Virtual Chase Thread 2011

[dogs32]

no.8

210 OAK HILL RUSK TX 3227 9470 AN EF1 TORNADO TOUCHED DOWN AT OAK HILL TEXAS. DAMAGE PATH WAS 1/2 MILE LONG AND 100 YARDS WIDE. DAMAGE CONSISTED OF 2 HOMES DAMAGED ... WITH ABOUT 1/2 OF THE ROOF TORN O (SHV)

Edited February 2, 2011 by dogs32

[TornadoJo]

no.8

210 OAK HILL RUSK TX 3227 9470 AN EF1 TORNADO TOUCHED DOWN AT OAK HILL TEXAS. DAMAGE PATH WAS 1/2 MILE LONG AND 100 YARDS WIDE. DAMAGE CONSISTED OF 2 HOMES DAMAGED ... WITH ABOUT 1/2 OF THE ROOF TORN O (SHV)

I take it the 2010 in black is actully 2011??.......

J x

[dogs32]

yes they have made a mistake Jo..

been like this for days :smiliz19:

Edited February 2, 2011 by dogs32

[craig1uk]

So when do we predict the season will start? Just been looking at previous virtual chase threads, and the 26th March looks common, so I'll go for that

[DubWeatherAddict]

So when do we predict the season will start? Just been looking at previous virtual chase threads, and the 26th March looks common, so I'll go for that

Whats gives the starter for the season?.... for there to be a moderate risk , or some tornadoes touching down?...

[Tom Lynch]

Whats gives the starter for the season?.... for there to be a moderate risk , or some tornadoes touching down?...

That is an interesting question and i would be interested to hear the thoughts of others.

Tom

[craig1uk]

Mod risk seems like a good place to start, maybe back to back risk days?

[Cookie]

Whats gives the starter for the season?.... for there to be a moderate risk , or some tornadoes touching down?...

That is an interesting question and i would be interested to hear the thoughts of others.

Tom

is their an actual season? with hurricanes in the Atlantic the vast majority fit neatly between June and end of November, where as tornadoes can happen in the USA all year around with the peak being from around April to July.

[Paul Sherman]

is their an actual season? with hurricanes in the Atlantic the vast majority fit neatly between June and end of November, where as tornadoes can happen in the USA all year around with the peak being from around April to July.

Of course there is a Season Rich

You would not want to be out with a Tour Group in Jan-March Or Aug-October for instance as you might get 1 or 2 chases if you are lucky. Whereas in May and June you should be able to treble that number and in rare cases we have chased 9/10 days. So the Tornado "Season" is most definately April to June with the Peak in May

Paul S

**If you have seen the Historical Data Thread I will put something up in here for March and August and let you pick the date, I will then list the number of Tornadoes in that 12 year period for both your dates, the results will be quite harsh and show when the Season is

[Gorky]

Still a ways out but the GFS has been very consistent in the early FI region for about 4 or 5 days now with the possibility of severe weather from the 20th onwards... Might not be enough moisture present early on, but the GFS has been showing a second system around the 24th quite consistently also with much better moisture return. Still a little early to say for sure if it's something we can virtual chase but it's something to keep an eye on for sure.

[Cookie]

Of course there is a Season Rich

You would not want to be out with a Tour Group in Jan-March Or Aug-October for instance as you might get 1 or 2 chases if you are lucky. Whereas in May and June you should be able to treble that number and in rare cases we have chased 9/10 days. So the Tornado "Season" is most definately April to June with the Peak in May

Paul S

**If you have seen the Historical Data Thread I will put something up in here for March and August and let you pick the date, I will then list the number of Tornadoes in that 12 year period for both your dates, the results will be quite harsh and show when the Season is

Ahh ok, I win the award for the stupid statement of the month

[Gorky]

Still a ways out but the GFS has been very consistent in the early FI region for about 4 or 5 days now with the possibility of severe weather from the 20th onwards... Might not be enough moisture present early on, but the GFS has been showing a second system around the 24th quite consistently also with much better moisture return. Still a little early to say for sure if it's something we can virtual chase but it's something to keep an eye on for sure.

As I suspected, the moisture return is probably not going to be sufficient for much beyond a wind and rain event tomorrow, despite such a deep LP system ejecting through the Plains. The 23rd and especially the 24th are still looking good although the GFS and ECM disagree on the location and speed of the trough by a long way. Both would result in some good favourable virtual chasing come mid-week!

Some pretty strong wording in the 4-8 day outlook despite not outlining an area due to the model discrepancies...

FROM WED/D5 ONWARD IS WHERE MODELS SUCH AS THE ECMWF AND GFS DIVERGE

SUBSTANTIALLY. THE GFS HAS AN UPPER LOW JUST OFF THE NRN BAJA CA

COAST BY 00Z THU...WHILE THE ECMWF HAS THE TROUGH AXIS ALONG THE

AZ/NM BORDER WITH UPPER HEIGHT FALLS OVERSPREADING THE SRN PLAINS

WED NIGHT INTO THU MORNING. IF THE LATTER SOLUTION OCCURS...SEVERE

THUNDERSTORMS WOULD BE LIKELY ACROSS PORTIONS OF OK AND TX...AS

EARLY AS WED NIGHT...THEN SPREADING EWD ON THU WITH A POTENTIALLY

SIGNIFICANT SEVERE WEATHER OUTBREAK FROM THE LOWER MS VALLEY INTO

THE OH VALLEY AHEAD OF A DEEPENING LOW. THE GFS...BEING MUCH

SLOWER...DEVELOPS A SEVERE THREAT ON LATE THU OVER OK/TX...WITH A

MUCH WEAKER UPPER TROUGH AND SURFACE LOW ON THUR AFFECTING THE SRN

PLAINS AND LOWER MS VALLEY.

[Paul Sherman]

So when do we predict the season will start? Just been looking at previous virtual chase threads, and the 26th March looks common, so I'll go for that

Let the Games and The Season Begin!

I would be 70/30% in favour for this to go MODERATE For Thursday

DAY 4-8 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0347 AM CST SUN FEB 20 2011

VALID 231200Z - 281200Z

...DISCUSSION...

AN ACTIVE PATTERN WILL PERSIST THROUGH THE PERIOD WITH THE POTENTIAL

FOR A SIGNIFICANT SEVERE WEATHER OUTBREAK ON THU/D5.

ON WED/D4...MODEL CONSENSUS HAS A BROAD BELT OF SWLY FLOW ALOFT FROM

NRN MEXICO ACROSS THE CNTRL AND ERN U.S...AHEAD OF AN UPPER TROUGH

AXIS THAT IS FORECAST TO BE IN THE VICINITY OF THE BAJA CA/SRN CA

COAST WED MORNING. WELL AHEAD OF THIS FEATURE...LOW LEVEL MOISTURE

WILL BEGIN TO STREAM NWD OFF THE GULF OF MEXICO AS A LARGE SURFACE

HIGH OVER THE ERN STATES GRADUALLY SHIFTS OFFSHORE.

BY THU MORNING...A SURFACE LOW IS FORECAST TO BE SOMEWHERE ACROSS

NWRN TX OR CNTRL OK WITH BOUNDARY LAYER DEWPOINTS AS HIGH AS 60F UP

TO THE LOW CENTER....AND UP TO A WARM FRONT THAT WILL EXTEND EWD

ACROSS NRN OK/AR OR PERHAPS SRN MO. A SURFACE LOW AND POTENT UPPER

LEVEL JET STREAK WILL THEN CONTINUE EWD ACROSS THE LOWER MS AND INTO

THE TN/OH VALLEYS BY 00Z.

UPPER LEVEL COOLING AND A PLUME OF STEEP DEEP LAYER LAPSE RATES WILL

OVERSPREAD THE WARM SECTOR...CREATING A VERY UNSTABLE SITUATION.

ALTHOUGH THE EXACT GEOMETRY OF THE TROUGH MAY NOT BE WELL HANDLED

THIS FAR IN ADVANCE...THE CURRENT MODEL DEPICTION WOULD INDICATE THE

POTENTIAL FOR NUMEROUS SUPERCELLS ALONG THE DRYLINE/COLD

FRONT...RATHER THAN A MORE LINEAR STORM MODE. IN THIS SCENARIO...A

SUBSTANTIAL TORNADO THREAT COULD MATERIALIZE BY AFTERNOON AND

EVENING.

BY FRI/D6...A SEVERE THREAT OF SOME FORM MAY REMAIN ALONG THE COLD

FRONT...AS IT APPROACHES THE ERN SEABOARD...BUT TIMING OF THE FRONT

AND PREDICTABILITY BECOME TOO LOW FOR ANY ADDITIONAL SEVERE AREAS.

[user700]

From reading the spc text, it does look like there maybe a outbreak on thursady in Dixie Alley.

Edited February 20, 2011 by danieluk

[Tom Lynch]

Yes i am keeping an eye on Thursday ,could be Texas or Oklahoma. Worth watching as things develop.

Tom

[Gorky]

This morning's Day 4 Update. Things are still on track for the first outbreak of the year. The GFs has had this nailed since deep FI only occasionally losing the severe threat for the odd run. I posted about it 10 days ahead of the 24th and only did so after seeing it consecutively for 3-4 days in the very long range. Very impressive... and I usually don't loook past about 4 days for accurate modelling

...DISCUSSION...

AN OUTBREAK OF SEVERE THUNDERSTORMS APPEARS LIKELY ON THU/D4 FROM

ERN OK/NERN TX EWD ACROSS MUCH OF AR...SRN MO...NRN MS...CNTRL AND

WRN KY AND TN...AND POSSIBLY CONTINUING INTO FRI/D5 ACROSS PORTIONS

OF THE MID ATLANTIC STATES.

MODELS ARE IN GOOD AGREEMENT IN DEPICTING A POTENT UPPER SHORTWAVE

TROUGH MOVING EWD ACROSS THE SRN PLAINS DURING THE DAY THU WITH A

SURFACE LOW DEEPENING FROM ROUGHLY OK AT 12Z TO MO/AR BY 00Z. AHEAD

OF THE DEEPENING LOW...A RELATIVELY WIDE MOIST/WARM SECTOR WILL BE

IN PLACE WITH BOUNDARY LAYER DEWPOINTS IN THE 60S F. STRONG FORCING

WITH THE UPPER TROUGH...COOLING MID LEVEL TEMPERATURES AND THE

PRESENCE OF VERY STRONG WIND PROFILES SUGGEST SIGNIFICANT SEVERE

WEATHER WILL BE POSSIBLE...INCLUDING TORNADOES AND VERY STRONG WINDS

IN ADDITION TO HAIL.

THE GREATEST THREAT AREA ON THU WILL LIKELY BE NEAR AND JUST S OF

THE SURFACE LOW TRACK DURING THE LATE AFTERNOON AND EVENING HOURS.

LATEST ITERATION OF NUMERICAL GUIDANCE SUGGESTS THAT THIS WOULD

INCLUDE MUCH OF AR...SRN MO...FAR NRN MS...AND MUCH OF WRN KY AND

TN.

SOME SEVERE THREAT WILL LIKELY PERSIST OVERNIGHT AND CONTINUE INTO

FRI/D5...ALTHOUGH INSTABILITY AND MOISTURE WILL BE LESS. AS

SUCH...THE EXPECTED SEVERE THREAT FRI WILL LIKELY BE COMPRISED OF

DAMAGING WIND GUSTS ASSOCIATED WITH AN INTENSE COLD FRONT AND A

STRONGLY FORCED LINE OF STORMS...FROM THE DELMARVA SWD ACROSS VA.

THESE STORMS WOULD LIKELY HAVE LITTLE INSTABILITY TO WORK WITH...AND

WOULD BE RELATIVELY LOW TOPPED...BUT A STRONG SURFACE PRESSURE

FALL/RISE COUPLET WOULD ENHANCE WIND POTENTIAL WITH THE LINE.

AFTER THE D4 TO D5 TIME FRAME...MODEL SOLUTIONS DIVERGE RAPIDLY.

..JEWELL.. 02/21/2011

[NL]

Latest charts are showing severe potential around unfavoured chasing territory namely Arkansas and then moving NE into Tennessee for this Thursdays severe (slight) risk, although there is potential around SE Oklahoma,NE Texas into Louisiana. CAPE values should be around 700J/kg, not high but not to bad for this time of year and will be only realised if theres not to much cloud to hinder development Biggest player here it seems are the wind profiles with shear being fairly modest although low level shear is forecast to come from a SSW direction and not a more favourable southern direction but will still bring in some nice gulf moisture pushing dew points up into the low 60's and as high as 70°F in Texas and Louisiana.

Severe probability.

http://www.spc.noaa.gov/products/outlook/day3otlk.html

[Paul Sherman]

Let the Games and The Season Begin!

I would be 70/30% in favour for this to go MODERATE For Thursday

As I expected we have our first MODERATE Of the Year and a SWODY2 As well

DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1255 AM CST WED FEB 23 2011

VALID 241200Z - 251200Z

...THERE IS A MDT RISK OF SVR TSTMS OVER CNTRL AND ERN AR...NRN

MS...AND WRN TN...

...THERE IS A SLGT RISK OF SVR TSTMS FROM ERN OK AND NERN TX EWD

INTO THE TN AND LOWER OH VALLEYS...

...SYNOPSIS...

A POTENT UPPER LOW...NOW OFF THE WRN COAST OF BAJA CA...WILL BE

PICKED UP BY THE SRN STREAM JET AND WILL EMERGE INTO SRN HIGH PLAINS

BY THU MORNING. AT THE SURFACE...LOW PRESSURE WILL DEEPEN AS IT

MOVES FROM NWRN TX/WRN OK EWD INTO NRN AR BY 00Z...AND CONTINUING

NEWD ALONG THE OH RIVER OVERNIGHT AND INTO FRI MORNING. INCREASING

SLY FLOW AHEAD OF THE LOW WILL AID IN MOISTURE TRANSPORT ACROSS THE

WARM SECTOR WHICH WILL BE BOUNDED ON THE N END BY A WARM FRONT

EXTENDING EWD FROM THE LOW...ROUGHLY ALONG THE 39.50 DEGREE PARALLEL

AT 00Z.

...ERN OK/NERN TX EWD ACROSS AR AND INTO KY AND TN...

THUNDERSTORMS ARE EXPECTED TO BE ONGOING ACROSS NWRN TX INTO SRN OK

THU MORNING NEAR THE SURFACE LOW AND NEAR THE DEVELOPING

DRYLINE/COLD FRONT SURGE. THESE STORMS WILL BE CAPABLE OF HAIL...AND

PERHAPS GUSTY WINDS. OTHER STORMS WILL EXTEND FROM KS EWD INTO THE

OH VALLEY WHERE A SWLY LOW LEVEL JET WILL ENHANCE LIFT ALONG AND

NEAR THE WARM FRONT.

THUNDERSTORMS SHOULD INTENSIFY DURING THE DAY FROM N TX INTO ERN OK

BY MID AFTERNOON...WITH A CONTINUED HAIL AND INCREASING SEVERE WIND

THREAT. VEERING LOW LEVEL WINDS MAY TEMPER THE INITIAL THREAT OF

TORNADOES. THE MOST DANGEROUS STORMS ARE EXPECTED DURING THE LATE

AFTERNOON INTO THE EVENING...FIRST ACROSS AR THEN SPREADING NEWD

ACROSS NRN MS AND WRN TN. HERE...850 MB FLOW IN EXCESS OF 60 KT IS

EXPECTED IN ASSOCIATION WITH THE DEEPENING LOW...WITH ENHANCED LOW

LEVEL HODOGRAPH CURVATURE ALONG THE RESIDUAL WARM FRONT.

TORNADOES...A FEW POSSIBLY STRONG...AND PARTICULARLY DAMAGING WINDS

WILL BE POSSIBLE MAINLY BETWEEN 00Z-06Z.

A CRITICAL COMPONENT TO THE SEVERE THREAT WILL BE THE PLACEMENT OF

THE WARM FRONT THROUGHOUT THE DAY...AS IT WILL DETERMINE THE TRACK

OF THE SURFACE LOW. CURRENTLY...THE MORE NRN ECMWF SOLUTION IS

PREFERRED...BUT A SWD SHIFT IN FUTURE MODEL GUIDANCE COULD RESULT IN

A COMPRESSION OF THE NRN EDGE OF THE SEVERE PROBABILITIES IN

SUBSEQUENT OUTLOOKS.

[Paul Sherman]

Forgot to Say - Please add your Target Location for the Virtual Chase.

If we were out there then we would be hanging around Little Rock with a View to Move East down towards Stuttgart for tomorrow Lunchtime as a Starting point, reason being is there aint much in Stuttgart and a lot more to do around Little Rock.

Think the chase area from there to Memphis or the Missouri Bootheel would be favourable as it is pretty flat, only problem with tomorrow is when the action starts to become favourable for Tors it could well be dark so a Nasty situation for places further East in Tennessee or Kentucky, Eastern Missouri etc with Night-time Twisters, typical early Season Dixie Alley!

Paul S

[TornadoJo]

Just a thought,

Any chance of some links to charts for the newbies who might not know where to find them. Would do myself but crazy busy at work!

Cheers

Jo

--x

[user700]

Hi, my chase target will be a place called Success in Arkansas near the north east Arkansas, Missouri border about 7 pm US time.

I am not very confidant because of the lack of Humidity.

I am using F5 data to forecast, so the time may not be accurate. Not sure if its our time are US time.

I will check tomorrow using GR Level 2 if I am right.

Any more chase targets?

Edited February 23, 2011 by danieluk

[chionomaniac]

Forgot to Say - Please add your Target Location for the Virtual Chase.

If we were out there then we would be hanging around Little Rock with a View to Move East down towards Stuttgart for tomorrow Lunchtime as a Starting point, reason being is there aint much in Stuttgart and a lot more to do around Little Rock.

Think the chase area from there to Memphis or the Missouri Bootheel would be favourable as it is pretty flat, only problem with tomorrow is when the action starts to become favourable for Tors it could well be dark so a Nasty situation for places further East in Tennessee or Kentucky, Eastern Missouri etc with Night-time Twisters, typical early Season Dixie Alley!

Paul S

Knowing the terrain must be invaluable for chases like this Paul. When deciding where to start from the Mississippi gets in the way big time. I guess knowing where to cross the river is invaluable and will influence the start position. I can see why you have chosen Stuttgart with the terrain in mind. If there is a good Mississippi crossing point then I may go slightly further east to Helena, otherwise Stuttgart most favourable. One may end up cr*pping oneself in Brownsville, NE of Memphis!!

[Gorky]

The I40 corridor between Little Rock and Memphis on the warm front has been the higher risk area progged for quite a few days (Not that impressed with the straighter hodos out in OK. I'm just not sure there's as much chance of that action coinciding nicely with daylight hours. I'm still a little less confident about tornados further west. I'd have to make my decision tomorrow on playing the I40 area which is reasonable terrain, or sticking with the hills but better lighting in OK. As for a virtual target, I'd stay the night in Fort Smith between the two target areas with Brinkley, Ar as the Eastern one and areas south and west of Fort smith as the Western area. If I went OK, I think the event will start early afternoon so the overnight stopover is biased towards that target although I'm 50/50 about chasing in the crappy terrain. I'm expecting the cold front to light up from Ft Smith down towards Dallas by 1pm if not earlier. Slightly concerned that it will bring only a wind threat and line out quickly. I'm guessing the best area for tornadoes would be South of Memphis around the 7-8pm US time which would put it into early night around the tristate area of MS/AR/TN although if moisture return is as beefy as predicted, this could shift further north uptwards Paducah, KY for instance

Leaving myself a lot of leeway as things are still very likely to change substantially before tomorrow!

[NL]

SPC have the moderate risk extending just short of N Eastern Texas. As Paul has mentioned looking increasingly likely that some strong tornadoes are possible late into the night.

http://www.spc.noaa....k/day2otlk.html

GIVEN BOUNDARY LAYER DESTABILIZATION AND INCREASINGLY DIFLUENT/

DIVERGENT UPPER FLOW WITH THE APPROACHING MID-LEVEL PERTURBATION

...WHICH IS PROGGED TO TAKE ON AN INCREASING NEGATIVE TILT

ORIENTATION...CONDITIONS MAY BECOME FAVORABLE FOR DISCRETE STORM

DEVELOPMENT ACROSS SOUTHERN AND EASTERN ARKANSAS DURING THE 21-23Z

TIME FRAME. COINCIDING WITH STRENGTHENING OF A SOUTHERLY 850 MB JET

IN EXCESS OF 50 KTS...UP TO 70 KT OR SO DURING THE EVENING

HOURS...AND THE EVOLUTION OF LARGE CLOCKWISE CURVED LOW-LEVEL

HODOGRAPHS BENEATH/NEAR A 90-100 KT 500 MB JET... POTENTIAL EXISTS

FOR SUPERCELLS CAPABLE OF PRODUCING STRONG TORNADOES.

ANY SUCH ACTIVITY IS EXPECTED TO FORM NEAR OR IN ADVANCE OF A

FRONTAL OR PRE-FRONTAL SQUALL LINE...WHICH APPEARS MORE CERTAIN TO

EVOLVE...BEFORE ADVANCING EASTWARD ACROSS UPPER PORTIONS OF THE

LOWER MISSISSIPPI VALLEY INTO THE TENNESSEE VALLEY THURSDAY NIGHT.

POTENTIAL FOR STRONG TORNADOES MAY PERSIST THROUGH THE 03-05Z TIME

FRAME ACROSS PARTS OF NORTHERN MISSISSIPPI AND WESTERN

TENNESSEE...WHILE DAMAGING WIND POTENTIAL CONTINUES DEEPER INTO THE

NIGHT TOWARD THE SOUTHERN APPALACHIANS.

Edited February 23, 2011 by NL

[Mesoscale]

if i had to guess where a tornado may occur i think north east Arkansas between Harrisburg and Cherry Valley in Poinsett county or a little bit south just north west of memphis in Crittenden county.

Edited February 23, 2011 by Mesoscale