02/05/08 FCST: TX,FL,GA,AL,MS,LA,TN,NC,SC,KY,VA,WV

[Justin E. Reed]

A large ridge will start to develop over the SE this weekend, allowing much warmer temperatures to penetrate all the way up into KY,WV and VA by Tuesday, bringing a healthy Southerly flow, loaded with warm temps and moisture from the GOMEX. A strong low pressure and trough will dig into the Plains by Monday, and move fast NEWD throughout MON-WED. An unstable airmass is very likely to be in place come Tuesday, and wind shear appears to be sufficient enough to allow for supercells, followed by a trailing squall lin along the frontl boundry. Unlike the previous event, temperatures will be warm across a large region, with plenty of moisture far north. Watching the models for the next few days, and by Sunday, we should have a general idea of the potential setup for Tuesday.NWS offices in Jackson, MS, and Mobile, AL have already stated the strong threat of severe wx on Tuesday.

NWS Jackson, MS:
A GREATER RISK FOR SEVERE THUNDERSTORMS EXISTS FOR LATE
MONDAY NIGHT THROUGH TUESDAY WHEN A STRONG COLD FRONT IS FORECAST TO
SWEEP ACROSS THE AREA. THE MODELS CONTINUE TO TREND MORE IMPRESSIVE
WITH THIS SYSTEM AND AT THIS TIME THEY SHOW NO LACK OF SHEAR OR
INSTABILITY. IF THIS CONTINUES THEN A SIGNIFICANT SEVERE WEATHER
EVENT COULD AFFECT THE ARKLAMISS REGION.

PERSONS IN THE OUTLOOK AREA SHOULD MONITOR LATER FORECASTS AND
OUTLOOKS CONCERNING THE SEVERE WEATHER POTENTIAL FOR EARLY NEXT WEEK.

.SPOTTER CALL TO ACTION STATEMENT...
THE ACTIVATION OF STORM SPOTTERS...HAM RADIO OPERATORS...AND
EMERGENCY MANAGEMENT PERSONNEL IN SUPPORT OF SEVERE WEATHER
OPERATIONS...MAY BE NEEDED FOR A TIME LATE ON SUNDAY BUT MORE
LIKELY OVER THE ENTIRE AREA ON TUESDAY.

 

[Justin Bailey]

I agree, its definately looking really interesting for much of the mid ms vly, ohio vly, tn vly, and deep south. however it is still a ways out. but you can bet your butt i'll be keeping an eye on the models til it gets here! these type of systems real early in the year tend to catch a bunch of people off guard!

 

[Brett Adair]

Very interesting indeed. BMX is honeing in on this event as well. Current inidications show very impressive wind fields overtop of some descent instability for a change. My biggest question would be does the mid level trough hang back. The GFS has shown a split of the energy with a wave riding north across the midwest and into the Lakes region instead of phasing things up. It still looks like a severe weather setup for a big area, but a potential outbreak situation if the phasing solution occurs overtop the Theta-E ridge/Instability axis.

 

[Justin E. Reed]

A few classified military models I ran this morning have painted a very very bad situation. Incredbile levels of shear, I have not seen shear like this on this model, so I researched, and boom, popped out a close run to April 7,2006. Temps are going to be in the 70's all the way up to Nashville, and mid 60's to Louisville, with dewpoints 55-60 that far north, and 60-65 in in Alabama, Mississippi and Louisiana. More than ample instability, the one kicker though, low clouds, as is usual this time of year with systems like these. Although, enough warming of the clouds could cause them to break up and allow enough sun to really get things going. I expect supercells, some strong ones at that in MS, LA, AL, and possibly TN, with a likely damaging squall line up to OH, IN, and KY, and then trailing with the front further south.

 

[Brett Adair]

The WRF is also showing sufficient instability now especially across CNTRL/ERN MS and WRN AL for explosive development Tuesday afternoon. Good shear combined with upper level support looks to make for an active afternoon. Low level CAPE is pretty high, so some significant tornado development will be possible with sustained supercells well ahead of the cold frontal boundary itself. Nice SFC convergence also looks to allow for supercells to develop over this region as the SFC cyclone intensifies and moves NE with high pressure on the east coast. Still a few days to go, but this continues to look like a potential higher end event.

 

[George Tincher]

There doesn't seem to be much point trying to pin down all the specifics this far in advance. But the GFS is progging a 1001mb low which will be centered over ERN OK at 12z Tuesday to move NE and deepens it to 992mb, reaching C IN by 00z with a fairly strong cold front extending off to the SW. The latest NAM run shows a relatively similar solution.

Both models seem to indicate dewpoints into the mid 50s will be pulled as far N as NW OH during this period in advance of the front, with mid 60s dewpoints reaching as far N as WRN TN with even stronger values along the Gulf Coast. Strong, deep layer shear appears to be likely over the entire region. So the stage appears to be getting set for another severe weather event Tuesday.

Now, as to type of severe weather, it appears (at this point anyway) that this will likely be a wind damage event primarily, as models want to quickly congeal this activity into a line. However, 0-6km shear seems sufficient for supercells over much of this area. There's not as much low level turning as I like showing up yet, but there is decent directional shear (southerly at the sfc, gradually turning to the SW with height) and very strong speed shear. I could certainly see tornadoes within the line to be a distinct possibility. And should any discrete action be able to form in advance of the line, there appears to be more than enough helicity to get them spinning. However, it seems CAPE appears to be showing up a little weaker than I would expect given the other projected parameters and conditions. Perhaps the model is having issues dealing with precip or something? The 0-3km CAPE looks a little better. Ah well, it should be better resolved going foward.

BTW, the SPC has now placed a huge 30% severe probability area in the SLGT risk on the new Day 3 outlook, extending from N of the Ohio River in IL, IN and OH all the ay to the Gulf Coast. This thing may very well get upgraded to a moderate risk by the time we hit Day 2. Looks like Tuesday will be a long day for folks in the OH and TN Valleys, all the way down to the Gulf.

Good luck to anyone who chases this. Storm motions look pretty speedy, especially over the NRN portion of the threat area.

 

[nickgrillo]

WRF sure paints a favorable synoptic environment for supercells (and tornadoes) on Tuesday afternoon, particularly from southern IN into western KY and TN. Strong deep-layer flow will poise for favorable kinematic profiles for strong and sustained surface-based supercells with the possibility of a strong tornado or two given the forecasted boundary layer SRH (with good low-level hodograph curvature closer to the sfc low, given the veering boundary layer flow) and moisture depth.

 

[Justin E. Reed]

I'm really starting to smell a MDT risk being thrown out tomorrow for Northern MS, NW AL, W & MDL TN, W KY, and possibly up to S IN. Atleast from what all the models are throwing out there. It's going to be quite breezy in Middle TN, 20-30 gusting to 40 at the surface, which is quite brisk for this time of year.

 

[Heidi Farrar]

I think we could add AR, MO, IL, IN & OH to the subject line

As of the most recent model runs, the WRF & GFS have come down slightly on CAPE projections for AR/MO over this period, but we're still looking at values from 500-1000+. ... I, too, was struck by the SPC's wording in regard to the wind fields:

THIS SYSTEM WILL BE ACCOMPANIED BY VERY STRONG DEEP-LAYER WINDS...INCLUDING A SSWLY H8 JET IN EXCESS OF 70 KT AND H5 FLOW WELL IN EXCESS OF 100 KT IN THE JET CORE AND AS HIGH AS 90 KT ATOP THE WARM SECTOR.

To me, this set-up is pretty reminiscent of the SW MO event in January, but with higher levels of instability likely to be in place over a much wider area. I expect to see a mod. risk for Tuesday over central AR east into the lower OH valley & middle TN & northern MS.

 

[Terry Tyler]

man, this is starting to look better and better as the time wears on...im starting to get excited...

latest NAM run shows a 120KT jet core...60+ tds and 140-200 0-3KM cape, and 0-1KM SRH of 200-300...instability and wind profiles are looking very stout...just experiencing 1-10-08 and now this?!

the sfc low is going to be sitting right where i always want it for these kind of set-ups central KS/MO...

 

[Brett Adair]

I'm thinking with the orientation of the SFC low, you can add most of AL/MS and maybe NW GA to that MDT risk. Pretty good shot at seeing a high risk if the instability ends up being stronger than currently forecast. The EML will have alot to do with that. Looks like the NAM/WRF wants to paint supercells over much of MS/TN/W AL well ahead of the FROPA. 0-1km Shear values definitely concur with that idea from this mornings run. I believe that we are looking at a fairly high end event from the OH valley all the way to the Gulf coast.

 

[Justin E. Reed]

Very concerned

Many offices are calling for a SIGNIFICANT severe wx event for Tuesday. high temps will be in the 70's in Middle TN, IN FEBRUARY!, also, near 70 in Louisville, KY, that is a very bad sign and rare for this time of year. Instability will not be an issue, just the amount of sunshine will be the bigger issue, but with Lapse rates, shear, CAPE, and others this significant, it really won't matter. These stroms will explosively develop, and quickly tap into the shear, and begin to rotate. I'm am gettin concerned about this situation, its somewhat reminicent of the setup for the April 7,2006 outbreak!, and we all saw what happened then. I was even able to dig up data that some of these models are producing, and April 16,1998 popped up. That produced the unforgettable Downtown Nashville F-3, the Waynesboro F-5, and hail the size of softballs and a 99mph gust at Nashville Int'l Airport(KBNA). This situation, to me, has HIGH written all over it, along with a large MDT risk.

 

[Brett Adair]

Many offices are calling for a SIGNIFICANT severe wx event for Tuesday. high temps will be in the 70's in Middle TN, IN FEBRUARY!, also, near 70 in Louisville, KY, that is a very bad sign and rare for this time of year. Instability will not be an issue, just the amount of sunshine will be the bigger issue, but with Lapse rates, shear, CAPE, and others this significant, it really won't matter. These stroms will explosively develop, and quickly tap into the shear, and begin to rotate. I'm am gettin concerned about this situation, its somewhat reminicent of the setup for the April 7,2006 outbreak!, and we all saw what happened then. I was even able to dig up data that some of these models are producing, and April 16,1998 popped up. That produced the unforgettable Downtown Nashville F-3, the Waynesboro F-5, and hail the size of softballs and a 99mph gust at Nashville Int'l Airport(KBNA). This situation, to me, has HIGH written all over it, along with a large MDT risk.

Generally thinking the same thing here. The combination of shear/dynamics/instability is by far the best we have seen in a while with no coastal convection to block off warm inflow.

 

[Jeff Snyder]

I haven't looked at the forecasts TOO much, but I can't be as gung-ho about the threat as others seem to be. From a kinematic standpoint -- yes, things look very interesting for a significant severe weather event. However, kinematics are not everything, as we all know. I just can't help but have a tempered forecast owing to the forecast marginal instability, or downright lack of instability as one moves into the Ohio River valley (or much north of Paducah, KY). Right now, I think the lack of significant destabilization may prohibit a significant tornado event (particularly one that would deserve a HIGH risk) across most of the area. Yes, high-shear environments have support significant tornadoes and widespread supercells in spite of marginal instability, but I have a hard time putting together a forecast for a significant tornado event or outbreak when we see instability as weak as it is forecast to be (largely, <750 j/kg in most of the areas being highlighted in this thread). My interest is higher farther south (say, southeastern AR, west-central and southwestern MS, and much of La) where it appears destabilization may result CAPEs closer to 1000 j/kg.

As it is now, it's looking to me like a relatively widespread wind event (with significant wind events) similar to what we saw last week in the KY/IL/IN/OH. I do expect to see a threat for strong tornadoes south of the Paducah area (namely, western TN, eastern AR, LA, and MS), but I'm not sure that tornadoes will be the primary threat. Model forecast CAPE fields likely are going to be sketchy given the widespread convection being developed by the models (with the resultant widespread decrease in CAPE owing to convective parameterization). Regardless, though, I have to wonder if we'll see "strung-out" supercells that get ripped to shreds in a relatively low CAPE, high shear environment. Obviously, vert. perturb. pressure gradients may well contribute more to updraft intensity than buoyancy / CAPE given the strong shear, but I'm not convinced that it may be enough.

 

[George Tincher]

The amount of SBCAPE forecast by the models thus far does look pretty puny anywhere outside the Gulf Coast, particularly LA and MS. However, taking a look at 0-3km CAPE paints a much different picture:

Considering the time of year, I am not overly surprised that SBCAPE is not highly impressive. However, that low level CAPE looks very impressive and over a wide area. Considering everything else, I think that is very significant. And FWIW, I see better instability with this system than some that have occurred already this year that produced tornadoes. I mean we saw a long track F3 in Wisconsin in CAPE values that barely hit 500j/kg. Sometimes you just never know.

 

[Jim Bishop]

This looks like a pretty widespread severe weather event for Louisiana, Eastern Arkansas, Mississippi and Western Tennessee. I'm not going to go into detail, but I would expect numerous tornadoes over the region mentioned, with a couple violent, along with many damaging wind reports.

This is supported by the 50-60 knot south-southwesterly 850mb jet underneath 500mb jet 65-85 knots. In addition, model suggest CAPE 500-1000j/kg across Louisiana, southern Mississippi and southern Arkansas and 250-500 further north. In low-topped supercell cases, you don't need more than 500j/kg CAPE for tornadoes, even violent tornadoes.

Pretty scary situation considering how fast the storms will be moving. The really scary part is the severe threat will continue well into the night time hours over Alabama, middle Tennesse and Kentucky - probably as a very intense squall line with imbedded meso producing tornadoes.

 

[Brian Stertz]

Looks like my target would be NE Arkansas into SE Missouri & MO Bootheel...or basically in that corridor between Little Rock and Poplar Bluff and points northeast (Oil Trough...oh no not again). I am probably sitting this one out...ETA forecasted storm motions are 50 kts. plus and things could be pretty hard for visibility for the most part with pretty low cloud bases. Looks like the strong and possibly violent tornado threat may be closer towards sunset given timing of the strong surface low approach into NE Arkansas. Best of luck to those chasing.

 

[Scott Weberpal]

I mean we saw a long track F3 in Wisconsin in CAPE values that barely hit 500j/kg. Sometimes you just never know.

Not entirely true. A RUC derived sounding during the Wisconsin EF3 event yielded 1200 j/kg of SBCAPE.

I digress to the original topic on hand. I MAY head for the MO bootheel or NE AR this evening to be in place for tomorrow, looks too good from an early season standpoint to not give it a shot.

Appears to be a nice zone of upper difluence overspreading this area between 18z and 00z. If this holds on tonights run I be more likely to give this one a shot. Can't really beat the terrain the the bootheel or NE AR.

 

[Tony Laubach]

I'm going to throw my hat in for Super Tuesday as well and be one of the crazies alon for tomorrow's ride.

I'm hopping a midnight flight from Denver tonight and will be leaving out of Atlanta first thing in the morning for SW Tennessee. Figuring I can make Memphis early enough in the afternoon if storms haven't already raced through by that point.

I'm very impressed with the conditions for tomorrow and think we'll see a few notable events before the day ends. Obviously with the storms speeds and not-so-favorable terrain, it'll be a challenge. Low cloud bases with the T/TDs spreads being next to nothing will also make for a challenge. Excellent shear with good CAPE will keep cells sustained for a while, so even with an early initiation, there should be no issues in "missing" the show.

Will follow the show back into Atlanta where I'll be on the first flight home in the morning to get to work on Wednesday.

 

[Danny Neal]

Without completely reiterating what was mentioned already, I said last night in the SC chat that based on those model runs I would target the Cape Girardeau area. Temps pushing 70 in some places with 60 plus Td. Like Tony just said shear will be great and CAPE will be sufficient for Feb standards and terrain/visibility will make for some interesting decision making. Storm motions won't be the most favorable either. If I were going out I would probably hang around Cape G.

 

[Heidi Farrar]

The WRF has certainly slowed things down considerably, which is reflected in the new SPC outlook, wherein the Mod. Risk/ 45% hatched area has been expanded well into AR.

(I hope the following is deemed appropriate for the forecast section - if not I appologize.)

Since I see several of you have pinpointed NE AR as a target area, I thought I would throw this bit of info into the air for anyone who might find it helpful to know.

As almost anyone who has ever chased (or lived) in AR knows, we have sort of an archaic road network. Many if not most of the secondary roads are unpaved (read: gravel/clay), and can pose their own problems during non-severe time (low-water bridges, etc). Since we've had snow two times so far this winter, the most recent being just a few days ago, the unpaved roads across this region are more than likely going to be a disaster, especially in the Ozark region. Potholes are at a maximum, slick ruts, etc. I just thought it might be worth mentioning, as a cautionary for anyone unfamiliar with the area, or for those who just might not have considered this aspect for tomorrow. This is not to say people should think twice about chasing here, just a hopefully helpful bit to think of when planning.

 

[Rocky Rascovich]

Without regurgitating all the other forecasts... I'm strongly considering hopping into the ol' honda civic and going east on I-40 for tomorrow afternoon's atmospheric melee'. the WRF has slowed down a tad on the advancement of this vortmax ejecting out from the southern plains into the mid Miss. valley. I'm hoping that the area between LIT and MEM will light up between 18Z to 0Z tomorrow (2/5). My concerns are several, rapid storm motions at aprox. 50kts, the column on the forecast soundings off the WRF looks pretty saturated in my target area... I'm suspecting lots of gunge to deal with, what I'm wondering is maybe a dry slot forming in northeast TX and move northeast toward MEM, this could allow for a brief window of opportunity where at least an hour of sunshine could trigger those capes to shoot over 1000g/kg.. I think the chances of some damaging long tracked tornadoes are about 50/50, maybe more so, the more sun we get.

As of now, instability values will be marginal at best because I doubt they'll be much clearing ahead of the squall line for tomorrow... what I really like is the low level shear, in general, helicities up thru 3km. look downright frightening.. this alone will be a major issue with strongly rotating updrafts with the discrete cells that form ahead of the squall line after about 19Z.

As far as the squall line itself... look for several reports of winds in excess of 70kts, hail up to 1.5" in diameter.. and anywhere from 12-25 (separate) confirmed tornado reports from NW LA.. up to the MO. bootheel on into western TN. and the eastern half of Ark. Later that evening, several additional tornado reports are likely around the Huntsville to Nashville area.

If I do this, I'll be out the door within the hour and try to make it to Memphis by midnight and reposition from there tomorrow. If I regain some of my sanity and don't do this, I'll be available for some nowcasting as this unfortunately good be a devastating day for the mid south.

Be safe if you venture out.

Rocky&family

cell phone# 405-226-2996

 

[Adam Lucio]

Ron you stole my target city!

IF I head out [currently trying to convince my partner] I too will probably play the northern extent of the MDT. Ive noticed that sometimes in events like this that the backing winds near the low and south of the warm front can offer an early show. I think anywhere from Frankfrot, KY to SErn MO to Nern AK and Wern TN have a decent shot an early show, before the main explosion takes place in the south.

Im not concerned with the apparent lack of CAPE that far north...what I would be most concerned with is leftover morning convection.

Good luck to those heading out, Im not entirely sure yet if I am going, but I too like the Jackson, TN target. On the way home I can enjoy the night time squall line before driving through winter weather back here in Chicago, would make for a very unique chase!

 

[Brian Emfinger]

the WRF has slowed down a tad on the advancement of this vortmax ejecting out from the southern plains into the mid Miss. valley.

Yeah I agree 100% with that. GFS seems to be slowing it down a bit every run as well. I think theres a pretty good chance that we could luck out with the storms being at their peak between LZK and MEM. That area..especially the eastern half of that area would be the best case scenario as far as terrain and visibility goes.

 

[Jim Cross]

I agree with Brian about southeast missouri. I am targeting the sikeston to poplar bluff area along highway 60. This is a west east highway which i think will give the best chance of staying ahead of any storms that fires over the area. With the speed of the storms i doubt if you would have much chance on a north south road. This area is mostly flat with a few hills towards poplar bluff but not to bad. I will head to Sikeston in the morning and stop there for more data and if need be could drop farther south on 55 towards missouri arkansas border. Good luck to all chasing tomorrow