2012 Severe Weather Outlook

Well...It looks like spring is almost here (even though as I type this there is strong cold advection doing its dirty work outside my window) and its time to try and poke my head into the future to see what spring may hold in terms of severe weather. Ive looked at a few sign and signals and this post will portray if they point to a more normal season which is pretty intense itself here in the southeast...or if the potential for severe weather is above or below normal.

I was gonna do some analogs for this season but since that didnt work out to well for the winter outlook I will stick to the facts here..nothing but the facts.

First lets look at where we are headed in terms of ENSO


Enlarge this image


What we see here is us headed out of La Nina and into weak El Nino territory most likely... but during spring we should be near neutral ENSO conditions and that will not hamper severe weather in any way that I can find. The important thing here is that we have two major changes going on with winter transitioning into summer and La Nina transitioning into El Nino.


Next we will look at severe weather trends over the first part of 2012 and compare them to the same time last year in 2011

Here we have the spc reports since the first of January this year..as you can see its been pretty active for what is supposed to be a cold time of the year.



When we look back at last years graph we can see that severe weather was almost nil for this time of year before the active timeframe spike occured.


One can draw several different conclusions from that... but the conclusion I am drawing already is that the Gulf of Mexico is very warm and will be primed by the time our "spike" gets here.


Now speaking of the Gulf of Mexico lets look at the water temps because this is the fuel for severe weather in our area.

Enlarge this image


Sure enough they are above normal. The lack of an extended period of colder weather over the southeast has allowed the waters of the gulf of Mexico to stay pretty warm and this is a pretty important signal that says an above normal severe wx season is likely. Now before you get too worked up there are some things that could possibly argue for a more normal or even below normal severe weather season.

The main thing that comes to mind is that the North Atalntic Oscillation has been mostly positive for many months and one could argue that it should be mostly negative this spring and this could offset an above average season to more of a normal type season. A negative NAO would try to suppress a Jet stream thats trying to come north due to seasonal change and could keep the stormtrack right over us or to our south mostly.

After looking at these and several more features I expect an average to above average severe weather season in terms of reports and there will likely be at least one major and widespread severe weather outbreak in the southeastern United States.

Snowstorm set to hit Tennessee

Im too busy to post a wrietup with this so here is my call map...If u have questions...register on our forum if youre not a member and you can read my thoughts there...the link is to the right of this post

Wintry Mess of Ice Sleet Snow and Rain

This is a forecast put together with todays SREF and NAM models..this forecast is highly dependant on the temp profiles of those models. If they are off a hair it could make for big changes in the outcome...this will ultimately be a nowcast situation but it seemed to be a rough one so I thought I would give it a shot

Light snow...sleet and freezing rain accumulations will be possible across most of the state on Monday and Tuesday. Particularly concerned for the East TN valley where I think the most ice accumulations will be possible.

Looking at soundings and mostly SREF data it appears that a mixed bag of weather will move into the state from west to east. With very low dewpoints already in place precip will move into the area as Virga but as the column becomes saturated precip will start to fall in the form of snow.

The snow could fall at impressive rates at times in the western and southern parts of the state. At some point the snow will transition to wintry mix and then to rain over most of the state. I imagine the plateau and mountain regions of the state could pick up several inches of snow in a fairly quick fashion.

The east TN valley poses a unique threat for Ice accumulation in excess of more than .10 inches due to the nature of local topography. After some possible light accumulations of snow the cold air might become trapped in low lying valley areas and freezing temps could stick around for a longer period of time but meanwhile the upper atmosphere temps will warm to above freezing resulting in longer periods of ice accumulations on top of light snow accums. Light Ice accums appear likely for parts of East TN valley

Old man winter has returned

A well developed southern stream shortwave will merge with a strong spoke of energy from a Upper low diving down out of canada and winter weather will result as a baroclinic zone sets up. A band of precip will develop along and in advance of an arctic cold front and will slide through the state tomorrow and Saturday. Where these two energies meet up will be ever important as to the outcome.

This precip will probably start as rain in most places but will quickly and dynamically change to snow due to strong cold air advection and wet bulbing. Flash like freezes will take place and driving conditions could become hazardous very quickly.

Due to the uncertainties I have just made a probability map and counties in grey have the best shot of seeing an inch or more of snow.

Eastern US Snow Storm threat Feb 11th-14th

Good Morning

After what has been an extremely warm winter things are changing as part of the Polar vortex relocates itself in Southeastern Canada. This feature may combine itself with a couple of other large scale features to produce a Noreaster the weekend before Valentines day. It all depends on where a subtropical jet strean shortwave starts to phase with the polar jet stream and its related vortex. This will set up a baroclinic zone along the east coast and a powerful low pressure system may form and ride up this zone in Miller A fashion.

The GFS has been the most consistant model showing this possibility and this remains the biggest eastern US winter threat of the season. The trend all winter has been for these southern stream shortwaves to cuttoff in the southwestern United States and remain cuttoff... but this shortwave is modeled to continue across the southern part of the conus without getting cuttoff from the polar jet and will likely phase with the northern stream at some point.

At the same time a northern stream wave of energy is moving across the northern tier of the US in tandem with the southern one. This will likely result in the most signifigant snowstorm in the eastern US this season but where the snow falls has yet to be determined. At this time guidance suggests a Gulf low threat and I have a higher than normal confidence level in accumulating snow in the Tennesseee valley.

Nothing written in stone yet but there is certainly a threat of winter weather in the eastern US near Valentines day or a couple of days before...the exact track of the stormcenter will decide who sees the accumulating snow.