LETS TALKS CANADIAN CLIPPER LOWS– the Saskatchewan Screamer

STARDATE  202312.05

The first question many will ask is   “what the hell is a Saskatchewan Screamer?”  The term is  well-known With  meteorologists and  climatologists in North America. The term was probably coined by David Ludlum the great weather historian of the mid and late 20th century. The Saskatchewan Screamer  is actually part of a larger group of peculiar type of weather systems that feature a disturbance Or a  SHORT  WAVE (S/W) at 500mb  that dives out of Southwest Canada in a generally ESE or  SE direction.

These kinds of weather systems are often referred to   “an  Alberta Clipper LOW” pressure system.  But that is not actually correct. The correct term is Canadian Clipper LOW . There are in fact  3 subcategories of Canadian Clipper LOWs. There is the more famous and well-known Alberta Clipper LOW but there is also a type of Canadian Clipper LOW that is referred to as a Saskatchewan Screamer.  And there is a third type known as a Manitoba Mauler  (NO I am NOT  making this up  — GOOGLE it if you don’t believe me)

The first image is from The Weather Channel which has the three different areas named.  The second image is a map showing the various typical trajectories of the three different type of Canadian Clipper LOWS.




That being said,  these three systems are very different from each other. Generally the Alberta Clipper is the weakest type of Canadian Clipper LOW and it usually does not drop any further south than I-80  and certainly never drops further south and I- 70.  As a general rule all of the snow associated with a  Canadian Clipper LOW  falls N  of the track of the surface LOW . 

 

Saskatchewan Screamer Clipper LOWs  are more dangerous and have a better chance to amplify into  moderate Ohio Valley snow events and possibly significant East Coast snowstorms. Any Saskatchewan Screamer that does undergo intensification and blows up as it nears the coast or just offshore is by definition a Miller B type of East Coast winter storm.

The reason  why Saskatchewan Screamers are far more energetic and dangerous and have the potential to bring accumulating and possibly significant snow is fairly obvious but it is overlooked. In order to get a LOW  pressure system or a short wave with a strongly embedded Vort Max to drop FROM Saskatchewan  southeast, it HAS to have a strong jet max/ jet streak on the back side (upstream) of the S/W  This has a tendency to drive the S/W  into either a NEUTRAL or NEGATIVE  tilt by the time it reaches the East Coast. This in turn allows for the surface LOW to hold together as crosses of the mountains and intensifies once it reaches either the Mid-Atlantic or New England coastal areas.

There are some famous historic Saskatchewan screamer Miller  B East Coast snowstorms of the  past  that have made it into the KU Canon. Specifically the  famous December 30th 2000 Millennium snowstorm which pounded New York City NY state and New England with heavy snow. This image shows the 500mb  maps In the 48 hours before the storm exploded off the New England coast. The map is self-explanatory. I have highlighted the northern shortwave as it formed and dropped out of Saskatchewan Canada and the various teleconnections late on 12/28/2000 .

Another example of a Saskatchewan screamer Canadian Clipper Low is the snow S.E.C.S. (Significant East Coast snowstorm) that occurred near the Spring Equinox in March 1958. Heavy snow of 10 to 30 inches of snow fell in northern VA  just to the N and NW of DC/ BAL  into the Philadelphia suburbs and the Lehigh Valley and NW NJ. The upper air map clearly shows a S/W  late on 3/18/58)  in Saskatchewan Canada (the red X)  that moves towards ND and then drops into the Upper Midwest. Note that as the S/W deepens into a full longwave Trough, the Trough  axis develops a severe negative tilt as it approaches the Appalachian Mountains which allows for a cyclogenesis to occur in the ideal position for a late winter snowstorm. 




Next time I will be discussing the more dangerous Manitoba Mahler Canadian Clipper LOW which if conditions are right almost always becomes a Major East Coast snowstorm  (MECS).  Some examples of a Manitoba molar is the historic snowstorm of February 1978 in the Northeast us and the historic snowstorm of January 30th 1966.

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