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Dorsetbred

Virtual Chase thread - 2013

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SPC today has a day three warning in effect where they quote

" ...TX TO IL SOUTHEAST ACROSS THE LOWER MS VALLEY...

THE WARM SECTOR TO NEAR ARLATEX BY

AROUND 00Z. DEEP CONVECTION WILL ERUPT ALONG THE ENTIRE LENGTH OF

THE SHARPENING COLD FRONT THROUGH THE LATE AFTERNOON WITH STORMS

COMING UNDER THE INFLUENCE OF EVER INCREASING DEEP-LAYER SHEAR/FLOW.

EXTENSIVE QLCS APPEARS LIKELY TO SPREAD EAST ACROSS THE MID/LOWER MS

VALLEY INTO TUESDAY NIGHT WITH CELL MOTIONS FORECAST IN EXCESS OF

50KT LEADING DAMAGING WINDS. LACK OF STRONGER CYCLONIC DEVELOPMENT

ALONG THE COLD FRONT SUGGESTS LINEAR MODE SHOULD DOMINATE BUT

SUPERCELLS AND LEWPS EMBEDDED IN THE LINE AND NEAR TRANSIENT FRONTAL

WAVE STRUCTURES WOULD POSE SOME TORNADO THREAT WITH TIME.

UNCERTAINTIES REGARDING OVERALL TIMING AND DEGREE OF SURFACE-BASED

DESTABILIZATION PRECLUDE HIGHER OR SIGNIFICANT PROBABILITIES AT THIS

FORECAST RANGE. HOWEVER...FUTURE UPGRADE TO MDT RISK SEEMS POSSIBLE

IF THESE DETAILS BECOME CLEARER..."

Time to begin the virtual chase, even though things are some way out, some early season activity MAY shortly begin.

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Been looking following this for a while. Whilst the SPC seem to think linear is more likely at the moment, I'm not so convinced. The CIPS tool which compares the forecasted setup with historical dates pulls up the day of the Enterprise Alabama tornado outbreak and Super Tuesday outbreak as similar analogues. Geographically, the Super Tuesday outbreak was over the same forecast area too. I don't expect anything to that level at the moment but definitely worth keeping an eye on. Even if linear is the primary storm mode, there should be spin ups within the line with the large amounts of shear present. Chasing is going to be next to impossible over the target area mind you with storm motions at 50kt+

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Ok time to put the snow boots away and look towards the plains. OKLAHOMA where the sun keeps shining all the time.

Tom

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I did try to post this but cant see it so better twice than not at all

Tom

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Things seem to be improving:

...SRN PLAINS THROUGH LOWER MS VALLEY REGION...

POTENTIAL EXISTS FOR A SIGNIFICANT SEVERE WEATHER EVENT TUESDAY WITH

DAMAGING WIND AND TORNADOES THE PRIMARY THREATS...ESPECIALLY DURING

THE EVENING AND OVERNIGHT IN MODERATE RISK AREA. OBSERVATIONS SHOW A

RESERVOIR OF MIDDLE TO UPPER 60S DEWPOINTS FROM CNTRL INTO SRN TX.

SLY BOUNDARY LAYER FLOW ALREADY EXISTS FROM THE SRN PLAINS INTO THE

LOWER MS VALLEY AND WILL STRENGTHEN TUESDAY IN ASSOCIATION WITH AN

INTENSIFYING LLJ. WIDESPREAD MULTI-LAYER CLOUDS WILL LIMIT BOUNDARY

LAYER WARMING DURING THE DAY. HOWEVER...MID 60S DEWPOINTS SHOULD

ADVECT AS FAR NORTH AS SERN OK INTO CNTRL AR AND NRN MS BENEATH A

PLUME OF 6.5 C/KM MID LEVEL LAPSE RATES RESULTING IN AT LEAST

500-1000 J/KG MLCAPE.

STORMS ARE EXPECTED TO DEVELOP WITHIN PRE-FRONTAL CONFLUENCE BAND

ACROSS CNTRL/ERN OK INTO NCNTRL/NERN TX EARLY TUESDAY AND SHIFT EWD

AND NEWD DURING THE DAY. OTHER STORMS MAY DEVELOP FARTHER SOUTH

THROUGH ERN TX DURING THE AFTERNOON ALONG MERGING PACIFIC FRONT AND

SHIFT EWD THROUGH THE LOWER MS VALLEY. THE BOUNDARY LAYER WILL

MOISTEN SUFFICIENTLY FOR THIS ACTIVITY TO BECOME SFC BASED. STORMS

WILL BE EMBEDDED WITHIN STRONG DEEP LAYER FLOW WITH A 50+ KT SLY LLJ

AND MID LEVEL WINDS INCREASING TO 80 KT. STORMS ARE EXPECTED TO

EVOLVE INTO A PREDOMINANT QLCS WITH EMBEDDED SUPERCELL AND BOWING

SEGMENTS POSING A RISK FOR DAMAGING WIND AND TORNADOES. TORNADO

THREAT MAY INCREASE OVERNIGHT...ESPECIALLY IN MODERATE RISK AREA

WHERE LLJ INTENSIFYING TO IN EXCESS OF 70 KT WILL BE COLLOCATED WITH

NRN EDGE OF MID 60S DEWPOINTS.

...UPPER MS VALLEY THROUGH TN VALLEY REGION...

OTHER STORMS WILL EXPAND NEWD THROUGH THE MID MS VALLEY AND SWRN

PARTS OF OH VALLEY WHERE INSTABILITY WILL BE MORE LIMITED...BUT

SUFFICIENT FOR A THREAT FOR DAMAGING WIND WITH PRIMARY MODE BEING

LINES AND BOWING SEGMENTS WITH MESO VORTICES. A FEW EMBEDDED

SUPERCELLS WILL ALSO BE POSSIBLE GIVEN SIZE OF HODOGRAPHS AND

STRENGTH OF DEEP LAYER FLOW/SHEAR SUGGESTING A FEW TORNADOES CANNOT

BE RULED OUT.

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Easy decision for me on todays risk. A knowledge of Arkansas is a must with dangerous Set-Ups like today, there are actually decent chase areas in AR, Squall line should be ongoing this afternoon and if positioning for today we must hope some discrete cells can fire in front (A good way in front) of the QLCS Before the front catches it up, SPC Seem quite bullish on Tornadic Supercells firing in a NE-SW Line from the Bootheel own to Shreveport area, so the easy decision for me would be a starting point of Little Rock (Arkansas) for todays risk, would expect to see a lot of wind damage reports with embedded Tornadoes in the line, but also the risk for a few Larger Tornadoes if any Supercells can get going in daylight in the warm sector.

Paul S

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Light the blue touch paper

THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF

WESTERN AND CENTRAL OKLAHOMA

FAR NORTHWEST TEXAS

EFFECTIVE THIS TUESDAY MORNING FROM 500 AM UNTIL NOON CST.

TORNADOES...HAIL TO 1 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS

TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 60 STATUTE

MILES EAST AND WEST OF A LINE FROM 25 MILES SOUTHWEST OF FORT

SILL OKLAHOMA TO 20 MILES NORTH NORTHWEST OF PONCA CITY OKLAHOMA.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU5).

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Possibly first tornado related death this year was recorded in Adairsville.

Also of note 22 injured - storm related

7 reported tornado's

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And the first killer Tornado for 9 months as well, they have had a good run

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Tornado warning posted:

* AT 411 PM CST...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A

SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO 14 MILES WEST OF

PICKWICK MOVING NORTHEAST AT 40 MPH.

* THE TORNADO WILL BE NEAR...

PICKWICK BY 430 PM CST...

COLUMBIA AND PINEBUR BY 440 PM CST...

IMPROVE BY 455 PM CST...

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And we have some numbers already

TORNADO TOTALS AND RELATED DEATHS...THROUGH SUN FEB 03 2013

NWS STORM PREDICTION CENTER NORMAN OK

0907 AM CST MON FEB 04 2013

...NUMBER OF TORNADOES... NUMBER OF KILLER TORNADO DEATHS TORNADOES

..2013.. 2012 2011 2010 3YR 3YR 3YR

...... PREL ACT ACT ACT ACT AV 13 12 11 10 AV 13 12 11 10 AV

JAN 64 - 79 16 30 42 1 2 0 0 1 1 2 0 0 1

FEB 0 - 57 63 1 40 0 15 1 0 5 0 7 1 0 3

--- -- -- --- ---- ---- ---- - -- --- -- --- - -- -- -- --

SUM 64 * PRELIMINARY ESTIMATE OF ACTUAL TORNADOES. FINAL VALUES WILL

BE ENTERED WHEN STORM DATA IS PUBLISHED LATER IN 2013.

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Posted · Hidden by Dorsetbred, February 22, 2013 - threat disappeared
Hidden by Dorsetbred, February 22, 2013 - threat disappeared

Looks as though early next week has some potential...

Quote

AS A MOIST WARM SECTOR OVERSPREADS MUCH OF THE CENTRAL AND EASTERN GULF STATES.

DEEP LAYER AND LOW-LEVEL SHEAR SHOULD BE MORE THAN SUFFICIENT FOR ORGANIZED SQUALL LINE AND SUPERCELL DEVELOPMENT...WITH THE RISK FOR DAMAGING WIND AND TORNADOES.

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Day two slight risk showing:

...THERE IS A SLGT RISK OF SVR TSTMS SOUTHERN HIGH PLAINS...

...SOUTHERN/CENTRAL HIGH PLAINS...

ISOLATED SUPERCELL THUNDERSTORMS MAY DEVELOP ALONG/NEAR

THE DRYLINE BY 00Z AS EML ERODES AND STEEPENING LAPSE RATES RESULT

IN MUCAPE VALUES FROM 500-1000 J/KG. LARGE HAIL AND ISOLATED STRONG

WIND GUSTS WILL BE THE MAIN SEVERE THREAT INTO THE EARLY EVENING.

HOWEVER...GIVEN FAVORABLE HODOGRAPHS AND RELATIVELY MOIST BOUNDARY

LAYER...A TORNADO OR TWO CAN NOT BE RULED OUT.

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With a mean trough due to set-up in the Western CONUS and some decent moisture return, could get the first significant action along the I35 this weekend.

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As it stands at the moment this coming Friday may be the next possibility and maybe Oklahoma Tuesday

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Could we be readying for tonight?

DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0728 AM CDT FRI MAR 29 2013

VALID 291300Z - 301200Z

...THERE IS A SLGT RISK OF SVR TSTMS LATE THIS AFTN AND EVE ACROSS

PARTS OF THE SOUTHERN HIGH PLAINS...

...SYNOPSIS...

UPPER FLOW WILL REMAIN SPLIT ACROSS THE CENTRAL AND EASTERN PACIFIC

INTO THE U.S. THROUGH THIS FORECAST PERIOD AND BEYOND...AS BLOCKING

BECOMES INCREASINGLY PROMINENT WEST OF THE PACIFIC COAST.

DOWNSTREAM OF THE CLOSED LOW PORTION OF THE BLOCK...WITHIN THE

SOUTHERN STREAM...BROAD RIDGING...CURRENTLY EXTENDING FROM THE

PACIFIC COAST STATES INTO THE PLAINS...DOES APPEAR LIKELY TO BECOME

INCREASINGLY SUPPRESSED. MODELS SUGGEST THAT THIS WILL OCCUR IN

RESPONSE TO THE EASTWARD PROGRESSION OF A SOUTHERN STREAM SHORT WAVE

IMPULSE THROUGH THE RIDGE...ACROSS THE SOUTHERN ROCKIES INTO THE

SOUTHERN HIGH PLAINS...AND THE FIRST COUPLE IN A SERIES OF SHORT

WAVE IMPULSES DIGGING WITHIN AN INCREASINGLY PROMINENT NORTHERN

STREAM...ACROSS WESTERN/CENTRAL CANADA INTO THE NORTH-CENTRAL UNITED

STATES.

UPPER DEVELOPMENTS...IN CONJUNCTION WITH A CONTINUING WEAK TO MODEST

RETURN FLOW OF MOISTURE FROM THE WESTERN GULF OF MEXICO INTO THE

SOUTHERN AND CENTRAL PLAINS...WHERE MID-LEVEL LAPSE RATES HAVE

BECOME QUITE STEEP...ARE EXPECTED TO SUPPORT AN INCREASING RISK FOR

THUNDERSTORMS LATER TODAY INTO TONIGHT. SOME OF THIS ACTIVITY COULD

BECOME SEVERE...MAINLY ACROSS PARTS OF THE SOUTHERN HIGH PLAINS.

...CENTRAL/SOUTHERN PLAINS...

WEAK CONVECTIVE DEVELOPMENT IS ONGOING ACROSS PARTS OF SOUTHEAST

KANSAS AND EASTERN OKLAHOMA INTO THE OZARK PLATEAU. THIS IS

ASSOCIATED WITH MOISTURE RETURN WITHIN A LOWER/MID TROPOSPHERIC WARM

ADVECTION REGIME...ABOVE A RESIDUAL COOL AND STABLE BOUNDARY

LAYER...ON THE NORTHEASTERN PERIPHERY OF MORE STRONGLY CAPPING

ELEVATED MIXED LAYER AIR WHICH HAS ADVECTED EAST OF THE SOUTHERN

ROCKIES. THIS ACTIVITY MAY PERSIST UNTIL WESTERLY 850 MB FLOW

ACROSS THE SOUTHERN PLAINS BEGINS TO BACK TO A MORE SOUTHERLY

COMPONENT TOWARD MID DAY...AHEAD OF THE APPROACHING SHORT WAVE

IMPULSE.

IN THE MEANTIME...STRONG SURFACE HEATING ACROSS THE SOUTHERN HIGH

PLAINS WILL CONTRIBUTE TO STEEPENING LOW-LEVEL LAPSE RATES...A

SHARPENING DRY LINE ACROSS THE TEXAS PANHANDLE AND SOUTH

PLAINS...AND A STRENGTHENING BAROCLINIC ZONE ACROSS THE TEXAS

PANHANDLE INTO THE RED RIVER VALLEY BY LATE THIS AFTERNOON. THESE

FEATURES...PARTICULARLY NEAR THEIR INTERSECTION ACROSS THE TEXAS

PANHANDLE/NORTHWEST TEXAS...SEEM LIKELY TO PROVIDE THE FOCUS FOR

STRONGEST CONVECTIVE DEVELOPMENT...IN THE PRESENCE OF MIXED LAYER

CAPE ON THE ORDER OF 1000-1500 J/KG.

GIVEN THE FAVORABLE THERMODYNAMIC ENVIRONMENT...VEERING OF WINDS

WITH HEIGHT BENEATH MODEST WESTERLY MID/UPPER FLOW SHOULD PROVIDE

SUFFICIENT SHEAR FOR SEVERE STORMS...INCLUDING SUPERCELLS...CAPABLE

OF PRODUCING LARGE HAIL AND LOCALLY DAMAGING WIND GUSTS. IT APPEARS

POSSIBLE THAT FORCING ASSOCIATED WITH THE MID-LEVEL IMPULSE COULD

CONTRIBUTE TO A CONSOLIDATING STORM CLUSTER ALONG THE FRONTAL ZONE

ACROSS PARTS OF SOUTHWESTERN OKLAHOMA AND NORTHWEST TEXAS DURING THE

EVENING HOURS...WITH PERHAPS A WINDOW OF OPPORTUNITY FOR MORE

WIDESPREAD STRONG/SEVERE GUSTS...BEFORE POTENTIAL DIMINISHES WITH

BOUNDARY LAYER COOLING.

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And we are off. 1.75" hail reported in Bromide, Johnson Country in Oklahoma, from a severe thunderstorm.

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Activity now picking up between Lubbock & Childress, heading towards Childress

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