Tuesday, March 16, 2010

Severe Weather/Chase Forecast: March 19th

Well, the next one is on its way down the pipe, so it's time to get the discussion rolling.


Both the GFS and ECMWF are in agreement as to the orientation of the system, showing a positive to neutrally tilted trough digging in through the West late on Thursday. Now currently, a nice negatively-tilted trough is working its way into the Northwest and it will eventually break down the ridge that has its grip over most of the west. The interesting thing here is that before the ridge breaks down and the trough digs across the west, some of the energy will be directed through the Canadian Praries, which will cause a surface feature that will tap the cold polar airmass... but I'll get to that in a moment.

The Surface:
A surface cyclone will slide from Alberta across the US/Canadian border on Thursday, in its wake, a deep cold pool pour down the lee of the Rockies. By the time Friday morning rolls around, the edge of the cold air will already be into Colorado (the NAM being more progressive than the GFS) Meanwhile, in Texas, surface troughing ahead of the digging upper level trough will begin to take shape. Moisture advection will be in full swing ahead of the system, though not for a long amount of time.

By 0Z Saturday (Friday night), the GFS has a strong airmass boundary from Amarillo to Chicago with cold air to the north (20's on the Colorado plains!) and warm, moist air to the south. (60's into KS, 70's in the TexPan with 50Td's into KS) Shear is great in Western Oklahoma, especially near the surface though winds aloft leave something to be desired. The 0Z run tonight backed off a bit on the instability, but still has 750J/kg near Woodward and though one shouldn't "bullseye" chase, Woodward or points a bit southward seems like a reasonable target, especially since I have a feeling that the 12Z NAM run is not going to make anyone happy about this situation, including myself, given its progress of the polar airmass.

The GFS isn't closing off a surface cyclone until 06Z on Saturday, south of I-40 along the Texas/Oklahoma border.

Given the dynamics, vertical profiles, and surface features, I don't see any reason why we shouldn't have a few supercells in W to NW Oklahoma on Friday afternoon/early evening.

I asked for the day off of work so I plan on going if the setup is the same or better. So, some of you may expect a text message tomorrow for carpooling options.

... another important thing to mention here is that the GFS is indicating there will be a LOT of snow behind the cold front. Palmer Divide amounts look to be 6+" (with strong northerly winds) and even more than a foot in the Salina, Kansas area by Saturday evening! This could be a very interesting system, so I'll be watching it very closely.

Your thoughts are welcome.



Scott said...

I might be in on this...Of course it would depend on me getting off work Friday. Fingers crossed for moisture returns!

Jayson Prentice said...
This comment has been removed by the author.
Jayson Prentice said...

I was just mentioning the potential for snow on the cold side of the system... Didn't go into too much detail this early, but am surprised to see the GFS and its' swath of 5-10"+ over KS/MO! http://bit.ly/bfYskC