Dryline Chasing-What Can I Expect?

[Joel Wright]

Does anyone have any pics of the dryline right before the storms explode? I know on visible satellite there seems to be a very definitive line between the cumulus field and clear skies. There must be a big difference in haze too if the dewpoints are that much different between the two air masses.

 

[Mickey Ptak]

There must be a big difference in haze too if the dewpoints are that much different between the two air masses.

I don't have any images but you can bet there is a BIG difference in haze/moisture. I recall several times when I was down at the lake (with no access to data) and there was a chance of severe weather the only way I could tell that I was out of that threat was to watch the moisture (haze) push off to the east. My point is when the dryline passes you by (or you pass it by) you can tell the difference.

Mick

 

[Mike Umscheid]

There must be a big difference in haze too if the dewpoints are that much different between the two air masses.

I don't have any images but you can bet there is a BIG difference in haze/moisture. I recall several times when I was down at the lake (with no access to data) and there was a chance of severe weather the only way I could tell that I was out of that threat was to watch the moisture (haze) push off to the east. My point is when the dryline passes you by (or you pass it by) you can tell the difference.

Mick

Hmm. I must not have good eyes. I don't think it's quite so obvious. I think many times out here in southwest KS you cannot tell visually if you are west/east of the dryline. The dryline mixes through DDC and sloshes back in the evening on a regular basis from April through June. Usually the only way I can tell where the dryline is is where the cumulus are developing (and the smell-of-money coming back into town when it sloshes back in the evening!). East of the dryline around GCK/DDC, the dewpoints are usually in the lower to mid 60s.. 70 dewpoints don't occur that often this far west... which I would think one would need to really get that "hazy" look on a routine basis. I bet it would take one heck of a sharp gradient of teens/20s dewpoints against lower 70s dewpoints to see this visual "haze" difference, but I doubt you'd see this north-south line... I dunno.. I've been out here 3 years and chased numerous dryline days, and such a thing has never been so obvious and defined as to go "whoa, I can see the dryline!".

The dryline is not a complete vertical interface either, it typically slopes to the east with height... so your surface to about 2km AGL total moisture content (i.e. precipitable water) is a little more gradual than what you might expect from looking at the surface obs. (example 14g/kg moisture may be only 200m thick just east of the surface dryline, but may be 1500m thick about 60 or 70 miles east of the surface dryline...where your real hazy conditions might become more noticeable).

 

[HAltschule]

The dryline itself is very difficult to see in the early stages of development. By far, the easiest way to locate the dryline is using the temperature/dewpoint analyses. This gives you a good idea where the dryline is located. As Mike said, it is often difficult to notice a difference when out in the air because it is a gradual change and likely still very hot. Hard to disctinguish right way. But once dewpoints drop from 85/69 at GLD to 79/10 at Limon, CO...you know where to find the dryline. Best bet is to get out in that vicinity along the interestate and watch for the line of cumulus that will form. I don't know of any better way to do it.

 

[David Drummond]

I agree with Mike in that up in KS, I have found it hard to tell by just feel or visual where the dryline was. However, down south of Amarillo, it sometimes can be quite dramatic. I find often on good storm days, it gets rather windy/dusty on the back side of the dryline in the midafternoon and muggy/hazy on the front of it.

Visually, that can be seen IF you are in the vicinity of the dryline. On days where it's really sharp and you drive through it on the surface, you often instantly know. You can feel it in your breathing, sometimes the windows might briefly fog up as the air inside equalizes with the air outside. It's not unheard of to jump 50 degrees in dewpoint within a 10 mile stretch. Not entirely common, but not unheard of. As Mike says though, where the dryline meets the surface, the moisture is rather shallow.

I remember one day back in 2000 it was clear as a bell out west and there was this cloud bank to the east. Dewpoints were very low (don't recall exactly now) west of the dryline and high to the east. We went into the low, foggy cloudbank to the east which lasted about 20 miles or so aroud Matador, TX, a supercell was already in progress to the east of that which we could see above the low clouds when we were behind the dryline (got a late start that day). This was the day Olney, TX was hit by a tornado from another storm later in the day. The dryline change was very dramatic that day.

 

[Mickey Ptak]

Hmm. I must not have good eyes.

Guess not because there have been many of times I have seen it and, hell, I can only see out of one eye. It’s not really that hard if you are paying close attention to it instead of glaring at a computer screen. And yes it is a gradual thing it’s not like it goes from lots of moisture to dry air in a split second. I cannot see it being any different in DDC then in OUN. A dryline is a dryline, when it moves past a weather geek knows it.

Mick

 

[Shane Adams]

I think identifying a dryline visually is one of the easiest things to do as far as "sky reading". In particular, dryline buldges. I'm no meteorologist, but I can tell if I'm east or west of a dryline.

 

[Mickey Ptak]

I have one more example: May 12 2004. We were sitting in Woodward, OK. It was hot and humid, as one might expect it to be east of a dryline. After a while we began to notice, and visually see, the dryline bulge. Yes I mean the dryline bulge, we could visually see it. There was no mistaking on where the dryline was, it was passing us by. If I remember correctly we had checked the surface plots and sure enough we where right.

You see, when I first started chasing I did not have the luxury of high tech gadgets. I learned the hard way and tried to learn by reading the sky the best as I could. That proves a very valuable skill when you are stuck with no data. Granted that may be why I didn’t see much in my yearly chase carrier, but non the less I know when the dryline has passed the majority of the time.

Mick

 

[Chris Lott]

Thanks for your replies, everyone. One day I will venture into Kansas but I hope this spring to pay a visit to West Texas and possibly Oklahoma. I have always heard if you want to see a mother of a storm, get on the dryline. I guess I'll either love it or be scared sh*%#less! :shock:

 

[Mickey Ptak]

Sorry I just keep think of different ways I locate the DL visually. lol

The first way I have already mentioned. Many times whether the moisture gradients are steep or not you can visually see the moisture haze decreasing as the dryline moves of to the east (like wise when it reverts back to the west during the over night hours). This may take time but you will see it if you are watching the sky and not your computer. If you pay close attention to the sky you can tell the difference between 70 to 50 Td. If you are paying attention.

The second, which has already been mentioned I believe, is to keep an eye out on the quality of the CU field. If the CU's become smaller and smaller with time you can probably bet that the boundary is passing you by or getting close to it at least. There are other factors that play a role in that also though.

The third is to keep an eye on your wind direction. Many times (but not all of the time) you will find a well-defined wind shift occur when the dryline moves past you. For example, when you are east of the dryline you will find you will most likely have a south or, more preferably, a southeast wind. When the dryline starts to pass by, however, you will find that the winds turn to more a SW or westerly direction depending on the definition of the dryline.

Now, these three things used together are great tools to locate the dryline visually. All three of them may be there or perhaps just one, but I guaranty, at least nine times out of ten, by using those visual tools you can locate the dryline if it is passing you by.

Happy hunting when you get out and about.

That's it I am done.

Mick

 

[Robert Dewey]

In theory (since I haven't been to the Plains yet), I would think that TX and the panhandle of OK would by far have the best / deepest drylines, and thus most identifiable (visually) drylines. They are closer to the source of the dry air, which is likely deeper (through the profile). That would erode the haze quite a bit quicker than areas that were further away from the dry air source (KS or NE, for instance)... Areas like eastern OK - it would probably be a bit harder to visually see because the depth of the dry air may not be as great, but if we're talking about a pretty strong dryline that mixes deep - then I'd say it's more than possible given what others have said.

In fact, shallow dry air would likely be the cause of what Angie mentioned - thunderstorms developing well behind the dryline. The sounding would most likely be an "inverted v" sounding - indicative of high microburst / dry microburst potential. RH values at the SFC are very low, while several hundred feet up moisture rapidly increases (again, shallow dry air).

That's my take on it, but every dryline is different, and the depth of the dry air is what would make the biggest difference.

In cases that Mick talks about where the clouds behind the dryline are shallow and lack vertical development / haze erodes- that would probably mean the dry air does in fact extend up quite a ways (and would probably be easy to locate visually)...

BTW, I have even seen pseudo-dryline/cold fronts way up here in MI... While the drop in SFC Td drops aren't impressive (20F over a period of two hours or so) - they do scour out the moisture right off the SFC quite quickly (while the T may actually increase for a couple hours before dropping off, unlike standard cold fronts). I have actually been able to identify the band of clouds that stretches the length of one of those fronts, which leads me to believe that its how much dry air hits the area just off the SFC that's most important to determining haze / cloud erosion.

 

[Gabe Garfield]

All this talk of drylines makes me think "I can't wait until I feel Tds in the 70s again!" Thanks guys... it's late December!

I agree with Mickey, to a certain extent...when a dryline is to your east, it is often easy to tell because the eastern horizon looks significantly hazier than it does to the west. I also agree with Mike that the most obvious demarcation of a dryilne is made up of the cumulus clouds that rise along and ahead of it.

On May 12, 2004, the dryline bulge was very obvious. The towering cumuli were arrayed in an arc shape with the point of the arc was just north of Alva, Oklahoma by late afternoon. Thus, the dryline was very easy to detect. Had this been in the morning, though, I think it would have been harder to detect because of the relative lack of vertical mixing and the resultant diffuse nature of the boundary.

Gabe

 

[Mike Umscheid]

I agree with Mickey, to a certain extent...when a dryline is to your east, it is often easy to tell because the eastern horizon looks significantly hazier than it does to the west. I also agree with Mike that the most obvious demarcation of a dryilne is made up of the cumulus clouds that rise along and ahead of it.

Gabe

And that's all I was trying to get at. I have never seen a sharp discontinuity in the haziness of the sky just by looking directly above if I am right at the dryline interface. You tend to see a gradual haziness to the east... versus to the west where your visby may be 50 miles (unless there's dust, of course!). Other senses....like the abrupt shift in wind from, say 17016KT to 23025G32KT...or the differential in the muggy feel to the air...tend to be better cues for me in fine tuning the location of a significant dryline type structure... if I am not peering at a computer screen

 

[Tim Stoecklein]

Other senses....like the abrupt shift in wind from, say 17016KT to 23025G32KT...or the differential in the muggy feel to the air...tend to be better cues for me in fine tuning the location of a significant dryline type structure...

I concur! I find I'm more likely to feel a dryline pass than I am to see it, with the exception of the cumulus. Minus cloud structure I think it is difficult to see a difference in your immediate area.

Tim

 

[Mickey Ptak]

All this talk of drylines makes me think "I can't wait until I feel Tds in the 70s again!" Thanks guys... it's late December!

lol I agree on with Gabe.

On May 12, 2004, the dryline bulge was very obvious. The towering cumuli were arrayed in an arc shape with the point of the arc was just north of Alva, Oklahoma by late afternoon. Thus, the dryline was very easy to detect. Had this been in the morning, though, I think it would have been harder to detect because of the relative lack of vertical mixing and the resultant diffuse nature of the boundary.
Gabe

I agree with you on that. It can be difficult determine where the DL is during the morning hours by just basing it off of CU and haze effect (mixing) because that is usually not visible in the early/mid morning hours. Again though, one could try and determine if the DL has passed via the wind direction. Regardless, close attention to wind direction is a useful tool while in the field with no data. Granted anyone with data would probably use the data before they would use their eyes in such a case. I know I would.

I would be interest to hear if others have any input on how they determine the dryline location visibly or physically. I am not say I am right nor wrong I am just sharing my experiences in the past. So if you have any input please don’t shy away because this is a good learning experience and debate IMO for all of us and may prove useful in 2006 for some of us.

Mick