Dry Slot

[Chris Hayes]

If you look at a radar image of the Ohio/PA/WV region, a regional radar image, you'll see a dry slot coming in and cutting off the snow and rain over eastern Ohio. I dont get why everytime we get a decent chance at a snowstorm, a dry slot comes in over eastern Ohio, where I live. Whats the deal with dry slots? :cry:

 

[Robert Dewey]

If you look at a radar image of the Ohio/PA/WV region, a regional radar image, you'll see a dry slot coming in and cutting off the snow and rain over eastern Ohio. I dont get why everytime we get a decent chance at a snowstorm, a dry slot comes in over eastern Ohio, where I live. Whats the deal with dry slots? :cry:

I don't know, but I'm about ready to give up on this winter... I mean come on, we have a 985MB slamming up through Ontario with a TON of moisture and lift, and STILL can't get alot of snow. It's been snowing for roughly 5 hours here and we have about 0.5 to 1.0 to show for it. The thing is, it's been snowing pretty heavily, but it's just not accumulating.

This is pathetic.

I wonder what snow ratios are - 5 inches of snow to 1 inch of rain? :roll:

 

[j_scheerer]

You're gonna hate me Rob, but we've got a lot of snow already.

 

[Michael P. Morris]

But take a look at the 12Z soundings from Detroit, Pittsburgh, etc. Each notes a precipitable water value on the order of 1.5 cm, which translates to 0.6 inches of liquid equivalent, or approximately 6 inches of snow. This is assuming you precipitate with 100 percent efficiency and are able to take advantage of the entire depth of the troposphere.

 

[Robert Dewey]

You're gonna hate me Rob, but we've got a lot of snow already.

How much do you guys have already? The models did paint quite a bit across your area...

Also... Michael - PW shouldn't be used to determine actual QPF values, let alone predict how heavy winter precipitation type will be. Winter precipitation (sn, zr, ip) is based more on dynamics rather than instability release. For example, look at lake effect snowstorms - They occur in low Td environments (and thus low PW environments) yet produce upwards of 2-3 feet of snow in a single storm, with actual QPF's larger than what the PW value usually is.

In addition, a single 10 to 1 ratio isn't always accurate. If I melted down what we have outside, I would more likely find a 5:1 ratio. My original assumption (and wrong assumption) with this storm is that we would be looking more at a 12 to 1 or even 15 to 1 ratio as the night progressed. With a storm total QPF project to be 1.00 inch by ALL the models, I expected at least 9-12 inches at some locations... With some areas getting up around 15-18 inches or more (especially by Port Huron).

Also, it appears as though this storm is moving slightly faster than first thought.

 

[j_scheerer]

How much do you guys have already? The models did paint quite a bit across your area...

I'd estimate there is at least 6 inches.

 

[Joel Wright]

Whats the deal with dry slots? :cry:

It's just bad luck I guess. Usually the dry slot for an intense storm punches in pretty close to the low pressure track. Sometimes it can extend a few hundred miles left of the track well into the "cold" side of the storm system. So even if you're cold enough for snow you can get cut off from the main precip shield. In many cases the heaviest snow falls very near the edge of where the dry slot sets up, so you can have a very sharp gradient between weak snow amounts and very heavy snow totals. Back when we used to get snowstorms, I always liked being positioned just barely left of where the dry punch ate in.

What you need is a low pressure to take the low road and keep you in the deformation zone, where you'll have no problem maintaining steady precip.