted by HAltschule
1. hail—Precipitation in the form of balls or irregular lumps of ice, always produced by convective clouds, nearly always cumulonimbus.

2. sleet or grains of ice, generally transparent, globular, solid grains of ice that have formed from the freezing of raindrops or the refreezing of largely melted snowflakes when falling through a below-freezing layer of air near the earth's surface;

Hail -- A type of frozen precipitation formed when rain droplets are lofted high into the atmosphere by strong updrafts repeatedly, adding new layers of ice with each up-and-down trip, until it is finally heavy enough to fall to the ground. Hail accompanies strong thunderstorms and is usually a summertime phenomenon.

Frozen rain drops in other words!

No matter...it is frozen rain whether it be a hydrometeor known as sleet, or whether it be one known as hail. I'll agree the two are very different in the way they form.

Thanks for the definitions, and good night

Pat

 

[Robert Dewey]

Originally posted by Pat Lawrence+--><div class='quotetop'>QUOTE(Pat Lawrence)</div>

<!--QuoteBegin-HAltschule

1. hail—Precipitation in the form of balls or irregular lumps of ice, always produced by convective clouds, nearly always cumulonimbus.

2. sleet or grains of ice, generally transparent, globular, solid grains of ice that have formed from the freezing of raindrops or the refreezing of largely melted snowflakes when falling through a below-freezing layer of air near the earth's surface;

Hail -- A type of frozen precipitation formed when rain droplets are lofted high into the atmosphere by strong updrafts repeatedly, adding new layers of ice with each up-and-down trip, until it is finally heavy enough to fall to the ground. Hail accompanies strong thunderstorms and is usually a summertime phenomenon.

Frozen rain drops in other words!

No matter...it is frozen rain whether it be a hydrometeor known as sleet, or whether it be one known as hail. I'll agree the two are very different in the way they form.

Thanks for the definitions, and good night

Pat[/b]

That's correct... They may look the same, but the processes that create hail or sleet are quite different. I have seen sleet in convective storms - but that's because the SFC temperature was 33-35F, and I was confident that there was very little in the way of an updraft, but I could be wrong. Judging by looks though, it's hard to tell the difference unless you're comparing anything larger than peas - which would likely be hail.

Just remember that sleet falls straight down, and doesn't re-circulate through the clouds before falling (i.e. it never gets caught up in an updraft). Hail on the other hand, re-circulates (remains in the updraft) until it's too heavy to remain in the air.

 

[Scott Olson]

We had some thunderstorms form last December that were slightly elevated. It most have been 20F outside. Tons of sleet were falling down for twenty minutes. If I remember correctly there was a layer of warmer air that partially melted the snow but near the surface it was COLD and it froze again.
-Scott.

 

[David Drummond]

We had a little bit of sleet this afternoon out here in Lubbock as well.

That mushy hail stuff you were talking about.... I usually get about 1 or 2 good late February thunderstorms out this way every year that puts down copious amounts of that stuff. Covers the roads to a depth of a few inches usually, it's pretty wild. You pick it up in your hand and it almost has the consistance of an old fashion snow cone (not this new shaved ice stuff).

 

[B Ozanne]

Since this is an educated weather forum I'd like to maintain that rain, snow, hail, graupel and sleet are different entities. They don't all form in the same way either.

Graupel is best described as rimed over snow. It happens when snow flakes are trapped in convective clouds and spend a longer time than normal inside the cloud. Often they can clump together.

 

[Scott Olson]

One way to distinguish graupel is its density. It's usually very light.