Dr. Jeff Masters' WunderBlog

The 45% tornado risk got shifted south.

WWUS40 KWNS 141948
WWP8

TORNADO WATCH PROBABILITIES FOR WT 0168
NWS STORM PREDICTION CENTER NORMAN OK
0248 PM CDT SAT APR 14 2012

WT 0168
PROBABILITY TABLE:
PROB OF 2 OR MORE TORNADOES : 40%
PROB OF 1 OR MORE STRONG /F2-F5/ TORNADOES : 20%
PROB OF 10 OR MORE SEVERE WIND EVENTS : 30%
PROB OF 1 OR MORE WIND EVENTS >= 65 KNOTS : 30%
PROB OF 10 OR MORE SEVERE HAIL EVENTS : 60%
PROB OF 1 OR MORE HAIL EVENTS >= 2 INCHES : 40%
PROB OF 6 OR MORE COMBINED SEVERE HAIL/WIND EVENTS : 70%

&&
ATTRIBUTE TABLE:
MAX HAIL /INCHES/ : 2.5
MAX WIND GUSTS SURFACE /KNOTS/ : 60
MAX TOPS /X 100 FEET/ : 500
MEAN STORM MOTION VECTOR /DEGREES AND KNOTS/ : 25030
PARTICULARLY DANGEROUS SITUATION : NO

&&
FOR A COMPLETE GEOGRAPHICAL DEPICTION OF THE WATCH AND
WATCH EXPIRATION INFORMATION SEE WOUS64 FOR WOU8.

$$

Quoting 1900hurricane:


WWUS40 KWNS 141948
WWP8

TORNADO WATCH PROBABILITIES FOR WT 0168
NWS STORM PREDICTION CENTER NORMAN OK
0248 PM CDT SAT APR 14 2012

WT 0168
PROBABILITY TABLE:
PROB OF 2 OR MORE TORNADOES : 40%
PROB OF 1 OR MORE STRONG /F2-F5/ TORNADOES : 20%
PROB OF 10 OR MORE SEVERE WIND EVENTS : 30%
PROB OF 1 OR MORE WIND EVENTS >= 65 KNOTS : 30%
PROB OF 10 OR MORE SEVERE HAIL EVENTS : 60%
PROB OF 1 OR MORE HAIL EVENTS >= 2 INCHES : 40%
PROB OF 6 OR MORE COMBINED SEVERE HAIL/WIND EVENTS : 70%

&&
ATTRIBUTE TABLE:
MAX HAIL /INCHES/ : 2.5
MAX WIND GUSTS SURFACE /KNOTS/ : 60
MAX TOPS /X 100 FEET/ : 500
MEAN STORM MOTION VECTOR /DEGREES AND KNOTS/ : 25030
PARTICULARLY DANGEROUS SITUATION : NO

&&
FOR A COMPLETE GEOGRAPHICAL DEPICTION OF THE WATCH AND
WATCH EXPIRATION INFORMATION SEE WOUS64 FOR WOU8.

$$

It's so small and cute:)

WWUS40 KWNS 141929
WWP7

TORNADO WATCH PROBABILITIES FOR WT 0167
NWS STORM PREDICTION CENTER NORMAN OK
0229 PM CDT SAT APR 14 2012

WT 0167
PROBABILITY TABLE:
PROB OF 2 OR MORE TORNADOES : 60%
PROB OF 1 OR MORE STRONG /F2-F5/ TORNADOES : 50%
PROB OF 10 OR MORE SEVERE WIND EVENTS : 30%
PROB OF 1 OR MORE WIND EVENTS >= 65 KNOTS : 30%
PROB OF 10 OR MORE SEVERE HAIL EVENTS : 70%
PROB OF 1 OR MORE HAIL EVENTS >= 2 INCHES : 60%
PROB OF 6 OR MORE COMBINED SEVERE HAIL/WIND EVENTS : 90%

&&
ATTRIBUTE TABLE:
MAX HAIL /INCHES/ : 2.5
MAX WIND GUSTS SURFACE /KNOTS/ : 60
MAX TOPS /X 100 FEET/ : 450
MEAN STORM MOTION VECTOR /DEGREES AND KNOTS/ : 22025
PARTICULARLY DANGEROUS SITUATION : NO

&&
FOR A COMPLETE GEOGRAPHICAL DEPICTION OF THE WATCH AND
WATCH EXPIRATION INFORMATION SEE WOUS64 FOR WOU7.

$$

How unusual is it for NWS to issue a PDS warning?
Anyone know when that last time they did that?

I thoroughly agree with 1093 LavosPhoenix: ...while I appreciate people posting those GRLevel3 and other maps of tornado velocities, given the number of tornadoes and storms around today,
please post the location of the storm and/or radar it is found on.
Yes, the maps have small cities shown but it isn't always obvious where it is.
Plus it helps correlate what storm you are talking about.
I'm just trying to keep track of all the storms; and as you know in an outbreak like this with many tornadoes, it can be somewhat difficult or annoying.

Uh-oh Greensburg, KS...

Quoting mlewchuk:
How unusual is it for NWS to issue a PDS warning?
Anyone know when that last time they did that?

It's pretty rare, only a few events a season require a PDS watch. The last one i believe was the March 2nd outbreak of this year.

From above:

tornado on the ground in the burdett storm via spotter

Quoting mlewchuk:
How unusual is it for NWS to issue a PDS warning?
Anyone know when that last time they did that?

A watch or a warning?

Quoting TropicalAnalystwx13:

A watch or a warning?

I think he means a tornado emergency.

Quoting WxGeekVA:


Uh-oh Greensburg, KS...

Looks like it's missing just to the west.

Quoting hurricanehunter27:
I think he means a tornado emergency.

Means

Potentially Dangerous Situation

Quoting mlewchuk:
How unusual is it for NWS to issue a PDS warning?
Anyone know when that last time they did that?

Find the last high risk day. They issue PDS watches during high risk days... on rare occasions maybe on higher-end moderate risk days.

Quoting redux:
tornado on the ground in the burdett storm via spotter

roped out

MESOSCALE DISCUSSION 0530
NWS STORM PREDICTION CENTER NORMAN OK
0301 PM CDT SAT APR 14 2012

AREAS AFFECTED...CNTRL/SWRN KS AND WRN OK

CONCERNING...TORNADO WATCH 165...

VALID 142001Z - 142030Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 165 CONTINUES.

DRYLINE CIRCULATIONS ADJACENT TO A N-S-ORIENTED ZONE OF SFC
CONFLUENCE CONTINUE TO FOSTER THE DEVELOPMENT OF DISCRETE SUPERCELLS
FROM CNTRL/SWRN KS INTO WRN OK. DURING THE NEXT HALF HOUR TO
HOUR...THE HIGHEST THREAT FOR TORNADOES ALONG WITH VERY LARGE HAIL
WILL EXTEND FROM CNTRL/SWRN KS INTO NWRN OK WITH NEWD/ENEWD-TRACKING
SUPERCELLS CURRENTLY IN HODGEMAN/PAWNEE COUNTIES KS...KIOWA COUNTY
KS...HARPER COUNTY OK...AND AN INCIPIENT CONVECTIVE PLUME IN ELLIS
COUNTY. VISIBLE SATELLITE IMAGERY SUGGESTS ADDITIONAL CUMULUS
DEVELOPING NEAR THE DRYLINE TOWARD THE RED RIVER...AND THE
PARTICULARLY DANGEROUS SITUATION TORNADO WATCH 165 HAD EARLIER BEEN
EXTENDED SWD TO THE TX/OK BORDER. WITH DEEP-LAYER SHEAR VECTORS
EXHIBITING A SUBSTANTIAL DRYLINE-ORTHOGONAL COMPONENT AND EFFECTIVE
SRH VALUES OF AROUND 300-500 M2/S2...DISCRETE SUPERCELLS CAPABLE OF
PRODUCING TORNADOES...SOME POSSIBLY STRONG TO VIOLENT...ALONG WITH
VERY LARGE HAIL AND DMGG STRAIGHT-LINE WINDS WILL BE OF CONCERN.

..COHEN.. 04/14/2012


ATTN...WFO...ICT...OUN...DDC...

LAT...LON 38699975 39049894 38969811 37979783 37049792 36119838
34679905 34369957 34829993 36949997 38699975

Quoting TropicalAnalystwx13:

A watch or a warning?

Thats a good clarification. If he means Tornado Emergency by PDS warning then those of course are more rare, usually requiring a confirmed large tornado heading into a populated area with a significant to threat of life and property. Either way I guess we got both questions answered now!

Quoting weatherh98:


Means

Potentially Dangerous Situation

He asked about a PDS warning which does not exist. There is a tornado emergency which is a storm with a large and extremely dangerous tornado.

the severe cell south of the Dodge City tornado box is nearing tornado conditions.

There is also another cell south of that one that just got upgraded to a severe TS with severe hail.

Quoting IceCoast:


Thats a good clarification. If he means Tornado Emergency by PDS warning then those of course are more rare, usually requiring a confirmed large tornado heading into a populated area with a significant to threat of life and property. Either way I guess we got both questions answered now!

Rare, although increasing in use in the last few years. Different offices/regions have different criteria for "emergency" wording. Although the thought is to use that wording for very high-end events, like confirmed large tornadoes almost certainly about to hit a major city, there is a 50% false alarm rate even for tornado emergencies.

Quoting hurricanehunter27:
He asked about a PDS warning which does not exist. There is a tornado emergency which is a storm with a large and extremely dangerous tornado.

Not exactly true; the new wording experiment for warnings does allow for three levels of warning:
Tornado Warning
PDS Tornado Warning
Tornado Emergency

Quoting hurricanehunter27:
He asked about a PDS warning which does not exist. There is a tornado emergency which is a storm with a large and extremely dangerous tornado.

Oh okayi gotchya thought y'all were talking about what a pds is haha

Quoting ScottLincoln:


Rare, although increasing in use in the last few years. Different offices/regions have different criteria for "emergency" wording. Although the thought is to use that wording for very high-end events, like confirmed large tornadoes almost certainly about to hit a major city, there is a 50% false alarm rate even for tornado emergencies.



Not exactly true; the new wording experiment for warnings does allow for three levels of warning:
Tornado Warning
PDS Tornado Warning
Tornado Emergency

So PDS warning were just created lol. Has one ever been issued?

Quoting hurricanehunter27:
So PDS warning were just created lol. Has one ever been issued?

not yet

Orthogonal deep layer shear (to the dryline):



SR Helicities of 300-500 m^2/s^2



Instability



Tornado jet fuel.

Another storm South West of Greensburg seems like it may produce something.

Quoting hurricanehunter27:
So PDS warning were just created lol. Has one ever been issued?

PDS warning is supposed to correlate to confirmed tornado in a tornado warning. I don't recall which offices are involved on the test, otherwise we could see if they had confirmed tornado warnings yet.

Quoting ScottLincoln:


PDS warning is supposed to correlate to confirmed tornado in a tornado warning. I don't recall which offices are involved on the test, otherwise we could see if they had confirmed tornado warnings yet.

The KS NWS office was issuing warning with different wording so I guess there one of them.

Quoting hurricanehunter27:
Another storm South West of Greensburg seems like it may produce something.

Yeah, it really flared up the last couple of frames. This one also looks like it will miss to the west though.

Quoting ScottLincoln:


PDS warning is supposed to correlate to confirmed tornado in a tornado warning. I don't recall which offices are involved on the test, otherwise we could see if they had confirmed tornado warnings yet.

From what I'm reading the test began on April 2nd in the following areas:
WFO St. Louis, MO
WFO Kansas City, MO
WFO Topeka, KS
WFO Wichita, KS
WFO Springfield, MO

There are a couple of very dangerous supercells embedded within this mass of rain.

This seems to be the tornado SE of Dodge City, but it may actually be the TS behind it. Crazy map doesn't make sense.

W8 Ford KS 69 dBZ 43,000 ft. 79 kg/mē 100% Chance 100% Chance 3.50 in. 41 knots SW (231)


W7 Republic KS 61 dBZ 41,000 ft. 34 kg/mē 90% Chance 100% Chance 1.50 in. 80 knots SW (226)

Quoting ScottLincoln:


PDS warning is supposed to correlate to confirmed tornado in a tornado warning. I don't recall which offices are involved on the test, otherwise we could see if they had confirmed tornado warnings yet.

One of the Kansas WFO's I believe issued a few warnings earlier with special wording. I don't recall them using the term PDS tornado warning, but the wording was most certainly more stern in delivering the message, i'll have to go back and look.

It's also a bummer about only having 50% accuracy on Tornado Emergency's. One would think it would be higher then this.

good to see they retired the name irene

Storm SW of Greensburg...

More rain is on tap for Puerto Rico tonight and part of Sunday,and after that, drier weather will arrive for most of next week.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
343 PM AST SAT APR 14 2012

.SYNOPSIS...A MID TO UPPER LEVEL TROUGH ACROSS THE WEST CENTRAL
ATLANTIC WILL CONTINUE MOVING EAST TONIGHT THROUGH SUNDAY
MORNING...AND WILL CONTINUE TO PUSH A FRONTAL BOUNDARY ACROSS THE
LOCAL ISLANDS. A MID TO UPPER LEVEL RIDGE IS EXPECTED TO PRODUCE
AN OVERALL DRIER WEATHER PATTERN ACROSS THE LOCAL AREA EARLY NEXT
WEEK.

&&

.DISCUSSION...THE FRONTAL BOUNDARY WILL CONTINUE PUSHING SLOWLY
ACROSS THE LOCAL AREA TONIGHT THROUGH SUNDAY...WITH AN OVERALL
DRIER AND MORE STABLE PATTERN EXPECTED TO ENCOMPASS THE LOCAL
ISLANDS SUNDAY NIGHT AND MONDAY AND PROBABLY CONTINUING THROUGH AT
LEAST TUESDAY AND WEDNESDAY. THROUGH TONIGHT AND MUCH OF SUNDAY...
STILL EXPECT A GOOD DEAL OF CLOUDINESS...SHOWERS AND A FEW
THUNDERSTORMS ACROSS THE LOCAL ISLANDS. ALTHOUGH NOT EXPECTING A
SIGNIFICANT HEAVY RAIN OR FLOOD EVENT AT THIS TIME...PERIODS OF
MODERATE TO HEAVY RAINFALL AND SOME URBAN AND SMALL STREAM
FLOODING WILL OCCUR...AND THERE COULD BE SOME LOCALIZED FLASH AND
RIVER FLOODING.

A GENERALLY FAIR WEATHER PATTERN IS EXPECTED FOR SUNDAY NIGHT AND
MONDAY THROUGH TUESDAY AND WEDNESDAY...BUT WITH INTERVALS OF
CLOUDINESS AND A FEW SHOWERS.

A HIGH SURF ADVISORY GOES INTO EFFECT FOR MOST OF THE ATLANTIC
COASTLINES AT 6 PM THIS EVENING. GIVEN EXPECTED BORDERLINE
CONDITIONS...OPTED TO NOT ISSUE AN NPW FOR WIND ADVISORY AT THIS
TIME. IT CERTAINLY WILL BECOME BREEZY TO WINDY LATER TONIGHT AND
SUNDAY...BUT FEEL IT WILL BE DIFFICULT TO REACH AND MAINTAIN THE
25 MPH OR GREATER SUSTAINED WINDS LOCAL CRITERIA.

&&

.AVIATION...MVFR CONDITIONS ARE LIKELY ACROSS THE PUERTO RICO AND
USVI TAF SITES AS SHOWERS ARE EXPECTED TO AFFECT THESE SITES THIS
EVENING AND TONIGHT...BRIEFLY REDUCING VISIBILITIES AND CAUSING
MVFR CEILINGS. TNCM AND TKPK IS EXPECTED TO REMAIN VFR UNTIL LATE
TONIGHT WITH THE OCCASIONAL PASSING SHOWERS. WINDS ARE EXPECTED
TO INCREASE SIGNIFICANTLY TO 15 TO 22 KNOTS WITH HIGHER GUSTS
TONIGHT THROUGH SUNDAY.

&&

.MARINE...A COLD FRONT WILL CONTINUE MOVING ACROSS THE REST OF
THE LOCAL ATLANTIC AND THEN CARIBBEAN COASTAL WATERS THE REST OF
THIS AFTERNOON THROUGH SUNDAY AND REACH NEAR 17 DEGREES NORTH BY
MONDAY. STRENGTHENING HIGH PRESSURE ACROSS THE ATLANTIC WILL
INCREASE THE WINDS SIGNIFICANTLY TONIGHT THROUGH SUNDAY...WITH
QUICKLY BUILDING SEAS. WINDS AND SEAS WILL BEGIN TO DIMINISH
MONDAY. SMALL CRAFT ADVISORIES ARE IN EFFECT FOR MOST OF THE
LOCAL COASTAL WATERS TONIGHT.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 74 80 72 81 / 90 40 20 20
STT 73 84 73 84 / 90 30 20 20

This one crossing from Oklahoma to Kansas looks like it could go tornadic very soon.

Quoting IceCoast:


One of the Kansas WFO's I believe issued a few warnings earlier with special wording. I don't recall them using the term PDS tornado warning, but the wording was most certainly more stern in delivering the message, i'll have to go back and look.

It's also a bummer about only having 50% accuracy on Tornado Emergency's. One would think it would be higher then this.

I think one of the goals, for better or worse, is to make the warnings scarier or more "risk-based" so that people will assess their risk better. My personal hope is that it does not instead just raise the level of complacency further by desensitizing folks to scarier wording.

I almost couldn't believe the statistic when I heard it, but that's what it is. 50% of tornado emergencies dont even have an actual tornado hit the place mentioned in the wording, let alone a big, destructive tornado. I'm sure that suggests to some a credibility issue...

Quoting WxGeekVA:


Storm SW of Greensburg...

Yah look at it now...

Inflow is looking ridiculous right now.

Quoting WxGeekVA:


Storm SW of Greensburg...

Strangely enough, the velocity doesn't show much rotation with that one right now. I have a feeling that will change soon though.

This doesn't look good

tornado Vortex Signatures

0 W7 Republic KS 61 dBZ 40,000 ft. 42 kg/mē 90% Chance 100% Chance 1.50 in. 74 knots SW (227)

0 Q1 Saline NE 61 dBZ 35,000 ft. 37 kg/mē 60% Chance 100% Chance 1.00 in. 27 knots SW (233)

0 E6 Republic KS 57 dBZ 29,000 ft. 17 kg/mē 30% Chance 90% Chance 0.50 in. 25 knots SW (223)


Severe Hail

1 W8 Kiowa KS 69 dBZ 42,000 ft. 75 kg/mē 100% Chance 100% Chance 4.00 in. 43 knots SW (233)

1 U8 Harper OK 63 dBZ 45,000 ft. 81 kg/mē 90% Chance 100% Chance 2.25 in. 35 knots SW (229)


NWS TORNADO WARNINGS

Both cells in Oklahoma.

On a line south of Dodge City

One is crossing the state line into Nebraska with a 3rd warning extended ahead of it.

It looks like storm initialization is taking place along the dryline in Kansas and Nebraska behind the blob.

Link Wow.

Per NOAA National Severe Storms Laboratory

DO NOT rely on FB or Twitter for your tornado warnings! NOAA Weather radio, nws.noaa.gov your best sources!

Five consecutive tornado warnings along the line from Kansas to just east of the Texas panhandle. Amazing!

Quoting islander101010:
good to see they retired the name irene

Yeah, I saw that as well!

At this rate a new tornadic cell is forming about every 30 to 45 minutes.

We could easily have an additional 30 tornadic cells before tomorrow morning at this rate.

The lead cell in Iowa continues to chug on, although it doesn't look tornadic.