Skip to content

Crazy Weekend or Crazy Models?

April 16, 2012

Heavy, wet snow, soaking rain and a tornado outbreak… all within the Mid-Atlantic states this weekend? Some models are ‘depicting’ a storm system that would be one for the record books… a scenario where heavy, wet, accumulating snow piles up 6″ in the mountains while a tornado outbreak hammers the coastal plain & 95 corridor.

European Forecast Model: Depicts cut off low over Mid-Atlantic states this weekend!

Cut off low pressure systems are called “cut off” because they become detached from the Jet Stream

  • A “Cut-Off Low” produces rapidly rising air that cools.  Cold rain can change rapidly over to heavy, wet snow directly underneath their track.    
  • Spin in the atmosphere (wind shear) also occurs with these systems as they practically behave like a ‘spinning top‘ on your table, traveling slowly (dislodged from the Polar Jet Stream).

Let’s begin with the Snow:  Here is the latest European Forecast Model run for Sunday — 3 to 6″ of snow for parts of the mountains?

Dark Green= 5 to 6" of snow across western New York and northwestern Pennsylvania. Mountains of NC, VA and WV and eastern Ohio also could see some snowfall accumulation if this model data is accurate this far out** Image Courtesy: weatherunderground.com

Global Forecast System (GFS) also shows Cut-off Low over the southeast this upcoming weekend (that would be the massive "donut" detached from the polar jet over Canada. Image taken from GFS forecast model (courtesy: http://mag.ncep.noaa.gov/NCOMAGWEB/appcontroller)

  • The prospects for a drought breaking, widespread soaking rain will increase ten fold if this system does indeed materialize.
  • Two to three inches of rain could easily fall over the drought stricken New England and Mid-Atlantic states.

Image taken from GFS forecast model (courtesy: http://mag.ncep.noaa.gov/NCOMAGWEB/appcontroller)

Finally, I would normally not pay any attention to such an exciting forecast almost 7 days out if the NAO and AO were not tanking!

When the Arctic Oscillation Index falls (drops below zero)... cold air is usually unleashed out of Canada.

The North Atlantic Oscillation tanks by weeks end: Indicative of Blocking... good for slowing down storms and allowing them to rapidly deepen producing apocalyptic weather events in New England and the Mid-Atlantic. :-) Or we can continue to soak up the pollen and dust in the air with 'hot as hell temperatures as the poor trees and plants wilt waiting for the skies to open up' -- water restrictions are coming... I'll take the snow, severe weather and soaking rain.

  • There is always the chance that the model data is garbage…. garbage in — garbage out— theory in computers… and we end up with a rain shower to settle the dust. LOL
  • One thing is for sure: if we have exciting weather, the local media will tell you about it Friday night… that’s why this is a weather blog — I share interesting possibilities early on so you can at least make a mental note.
One Comment leave one →
  1. Jason permalink
    April 18, 2012 6:45 AM

    Goodbye pollen!!!

    Oh wait, rain feeds trees and makes more pollen. Drat! :-)

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: