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Plains tornado threat Mon 5/27-Fri 5/31


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What do you think their primary concern is regarding initiation/convection?  The info I'm looking at seems to warrant a 15% hatched area, as you stated those hodo's are really impressive.  Always plenty of time left today for an upgrade...but I'd definitely be worried about the potential for long track tornadoes today.

Tornadic storms will be moving far too slow given the fully backed low level flow, so long tracked tornadoes unlikely. I am always scared of these upslope events. The worst outbreak I saw when I was at North Platte was a similar event. The end result was discrete supercells from afternoon to midnight...and a stack of 60+ warnings the next day to verify. A big tor outbreak is probably not likely, but this day will likely end with a swath of high end hail/wind reports and the possibility of a few strong tors.

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12z NAM rolling in has some of the sickest looking hodographs I have seen in the plains in a long time. These quasi upslope events are always tricky events to forecast since initiation is not always associated with a well defined boundary, but today has serious potential for a long lived supercell event. A chasers dream today if storms don't cluster early. Even if they do, the nature of these events can lend themselves to multiple rounds as clusters form farther E with repeat rounds of DMC farther W. 

 

Today could troll us chasers rather hard, given the potential "quasi-upslope" initiation mechanism you mentioned. I think everyone and their dog will converge on SLN by mid afternoon, and I'll probably be among them. But there's a non-negligible chance that the best daylight storm could be much farther W in that more upslope/wrap-around regime. Same kind of thing happened on 2011-06-19... not sure whether you were working at LBF for that?

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Today could troll us chasers rather hard, given the potential "quasi-upslope" initiation mechanism you mentioned. I think everyone and their dog will converge on SLN by mid afternoon, and I'll probably be among them. But there's a non-negligible chance that the best daylight storm could be much farther W in that more upslope/wrap-around regime. Same kind of thing happened on 2011-06-19... not sure whether you were working at LBF for that?

Man you are good.

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Tornadic storms will be moving far too slow given the fully backed low level flow, so long tracked tornadoes unlikely. I am always scared of these upslope events. The worst outbreak I saw when I was at North Platte was a similar event. The end result was discrete supercells from afternoon to midnight...and a stack of 60+ warnings the next day to verify. A big tor outbreak is probably not likely, but this day will likely end with a swath of high end hail/wind reports and the possibility of a few strong tors.

Thank you for some clarification.

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This setup tomorrow is a bit reminiscent of the Hallam event in 2004 albeit shifted a bit further south with the same kind of broad, low amplitude wave passing through a highly unstable warm sector, and a sfc low in a rather similar position and orientation. It is the number four analog with CIPS tonight.

Yeah unfortunately these two setups are all too similar synoptically.

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post-3675-0-18840900-1369681432_thumb.gi

 

MESOSCALE DISCUSSION 0819
NWS STORM PREDICTION CENTER NORMAN OK
0200 PM CDT MON MAY 27 2013

AREAS AFFECTED...NEB PANHANDLE...W-CNTRL NEB...NE CO...NW KS

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 271900Z - 272000Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...TSTM INITIATION IS EXPECTED ACROSS PORTIONS OF THE CNTRL
HIGH PLAINS SOON. SVR STORMS ARE EXPECTED AND WW WILL LIKELY BE
NEEDED.

DISCUSSION...SURFACE ANALYSIS AND VISIBLE SATELLITE IMAGERY SHOW
TSTM INITIATION IS ONGOING ACROSS NE CO AND FAR SW WY AS AN OUTFLOW
BOUNDARY MOVES SWWD THROUGH THE REGION. AKO /IN NE CO/ RECENTLY
OBSERVED A WIND SHIFT FROM NLY TO ELY COINCIDENT WITH A DEWPOINT
INCREASE FROM 44 TO 58 DEG F AS THE OUTFLOW BOUNDARY MOVED THROUGH.
ENHANCED CONVERGENCE ALONG THIS BOUNDARY AS WELL AS AN ASSOCIATED
INCREASE IN MOISTURE IN CONJUNCTION WITH INCREASING LARGE SCALE LIFT
ASSOCIATED AN APPROACHING DISTURBANCE WILL SUPPORT AT LEAST
SCATTERED TSTM DEVELOPMENT THIS AFTERNOON.
THE AIRMASS OVER THE
REGION IS CHARACTERIZED BY STEEP MID-LEVEL LAPSE RATES AND AMPLE
LOW-LEVEL MOISTURE /DEWPOINTS IN THE 60S/ WITH MODERATE TO STRONG
INSTABILITY AS A RESULT. THIS INSTABILITY COUPLED WITH THE ENHANCED
MID-LEVEL FLOW WILL RESULT IN ORGANIZED SVR STORMS.

PRIMARY THREAT IS SVR HAIL/WIND BUT THERE APPEARS TO BE AN ENHANCED
TORNADO RISK N OF THE SFC LOW IN WRN KS. IN THIS AREA...ELY WIND
WILL CONTINUE TO ADVECT MOISTURE WWD INTO AN AREA WITH WIND PROFILE
FAVORABLE FOR A TORNADOES. ALL OR PART OF THIS AREA WILL LIKELY NEED
A WW BEFORE 19Z. FARTHER E...THE INITIATION STILL APPEARS TO BE AT
LEAST A FEW HOURS AWAY AS THE CAP REMAINS STRONG.


..MOSIER/MEAD.. 05/27/2013

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DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0240 PM CDT MON MAY 27 2013

VALID 272000Z - 281200Z

...THERE IS A MDT RISK OF SVR TSTMS ACROSS PORTIONS OF NRN/CNTRL KS
AND SRN NEB...

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK FROM
THE HIGH PLAINS OF WEST TX TO SERN MT...EWD INTO THE OH VALLEY...

...CNTRL HIGH PLAINS...

MINOR WWD ADJUSTMENTS HAVE BEEN MADE TO THE CATEGORICAL MDT RISK
ACROSS THE CNTRL PLAINS...PRIMARILY NORTH OF I-70 ALONG THE NEB
BORDER. ELY BOUNDARY LAYER FLOW HAS STRENGTHENED ACROSS NRN KS IN
WAKE OF EARLY MORNING MCS AND CONVECTIVE OUTFLOW APPEARS TO BE
ENHANCING UPSLOPE COMPONENT JUST NORTH OF SFC LOW OVER GOVE/LANE
COUNTIES. CONSIDERABLE AMOUNT OF CONVECTION HAS RECENTLY DEVELOPED
OVER ERN CO AND THIS ACTIVITY SHOULD SPREAD INTO NWRN KS/SWRN NEB
WHERE AFOREMENTIONED FAVORABLE LOW LEVEL FLOW HAS FORCED SFC DEW
POINTS ABOVE 60F TO THE KS/CO BORDER. ADDITIONALLY...AN AGITATED CU
FIELD IS NOW PRESENT WEST OF HLC AND TSTMS COULD EVOLVE FROM THIS
THICKENING MASS OVER THE NEXT FEW HOURS. GIVEN THE VERY WARM
TEMPERATURES AT 700MB INITIATION SWD ALONG THE DRYLINE MAY NOT
COMMENCE FOR SEVERAL MORE HOURS.

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BULLETIN - EAS ACTIVATION REQUESTED

TORNADO WARNING

NATIONAL WEATHER SERVICE CHEYENNE WY

205 PM MDT MON MAY 27 2013

 

THE NATIONAL WEATHER SERVICE IN CHEYENNE HAS ISSUED A

 

* TORNADO WARNING FOR...

  CENTRAL BANNER COUNTY IN THE PANHANDLE OF NEBRASKA...

  NORTHEASTERN KIMBALL COUNTY IN THE PANHANDLE OF NEBRASKA...

 

* UNTIL 230 PM MDT

 

* AT 201 PM MDT...A CONFIRMED TORNADO WAS LOCATED 11 MILES NORTH OF

  KIMBALL...AND MOVING EAST AT 25 MPH.

 

  HAZARD...DAMAGING TORNADO AND QUARTER SIZE HAIL.

 

  SOURCE...WEATHER SPOTTERS CONFIRMED TORNADO.

 

  IMPACT...MOBILE HOMES WILL BE HEAVILY DAMAGED OR DESTROYED.

           SIGNIFICANT DAMAGE TO ROOFS...WINDOWS AND VEHICLES WILL

           OCCUR. FLYING DEBRIS WILL BE DEADLY TO PEOPLE AND ANIMALS.

           EXTENSIVE TREE DAMAGE IS LIKELY.

 

* THE TORNADO WILL AFFECT MAINLY RURAL AREAS OF CENTRAL BANNER AND

  NORTHEASTERN KIMBALL COUNTIES.
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NWUS55 KCYS 272015
LSRCYS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
215 PM MDT MON MAY 27 2013

..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..

0215 PM TORNADO 11 N KIMBALL 41.39N 103.66W
05/27/2013 BANNER NE TRAINED SPOTTER

SPOTTER REPORTS TWO TORNADOES ON THE GROUND.


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MESOSCALE DISCUSSION 0820
   NWS STORM PREDICTION CENTER NORMAN OK
   0323 PM CDT MON MAY 27 2013

   AREAS AFFECTED...PART OF NWRN KS INTO NORTH CENTRAL KS AND SOUTH
   CENTRAL NEB

   CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY

   VALID 272023Z - 272130Z

   PROBABILITY OF WATCH ISSUANCE...80 PERCENT

   SUMMARY...TSTMS ARE EXPECTED TO DEVELOP OVER NORTH CENTRAL KS AND
   SOUTH CENTRAL NEB IN THE NEXT FEW HOURS...WITH THE STRONGER STORMS
   BECOMING CAPABLE OF POSING A TORNADO THREAT...AND PRODUCING VERY
   LARGE HAIL AND DAMAGING WINDS. A TORNADO WATCH WILL BE COORDINATED
   DURING THE NEXT HOUR OR TWO WITH WFO/S ACROSS NWRN-NORTH CENTRAL
   KS/SOUTH CENTRAL NEB.

   DISCUSSION...20Z SURFACE ANALYSIS INDICATED AN AREA OF LOW PRESSURE
   REMAINS CENTERED OVER WEST CENTRAL KS /JUST S OF KHLC/...WITH ELY
   WINDS ON THE NRN PERIPHERY OF THIS LOW HAVING INCREASED OVER NORTH
   CENTRAL KS.  THIS LATTER FACTOR IS FAVORING A STRENGTHENING OF LOW
   LEVEL CONVERGENCE INVOF THE WRN EXTENT OF A CONVECTIVE OUTFLOW
   BOUNDARY FROM THE EARLIER LOWER MO VALLEY MCS...WITH THE STRONGEST
   CONVERGENCE LOCATED NEAR AND N OF I-70 BETWEEN COLBY AND HAYS KS.
   AN ENHANCED CU FIELD WAS LOCATED IN THIS AREA AND EXTENDED INTO
   SOUTH CENTRAL NEB...WHERE INITIAL TSTM DEVELOPMENT WILL BE MOST
   PROBABLE.

   IN ADDITION TO LOW LEVEL CONVERGENCE...AN INCREASE IN FORCING FOR
   ASCENT IS EXPECTED TO SPREAD INTO KS THE NEXT FEW HOURS AS THE EXIT
   REGION OF A 40-50 KT SWLY MIDLEVEL JET EMERGES NEWD INTO THE
   WRN/CENTRAL KS.  EFFECTIVE BULK SHEAR IS ALREADY SUFFICIENT FOR
   SUPERCELLS...ONCE STORMS DEVELOP...WHILE THE INCREASED ELY SURFACE
   WINDS HAVE SUPPORTED AN INCREASE IN LOW LEVEL SHEAR /EFFECTIVE SRH
   ACROSS THE DISCUSSION AREA IS 200-300 M2 PER S2/ FAVORING A TORNADO
   POTENTIAL.

   ..PETERS/MEAD.. 05/27/2013

post-89-0-38740300-1369687097_thumb.gif

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