Tornado outbreak - February 10-11, 8+ dead

[CrazyC83]

Seems to be no real surprise here. The Day 2 (Wednesday) will also be one to watch.

[CrazyC83]

I saw the update - HINTS OF A HIGH RISK AT 13Z!!!

[RL3AO]

IF CONFIDENCE BECOMES GREATER IN THE
TRACK OF THE PRIMARY SURFACE LOW...PORTIONS OF THE MODERATE RISK
AREA MAY NEED TO BE UPGRADED TO A HIGH RISK.

[CrazyC83]

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1208 AM CST TUE FEB 10 2009

VALID 101200Z - 111200Z

..THERE IS A MDT RISK OF SVR TSTMS ACROSS ERN OK
NORTH CENTRAL
AND NERN TX...NWRN LA...AND MUCH OF AR FOR LATE THIS AFTERNOON INTO
TUESDAY NIGHT...

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MODERATE RISK
FROM EAST TX/LA NWD TO LOWER MO/MID MS VALLEYS...

...SIGNIFICANT SEVERE WEATHER OUTBREAK INCLUDING TORNADOES AND
DAMAGING WINDS IS EXPECTED TO DEVELOP LATE THIS AFTERNOON AND
PERSIST INTO TUESDAY NIGHT ACROSS THE ERN HALF OF OK...NORTH
CENTRAL-NERN TX INTO NWRN LA AND MUCH OF AR...

..SYNOPSIS

STRONG UPPER TROUGH...CURRENTLY MOVING THROUGH THE LOWER CO RIVER
VALLEY WITH AN ACCOMPANYING 95 KT MID LEVEL JET MAX...WILL TRANSLATE
EWD REACHING THE SRN HIGH PLAINS BY 00Z. THIS TROUGH WILL THEN
BECOME NEGATIVELY TILTED AND DEEPEN TUESDAY NIGHT AS IT TRACKS ENEWD
TOWARD ERN KS/ERN OK. MODELS SUGGEST A SMALL CLOSED LOW SHOULD
DEVELOP OVER SERN KS/ERN OK BY 12Z WEDNESDAY. A 90+ KT MID LEVEL
JET WILL SPREAD EWD ACROSS NRN TX AND OK TUESDAY NIGHT...WITH THE
STRONGEST CORE OF MID LEVEL WINDS /110 KT/ EXPECTED TO SPREAD ACROSS
NRN TX TO THE ARKLATEX BY 12Z WEDNESDAY.

WHILE MODELS TEND TO AGREE WITH THE TRACK OF THE UPPER TROUGH...THEY
DIFFER WITH THE TRACK OF THE PRIMARY SURFACE LOW. THE NAM IS THE
FARTHEST NORTH TAKING THE LOW ACROSS KS INTO CENTRAL MO THIS
FORECAST PERIOD...WHILE THE GFS SUGGESTS THE SURFACE LOW WILL TRACK
ENEWD ACROSS CENTRAL/NRN OK INTO SRN MO BY 12Z WEDNESDAY. A FAIRLY
LARGE WARM SECTOR SHOULD DEVELOP TODAY... EXTENDING NWD THROUGH ERN
KS AND MUCH OF MO AS SLY LOW LEVEL WINDS TRANSPORT MOISTURE NWD...
WITH A WARM FRONT POSSIBLY REACHING NRN MO INTO CENTRAL IL. A
PACIFIC COLD FRONT ACCOMPANYING THE UPPER TROUGH WILL MOVE INTO
CENTRAL PARTS OF OK/TX BY MID-LATE AFTERNOON WHERE IT WILL MERGE
WITH A DRY LINE. THIS FRONT IS PROGGED TO SURGE EWD REACHING ERN
MO...ERN AR...AND EXTEND SWWD INTO THE NWRN GULF BY 12Z WEDNESDAY.

..SRN PLAINS/LOWER MS VALLEY NWD TO NRN MO/MID MS VALLEY

LOW LEVEL MOISTURE RETURNING NWD ACROSS THE WARM SECTOR TODAY
BENEATH A PLUME OF STEEP MID LEVEL LAPSE RATES EMANATING NEWD FROM
THE MEXICAN PLATEAU WILL AID IN DESTABILIZATION. SURFACE DEWPOINTS
IN THE LOWER 60S ARE EXPECTED TO REACH NERN TX/SERN OK AND INTO
CENTRAL AR. ALTHOUGH CLOUDINESS WILL TEND TO LIMIT SURFACE HEATING
EAST OF THE DRY LINE...A MODERATELY UNSTABLE AIR MASS IS EXPECTED TO
DEVELOP ACROSS CENTRAL/ERN OK INTO CENTRAL/ NERN TX.

MODELS CONTINUE TO SUGGEST TSTM DEVELOPMENT WILL BE POSSIBLE BY
EARLY-MID AFTERNOON ACROSS PARTS OF ERN TX/SERN OK INTO ADJACENT
PARTS OF AR/LA. SOME SURFACE HEATING WITHIN THE MOISTURE RETURN
SHOULD PROVE SUFFICIENT FOR CONVECTION TO DEVELOP WITHIN A WEAKLY
CAPPED AIR MASS. DIFFLUENT FLOW ALOFT ACROSS THE ARKLATEX REGION BY
AFTERNOON SUGGESTS THIS EARLY ACTIVITY SHOULD BE DISCRETE... WHILE
STRENGTHENING SLY WINDS ACROSS THIS AREA INTO THE AFTERNOON WILL
RESULT IN CURVED HODOGRAPHS/TORNADO POTENTIAL.

GREATER SEVERE WEATHER THREAT IS EXPECTED TO DEVELOP ALONG THE DRY
LINE IN CENTRAL OK TO CENTRAL TX BY LATE AFTERNOON /AFTER 21Z/...
GENERALLY ALONG OR JUST EAST OF THE I-35 CORRIDOR. ADDITIONAL
STRENGTHENING OF THE SLY LLJ /50+ KT/ FROM E TX/LA TO ERN KS/MO WILL
RESULT IN LARGE CURVED HODOGRAPHS AND THE LIKELIHOOD FOR
STRONG/SIGNIFICANT TORNADOES AS STRONG UPPER FORCING WITH THE TROUGH
SPREADS INTO THE SRN PLAINS. IF CONFIDENCE BECOMES GREATER IN THE
TRACK OF THE PRIMARY SURFACE LOW...PORTIONS OF THE MODERATE RISK
AREA MAY NEED TO BE UPGRADED TO A HIGH RISK.

A SIGNIFICANT DAMAGING WIND THREAT IS FORECAST TO DEVELOP BY EARLY
TUESDAY EVENING AS THE COLD FRONT OVERTAKES THE DRY LINE...AND
STRONG WLY LOW-MID LEVEL WINDS SPREAD EWD ACROSS SRN OK/NRN TX
REACHING THE ARKLATEX REGION BY 11/09Z AND INTO NRN LA AND CENTRAL
AR LATE IN THE PERIOD.

AS THE WARM SECTOR SPREADS FARTHER N TOWARD THE LOWER MO VALLEY...
TSTM ACTIVITY DEVELOPING THIS EVENING ACROSS OK/AR WILL TRACK NEWD
WITH THERMODYNAMIC/KINEMATICS FAVORABLE FOR HAIL...STRONG WINDS AND
POSSIBLY TORNADOES EXTENDING THROUGH ERN KS AND MUCH OF MO.

..PETERS.. 02/10/2009

[CrazyC83]

Long day ahead! Might want to get sleep soon...

As for the day 2, I'd be tempted to go up to a moderate risk but pinpointing is difficult - I'd do a very large 30% stretching from the Ohio Valley (even north of there) to the Gulf of Mexico, with hatching in some areas.

[CrazyC83]

Day 2: 45% but not hatched, still slight risk (should be moderate in the later update)

SPC AC 100612

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1212 AM CST TUE FEB 10 2009

VALID 111200Z - 121200Z

...THERE IS A SLGT RISK OF SVR TSTMS WED ACROSS A BROAD AREA EAST OF
THE MISSISSIPPI VALLEY INTO THE APPALACHIANS....

A SIGNIFICANT CONVECTIVE OUTBREAK...INCLUDING THE RISK FOR SEVERE
STORMS...IS EXPECTED TO CONTINUE INTO AND THROUGH MUCH OF THIS
FORECAST PERIOD...WITH THE THREAT AREA SHIFTING INTO AREAS EAST OF
THE LOWER/MIDDLE MISSISSIPPI VALLEY THROUGH THE WESTERN SLOPES OF
THE APPALACHIANS.

...SYNOPSIS...
LATEST SHORT TERM MODELS CONTINUE TRENDS OF PREVIOUS GUIDANCE...
INDICATING THAT A SERIES OF VIGOROUS SHORT WAVE IMPULSES WILL
PROGRESS INTO AND THROUGH A BROADER SCALE TROUGH IN THE MAIN BELT OF
WESTERLIES CURVING FROM THE EASTERN PACIFIC THROUGH THE SOUTHWESTERN
AND SOUTH CENTRAL UNITED STATES. ONE OF THESE FEATURES IS EXPECTED
TO BE IN THE PROCESS OF ACCELERATING OUT OF THE TROUGH...INTO THE
MIDDLE MISSISSIPPI VALLEY BY 12Z WEDNESDAY...BEFORE CONTINUING
AROUND THE NORTHERN PERIPHERY OF SUBTROPICAL RIDGING...INTO THE
LOWER GREAT LAKES/MID ATLANTIC COAST REGION BY 12Z THURSDAY. A
CONSOLIDATING DEEP SURFACE CYCLONE IS PROGGED TO ACCOMPANY THIS
IMPULSE...WITH A TRAILING COLD FRONT SURGING EAST OF THE MISSISSIPPI
VALLEY...TOWARD THE ATLANTIC SEABOARD. A BROAD 50-70+ KT SOUTHERLY
LOW-LEVEL JET WITHIN THE WARM SECTOR...COUPLED WITH THE
NORTHEASTWARD PROPAGATION OF A 100+ KT 500 MB JET STREAK...APPEAR
LIKELY TO CONTRIBUTE TO A VERY STRONG AND SHEARED ENVIRONMENT ACROSS
MUCH OF THE OHIO AND TENNESSEE VALLEYS.

THIS ENVIRONMENT WILL BE VERY FAVORABLE FOR SEVERE STORM DEVELOPMENT
GIVEN SUFFICIENT DESTABILIZATION. AND...AT LEAST ENOUGH INSTABILITY
FOR THUNDERSTORM DEVELOPMENT APPEARS PROBABLE...THOUGH THE MAGNITUDE
REMAINS UNCLEAR AT THE PRESENT TIME. THIS QUESTION...COUPLED WITH
LINGERING MODEL DISCREPANCIES...PRECLUDES THIS ISSUANCE OF A HIGHER
CATEGORICAL OUTLOOK THAT COULD ACCOMPANY A SYSTEM OF THIS
STRENGTH...AT THE PRESENT TIME.

...OHIO/TENNESSEE VALLEYS...
WARM ADVECTION PRECIPITATION...NORTH OF THE OHIO RIVER...AND
CONSIDERABLE LOW CLOUD COVER IN THE WARM SECTOR TO THE SOUTH...ARE
EXPECTED TO HAMPER DESTABILIZATION WEDNESDAY. ADDITIONALLY...
MODELS REMAIN SUGGESTIVE THAT ELEVATED MIXED LAYER AIR MAY ADVECT
NORTHWARD AHEAD OF A FRONTAL SQUALL LINE...WHICH IS EXPECTED TO BE
SPREADING THROUGH THE LOWER MISSISSIPPI VALLEY AT THE OUTSET OF THE
PERIOD. EVEN WITH SURFACE DEW POINTS INCREASING THROUGH THE MID
50S...FORECAST SOUNDINGS GENERALLY STILL INDICATE THAT THIS COULD
PRECLUDE...OR AT LEAST LIMIT...PRE-FRONTAL STORM DEVELOPMENT ...AND
ALLOW FOR THE REALIZATION OF ONLY WEAK CAPE AT OR BELOW 500 J/KG
WHERE THE FRONT STRONGLY FORCES DEVELOPMENT. HOWEVER...GIVEN THE
VERY STRONG DYNAMIC FORCING FOR UPWARD VERTICAL MOTION...WITH DEEP
LAYER MEAN FLOW FIELDS INCREASING IN EXCESS OF 50 KTS...IT SEEMS
PROBABLE THAT A SIGNIFICANT SQUALL LINE WILL PROGRESS THROUGH MUCH
OF THE OHIO AND TENNESSEE VALLEYS ACCOMPANIED BY THE RISK FOR
CONSIDERABLE DAMAGING WIND POTENTIAL. THIS MAY INCLUDE AREAS HARD
HIT BY THE RECENT ICE STORM.

...CENTRAL/EASTERN GULF COAST...
BOUNDARY LAYER WILL POSSESS HIGHER MOISTURE CONTENT THAN FARTHER
NORTH...BUT LOWER/MID-TROPOSPHERIC INHIBITION IS EXPECTED TO BE
STRONGER...AND THIS WILL STRENGTHEN FROM EAST TO WEST THROUGH THE
DAY AS THE SHORT WAVE TROUGH LIFTS NORTHEAST OF REGION. BEFORE THIS
OCCURS THOUGH...AN ISOLATED SUPERCELL MAY BE POSSIBLE...
PARTICULARLY FROM THE ALABAMA/FLORIDA PANHANDLE COASTS INTO THE
SOUTHERN APPALACHIANS.

...MID ATLANTIC STATES...
REMNANT...WEAKENING OHIO VALLEY SQUALL LINE MAY SPREAD EAST OF THE
ALLEGHENIES INTO NORTHERN MID ATLANTIC COASTAL AREAS LATE WEDNESDAY
NIGHT. WITH THE STRONG FLOW FIELD...THIS COULD CONTINUE TO ENHANCE
THE RISK FOR AT LEAST SPORADIC DAMAGING WIND GUSTS.

..KERR.. 02/10/2009

CLICK TO GET WUUS02 PTSDY2 PRODUCT

NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
CURRENT UTC TIME: 0619Z (1:19AM), RELOAD THIS PAGE TO UPDATE THE TIME

[CrazyC83]

IMO, the day 2 threat is underestimated in MS/AL/GA where I think the best chance for discrete supercells exists.

But day 1 should be interesting...this is a tough call. A major tornado outbreak is definitely possible though.

[Bunkertor]

Is this because the underestimated last years Feb.-event ? I dunno.

[RL3AO]

This is kinda sad, but I have by browser all set up with every site refreshing every minute or two.




Yes. That is seven sites in one window all refreshing every two minutes. Very sad indeed.

[JonathanBelles]

Jeez, How do you get all of that to work?

[RL3AO]

I hope I don't crash the CoD site.

[Bunkertor]

RL ! Props: cool setup

[Cookie]

we're just starting to get into that time of year so stay safe guys.

[Shockwave]

It looks like our chance of severe storms has increased a bit here. Still mainly a wind event, but an isolated tornado or two can't be ruled out either. Does anyone think that areas in Middle TN and Central KY could get into a PDS Severe T'storm Watch tomorrow?

[Bunkertor]

It looks like our chance of severe storms has increased a bit here. Still mainly a wind event, but an isolated tornado or two can't be ruled out either. Does anyone think that areas in Middle TN and Central KY could get into a PDS Severe T'storm Watch tomorrow?

Nah, weather PDS will be issued tomorrow depends on how this event will develop today. I´d say no chance to forcast that.

[Shockwave]

It looks like our chance of severe storms has increased a bit here. Still mainly a wind event, but an isolated tornado or two can't be ruled out either. Does anyone think that areas in Middle TN and Central KY could get into a PDS Severe T'storm Watch tomorrow?

Nah, weather PDS will be issued tomorrow depends on how this event will develop today. I´d say no chance to forcast that.

I know they can't forecast a watch itself, but from what the models have putting out, the risk for a PDS watch looks possible for the Wednesday time frame with a widespread damaging wind event being possible.

[Cookie]

when is the worst of the weather expected to occur?

[Bunkertor]

when is the worst of the weather expected to occur?

Try this one. Nice roundup http://www.accuweather.com/news-top-hea ... 2-10_09:41

[Bunkertor]

p.s. SPC was quick. Remained stable, but upgrade still not ruled out

[Cookie]

when is the worst of the weather expected to occur?

Try this one. Nice roundup http://www.accuweather.com/news-top-hea ... 2-10_09:41

thanks great site