April 24-30th Severe Potential

[HillsdaleMIWeather]

MESOSCALE DISCUSSION 0456

NWS STORM PREDICTION CENTER NORMAN OK

0135 PM CDT TUE APR 26 2016

AREAS AFFECTED...CNTRL/ERN KS...FAR NERN OK...FAR SERN NEB

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

VALID 261835Z - 262030Z

PROBABILITY OF WATCH ISSUANCE...95 PERCENT

SUMMARY...TSTM COVERAGE WILL RAPIDLY INCREASE BY MID-AFTERNOON

ACROSS CNTRL/ERN KS...WITH VERY LARGE HAIL...DMGG WIND GUSTS...AND A

FEW TORNADOES POSSIBLE. A TORNADO WATCH WILL LIKELY BE ISSUED IN THE

NEXT 1-2 HRS.

DISCUSSION...A BROAD ZONE OF MID-UPPER LEVEL ASCENT PRECEDING A

LARGE WRN CONUS TROUGH WILL OVERSPREAD MUCH OF KS WITHIN THE NEXT

FEW HRS...PROMOTING INCREASING POTENTIAL FOR RAPID TSTM DEVELOPMENT

BY MID-AFTERNOON. SFC ANALYSIS FROM 18Z PLACES A SFC LOW JUST E OF

GBD...WITH AN ATTENDANT DRYLINE PROTRUDING GENERALLY SWD INTO NWRN

OK...WITH A QUASI-STATIONARY FRONT EXTENDING EWD ACROSS NERN KS. WRN

SEGMENT OF OUTFLOW BOUNDARY ASSOCIATED WITH EARLIER MCS HAS STALLED

ACROSS E-CNTRL KS...AND WEAK SFC PRESSURE FALLS TO THE N SUGGEST

THIS BOUNDARY MAY RETREAT NWD. EACH OF THESE FEATURES MAY PROVIDE A

FOCUS FOR CONVECTIVE INITIATION THIS AFTERNOON AS THE COMBINATION OF

DIURNAL HEATING AND FORCING FOR ASCENT WILL RESULT IN SUFFICIENT

EROSION OF CINH FOR SCATTERED TSTM DEVELOPMENT.

THE THERMODYNAMIC ENVIRONMENT IN PLACE ACROSS THE CNTRL

PLAINS...CHARACTERIZED BY VERY STEEP MIDLEVEL LAPSE RATES AND RICH

BOUNDARY-LAYER MOISTURE...WILL BE FAVORABLE FOR VERY LARGE HAIL SOON

AFTER INITIAL TSTM DEVELOPMENT...ESPECIALLY AS TSTMS MAINTAIN

DISCRETE OR CLUSTER MODE TYPES. TORNADO POTENTIAL IS SOMEWHAT

COMPLICATED BY A SUBSTANTIAL MERIDIONAL COMPONENT TO THE DEEP-LAYER

FLOW AND GRADUAL TEMPORAL BACKING OF THE UPPER-LEVEL FLOW...AND

MODEST LOW-LEVEL SHEAR ACROSS THE WARM SECTOR. HOWEVER...TORNADO

POTENTIAL WILL BE ENHANCED IN A RELATIVE SENSE NEAR THE TRIPLE POINT

ACROSS CNTRL KS...AND IN VICINITY OF THE QUASI-STATIONARY FRONT AND

OUTFLOW BOUNDARY...BUT STRONG SLY COMPONENT TO STORM MOTIONS MAY

RESULT IN ONLY A BRIEF PERIOD OF INTERACTION WITH THESE BOUNDARIES.

LATEST OBSERVATIONAL TRENDS AND CAM GUIDANCE SUGGEST CONVECTIVE

INITIATION WILL OCCUR DURING THE 19-21Z PERIOD OVER CNTRL KS. A

SEPARATE AREA OF CONCERN EMANATING OUT OF EXISTING ELEVATED

CONVECTION ORIGINATING OVER CNTRL OK MAY ALSO EXHIBIT INCREASING

ASSOCIATED SVR POTENTIAL ACROSS NERN OK AND INTO SERN KS. A TORNADO

WATCH WILL LIKELY BE COORDINATED IN THE NEXT 1-2 HRS.

..ROGERS/CORFIDI.. 04/26/2016

ATTN...WFO...EAX...TSA...OAX...TOP...ICT...OUN...GID...DDC...

[Chicago Storm]

First attempt at initiation in OK, from Watonga up towards Medford.

[ZackH]

For those who are curious. SPC is answering questions from people on twitter, and still said they are assessing the tornado risk for an upgrade... Also said that a PDS watch was possible too.

 

This statement is a bit out of context... they simply said they keep all options on the table... as do all forecasters working full time on any event. They aren't going to say its not possible when they aren't even 100% sure how things are going to evolve. They aren't just going to stop assessing the tornado risk.

[jojo762]

This statement is a bit out of context... they simply said they keep all options on the table... as do all forecasters working full time on any event. They aren't going to say its not possible when they aren't even 100% sure how things are going to evolve. They aren't just going to stop assessing the tornado risk.

I didn't take it out of context really. I said they were assessing the risk for a possible upgrade--which is essentially what the tweet said. While what you say is 100% accurate it wasn't out of context really... I was talking about the tweet that asked about if there was a chance of a high for hail or Tornadoes-- and they answered "We do not issue HIGH risks for hail. Still assessing for TOR." Which in my mind means they are assessing the risk for a possible upgrade, probably to MDT for tornadoes, which given how things have evolved seems possible over OK.

[wildwestpb]

Lastest Mesoscale Discussion

http://mesonet.agron.iastate.edu/wx/afos/p.php?pil=SWOMCD&e=201604261853
 

[wildwestpb]

Latest from the NWS OUN
https://twitter.com/NWSNorman/status/725035679755821056

[jojo762]

No mention of strong tornadoes in ether MD.

[Superstorm93]

1:56 CT 

 

 

ONE-MINUTE VISIBLE SATELLITE IMAGERY SHOWS
WIDESPREAD CU DEVELOPMENT WITHIN THE WARM SECTOR. CINH CONTINUES TO
ERODE AS SFC TEMPERATURES ARE HEATING INTO THE UPPER 70S AND LOWER
80S F. THE LEADING EDGE OF STRONGER FORCING FOR ASCENT ALOFT
ACCOMPANYING AN IMPULSE MOVING ACROSS NM IS SPREADING INTO THE TX
PANHANDLE/SOUTH PLAINS ATTM. AS THIS INTERSECTS THE DRYLINE...RAPID
TSTM INITIATION WILL OCCUR THIS AFTERNOON WITH SUPERCELLS LIKELY. 

 

[Superstorm93]

 

 

TORNADO POTENTIAL IS SOMEWHAT
COMPLICATED BY A SUBSTANTIAL MERIDIONAL COMPONENT TO THE DEEP-LAYER
FLOW AND GRADUAL TEMPORAL BACKING OF THE UPPER-LEVEL FLOW...AND
MODEST LOW-LEVEL SHEAR ACROSS THE WARM SECTOR. HOWEVER...TORNADO
POTENTIAL WILL BE ENHANCED IN A RELATIVE SENSE NEAR THE TRIPLE POINT
ACROSS CNTRL KS...AND IN VICINITY OF THE QUASI-STATIONARY FRONT AND
OUTFLOW BOUNDARY...BUT STRONG SLY COMPONENT TO STORM MOTIONS MAY
RESULT IN ONLY A BRIEF PERIOD OF INTERACTION WITH THESE BOUNDARIES.

 

[Superstorm93]

Easy to see the TCU in western Oklahoma and southern KS

 

[nrgjeff]

Perhaps SPC meant raise to 15% hatched TOR which is still MDT. Current MDT is for hail. @NWSSPC also says High does not seem warranted.

 

However those 18Z soundings are a significant development with 500-200 mb from the southwest. Little VBV around 700 mb is not a problem (for chasers) if those 500/200 mb levels stay just somewhat veered through 00Z. Note the high cloud tags on the Tulsa area storms, veered upstairs.

[Superstorm93]

Cloud tops cooling very rapidly in OK/KS now...

 

[wildwestpb]

SVR Thunderstorm for Grant Co. OK

http://mesonet.agron.iastate.edu/vtec/#2016-O-NEW-KOUN-SV-W-0141/USCOMP-N0Q-201604261910

Took 17 minutes from significant weather advisory to severe.

 

First TOR Watch out

http://www.spc.noaa.gov/products/watch/ww0108.html
80% torn probabilities, 40% EF2+

[yoda]

URGENT - IMMEDIATE BROADCAST REQUESTED   TORNADO WATCH NUMBER 108   NWS STORM PREDICTION CENTER NORMAN OK   215 PM CDT TUE APR 26 2016   THE NWS STORM PREDICTION CENTER HAS ISSUED A   * TORNADO WATCH FOR PORTIONS OF      CENTRAL AND EASTERN KANSAS     SOUTHERN NEBRASKA   * EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 215 PM UNTIL     900 PM CDT.   * PRIMARY THREATS INCLUDE...     SEVERAL TORNADOES LIKELY WITH A COUPLE INTENSE TORNADOES       POSSIBLE     WIDESPREAD LARGE HAIL LIKELY WITH ISOLATED VERY LARGE HAIL       EVENTS TO 3.5 INCHES IN DIAMETER POSSIBLE     SCATTERED DAMAGING WIND GUSTS TO 70 MPH LIKELY   SUMMARY...THUNDERSTORMS...INCLUDING SUPERCELLS AND OTHER SUSTAINED   STORM CLUSTERS...EXPECTED TO POSE A MULTI-MODE SEVERE THREAT ACROSS   PARTS OF KANSAS AND NEBRASKA THROUGH EARLY TONIGHT...WITH   TORNADOES...LARGE HAIL...AND LOCALLY DAMAGING WIND ALL LIKELY.   THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 80 STATUTE   MILES EAST AND WEST OF A LINE FROM 50 MILES WEST NORTHWEST OF   BEATRICE NEBRASKA TO 65 MILES SOUTHEAST OF WICHITA KANSAS.  FOR A   COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE   UPDATE (WOUS64 KWNS WOU8).

[Natester]

Cell just south of El Dorado, Kansas has that unsettling look.  Might be our first tornado producer.

[Superstorm93]

[jojo762]

Cell just south of El Dorado, Kansas has that unsettling look.

certainly does. In the wide open warm sector too--which is a bit surprising.

[jojo762]

That tornado watch in KS is pretty high-end with 80/40 probs.

[MUWX]

certainly does. In the wide open warm sector too--which is a bit surprising.

I would say the cell near wakita looks much better. No rotation but it looks like it could be trying to get its act together.

[brettjrob]

Pretty impressed that we've made it this far without widespread, vigorous CI today. So many of the infamous VBV busts have been complicated by morning convection and/or very early initiation of the main show. If we can hold off another hour or so across W OK and NW TX, this may be a good test of VBV's mitigation factor in near-isolation.

[southmdwatcher]

The new Tornado watch for OK/TX is PDS with 90/80 probs...wow

[MattPetrulli]

PDS just came out for OK. 

[yoda]

The new Tornado watch for OK/TX is PDS with 90/80 probs...wow

 

 

http://www.spc.noaa.gov/products/watch/ww0109.html

[MattPetrulli]

Just anyone know who issued that watch? Really far south. 

[yoda]

Just anyone know who issued that watch? Really far south. 

 

Corfidi did... at least as in the watch has his signature at the bottom of it

[mfgmfg]

Are the high probabilities due to the proportionally large watch area?

[mappy]

Are the high probabilities due to the proportionally large watch area?

 

Nope. Based on the chances of tornadoes occurring in that area. PDS watches can large or small in size. 

[Brick Tamland]

Hope you guys stay safe. Weather has been boring here all spring, so going to be watching this closely.

[hm8]

Are the high probabilities due to the proportionally large watch area?

Not to get off topic but that's something I've always wondered.

The probabilities are worded like "Probability of 2 or more tornadoes" within the watch area. So just based on that I'd think larger watches would have higher probabilities associated with them...

[nwohweather]

Impressive environment around Wichita. 5000 J/KG and EHI of 3-5. SRH could be better but we'll see here