STORM2K

I'm looking at some super-long-range models and they suggest two severe weather events ahead, both in the central and southeastern states. The SPC has been cautious on this and I feel the same way for now. They do warrant mention.

November 10-11: Moderately severe weather. Not a major outbreak at this point.

November 14: The big one. Some early models suggest a massive tornado outbreak from a 991mb low and attached cold front, especially in the southern Mississippi Valley centered around Memphis, but stretching up into Indiana and Ohio. However, models are very much conflicting.

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0324 AM CST MON NOV 06 2006

VALID 091200Z - 141200Z

...DISCUSSION...

THE ECMWF...GFS AND MOST OF THE MRF ENSEMBLE MEMBERS HAVE TRENDED
TOWARD A LESS AMPLIFIED SOLUTION IN HANDLING UPPER TROUGH FORECAST
TO REACH THE PLAINS BY 11/10. THE ECMWF IS THE MORE AMPLIFIED OF THE
MODELS...BUT EVEN IT IS SLIGHTLY LESS AMPLIFIED THAN THE PREVIOUS
RUN. SOME THREAT FOR SEVERE WEATHER MAY EXIST FROM PORTIONS OF THE
SRN PLAINS THROUGH THE LOWER MS VALLEY FROM 11/10 THROUGH 11/11
ALONG AND AHEAD OF THE COLD FRONT. HOWEVER...IF THE LESS AMPLIFIED
MRF SOLUTION VERIFIES...THREAT MAY NOT BE AS ROBUST AS EARLIER
ADVERTISED. GIVEN THE LARGE MODEL SPREADS AND HIGHLY UNCERTAIN
PATTERN...WILL NOT INTRODUCE A RISK AREA AT THIS TIME.

A MORE SIGNIFICANT THREAT OF SEVERE WEATHER MAY MATERIALIZE FROM
11/12 THROUGH 11/14 FROM THE PORTIONS OF THE SRN AND CNTRL PLAINS
THROUGH THE LOWER AND MID MS VALLEY. BOTH THE GFS AND ECMWF FORECAST
A BROAD UPPER TROUGH WITH STRONG JET MAXIMA OVER THIS REGION WITH
ATTENDANT LEE CYCLOGENESIS. HOWEVER...THE ECMWF FORECAST A MORE
SIGNIFICANT INTRUSION OF CP AIR INTO THE GULF IN WAKE OF ANTECEDENT
SHORTWAVE TROUGH AND ITS ATTENDANT COLD FRONT. THIS WOULD IMPLY
MOISTURE RETURN WOULD BE MORE LIMITED. THE GFS IS ADVERTISING LESS
OF A GULF INTRUSION...AND SUGGEST MOISTURE RETURN WOULD BE
SUFFICIENT FOR A POTENTIAL SIGNIFICANT SEVERE WEATHER EPISODE OVER
PORTIONS OF THE SRN PLAINS AND LOWER-MID MS VALLEY. WOULD PREFER TO
WAIT TO SEE IF MODELS DEVELOP BETTER CONSISTENCY BEFORE INTRODUCING
A RISK AREA.

..DIAL.. 11/06/2006

Scary model predictions. Courtesy of Plymouth State Weather Center. http://vortex.plymouth.edu/models.html

The SPC is picking up the words "significant severe" for Wednesday the 15th.

I have been watching this system since nearly the beginning of this month. A strong Pac Jet is plowing through and depending on where the trough amplifies and where/when the low develops will determine if this is a full fledged tornado outbreak or a complete bust.

The models during this timeframe have been in the proverbial "crapper" due to the progressive Pac Jet pattern. So any finer details will have to wait until we get some raob data to inject into the models. Unfortunately that will have to wait until the night before the event.

These system are not only difficult to forecast at this time of year, they are also kind of overlooked by the general (maybe those that are not as weather conscious as they should be) public. Tornadoes in November? Who knew? These are the kind that can reck havoc, more than the spring storms, when everyone is usually expecting them.

Soem models no longer say so...lol. No instability. Thermodynamics just aren't there.

i dont think we're going to see many tornadoes, right now temps look like they'll only be around 60-65, which isnt cold, but temps around 70-75 would be better for severe weather. it looks like we are just going to see a lot of rain with this and maybe some snow in southern WI, but temps look like they will be a few degrees too warm for snow, around 35-40. but its something to keep an eye on in case the dynamics start looking better, because this looks like it will be a powerful storm, and if we can get some instibility, this storm might raise hell.

Models are still split. I am still thinking it is going to bad though, with the focal point in northern MS/northern AL (17 year anniversary for Huntsville, AL!)

However, the potential is still there for it to extend as far north as at least Indiana and Ohio, resembling November 15 last year. I am thinking this has a slight chance of even being a border-to-border outbreak.

Main threat? Due to the screaming jet stream, I still think it will be a tornado event mostly, perhaps becoming a squall line as it moves eastward late on Wednesday.

The three question marks in the title indicate a great deal of uncertainty. One or two of them will be removed if it becomes more likely.

i'm not seeing the potential for any severe weather with this storm. i do howevere see quite a bit of potential for snow which is what i think the main threat will be.

CrazyC83 wrote:Models are still split. I am still thinking it is going to bad though, with the focal point in northern MS/northern AL (17 year anniversary for Huntsville, AL!)

However, the potential is still there for it to extend as far north as at least Indiana and Ohio, resembling November 15 last year. I am thinking this has a slight chance of even being a border-to-border outbreak.

Main threat? Due to the screaming jet stream, I still think it will be a tornado event mostly, perhaps becoming a squall line as it moves eastward late on Wednesday.

No chance of it being a border-to-border outbreak. In fact, the chances of it even being an outbreak is very slim. Yeah we've got screaming dynamics, but w/o instability we will only see an isolated tornado or two.

I concur. The dynamics are just not there. Yes, there will be thunderstorm... and yes there may be an occasional severe thunderstorm, but nothing "outbreak-worthy."

senorpepr wrote:I concur. The dynamics are just not there. Yes, there will be thunderstorm... and yes there may be an occasional severe thunderstorm, but nothing "outbreak-worthy."

no no no no

Dynamics will be plenty...90-100 kts at the H5 level is incredible. It's the low level stuff that's lacking. There just isn't sufficient moisture advection.

wxmann_91 wrote:

senorpepr wrote:I concur. The dynamics are just not there. Yes, there will be thunderstorm... and yes there may be an occasional severe thunderstorm, but nothing "outbreak-worthy."

no no no no

Dynamics will be plenty...90-100 kts at the H5 level is incredible. It's the low level stuff that's lacking. There just isn't sufficient moisture advection.

First, be respectful. There are better ways to disagree than to stamp your feet and say "no no no no."

Secondly... even with 90-100kt at 500mb, there isn't significant shear. The winds throughout troposphere are southwesterly. You will NEED that shear if you want sparks to fly. In this case, it's not really happening. It isn't just a lack of moisture.

Sorry for being disrespectful. But 90 kt at 500mb is indeed a significant amount of speed shear. If you mean directional shear, okay, maybe a bit lacking on the 15th, but there is plenty of speed shear. With just a teeny bit more moisture and instability, the sparks will fly - and this could become quite a memorable event. The way the models are now, that is unlikely, but when you're working with such strong shear, models don't need to be off much for significant severe.

But yeah, this is impressive to say the least:



EDIT: Just realized that only shows 70 kt. Nevertheless, that is more than sufficient for supercells given adequete moisture/instability (which we do not have now).

wxmann_91 wrote:EDIT: Just realized that only shows 70 kt. Nevertheless, that is more than sufficient for supercells given adequete moisture/instability (which we do not have now).

Hence the lack of dynamics for an outbreak.

BTW, between 850 and 500mb it's about 30-40kt of shear, from what I see.

SHV forecast sounding for 0Z Wed from the NAM.

71 kt of 0-6km shear. Threshold for supercells is about 30-40 kt. Also note the hodograph and SRH values (not to mention the LCL's). Only thing lacking again is instability.

Click to enlarge.

ok, i still dont see where you guys are getting the idea of supercells and tornadoes. maybe you are talking about part of the low farther south than i am watcing, because where i am watching (IA/MO/WI/IL/IN/OH/MI) it doesnt look like there is going to be any severe weather because two key things are missing. although there might be some upper air support for severe weather, in this area we are missing the fundamental surface temps which look like they'll be maybe 55-60, which obviously isnt enough for a severe weather outbreak, let alone a tornado outbreak. and two we are missing moisture with dp's not high enough for severe weather. about the only place i can see severe weather happening i Alabama and southern Georgia, and maybe thats where you guys are talking about, but otherwise i just dont see it happening unless i'm missing something.

Dean,

You are looking too far north. Here's SPC's Day 2 Convective Outlook to give you an idea of the threat area:

the weatherman just said orlando may be under the gun again as well as areas north and west of orlando.