Jump to content

*** PLEASE REGISTER AND JOIN OUR DISCUSSION!!! ***

THE STAFF WANT YOU TO JOIN US AT PHILLYWX!!!

Register as a member today, and become part of the Delaware Valley weather community!

Our pro and seasoned amateur meteorologists, and weather enthusiasts from around the PA and NJ area together form a great group discussion, and we're asking folks that read our site today to register as members and post along with us!

Don't be intimidated if you're not an expert, ask questions if you're curious or want to build your knowledge!

Whether it's adding to our local profiles by reporting observations (and maybe becoming a SkyWarn Spotter!), or contributing more on the model interpretation side, we'd like you to join us in a constructive and insightful dialogue around all things Philly Weather!


Sign in to follow this  
zwerob

sleet when above freezing

Recommended Posts

I know for freezing rain and sleet, you have to have a warm air layer overtaking freezing temperatures above the  ground. The flakes above melt to rain drops and freeze into ice pellets or freezing rain depending on the layer of warm air. W/O freezing  temps above ground level to freeze rain into ice pellets/sleet, how does precipitation come down as sleet? Can someone go into detail about what fronts are involved (warm/occluded/stationary/cold), wind direction (Sn unlikely with SE winds in this region according to Bolaris) and how this affect the type of precipitation? Links to visuals would be cool. Thanks, Rob

Share this post


Link to post
Share on other sites

I know for freezing rain and sleet, you have to have a warm air layer overtaking freezing temperatures above the  ground. The flakes above melt to rain drops and freeze into ice pellets or freezing rain depending on the layer of warm air. W/O freezing  temps above ground level to freeze rain into ice pellets/sleet, how does precipitation come down as sleet? Can someone go into detail about what fronts are involved (warm/occluded/stationary/cold), wind direction (Sn unlikely with SE winds in this region according to Bolaris) and how this affect the type of precipitation? Links to visuals would be cool. Thanks, Rob

 

First, its quite possible to have a cold layer sandwiched between two warm layers... i.e., a melting layer, a re-freezing layer, and then above freezing right at the ground. 

 

Second, a very dry layer below the warm layer can evaporationally cool raindrops below freezing, causing them to re-freeze. 

 

Sleet definitely can and has happened on southeast winds.  I'd say winds with a significant west to northwest component are the least likely to result in sleet, but I don't have facts and figures to back me up.  Just experience.  Usually, anything pellety and frozen that you see with west to northwest winds is actually graupel, not sleet.

  • Like 1

Share this post


Link to post
Share on other sites

aab32dacfc2e5d2b6392d8db75518efb.jpg

Usually,

Warm fronts are the boundary responsible for mixed precip events, as warm air surging into the cold air rises. The colder, denser air stays below it. Not always, but a majority of events.

  • Like 2

Share this post


Link to post
Share on other sites

Freezing rain falls frozen, melts (in a warm layer) and refreezes on contact with the surface. The bottom cold layer is too shallow to freeze before making contact with the ground. Sleet falls falls frozen, melts, and refreezes before making contact with the ground. The cold layer is larger than that of freezing rain, which is why it has time to freeze again before it hits the ground. Upper air soundings (skew-t's) are a great way to tell what kind of precip will fall. 

269bcb325e78284a53091838952295ec.jpeg?it

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...