Severe (tornado + wind) event looming: 01/30-01/31 Wed.-Thursday

[Ground Scouring]

Original mention here

 

I think this deserves a separate thread as the 12Z GFS and its ensembles in particular are showing a prolonged rain threat with isolated 24-hour QPF in excess of 3.0" over a wide swath of the TN Valley and the Southern Appalachians next Wednesday-Thursday with a big wind event (either a squall line or bowing QLCS) covering the same area. The 00Z ECMWF has jumped onboard as well and model consistency has grown over the past day. Given the 850-mb vector and the PWAT in excess of 2" preceding the cold front, the possibility for training storms embedded in the squall line seems quite probable.

 

CIPS analogs

[metalicwx366]

Ugh.I was hoping you would say GA/FL and Carolinas. Just dry here.

[NavarreDon]

At work & haven't looked at the models. This will not be a good thing in the Mnts. with all the recent rains. Flooding will def. be a issue.

[franklin NCwx]

Not what we need in the rain dept. We have had too much run. Im tired of my yard being mud.

[franklin NCwx]

Not what we need in the rain dept. We have had too much run. Im tired of my yard being mud.

[Tacoma]

Not what we need in the rain dept. We have had too much run. Im tired of my yard being mud.

why can we not have a snowstorm like this.  its always rain when a big storm shows up,  it gets cold and we have a little moisture and I mean a little then we have a big storm and its to warm to snow,  can't we catch a break?

[Marion_NC_WX]

6-plus inches of rain for me this month...might as well finish it off with a couple more inches.

[POWERSTROKE]

Not what we need in the rain dept. We have had too much run. Im tired of my yard being mud.

I can sod it for you!! Lol

[tnweathernut]

Over 8 inches of rain in and around the Tricities this month. We do NOT need any more. Though honestly......I am more concerned with wind at this point. Our tree root structures are overly saturated as it is. It would only take a marginal wind event with another inch or two of rain to pull down some big trees and cause damage.

[RevDodd]

If the jet is able to mix down like the D4 SPC notes, folks who've had all the rain this month may be looking at downed trees and power lines.

[Ground Scouring]

The latest trends on the NAM suggest more of a widespread tornado threat with discrete cells and a broken QLCS rather than a solid squall line--this would reduce the potential for widespread and heavy rainfall given a somewhat-stronger EML and shear vectors favoring more-distinct activity. But the threat looks to extend all the way across the TN Valley and N AL on the early morning of 01/30 and then into the Carolinas overnight on 01/30-01/31.

[audioguy3107]

Here's the latest day 4 outlook, we'll probably get a clearer picture of what may be in store tomorrow.  As usual, instability will most likely be the limiting factor as with most wintertime severe threats.

 

[AbsolutZero]

00Z NAM STP still not too shabby, but trend is lower.

 

[audioguy3107]

00Z NAM STP still not too shabby, but trend is lower.

 

Noticed that as well, but still, not bad numbers for a late January severe threat.....could see more instability if we could keep the token preliminary showers out of the area before the main event, but you know how that goes in this part of the SE.

[Marion_NC_WX]

Robert has sent out a couple facebook updates this morning focusing on the non-thunderstorm wind threat. The GFS is showing a LLJ in excess of 50 mph coming up along the eastern slopes of the Appalachians on Wednesday afternoon. That's rare for my specific location.

[Hammer]

Noticed that as well, but still, not bad numbers for a late January severe threat.....could see more instability if we could keep the token preliminary showers out of the area before the main event, but you know how that goes in this part of the SE.

 

That map looks more like what I have seen in my past seven years in North Georgia... although I don't recall tornadic activity this early in the season - usually around Easter... models will be interesting to watch, for sure.

[WilkesboroDude]

Blacksburg thinks a possible High Wind Watch so they don't have to issue severe warnings.

[NavarreDon]

GSP's overnight:

 

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...AS OF 245 AM MONDAY...A FULL LATITUDE TROUGH WILL STRETCH ACROSS THEPLAINS ON TUE...WITH A RIDGE AXIS MIGRATING OFF THE ERN SEABOARD. ADEEP MOISTURE FEED FROM THE GULF OF MEXICO WILL DEVELOP AHEAD OF THETROUGH THROUGH TUE...BUT WITH ANY SHOWERS CONFINED MAINLY TO THE SRNAPPALACHIANS. SFC DEWPOINTS WILL REBOUND RAPIDLY IN THE SRLYFLOW...BUT A WEAK CAPPING INVERSION WILL LIMIT THE POTENTIAL FOR ANYCONVECTION TUE AFTN/EVENING. PRECIPITATION CHANCES WILL REMAINGREATEST IN AND NEAR THE MTNS LATE TUE THROUGH TUE NIGHT...WITH AFOCUS ON SRLY UPSLOPE AREAS.THE SOUTHERLY 850 MB JET ADVANCING AHEAD OF THE APPROACHING SFC COLDFRONT WILL MOVE INTO THE SRN APPALACHIANS TUE NIGHT TO PRODUCE VERYWINDY CONDITIONS AND INCREASING COVERAGE/INTENSITY OF RAIN SHOWERS.THE PLUME OF HIGHER PRECIPITABLE WATER ALONG WITH UPSLOPEENHANCEMENT COULD PROVIDE ENOUGH RAIN TO SATURATE THE SOIL AND SETTHE STAGE FOR HYDROLOGY PROBLEMS ON WED WITH THE MAIN FRONTALPASSAGE. IN ADDITION...WIND PROFILES QUICKLY BECOME IMPRESSIVEOVERNIGHT TO POSSIBLY POSE A HIGH WIND THREAT ACROSS THE SRN MTNS.BOTH A FLASH FLOOD WATCH AND A HIGH WIND WATCH COULD BE NEEDED ATSOME POINT...BUT WILL HIGHLIGHT THESE HAZARDS IN THE HWO AT PRESENT.THE FORECAST MODELS ARE FAIRLY CONSISTENT ON A WED AFTN COLD FROPA.THIS EVENT WILL BE VERY STRONGLY FORCED...WITH SIGNIFICANT FRONTALCIRCULATIONS...DEEP LAYER DPVA...STRONG UPPER DIVERGENCE...ANDTREMENDOUS WARM ADVECTION. IN ADDITION...THE CAP IN THE THERMALPROFILES SHOULD DISAPPEAR AND INSTABILITY ON THE ORDER OF 500 J/KGMLCAPE SHOULD BE REALIZED ACROSS NE GA...UPSTATE SC...AND THE NCPIEDMONT. ANY MIXING WITH SHOWERS/TSTMS IN THE STRONG GRADIENT FLOWCOULD BE ENOUGH TO KNOCK DOWN SOME TREES...BUT THIS INSTABILITY WILLGREATLY INCREASE THE POTENTIAL FOR WIND DAMAGE. IN ADDITION...THESRLY 850 MB JET OF 65 TO 70 KT AND SFC TO 1 KM SHEAR VALUES NEAR 50KT WILL MAKE ISOLD TORNADOES A THREAT. THE SPC DAY 3 SLIGHT RISKDEPICTS THIS WELL.FOLLOWING FROPA...SNOW LEVELS WILL CRASH ACROSS THE MTNS WEDNIGHT...WITH WNW UPSLOPE FLOW MOISTURE WRINGING OUT SNOW SHOWERSOVER THE WRN MTNS THROUGH DAYBREAK THU. VERY WET UPSTREAM SOILCONDITIONS COULD PRODUCE SNOW TOTALS SLIGHTLY HIGHER THAN INDICATEDIN MODEL QPF. THE POTENTIAL FOR ACCUMULATING WRN MTN SNOWFALL WILLALSO BE ADVERTISED IN THE HWO.

[WilkesboroDude]

I doubt there will much tornado threat where snow/sleet cover is still hanging around in WNC. At least I never seen it happen yet.

[DaculaWeather]

More likely a sustained high wind event out ahead of the main squall line. Should be interesting to follow.

[DaculaWeather]

Steven, are your thoughts still the same on this one? 

 

00Z NAM STP still not too shabby, but trend is lower.

 

[DaculaWeather]

Looks like the winds come together all the way from the upper levels to the lower. Here's a 200 mb, 300 mb, and 500 mb image from the same time period.

 

 

 

[nrgjeff]

After backing off at 06Z, the 12Z WRF/NAM now insisting on that negatively tilted trough and pre-frontal wind shift again. I don't believe it. We're still talking 48-60 hours which is not yet it's strong point. GFS/EURO both going neutral to positive tilt, and only CF storms. You have to agree with that based on pattern recognition. When is the last time we got a negative tilt this winter? Been a while.

 

While a negative tilt could bring tornadoes, I don't see it in the cards. Back in 1999 Arkansas got walloped with a January negative tilt. You don't have to be in the Deep South to get tornadoes in the dead of winter. However like I said, doubt it's in the cards this time. In fact if the trough is positive NC may stay stable, Just kidding, there will be enough wind and mixing either way.

 

What I see is heavy rain from Arkansas through the Tennessee Valley into the Carolinas. Some heavy rain in the Deep South too. Thunderstorm winds and synoptic winds may be hard to differentiate from Arkansas though the Mid South to the Carolinas and Virginia. However I strongly agree with SPC this is not a tornado set-up. It will be good to hear some thunder, but it's just wind and rain.

[GaffneyPeach]

I recall a similar set-up in/around January 19, 1978. If someone could look that date up. The winds howled all night and we woke up to a mess the next day. Outbuildings and small structures scattered all over. I don't recall any storms but I'll never forget those winds.
Thanks, Peach

[Cheeznado]

I agree this is not a prime tornado setup, but given the very strong dynamics I think there is a pretty good chance of at least a few imbedded QLCS tornadoes lasting well into the night across the South, with maybe even one or two supercell tornadoes ahead of the main line, especially in AR/LA early tomorrow evening. Despite the poor timing here in GA, this is such a dynamic system even a noon passage of the line Wednesday could result in a fair amount of problems from wind. This looks like one of the better January severe setups in a while, maybe not from a tornadic standpoint, but there will likely be a ton of wind reports.

[Cheeznado]

I agree with this upgrade. The next two days should be interesting, all models now show a strong short wave going negative tilt.

 

 

 

[calm_days]

 

This is not a spoiler as much as it is a model that will probably change before wednesday so I want to let it be optional.  It is between a simulated radar and a traditional model, from a Nasa-goddard system.

 

Someone in the January 25th topic and I had a conversation about it!  The precipitation returns weren't too accurate but the placement and movement of the precipitation were fairly accurate a few days out. 

[NavarreDon]

Great afternoon from GSP....I am surprised there is not more going on in this thread!

 

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...AS OF 245 PM MONDAY...THE MAIN CONCERN IS THE PASSAGE OF A STRONGCOLD FRONT ON WEDNESDAY THAT IS MUCH MORE REMINISCENT OF A MARCH ORAPRIL FRONTAL PASSAGE THAN ONE IN LATE JANUARY. THIS SYSTEM WILLPOSE A MYRIAD OF THREATS FOR MIDWEEK. BEFORE WE GET THERE...IMPROVING MOIST SOUTHEASTERLY FLOW AT LOW LEVELS AHEAD OF THE FRONTWILL FORCE AN AREA OF SHOWERS THAT STARTS NEAR THE BLUE RIDGE ANDEXPANDS FROM THERE. PRECIP CHANCES START IN THE CHC RANGE ON THESC/NC BORDER NEAR THE BLUE RIDGE AND GRADUALLY RAMP UP TOCATEGORICAL BY THE END OF THE TUESDAY NIGHT PERIOD WHILE FANNING OUTOVER THE REST OF THE MTNS...FOOTHILLS...AND INTO THE WRNPIEDMONT/UPSTATE. INCREASING SOUTHERLY FLOW ALOFT WILL PROBABLYBRING HOWLING WINDS A FEW THOUSAND FEET AGL...BUT AS IN MOST WARMADVECTION CASES...THIS SHOULD ONLY AFFECT THE HIGHEST RIDGETOPS ANDPEAKS ACROSS THE NC MTNS WHILE THE VALLEYS REMAIN PROTECTED.AT SUNRISE WEDNESDAY...THE MAIN FRONTAL PRECIP BAND IS EXPECTED TOBE OVER THE TN VALLEY. THIS SYSTEM HAS MUCH GOING FOR IT...INCLUDINGSTRONG UPPER DIVERGENCE IN THE RIGHT ENTRANCE REGION OF THE JET ANDSTRONG LOW LEVEL MOISTURE FLUX CONVERGENCE. MID LEVEL FORCING COULDBE BETTER AS THE BEST DPVA AND WARM ADVECTION WILL PROBABLY LIFT NEOVER THE CENTRAL APPALACHIANS. NEVERTHELESS...THE FORCING WILL BEMORE THAN ADEQUATE AND THE MOISTURE WILL BE DEEP AND QUITEIMPRESSIVE WITH A PRECIPITABLE WATER ANOMALY OF NEARLY 4 STDDEVIATIONS ABOVE NORMAL. THERE IS SOME CONCERN THAT QPF FROM THEMODELS COULD BE UNDERDONE...AS THIS CASE LOOKS A BIT MORE LIKE THEANAFRONT SLOWER MOVING CONVECTION CASE IN THE MAHONEY AND LACKMANN(2007) PAPER. THE FACTOR THAT MIGHT PREVENT WIDESPREAD HEAVYRAINFALL AND LIMIT THE FLOOD POTENTIAL WOULD BE THAT THE SYSTEM ISNOT EXPECTED TO STALL. CATEGORICAL POP IS A GIVEN FOR WEDNESDAY...BUT IT MIGHT TAKE THE MORNING TO GET THERE ACROSS THE NC PIEDMONT.PRESENT INDICATIONS ARE THAT A SEVERE WEATHER PRODUCING QUASI LINEARCONVECTIVE SYSTEM WILL BLAST ACROSS THE WESTERN CAROLINAS DURING THEDAYLIGHT HOURS. FLOW ALOFT WILL BE STRONG ENOUGH THAT WE MAY BE ABLETO MIX DOWN VERY STRONG WIND GUSTS IN THE WARM ADVECTION FLOW AHEADOF THE SQUALL LINE...WITH GUSTS PERHAPS TOPPING 40 MPH. THE SHEARSHOULD BE GREATER THAN 40 KT COURTESY OF A STRENGTHENING 60+ KT LOWLEVEL JET THAT TRANSLATES EAST ACROSS THE REGION IN THE AFTERNOON.THE ONLY PROBLEM WILL BE INSTABILITY...BUT WE SHOULD BE UNWEDGED...AND EVEN THE GFS GIVES CAPE AROUND 200 J/KG...WHICH SHOULD BESUFFICIENT. WE WILL HAVE TO BE ON THE LOOKOUT FOR LINEAR CONVECTIONDEVELOPING TO OUR WEST EARLY IN THE DAY. THE AREA ALONG AND S OFI-85 WOULD BE MOST FAVORED IN THE AFTERNOON AND EARLY EVENING. ALTHOWE HAVE SEEN NUMEROUS POTENTIAL EVENTS FAIL THUS FAR...SOONER ORLATER OUR LUCK WILL RUN OUT. THE HIGH WIND...HEAVY RAIN...AND SEVEREWEATHER THREATS ARE ALL IN THE FOURTH TO FIFTH PERIOD...TOO EARLYFOR WATCHES...SO IT WILL BE DISCUSSED IN THE HWO.

[deltadog03]

[Jon]

Great afternoon from GSP....I am surprised there is not more going on in this thread!

It will pick up tomorrow when the Day 2 graphic from SPC is updated to put more of us in the mix

 

Hires 4km NAM reflectivity shows squall line from GA to NC Mountains...storm starts to break up over NC and the severe threat looks to be gone for NC as soon as it started... greatest chance for severe will probably be around 4-6pm, very small window for most areas. Central, N GA/ N SC might get interesting around this time, IMO....still a lot to look at and I'm only looking at the NAM btw.