Significant Severe Weather Outbreak Possible 04/26-30/2014

[CrazyC83]

Activity today is completely unrelated to this possible outbreak.

Sunday and Monday look like the big days, although I am still wondering about Tuesday. Saturday looks like a good day for chasers if they don't bust, since that is when I think the least populated areas get involved (i.e. western Oklahoma, western Kansas).

[EF-5bigj]

My local weather is saying monday looks like the worst day. Never mind Monday and Tuesday...

[TwisterFanatic]

Probably for your area, but Sunday is looking very rough as well.. Tulsa NWS still using very strong wording, IE: Strong Tornadoes.

Saturday is more of heating forced storms on the dryline until late evening when the speed max kicks in from the west. Some more of those high based photogenic supercells and maybe one or two will become surface based late in the evening.

[Bunkertor]

This is from Masters:

Weekend tornado and severe weather outbreak coming for the Plains
A significant multi-day severe weather event is expected Saturday, Sunday, and Monday across the Central U.S. A strong low pressure system will trundle slowly across the region, spawning supercell thunderstorms capable of generating large hail, damaging winds, and a few strong tornadoes. The action will begin Saturday afternoon along a swath from Central Texas northwards into Oklahoma and Kansas, then gradually shift eastwards on Sunday and Monday. Recent runs of the GFS and European model have been very consistent in showing moderate to extreme instability in the warm air ahead of the storm's cold front Saturday through Monday, and this weekend's severe weather outbreak has the potential to be the most dangerous one of this relatively quiet 2014. This year has yet to spawn a killer tornado, setting a new record for latest date of the year's first killer tornado. The previous record belonged to 2002, when the year's first killer tornado struck April 21 (an F-3 that killed a man in a mobile home in a rural area of Wayne County, Illinois.) The relatively cool and dry weather across Tornado Alley so far this year has led to no EF-3 or stronger tornadoes as of April 23, and that's also a record-long wait since modern tornado records began in 1950. According to tornado historian Tom Grazulis' book, Significant Tornadoes 1680-1991, "serious efforts" to document all tornadoes began in 1953, which was the first full year of tornado watches issued by the U.S. Weather Bureau, now the National Weather Service.

I'll have a new post on Friday.

[TropicalAnalystwx13]

Day 2 (Saturday) Slight risk still. Timing of the upper-level trough will make all the difference. Looks like it'll arrive just late enough to make Saturday largely insignificant in the tornado department, but we'll see.

[Extratropical94]

Day 3 with moderate risk:

Edit: This is the 13th time the SPC issues a moderate risk for day 3. (according to Wikipedia)

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0229 AM CDT FRI APR 25 2014

VALID 271200Z - 281200Z

...THERE IS A MDT RISK OF SVR TSTMS FOR THE ARKLATEX AREA...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MO VALLEY TO THE WRN
GULF COAST...

...SUMMARY...
OUTBREAK OF SEVERE STORMS POSSIBLE ON SUNDAY ACROSS PARTS OF THE
CENTRAL STATES WITH LARGE HAIL...DAMAGING WINDS...AND TORNADOES.

...SYNOPSIS...
A VIGOROUS SHORTWAVE TROUGH EXPECTED TO BE CENTERED IN THE LEE OF
THE SRN ROCKIES AT 12Z/SUN WILL SUBSTANTIALLY SLOW AS IT PROGRESSES
TOWARDS NEB. AN ATTENDANT MID-LEVEL JET /AOA 50 KT AT 500 MB/ WILL
PERSIST FROM THE DESERT SW...CURLING NWD FROM THE RED RIVER TO THE
MO VALLEY. AT THE SURFACE...A CYCLONE SHOULD DRIFT EWD OVER THE
CNTRL PLAINS WITH A WARM FRONT ARCING EWD ACROSS THE CORN BELT TO
THE LOWER OH VALLEY. A DRYLINE/WEAKENING PACIFIC COLD FRONT SHOULD
REACH ERN KS/OK INTO DEEP S TX IN THE LATE AFTERNOON.

...MO VALLEY TO THE WRN GULF COAST...
THE WARM SECTOR WILL BECOME INCREASINGLY BROAD/MOIST BENEATH AN EML
WITH LOWER 60S SURFACE DEW POINTS BECOMING ESTABLISHED NEAR THE WARM
FRONT AND MIDDLE TO UPPER 60S INTO THE LOWER/MID-MS VALLEYS AND
ARKLATEX BY SUN AFTERNOON. INITIALLY STEEP MID-LEVEL LAPSE RATES
ALONG WITH MODERATE TO STRONG DEEP-LAYER SHEAR WILL SUPPORT AN
EXPANSIVE AREA OF ORGANIZED SEVERE POTENTIAL.

AREAS OF CONVECTION SHOULD BE ONGOING AT 12Z/SUN ACROSS PARTS OF THE
SRN PLAINS TO MID-MO VALLEY. SOME OF THIS ACTIVITY MAY ALREADY BE
SURFACE-BASED OR WILL TRANSITION TO BECOMING SO AS DIURNAL HEATING
ENSUES. CLUSTERS OF ISOLATED TO SCATTERED SEVERE STORMS WILL BE
POSSIBLE AS CONVECTION LIKELY DEVELOPS N/E.

THE MOST PROBABLE SEVERE RISK SHOULD DEVELOP ALONG AND AHEAD OF THE
DRYLINE TOWARDS PEAK HEATING...WITH CONFIDENCE GREATEST IN THIS
OCCURRING NEAR THE SRN PERIPHERY OF EARLY DAY STORMS /CENTERED OVER
THE ARKLATEX/. WITH ROBUST HEATING OCCURRING ACROSS TX...MLCAPE
SHOULD PUSH 2500 J/KG AHEAD OF THE DRYLINE. HODOGRAPHS APPEAR QUITE
CONDUCIVE TO SUPERCELLS...CAPABLE OF PRODUCING VERY LARGE HAIL AND
STRONG TORNADOES. WITH THE DRYLINE STALLING ACROSS NERN TX SUN
EVENING...TRAINING SUPERCELL CLUSTERS MAY CONTINUE INTO THE NIGHT.

ALONG THE DRYLINE FARTHER N INTO THE MO VALLEY...EARLY DAY
CONVECTION MAY TEND TO LIMIT A GREATER SEVERE RISK. BUT WITH STRONG
INSOLATION...MODERATE BUOYANCY MAY DEVELOP WITHIN A STEEP LAPSE RATE
ENVIRONMENT. ALTHOUGH DEEP-LAYER WIND PROFILES SHOULD BE LARGELY
MERIDIONAL...SUFFICIENT CURVATURE TO THE LOW-LEVEL HODOGRAPH WOULD
SUPPORT UPDRAFT ROTATION...WITH ALL SEVERE HAZARDS POSSIBLE.

[TwisterFanatic]

Tulsa NWS is really trying to get peoples attention. They mentioned 'Strong, long track Tornadoes threetimes in the discussion this morning.

[Cyclenall]

I looked at the worst tornado outbreak of 2011 to see what the long range outlook from the SPC was for April 26-28. I remember what the map looked like but not the discussion or the header. Turns out they didn't even have headers at that time so we can't compare to see if they mentioned strong tornadoes. This is what they said 6 days beforehand which is the closest in that thread:

...DISCUSSION...
MEDIUM-RANGE MODELS IN FAIRLY GOOD AGREEMENT THROUGH DAY 7 /THU.
4-28/...WITH RESPECT TO A LARGE TROUGH NOW MOVING INTO/DEVELOPING
ACROSS THE WRN CONUS. THE TROUGH IS FORECAST TO EJECT/EVOLVE SLOWLY
EWD ACROSS THE CENTRAL AND ERN U.S. THROUGH DAY 7...AND AS IT
DOES...AN ASSOCIATED SURFACE COLD FRONT WILL ALSO SHIFT SLOWLY EWD
ACROSS THIS REGION.

*cut*

A SIMILAR THREAT APPEARS POSSIBLE DAY 5...AS THE INITIAL SHORT-WAVE
TROUGH EJECTS NNEWD AND A SECOND SHORT-WAVE FEATURE DIGS SEWD
TOWARD/INTO THE BASE OF THE LARGER-SCALE TROUGH.

ATTM...SPECIFICS OF THE SEVERE WEATHER THREAT GET MORE DIFFICULT TO
DISCERN DAY 6 /WED. 4-27/ AND BEYOND...AS THE FRONT SHIFTS E OF THE
MS VALLEY.

..GOSS.. 04/22/2011

Link: viewtopic.php?f=24&t=110691&st=0&sk=t&sd=a

There is no mention anywhere of strong tornadoes in either the Day 7, 6, or 5 timeframe but not sure on Day 4 for the 27th. What is ominous is when looking at the 1st page of this S2K thread, a lot of the posts are matching up with those time-sensitive images that happen to fall around the time of this expected outbreak. Is the 3 year anniversary trying to channel 3 years ago or something?



ZCZC SPCSWOD48 ALL
ACUS48 KWNS 250851
SPC AC 250851

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0351 AM CDT FRI APR 25 2014

VALID 281200Z - 031200Z

...DISCUSSION...
...MULTI-DAY SEVERE EPISODE SHOULD CONTINUE INTO AT LEAST TUESDAY
FROM THE OH VALLEY TO THE CNTRL GULF COAST. POTENTIAL EXISTS FOR A
SEVERE WEATHER OUTBREAK INCLUDING STRONG TORNADOES...

ACTIVE SEVERE WEATHER PATTERN WILL PERSIST WITH A BROAD UPPER-LEVEL
TROUGH CENTERED OVER THE CNTRL CONUS. ECMWF/GFS/UKMET/CMC ARE RATHER
CONSISTENT WITH THE EVOLUTION OF INTENSE MID-LEVEL SPEED MAXIMA
ROTATING THROUGH THE BASE OF THE TROUGH INTO D5/TUE. THESE WINDS
WILL OVERSPREAD PARTS OF A BROAD WARM/MOIST SECTOR CHARACTERIZED BY
60S SURFACE DEW POINTS. DESPITE MULTIPLE DAYS OF EXTENSIVE WARM
SECTOR CONVECTION...DIURNAL HEATING COUPLED WITH W/SWLYS IN THE
MID-LEVELS SHOULD RECHARGE/STEEPEN LAPSE RATES...POTENTIALLY
YIELDING MODERATE TO STRONG INSTABILITY EACH AFTERNOON. OF THE TWO
DAYS HIGHLIGHTED...D5/TUE APPEARS TO HAVE SLIGHTLY GREATER OUTBREAK
POTENTIAL WITH A 90+ KT 500-MB JET EJECTING OUT OF THE BASE OF THE
TROUGH.

..GRAMS.. 04/25/2014

Very ominous talk for Tuesday, saying its the most likely for a major tornado outbreak. Its size is large for coverage. Takes up the entire states of MS, LA. Haven't seen overlap like that either in eons.

Here is a NAM 4-km 2-5km Max Updraft Helicity for 42 hours from now which shows an immense one right over Chickasha OK, then over northern Norman, finally weakening over the heart of downtown OKC:



Take it as entertainment but realize what a worst case scenario that is. That's in the middle of the night too.

Here is SigTor for Sunday:

Tulsa NWS is really trying to get peoples attention. They mentioned 'Strong, long track Tornadoes threetimes in the discussion this morning.

Feel free to post a snippet of that, would like to see.

[ronyan]

Here's part of the discussion out of the Tulsa, NWS office:

EXTENDED DISCUSSION...
AN ELEVATED RISK OF SIGNIFICANT SEVERE WEATHER IS FORECAST SUNDAY.
THIS INCLUDES THE POTENTIAL FOR STRONG...LONG-TRACK TORNADOES...
VERY LARGE HAIL...AND DAMAGING STRAIGHT LINE WINDS. THE MOST
LIKELY TIME WINDOW FOR THE MOST SIGNIFICANT SEVERE WEATHER WILL BE
BETWEEN 1 PM AND 10 PM. THE GREATEST RISK AREA WILL BE IN AREAS
ALONG AND EAST OF HIGHWAY 75.

A DRYLINE WILL SURGE EAST ACROSS OKLAHOMA SUNDAY. A ROUND OF
STORMS WILL LIKELY FORM LATE SATURDAY NIGHT INTO EARLY SUNDAY OUT
WEST AND WILL THEN MOVE ACROSS THE REGION DURING THE MORNING AND
MIDDAY HOURS. THIS ACTIVITY WILL POSE A LARGE HAIL AND DAMAGING
WIND RISK...AND POSSIBLY ISOLATED TORNADOES SHOULD STORMS BECOME
MORE SURFACE BASED TOWARD EARLY AFTERNOON. ANOTHER ROUND OF STORM
DEVELOPMENT IS EXPECTED SUNDAY AFTERNOON AHEAD OF THE DRYLINE...AND
THIS ROUND WILL POSE THE GREATEST RISK OF WIDESPREAD SIGNIFICANT
SEVERE WEATHER. ATMOSPHERIC CONDITIONS WILL BE FAVORABLE FOR THE
DEVELOPMENT OF STRONG...LONG-TRACK TORNADOES...AS WELL AS HAIL TO
3 INCHES IN DIAMETER...AND DAMAGING STRAIGHT LINE WINDS TO 70 MPH.

[Fehize]

My work closely associates with weather, and I had a good, 2hr long discussion with the airport's weather crew yesterday. The models they were looking at are indicating some serious storms incoming, and, since they are weather guys, are really excited for it. And apprehensive. As a joke [or so I hope], they told me to get ready in case all of our aircraft have to escape as one giant flight to other places.

Nevertheless, trees are getting cut, storm plan words have gone around, and word has spread about these coming days. I'll be seeing radar raws from 60 miles out or so, considering I work those days.

And a guy from Meridian, eh? Hi from Columbus! Our planes buzz by your city a lot.

[WeatherGuesser]

I looked at the worst tornado outbreak of 2011 to see what the long range outlook from the SPC was for April 26-28. I remember what the map looked like but not the discussion or the header. Turns out they didn't even have headers at that time so we can't compare to see if they mentioned strong tornadoes.

Remember that NOAA has generally ramped up the drama quite a bit across the board, trying to get peoples' attention. Hurricane statements all the way down to Severe Thunderstorm Watches and Flood Watches have been more strongly worded in the last couple of years.

[CrazyC83]

It might continue at least into Wednesday as well in the Southeast (mainly the Carolinas/Virginia).

[TropicalAnalystwx13]

Y'all thought NWS Tulsa was being bullish? Let's try NWS Birmingham:

THE WEATHER SITUATION REMAINS MOSTLY UNCHANGED AS WE MOVE INTO EARLY
NEXT WEEK. MULTIPLE ROUNDS OF SEVERE WEATHER WILL BE POSSIBLE ACROSS
THE AREA WITH TORNADOES...DAMAGING STRAIGHT LINE WINDS...HAIL... AND
FLOODING POSSIBLE. FOR THE MAJORITY OF THE FORECAST EARLY NEXT WEEK
HAVE SIDED WITH THE MORE CONSISTENT ECMWF WITH THE EVOLUTION OF THE
SEVERE WEATHER THREAT. THE FIRST ROUND WILL COME EARLY MONDAY
MORNING. MODELS INDICATE THAT AN MCS WILL FORM ALONG THE
MID-MISSISSIPPI RIVER VALLEY AND PROGRESS EASTWARD. THE MCS WILL BE
ON A WEAKENING TREND AS IT MOVES ACROSS THE STATE LINE. BASED ON THE
LATEST MODEL GUIDANCE...DO NOT HAVE ANYTHING IN THE HWO FOR LATE
SUNDAY NIGHT BUT IF MODEL TRENDS HOLD THE MCS TOGETHER WILL NEED TO
ADD THE MENTION FOR SOME SEVERE STORMS SUNDAY NIGHT INTO EARLY
MONDAY. THE SECOND ROUND WILL COME AS A MORE ROBUST SHORTWAVE TROUGH
ROTATES AROUND THE BASE OF THE CLOSED UPPER LEVEL LOW. THE LOW LEVEL
JET WILL INCREASE TO 45-55 KTS AS THE SHORTWAVE TROUGH MOVES CLOSER.
THIS WILL INCREASE THE 0-1 KM SRH TO 200-300 M2/S2 AND WILL BE MORE
THAN SUFFICIENT FOR LOW LEVEL ROTATION. MUCAPE VALUES WILL BE AROUND
1000-1500 J/KG WITH UPPER LEVEL HEIGHT FALLS AND COOLER TEMPERATURES
ALOFT. THE DEEP LAYER 0-6 KM BULK SHEAR WILL BE AROUND 50-60 KTS
MORE THAN ENOUGH TO MAINTAIN UPDRAFT INTENSITY AND FOR THE
LIKELIHOOD FOR SUPERCELLS TO FORM. THIS REMAINS A RATHER CONCERNING
SITUATION AS WE MOVE INTO THE OVERNIGHT HOURS ON MONDAY. MODELS
CONTINUE TO BE CONSISTENT WITH THIS SOLUTION AND HAVE INCREASED POPS
DURING THE EARLY PORTION OF THE WORK WEEK. THE GFS CONTINUES TO SHOW
A SLOW EVOLUTION OF THE FIRST ROUND WITH THE SHORTWAVE WAVE TROUGH A
BIT FURTHER TO THE NORTH. FOR NOW...WILL CONTINUE TO SIDE WITH THE
MORE CONSISTENT ECMWF. IF THE GFS SOLUTION WERE TO VERIFY THE MAIN
THREAT WITH THE FIRST WAVE WILL REMAIN OVER THE NORTHWESTERN HALF OF
THE FORECAST AREA. HOWEVER..THE ECMWF INDICATES THAT THE FIRST ROUND
WILL PUSH THROUGH THE AREA EARLY TUESDAY WITH THE ENTIRE FORECAST
AREA BEING AFFECTED MONDAY NIGHT INTO TUESDAY MORNING. THE THIRD AND
HOPEFULLY FINAL ROUND OF SEVERE WEATHER WILL OCCUR AS ANOTHER
SHORTWAVE TROUGH ROTATES THROUGH THE MAIN CLOSED LOW LATE TUESDAY
INTO EARLY WEDNESDAY. FLOODING WILL BE A HIGH THREAT AS WELL WITH
MULTIPLE ROUND OF STORMS EXPECTED. FLASH FLOOD GUIDANCE REMAINS
RATHER HIGH BUT THESE STORMS SHOULD BE PROFICIENT RAINFALL PRODUCERS
AND WILL CAUSE FLOODING ISSUES ACROSS CENTRAL ALABAMA. THE SEVERE
WEATHER PARAMETERS REMAIN FAIRLY SIMILAR WITH THE LAST WAVE WITH
SLIGHTLY HIGHER DEEP LAYER SHEAR POSSIBLE. BASED ON THE LATEST MODEL
GUIDANCE A FEW STRONG TO VIOLENT TORNADOES CANNOT BE RULED OUT
ACROSS THE FORECAST AREA. NOW IS THE TIME TO PREPARE FOR THE SEVERE
WEATHER THREAT EARLY NEXT WEEK. PLEASE PREPARE TO TAKE YOUR SEVERE
WEATHER PRECAUTIONS EARLY NEXT WEEK.

[cycloneye]

Hail of the size of a quarter.

[CrazyC83]

Using the words violent tornadoes in a 4-5 day threat range is unheard-of.

[WeatherGuesser]

PAH Chimes in ....

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PADUCAH KY
410 PM CDT FRI APR 25 2014

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHERN
ILLINOIS...SOUTHWEST INDIANA...WESTERN KENTUCKY AND SOUTHEAST
MISSOURI.


.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THUNDERSTORMS ARE FORECAST FROM SUNDAY THROUGH TUESDAY NIGHT.
MULTIPLE ROUNDS OF SEVERE WEATHER AND HEAVY RAINFALL WILL BE
POSSIBLE FROM SUNDAY NIGHT THROUGH TUESDAY. THE POTENTIAL EXISTS
FOR A SIGNIFICANT OUTBREAK OF SEVERE STORMS IN THIS PERIOD...WITH
LARGE...LONG TRACK TORNADOES...VERY LARGE HAIL...AND DESTRUCTIVE
STRAIGHT LINE WINDS ALL POSSIBLE. IN ADDITION...EACH ROUND OF
THUNDERSTORMS WILL PRODUCE LOCALLY HEAVY RAINFALL...AND MAY
EVENTUALLY LEAD TO SOME FLASH FLOODING IN AREAS THAT RECEIVE
MULTIPLE ROUNDS OF VERY HEAVY RAIN.

[CrazyC83]

Dates need to change as well, extend out to April 29.

I have a bad feeling about this...

[TropicalAnalystwx13]

Dates need to change as well, extend out to April 29.

I have a bad feeling about this...

Changed. I forgot I could change it myself.

[EF-5bigj]

Well I hope everyone stays safe it's almost the 27th and There is yet another tornado outbreak happening that's Dixie Alley for you...

[CrazyC83]

How high will the initial updates for the day ahead go?

* I don't think a MDT will be initiated for Day 1. I'm thinking 30H hail, 30 wind and 5 tornado.

* I can see the MDT area expanding for Sunday (Day 2), and mentions of an upgrade to HIGH. But too soon to go all-in.

* I also think there will be a MDT for Monday (Day 3) right away, and very strong wording for Tuesday (Day 4) and Wednesday (Day 5).