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Short-Term Severe/Flooding Discussion


Quincy
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Similar today is similar to, but somewhat less impressive than yesterday for the southern High Plains. Decent obs coming out of far southeastern New Mexico into portions of Big Bend country as of midday. Though an isolated tornado is possible, probably near the NM/TX border, the bigger threat should be large hail - like yesterday. Slowly moving storms and yet another threat for MCS action in west Texas up into the panhandle this evening.

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Mildly interested in the tornado threat across N TX/OK east of I-35 tomorrow. NAM forecast soundings during the afternoon/evening around Ada/Atoka/McAlester exhibit extreme 0-1 km AGL bulk shear and SRH >250 m2 s-2, with "skinny CAPE" of 500-1000 J/kg. Hopefully the extratropical transition is as far along as possible to minimize the messiness. Such setups have resulted in decently visible and persistent tubes before, e.g. 8 Sep 2010 in DFW. Granted, the most likely area for anything like that in this case will be farther E over the Ouachitas/Ozarks, unfortunately.

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  • 2 weeks later...

A line of storms quickly developed NW of DDC and basically automatically put down a landspout.. Love it.

THE NATIONAL WEATHER SERVICE IN DODGE CITY HAS ISSUED A

* TORNADO WARNING FOR...
CENTRAL HODGEMAN COUNTY IN SOUTHWESTERN KANSAS...

* UNTIL 630 PM CDT

* AT 600 PM CDT...A CONFIRMED LANDSPOUT TORNADO WAS LOCATED 12 MILES
SOUTHWEST OF JETMORE...MOVING EAST AT 25 MPH.

HAZARD...TORNADO.

SOURCE...PUBLIC CONFIRMED TORNADO.

IMPACT...EXPECT DAMAGE TO MOBILE HOMES...ROOFS AND VEHICLES.

* THE TORNADO WILL BE NEAR...
JETMORE AROUND 615 PM CDT.

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Pretty strong supercell in NW Nebraska... Actually there are quite a number of impressive supercells/line segments across W NE. Including a TOR warned supercell.

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 515 PM MDT

FOR NORTH CENTRAL BOX BUTTE AND SOUTHEASTERN DAWES COUNTIES...

AT 500 PM MDT...A SEVERE THUNDERSTORM WAS LOCATED OVER BOX BUTTE
CAMPGROUND...OR 25 MILES SOUTH OF CHADRON...MOVING SOUTHEAST AT 40
MPH.

THIS IS A VERY DANGEROUS STORM.

HAZARD...BASEBALL SIZE HAIL AND 60 MPH WIND GUSTS.

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The environment isn't particularly impressive to the south (weak shear), but moderate instability and steep lapse rates are helping. Can't imagine the southern storms latest severe too long. Much stronger wind shear across Nebraska and some guidance favors upscale growth with a cluster eventually making it to northern Missouri overnight. Wouldn't be surprised if that convection stays robust for a while.

As a front/boundary shifts south, may actually see some storms across Oklahoma and Arkansas tomorrow that could feature some severe wind/hail.

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A tornado has been reported at Gardar, ND. The storm cell was kind of a mess. The storm dropped almost straight south out of Canada. You don't see too many tornadic storms dropping out of Canada.

 

Edit:

swarm of tornadoes in northeastern North Dakota

 

2015_06_27_2137z_KMVX_tornadoes.png

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The Aberdeen sounding didn't make it past 400mb, but there was no shortage of shear observed. I wasn't monitoring this threat closely, but the setup now includes a modest 1008mb surface low in eastern ND with moderate instability, favorable wind shear, a nicely timed vorticity lobe and the region lies on the nose of a 45-50kt 500mb jet. 00z mesoanalysis was showing in excess of 250 m2s-2 0-1km SRH near the most vigorous storms.

2015062800.72659.skewt.parc.gif

Looking at tomorrow, I don't think the setup is nearly as volatile, but I'd suspect there is a decent amount of severe thunderstorm activity across Missouri and vicinity. The directional shear does not look at favorable as today was. There is also a lack of clarity on the placement of a (secondary?) surface low. WPC was pinning this near the KS/MO border tomorrow afternoon with a warm front segment across northern MO. While the RGEM was similar, the NAM/GFS keep the main low moving SE through Iowa and a cold front dropping south through KS/MO. 

 

Nonetheless, any outflow boundaries from overnight/early day convection tomorrow could come into play tomorrow afternoon. Instability will not be an issue and shear would support supercells. This is echoed by the 4km NAM simulated radar progs. However, if we are dealing with more of a cold front and winds are out of the SW ahead of it, the tornado threat will probably remain low end/marginal. The upper level winds are progged to be NW to NNW, so there will still be decent directional shear, even without backing winds near the surface.

 

Analog guidance showed several events with a corridor of severe thunderstorm reports, including tornadoes, extending from the eastern Dakotas/Minnesota, down into Missouri.

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Seeing some intriguing forecast soundings from both the NAM and GFS for southeastern Kansas into west-central Missouri tomorrow. Ongoing convection is one of the biggest issues, although if some storms can develop on the southwestern flank of that action, they'll be tapping into a forecast environment that is very supportive of severe thunderstorms. Looking closer, it appears that the models want to develop a small area of low pressure near the KS/MO border. Another convoluted setup that has many issues, but nonetheless, SPC did introduce a SLGT risk area in the 1730 Day 2 outlook.

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Seeing some intriguing forecast soundings from both the NAM and GFS for southeastern Kansas into west-central Missouri tomorrow. Ongoing convection is one of the biggest issues, although if some storms can develop on the southwestern flank of that action, they'll be tapping into a forecast environment that is very supportive of severe thunderstorms. Looking closer, it appears that the models want to develop a small area of low pressure near the KS/MO border. Another convoluted setup that has many issues, but nonetheless, SPC did introduce a SLGT risk area in the 1730 Day 2 outlook.

Right now: tornado watch has been issued in the radar-hole-land of west ND, east MT.

 

Tomorrow, I agree with you. The area from Kansas City to the MO/AR border should see several thunderstorms. I think there will be some severe wx in this area, and also some areas of elevated T-storms that are sub-severe.

 

NAM 84-hr rain totals show pretty high rain amounts, most of Missouri, to Memphis and Paducah.

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Missouri, and possibly E/SE KS, looks potentially interesting tomorrow afternoon and evening. SPC has highlighted a SLGT Risk across the area, and mentions supercells being a possiblity, which given the environment seems warranted. 18Z CAM forecast soundings show moderate to extreme instability building across KS/MO with MUCAPE values 3000-5000+J/KG, juxtaposed to relatively impressive directional shear. 0-3KM Shear of 30-40kts/ 0-3KM SRH of 200-400m2/s2, and 0-6KM shear of 40-50kts... Cap really starts to diminish by 21-23Z across much of the area. Appears that CI is likely by 22-23Z across MO pending the results of the morning MCS, and that there isn't a substantial amount of residual cloud cover or any pesky convection on the apex of the dying LLJ/WAA. In the event that there is minimal thermodynamic and kinematic impact from the MCS, convection would likely explode along the boundary/OFB in the form of supercells capable of large hail, with some incidences of very large hail, damaging winds, and a few tornadoes. Eventually growing upscale into a forward propagating MCS capable of large hail and damaging winds... As usual, wherever the OFB from the morning MCS across MO/KS  resides is where the highest potential for tornadoes will reside, since LLVL SHR/SRH will be locally maximized. Furthermore, very heavy rain/ flooding will also be of concern evidenced by PWAT's approaching and over 2in, and a morning MCS going over the same area that the afternoon/night storms will go over... 2-5+IN of rain could occur over C MO, basing off of most recent model guidance. and FWIW the 4KM NAM (which is likely over doing the rainfall) has an area of 7+IN across a wide area, and even an area of 11-15IN  across C MO by 12Z Thursday, which of course would likely cause a prolific flood concern.  

 

EDIT: Also 00Z NAM/4K NAM continue with the same general idea...

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The severe potential is really going to heavily depend on the track and coverage of the morning MCS. The HRRR seems to be a bit more expansive, while the NAM is quick to weaken. The NAM solution shows strong to locally extreme instability developing in its wake. Even the latest HRRR shows moderate instability already in place near the MO/KS border by 17z. We'll have to see how convective trends look in the morning for more clarity. At the very least, as mentioned above, some areas are going to see quite a bit of rain. The NW flow and trajectories would probably favor some training too.

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mcd1271.gif

MESOSCALE DISCUSSION 1271
NWS STORM PREDICTION CENTER NORMAN OK
0347 PM CDT WED JUL 01 2015

AREAS AFFECTED...ERN KS...WRN MO AND NRN AR

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 012047Z - 012315Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...A SEVERE THREAT IS EXPECTED TO DEVELOP ACROSS ERN KS AND
WRN MO LATE THIS AFTERNOON INTO EARLY THIS EVENING. LARGE
HAIL...WIND DAMAGE AND A COUPLE TORNADOES MAY OCCUR WITH THE
STRONGER CELLS. WW ISSUANCE WILL LIKELY BE NEEDED WITHIN THE NEXT 1
TO 2 HOURS ONCE CELLS BEGIN TO INITIATE.

DISCUSSION...LATEST SFC ANALYSIS SHOWS A 1006 MB LOW OVER CNTRL KS
WITH A QUASI-STATIONARY FRONT EXTENDING EWD FROM THE LOW ACROSS ERN
KS AND CNTRL MO. AN AXIS OF STRONG INSTABILITY IS LOCATED FROM NEAR
THE BOUNDARY EXTENDING SWD ALONG THE KS-MO STATE LINE WHERE MLCAPE
IS ESTIMATED FROM 3000 TO 4000 J/KG. SHORT-TERM MODELS SUGGEST THAT
CONVECTION WILL INITIATE WHERE THE INSTABILITY AXIS MEETS THE FRONT
WITH THUNDERSTORMS DEVELOPING AND MOVING SSEWD ACROSS ERN KS AND WRN
MO. THE MOST LIKELY TIME FOR INITIATION WOULD BE IN THE 2130 TO 2230
TIMEFRAME WHICH IS SUPPORTED BY THE LATEST HRRR RUN. THE WSR-88D VWP
AT KANSAS CITY AND SPRINGFIELD SHOW WIND PROFILES FAVORABLE FOR
SUPERCELLS WITH 0-6 KM SHEAR NEAR 45 KT AND SUBSTANTIAL DIRECTIONAL
SHEAR IN THE 0-3 KM LAYER. THIS COMBINED WITH THE STRONG INSTABILITY
SHOULD BE FAVORABLE FOR LARGE HAIL AND WIND DAMAGE. LOOPED
HODOGRAPHS ALSO SUGGEST THAT A TORNADO THREAT MAY DEVELOP WITH THE
MORE DOMINANT SUPERCELLS.

..BROYLES/HART.. 07/01/2015

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Looks like storms are struggling thus far in the first thirty minutes or so of development. A few cells are showing up on KEAX right now... Most notability a storm over KC, and another storm SW of Carrolton, MO, the Carrolton storm is more interesting looking really, and has exhibited some rotation about 3,000ft up, and also depicts an elongated curved look on radar... Lets see, looks like storms might struggle to become SFC-based... But if they do then it could get at least semi-interesting, with some chance at a few tornadoes. 

 

EDIT: TOR watch just got issued.

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Too much warming around 700mb, but the cap is starting to erode a bit. Would expect at least one or two intense supercells at the over the next 1-4 hours. Most likely in west-central Missouri. Perhaps lose to the southeast side of KC metro.

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TDS and TVS as well

BULLETIN - EAS ACTIVATION REQUESTED

TORNADO WARNING

NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO

654 PM CDT WED JUL 1 2015

 

THE NATIONAL WEATHER SERVICE IN PLEASANT HILL HAS ISSUED A

 

* TORNADO WARNING FOR...

  SOUTHEASTERN JACKSON COUNTY IN WEST CENTRAL MISSOURI...

 

* UNTIL 730 PM CDT

 

* AT 652 PM CDT...A CONFIRMED TORNADO WAS LOCATED NEAR LEE'S

  SUMMIT...AND MOVING SOUTHEAST AT 20 MPH.

 

  HAZARD...DAMAGING TORNADO AND PING PONG BALL SIZE HAIL.

 

  SOURCE...WEATHER SPOTTERS CONFIRMED TORNADO.

 

  IMPACT...FLYING DEBRIS WILL BE DANGEROUS TO THOSE CAUGHT WITHOUT

           SHELTER. MOBILE HOMES WILL BE DAMAGED OR DESTROYED. DAMAGE

           TO ROOFS...WINDOWS AND VEHICLES WILL OCCUR. TREE DAMAGE IS

           LIKELY.

 

* LOCATIONS IMPACTED INCLUDE...

  GREENWOOD...LAKE LOTAWANA...LONE JACK AND TARSNEY LAKES.

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