re: Tornado! Cards vs Cubs

Looking at the HRRR again for this evening, the ingredients are definitely there for severe weather. The HRRR is the "High Res Rapid Refresh" model, which is an experimental hi res version of the "Rapid Refresh" model, which is a short range model run every hour based on the WRF and GFS models, especially used for severe weather.

I don't feel like typing much but here is a slightly modified explanation I compiled from Jeff Haby's site and apply it to today. Just in case anyone wants to understand models a little more..

First I'll show the CAPE (Convective Available Potential Energy) values:

High CAPE means storms will build vertically very quickly. The updraft speed depends on the CAPE environment.

Hail: As CAPE increases (especially above 2,500 J/kg) the hail potential increases. Large hail requires very large CAPE values.

Downdraft: An intense updraft often produces an intense downdraft since an intense updraft will condense out a large amount of moisture. Expect isolated regions of very heavy rain when storms form in a large or extreme CAPE environment.

Lightning: Large and extreme CAPE will produce storms with abundant lightning.

4. Pitfalls:

a. Storms will only form and the CAPE actualized if the low level capping inversion is broken.

b. CAPE magnitude can rise or fall very rapidly across time and space.

Operational significance of CAPE:

CAPE
1 - 1,500 Positive
1,500 - 2,500 Large
2,500+ Extreme



Next we will look at CIN (Convective Inhibition)

CIN is also known as the cap. You need to break the cap for the lifting to reach the CAPE to form deep convection.

As you can see CIN is non existent for many areas, most likely due to daytime heating..



Next is the LI, or Lifted Index.


A negative LI indicates that the PBL is unstable with respect to the middle troposphere. This is an environment in which convection can occur. The more negative the LI the more unstable the troposphere and the more buoyant the acceleration will be for rising parcels of air from the PBL. Keep in mind the capping layer (CIN) must be broken before lower PBL based lifting is able to move into the +CAPE region of a sounding and develop into deep convection.

LI Values:
Positive number Stable
0 to -4 Marginal instability
-4 to -7 Large instability
-8 or less Extreme instability



Finally, I show you the EHI, or Energy Helicity Index:

The Energy Helicity Index (EHI) is a combination of two indexes. By itself, it is the best index available for tornado prediction since it combines both CAPE and Helicity.

EHI > 1 : Supercell potential
1 to 5 : up to F2, F3 tornadoes possible
5+ : up to F4, F5 tornadoes possible



Couple these ingredients with the immense amount of gulf moisture feeding into the area, I'd say the best chance for severe weather today is in this area:

I don't like the way a lot of those numbers look for NTX.

quote:

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STP values

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Damn, though that said SFP at first glance. Was kinda hoping we could friendzone these tornados.

Thanks I see my mistake

Not to mention... the KFDR Radar went down today...

quote:

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MESSAGE DATE: MAY 07 2015 18:10:12

KFDR 88D MAINTENANCE IS OUT OF SERVICE. TECHNICIANS HAVE BEEN
NOTIFIED. RESTORATION TIME IS UNKNOWN.FM WFO/OUN 5/7/14 1812 UTC

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and look where it's located.

Have a friend flying DFW-ORD in an hour, should make for a fun bumpy ride on the 787. I've been keeping an eye on how close his flight gets to some of these storms

there it is:



430 PM CDT THU MAY 7 2015

THE NWS STORM PREDICTION CENTER HAS ISSUED A

* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
SOUTH-CENTRAL OKLAHOMA
NORTH-CENTRAL TEXAS

* EFFECTIVE THIS THURSDAY AFTERNOON FROM 430 PM UNTIL MIDNIGHT
CDT.

* PRIMARY THREATS INCLUDE...
ISOLATED VERY LARGE HAIL EVENTS TO 2.5 INCHES IN DIAMETER
POSSIBLE
ISOLATED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE
A TORNADO OR TWO POSSIBLE

SUMMARY...A NORTH-SOUTH-ORIENTED BAND OF THUNDERSTORMS IS EXPECTED
TO CONTINUE EWD ALONG THE RED RIVER THIS AFTERNOON INTO EVENING.
THE ENVIRONMENT WILL BE SUPPORTIVE OF EMBEDDED SUPERCELL STRUCTURES
WITH A RISK FOR LARGE HAIL...DAMAGING STRAIGHT LINE WINDS AND
PERHAPS A BRIEF TORNADO OR TWO.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 60
STATUTE MILES EAST AND WEST OF A LINE FROM 70 MILES SOUTHWEST OF
SHERMAN TEXAS TO 30 MILES EAST NORTHEAST OF ARDMORE OKLAHOMA.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU1).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.

Open house in May? I'm confused

Another one:

god damn you are on top of this shite.