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

[Disc]

I don't see this being a very big tornado threat for the Carolinas and GA areas. Right now things are pointing towards some sort of squall line or maybe a QLCS event depending on where the best instability is located throughout the warm sector. Any convection could tap into the 60kt LLJ and bring some 850mb-925mb winds to the surface.

[deltadog03]

[Shawn]

I don't see this being a very big tornado threat for the Carolinas and GA areas. Right now things are pointing towards some sort of squall line or maybe a QLCS event depending on where the best instability is located throughout the warm sector. Any convection could tap into the 60kt LLJ and bring some 850mb-925mb winds to the surface.

 

I agree with this statement 100%.  I've been looking at the models for the last few days and although descret cells are popping up on the HI-RES radar models, I think they'd be heavy downpours with wind and possibly a good bit of lightening down here in my area of SC.  What worries me the most are areas who have seen way too much rain recently and will have the heavy winds (I'd expect quite a few Wind advisories/warnings soon) being able to take advantage of the weaker ground/root system.  It looks like the low level jet around my back yard will be around 50-60KTS max possbile mixing down towards the surface at best so I think we will luck out here.  The mountains are another beast though for NC/Extreme Upstate SC, NE GA.

 

Another aspect of this storm is the rainfall.  SREF mean had around half an inch locally around CAE, but with the gulf fully open I believe it has a chance to be a bit higher if a few of the descrete cells do pass through especially considering that half the members (sref) also show much more.  Here's some data from it for various areas:

 

21Z SREF Ensembles:

CAE: Mean (0.49), Highest (0.89), Lowest (0.11)

ATL: Mean (0.88), Highest (1.59), Lowest (0.43)

GSP: Mean (0.90), Highest (1.52), Lowest (0.42)

RDU: Mean (0.45), Highest (0.71), Lowest (0.14)

CHS: Mean (0.24), Highest (0.65), Lowest (0.05)

Sorry, CLT not available.

 

For those interested in CAE:

00z NAM that lines up pretty well with the 21z SREF Mean QPF Wise:

  42 01/30 18Z   75     61     197      21    0.02  0.02    565    573   12.4 -10.3 1009  73 -TSRA 026BKN123    0.0   11.6
  45 01/30 21Z   78     59     194      23    0.01  0.01    565    570   12.7 -11.6 1005  91 -RA   062BKN275    0.0   11.8
  48 01/31 00Z   74     60     196      24    0.01  0.01    565    569   12.4 -11.0 1004  96 -TSRA 070BKN283    0.0   11.9
  51 01/31 03Z   59     55     284      21    0.43  0.02    559    567    7.6 -12.4 1008 100 -TSRA 012OVC213    0.0   13.2

[yoda]

[DaculaWeather]

http://www.daculaweather.com/4_spc_pwo.php

 

 

 

PUBLIC SEVERE WEATHER OUTLOOK  NWS STORM PREDICTION CENTER NORMAN OK0409 AM CST TUE JAN 29 2013...THE MOST SIGNIFICANT THREAT FOR SEVERE THUNDERSTORMS IS EXPECTEDOVER PARTS OF THE OZARK REGION AND THE LOWER MISSISSIPPI VALLEY THISEVENING THROUGH TONIGHT...THE NWS STORM PREDICTION CENTER IN NORMAN OK IS FORECASTING THEDEVELOPMENT OF DAMAGING WINDS AND A FEW TORNADOES...SOMESTRONG...OVER PARTS OF THE OZARK REGION AND THE LOWER MISSISSIPPIVALLEY THIS EVENING THROUGH TONIGHT.THE AREAS MOST LIKELY TO EXPERIENCE THIS ACTIVITY INCLUDE       MUCH OF SOUTHERN...CENTRAL AND EASTERN ARKANSAS       FAR NORTHERN LOUISIANA       FAR SOUTHEAST MISSOURI       NORTHWEST AND WEST CENTRAL MISSISSIPPI       FAR SOUTHWEST TENNESSEE       FAR NORTHEAST TEXAS

[DaculaWeather]

From Atlanta this morning:

 

AS FAR AS THE SEVERE POTENTIAL...WOULD STILL LOOK LIKE A BORDERLINE EVENT IF NOT FOR EXTREME 925MB WINDS PROJECTED. 50 TO 
55 KT WINDS AT THIS LEVEL PUT IT A FULL 5 STANDARD DEVIATIONS FROM THE NORM MAKING THIS A HIGHLY ANOMALOUS EVENT. THIS WOULD MAKE CAPE FOR THIS EVENT LARGELY IRRELEVANT AS EVEN SHRA ACTIVITY WOULD BE CAPABLE OF PRODUCING THE MOMENTUM TRANSPORT NEEDED TO BRING WINDS TO SURFACE. EVEN WITH THAT SAID...NAM12 STILL PRODUCES A HEALTHY AMOUNT OF INSTABILITY WITH 1000 J/KG FOR WEST CENTRAL GEORGIA. FEEL THIS MAY BE OVERDONE AS IT IS MAINLY IN AFTERNOON AND COUNTING ON A FASTER PROGRESSION AT THIS POINT WHICH WOULD RESULT IN LOWER VALUES. WILL PLAY UP THE FACT IN HWO THAT GRADIENT WINDS WILL BE CAPABLE OF PRODUCING DAMAGING WINDS LATE TUESDAY NIGHT AND CERTAINLY WED WITH THE SHOWER ACTIVITY. WILL ALSO HAVE HIGH WIND WATCH FOR THE MOUNTAINS FOR THIS EVENT.

[CandymanColumbusGA]

Yeah... The wind threat with this system is what I'm most concerned about. Could a tornado spin up? Sure, but it's not all that likely.... It was impressive to see a 150+knot jet streak show up at 500 mb on the GFS near the Great Lakes. That's some serious wind! I'm forecasting sustained winds between 20-30 mph with gusts up to 40 mph ahead of the line of storms... Should be entertaining tomorrow!

[NavarreDon]

GSP's overnight.

 

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...AS OF 250 AM TUE...THE CENTRAL CONUS TROUGH/ATLANTIC RIDGE PATTERNON WED WILL STEADILY DEAMPLIFY THROUGH THE SHORT TERM PERIOD. THISWILL PUSH A SHARP COLD FRONT ACROSS THE REGION WED. FORCING ANDMOISTURE SHOULD BE PLENTIFUL. A STRONG FRONTOGENETICAL CIRCULATIONSHOULD DEVELOP AROUND THE FRONTAL ZONE...THE 140+ KT UPPER JETLETPARALLEL TO SRN APPALACHIANS WILL PROVIDE THE BEST UPPER DIVERGENCEOVER THE REGION WED AFTN...AND TREMENDOUS WARM ADVECTION WILL ARRIVEON THE STRENGTH OF A 60 TO 70 KT LOW LEVEL JET. PRECIPITATION WILLBE HEAVIEST ALONG THE SRN ESCARPMENT OF THE EXTREME SOUTHERNAPPALACHIANS IN UPSLOPE FLOW...BUT WITH HEAVY RAINFALL LIKELYEXTENDING NORTHWARD ACROSS THE MTNS AND FOOTHILLS THROUGH THE DAY ASTHE FRONTAL ZONE ARRIVES. WORKING IN FAVOR OF FLOODING WILL BE VERYHIGH PRECIPITABLE WATER VALUES RUNNING ABOUT 3 STANDARD DEVIATIONSABOVE NORMAL. HOWEVER...THE RELATIVE BREVITY OF THE HEAVYRAINFALL...ALONG WITH SOME POTENTIAL FOR GULF COASTAL CONVECTION TOINHIBIT SRN APPALACHIAN RAINFALL...WILL LOWER CONFIDENCE ONWIDESPREAD FLOODING. FOR NOW...WILL ADVERTISE A FLOOD WATCH ONLYALONG THE SRN ESCARPMENT AREAS FROM RABUN GA TO HENDERSON NC WHERETHE BEST OVERLAP OF LOW FLOOD GUIDANCE AND 2 TO 3 INCH QPF EXISTS.HIGH WINDS WILL LIKELY ALSO BE AN ISSUE DURING THIS TIME FRAME WED.DAMAGING WINDS COULD AFFECT THE HIGHER ELEVATIONS AS EARLY ASDAYBREAK ONCE THE STOUT 850 MB JET RAMPS UP. ONCE THE BETTER SHOWERSARRIVE...MOMENTUM WILL LIKELY MIX DOWN TO THE GROUND IN MANY PLACESTO CAUSE WIND DAMAGE. A HIGH WIND WATCH WILL BE POSTED OVER MOST OFTHE MOUNTAINS. HIGH WINDS WILL CERTAINLY BE POSSIBLE WITH ANYSHRA/TSRA EAST OF THE MTNS...BUT THIS MAY WELL GET HANDLED BYCONVECTIVE WARNING PRODUCTS. STILL...A WIND ADVISORY MAY BE NEEDEDTHROUGHOUT THE CWFA AT SOME POINT. REGARDING THE CONVECTIVEPOTENTIAL...SFC BASED CAPE VALUES AROUND 500 J/KG ARE STILL EVIDENTON THE MORE UNSTABLE MODELS AND THIS SEEMS REASONABLE GIVEN THEDISSIPATING CAP AND SURGING DEWPOINTS. WIND SHEAR WILL BE PLENTIFULFOR THE AFORE MENTIONED WIND DAMAGE THREAT AS WELL AS ISOLD HIGHSHEAR LOW CAPE TORNADOES. IF WE GET JUST A BIT MOREHEATING...PARAMETERS COULD RISE INTO THE LOW END SUPERCELL RANGE BUTHSLC TYPE CONVECTION APPEARS MORE LIKELY FOR NOW. THE HEAVYRAIN...WIND...AND SEVERE THREATS WILL BE MENTIONED IN THE HWO WHEREAPPROPRIATE.

[GeneR4]

The part about "...it is becoming more apparent that the
threat for tornadoes has been downplayed to this point..."
it a little worrisome.

Area forecast discussion...updated
National Weather Service Huntsville Alabama
606 am CST Tuesday Jan 29 2013


Update...
for 12z tafs


&&


Discussion...
/issued 549 am CST Tuesday Jan 29 2013/
the Tennessee Valley remains beneath a strong southwesterly middle-
level flow regime this morning...downstream from a powerful
longwave trough extending from the northern rockies south-
southwestward into Arizona. A potent 500-mb vorticity maxima --
currently spreading eastward across Sonora and through the base of
this longwave trough -- is forecast by all nwp guidance to eject
northeastward into the Southern Plains today as a 150-160 knot high-
level jet and the entire longwave trough begin to migrate eastward.
This regime will contribute to a deepening surface low across
southern Kansas/ northern Oklahoma...with an associated Pacific front
trailing southwestward from the low across southern Oklahoma and into
central Texas. Expect south-southeasterly winds to increase subtly
through the day as this occurs...with strong low-level warm/moist
advection resulting in a persistent deck of thick stratus and
perhaps a bit more light shower activity than was observed yesterday.


The previously mentioned middle-tropospheric vorticity maximum is forecast to
become increasingly stretched/sheared as it ejects northeastward
into the middle/upper-Mississippi Valley region by 12z Wednesday and
across the Central Plains later in the day. This will be accompanied
by significant deepening of the associated surface low as it tracks
northeastward...reaching the northern Great Lakes by 12z Wednesday.
Although there are still differences regarding timing...it appears
that the trailing Pacific front will reach northwest Alabama between
9-11z...Interstate 65 between 13-15z...and northwest Georgia between
16-18z. The evolution of similar events in the past and dynamic
nature of this system suggest that the timing listed above may be a
bit too slow...but will stick with this schedule for now. A potent
squall line or qlcs feature will accompany the passage of this
front...with damaging straight-line winds /some in excess of 70 miles per hour/
the primary threat. However...it is becoming more apparent that the
threat for tornadoes has been downplayed to this point...and will
likely be higher than what we were advertising previously. Models
agree on various parameters that would argue for a higher tornado
threat...such as dewpoint values in the 60-65f range...and 0-1 km
helicity values of 400-500 m2/s2...which will be more than sufficient
for tornadoes even with MUCAPE values of 150-300 j/kg. The highest
risk for tornadoes will come with pronounced bowing segments or line
echo wave patterns that develop within the broader qlcs structure.
The threat for storms will end rather abruptly as the Pacific front
surges eastward into Georgia by middle-day Wednesday...with perhaps some
light rain or drizzle continuing through the afternoon as the true
cold front moves into the region. Any lingering precipitation in the
favorably strong upslope flow regime across the Cumberland
Plateau/northeast Alabama will likely fall as snow on Thursday
evening...and feel confident enough to add in a low pop for this.

[HurricaneTracker]

500mb winds really crank tomorrow afternoon, per recent NAM.  Many values over 100kt, with some at or over 130kt!

 

[DaculaWeather]

75 kts at 5000 feet, 65 kts at 2500. 

[Brick Tamland]

Yes, this part does make me more nervous.

 

 However...it is becoming more apparent that the
threat for tornadoes has been downplayed to this point...and will
likely be higher than what we were advertising previously. Models
agree on various parameters that would argue for a higher tornado
threat...such as dewpoint values in the 60-65f range...and 0-1 km
helicity values of 400-500 m2/s2...which will be more than sufficient
for tornadoes even with MUCAPE values of 150-300 j/kg.

 

I hope folks are not caught off guard because it is January and they are thinking we can't get tornadoes in winter.

[DaculaWeather]

James Spann:

 

As discussed here for several days, the primary threat remains damaging straight line winds along the QLCS (quasi linear convective system). The low level jet (around 5,000 feet) is screaming, with winds of over 75 knots, and it won’t take much to transfer that down to the surface. If your county comes under a severe thunderstorm warning, you will need to take it seriously. In fact, with this kind of setup I would take it like a tornado warning since there is potential for widespread damaging winds that exceed 75 mph along the line, which will knock down many trees and power lines, and have the potential to create some structural damage. Not sure I would want to be in a mobile home as this line comes through… just something to think about.

[K4CF]

75 kts at 5000 feet, 65 kts at 2500. 

Are those heights ASL or above surface?

[Mr Bob]

So Huntsville is worried about the downplaying of tornadoes yet the front page of their website is showing a small up top headline with a wind advisory for tonight otherwise just the forecast for warm temps and cloudy skies. Meanwhile Morristown has it smeared all over their page....Who is doing the disservice here?

[deltadog03]

updated 4KM RPM out to 27 hours....(only goes out that far on the 4km)

 

https://www.facebook.com/41FirstAlert

[Brick Tamland]

WRAL saying the best chance for severe weather around here will be tomorrow night between 8 and midnight.

[DaculaWeather]

http://www.spc.noaa.gov/products/md/md0068.html

[burgertime]

Hi-Res NAM is going bonkers for qpf in WNC and parts of GA for tomorrow. Most of GA from ATL north is in 3 inches with parts of SW NC with 6+ inches.  Looks to really flair up some severe storms there. 

[DaculaWeather]

Hi-Res NAM is going bonkers for qpf in WNC and parts of GA for tomorrow. Most of GA from ATL north is in 3 inches with parts of SW NC with 6+ inches.  Looks to really flair up some severe storms there. 

I think it's going to be a rough day here tomorrow.

[franklin NCwx]

Hi-Res NAM is going bonkers for qpf in WNC and parts of GA for tomorrow. Most of GA from ATL north is in 3 inches with parts of SW NC with 6+ inches.  Looks to really flair up some severe storms there. 

As usual SW NC wins in the rain dept. We have had too much rain this winter. Enough is enough!

[deltadog03]

I would say from middle Georgia, Northern Georgia, upstate South Carolina, Western North Carolina really have to pay attention to the weather tomorrow.

[calculus1]

Hi-Res NAM is going bonkers for qpf in WNC and parts of GA for tomorrow. Most of GA from ATL north is in 3 inches with parts of SW NC with 6+ inches.  Looks to really flair up some severe storms there. 

 

Yeah, here's the map for 60-hour total qpf.  Yet, some of these totals might be slightly influenced by the subsequent clipper system(s).

 

[GeneR4]

So Huntsville is worried about the downplaying of tornadoes yet the front page of their website is showing a small up top headline with a wind advisory for tonight otherwise just the forecast for warm temps and cloudy skies. Meanwhile Morristown has it smeared all over their page....Who is doing the disservice here?

 

Their 'Long Term' tab does show the Strong/Severe storms, the 'Short Term' shows today's weather.  But I do see your point, even BMX has it as the 'Main page'.  Perhaps they will update this afternoon.

[DaculaWeather]

You mean this?

[NavarreDon]

Nice write up by MOB on primary threats downstream:

 

.LONG TERM [WEDNESDAY THROUGH MONDAY]...WEATHER MODELS PIVOT A SHARP
LONGWAVE HIGH LEVEL TROF AND STRONG COLD FRONT EASTWARD ACROSS THE
MISSISSIPPI VALLEY WEDNESDAY. EMBEDDED IN THIS TROF AND AHEAD OF THE
FRONTAL ZONE...IS A STRONG 300 MB HIGH LEVEL JET STREAK...CONTAINING
WINDS OF 130-140 KNOTS. THE FORECAST AREA COMES UNDER THE INFLUENCE
OF THE FAVORED RIGHT REAR QUADRANT OF THIS JET STREAK AND ENHANCED
DEEP LAYER LIFT SPREADS EASTWARD WEDNESDAY MORNING INTO THE EARLY
AFTERNOON OVER THE FORECAST AREA. WORKING DOWN INTO THE LOWER
LEVELS...A VERY STRONG 850 MB JET STREAK INTENSIFIES TO SOME 50 TO 60
KNOTS ABOUT 5000 FEET OFF THE SURFACE. THE LIMITING FACTOR
FORECASTERS SEE IS WEAK LAYER CONVECTIVE POTENTIAL ENERGY (CAPE) WITH
VALUES AT OR BELOW 500 J/KG. THE CAVEAT AND OF CONCERN IS THE STRONG
WIND FIELD ALOFT AND VEERING WINDS THAT ADVANCES ACROSS THE AREA
WEDNESDAY...RESULTING IN PRONOUNCED SHEAR IN THE WARM SECTOR. THIS
ALONE...WILL MAKE FOR A BREEZY TO WINDY DAY ON WEDNESDAY.

GIVEN THE WEAK CAPE BUT VERY STRONG SHEAR...THE ENVIRONMENT WILL BE
SUPPORTIVE AND FAVORABLE FOR SEVERE WEATHER AND ISOLATED TORNADOES
WEDNESDAY. EXPECT THE PRIMARY THREAT TO BE DAMAGING STRAIGHT LINE
WINDS IN EXCESS OF 60 MPH...IN LINE SEGMENTS AND BOWING
STRUCTURES...TIED CLOSER TO AND OUT AHEAD OF FRONTAL ZONE. THIS TO
OCCUR EVEN IF THERE IS LITTLE OR NO LIGHTNING ACTIVITY AS HIGHER
MOMENTUM AIR IS DRAWN DOWN TO THE SURFACE. ALTHOUGH THE MAIN LINE
MOVES EASTWARD...DUE TO EXTREMELY STRONG DEEP LAYER
WINDS...INDIVIDUAL STORM MOTION WITHIN THE LINE WILL BE NORTHEASTWARD
AT A RAPID 40 TO 50 MPH. THE FASTER OF THIS RANGE OVER THE INTERIOR
WHERE DEEP LAYER FLOW IS STRONGEST. THIS IS CONSISTENT WITH BUFR
SOUNDING FORECASTS OF 0-6KM STORM MOTION AT 35 TO 40 KNOTS. THUS...SEVERE
WEATHER IMPACTS WILL LIKELY HAPPEN VERY QUICKLY IF A WARNING IS
ISSUED UPSTREAM FROM YOU. DO NOT VENTURE OUTSIDE OR WAIT FOR A THREAT
TO APPEAR IMMINENT BEFORE TAKING ACTION. STAY TUNED FOR THE VERY
LATEST UPDATES.

LATEST TIMING BRINGS THE MAIN SQUALL LINE VERY CLOSE TO OUR
SOUTHEAST MISSISSIPPI COUNTIES AROUND 30.12Z / 600 AM LOCAL WITH
POTENTIAL OF SCATTERED DEVELOPMENT SPREADING NORTHEASTWARD OFF THE
MISSISSIPPI SOUND AT SAME TIME. THE LINE REACHES I-65 CORRIDOR BY
NOON...AND THEN EXITS THE FORECAST AREA MID/LATE AFTERNOON.

 

[eyewall]

I just hope for something chaseable within reasonable distance tomorrow before dark

[DaculaWeather]

Storm reports are already starting to pop up, mainly wind and hail so far.

http://www.daculaweather.com/4_spc_storm_reports.php

[NavarreDon]

Storm reports are already starting to pop up, mainly wind and hail so far.

http://www.daculaweather.com/4_spc_storm_reports.php

 

 

PRELIMINARY LOCAL STORM REPORT

NATIONAL WEATHER SERVICE SPRINGFIELD MO

1126 AM CST TUE JAN 29 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...

..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....

            ..REMARKS..

1118 AM     TSTM WND GST     OSCEOLA                 38.05N 93.70W

01/29/2013  E65 MPH          ST. CLAIR          MO   TRAINED SPOTTER

 

 

PRELIMINARY LOCAL STORM REPORT

NATIONAL WEATHER SERVICE SPRINGFIELD MO

1114 AM CST TUE JAN 29 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...

..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....

            ..REMARKS..

1102 AM     TSTM WND DMG     3 S CEDAR SPRINGS       37.83N 93.89W

01/29/2013                   CEDAR              MO   LAW ENFORCEMENT

            BARN AND POWER LINES REPORTED DOWN OR DAMAGED.

 

[Disc]

 

 

 

 ...SERN U.S. THROUGH OH VALLEY AND MID ATLANTIC REGION...      PARTIALLY MODIFIED GULF AIR WILL HAVE ALREADY ADVECTED THROUGH THE   WARM SECTOR ALONG A VERY STRONG AND EXPANSIVE 65-75 KT SLY LLJ.   DEWPOINTS WILL RANGE FROM MID TO UPPER 60S OVER SRN PORTIONS OF THE   GULF COASTAL STATES TO UPPER 50S OR AROUND 60 FROM THE OH VALLEY   INTO THE MID ATLANTIC REGION. HOWEVER...INSTABILITY IS EXPECTED TO   REMAIN MARGINAL DUE TO WIDESPREAD CLOUDS AND WEAK LAPSE RATES.   MLCAPE SHOULD RANGE FROM AOB 800 J/KG OVER THE SERN STATES TO AOB   500 J/KG FARTHER NORTH ACROSS THE OH VALLEY AND MID ATLANTIC.       EXPANSIVE LINE OF STORMS WILL BE IN PROGRESS WEDNESDAY MORNING ALONG   AND JUST AHEAD OF COLD FRONT FROM THE OH VALLEY SWD THROUGH THE TN   AND LOWER MS VALLEY REGIONS POSING AN ONGOING SEVERE THREAT.   ACTIVITY WILL CONTINUE THROUGH THE REMAINDER OF SERN STATES AND OH   VALLEY DURING THE DAY AND CAROLINAS TO MID ATLANTIC WEDNESDAY   EVENING AND OVERNIGHT. STORMS WILL BE  EMBEDDED WITHIN VERY STRONG   DEEP LAYER WIND PROFILES WITH EFFECTIVE SHEAR IN EXCESS OF 60 KT   ALONG WITH LARGE 0-1 KM HODOGRAPHS SUPPORTING THE LIKELIHOOD OF   EMBEDDED BOWING STRUCTURES...MESO-VORTICES AND SUPERCELLS. POTENTIAL   FOR LARGE SCALE ASCENT WITHIN UPPER JET ENTRANCE REGION AND WEAK CAP   SUGGEST A FEW DISCRETE SUPERCELLS MIGHT DEVELOP ALONG CONVEYOR BELT   AHEAD OF THE LINE...ESPECIALLY OVER A PORTIONS OF THE SERN STATES   WHERE HIGHER BOUNDARY LAYER DEWPOINTS AND INSTABILITY SHOULD RESIDE.   PRIMARY THREATS WILL BE DAMAGING WIND AND A FEW TORNADOES...WITH THE   GREATER TORNADO THREAT EXPECTED OVER THE SERN STATES. THE MARGINAL   THERMODYNAMIC ENVIRONMENT PRECLUDES AN UPGRADE TO A MODERATE RISK AT   THIS TIME...BUT AREA WILL CONTINUE TO BE EVALUATED.