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June 17th-22nd severe threat


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Just curious what does 80dBz mean, and what is the difference between fixed cape and mucape.

The 80 I mentioned was a VIL. For a while, it seemed popular when the 88D was new for estimating hail stone size. Vertically integrated liquid, but ice is more reflective than water, so the name is a little inaccurate. Hail to VIL, from my understanding, is somewhat complex, for a while I used to see mention of VIL of the day, but now, not so much. I still see NWS give hail estimates based on radar, not sure if that is VIL based or something else.

MUCAPE is Most Unstable Cape. SB is surface based. I often prefer mixed layer myself. Quick Google find...

http://www.emc.ncep.noaa.gov/mmb/tips/tip.jul02.html

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Just curious what does 80dBz mean, and what is the difference between fixed cape and mucape.

in short, dBz is the power returned to the radar when the beam reflects off raindrops, hail, bees, snow, debris, etc.

80 dBz is a very high and very rare value of this quantity - usually means there are very large objects airborne (large hail or debris)

i'm assuming "fixed cape" is usually computed for a parcel lifted from the surface

most unstable cape is the highest cape value of cape for an air parcel lifted from any height in the atmospheric column. In the case of elevated convection, air parcels lifted above an inversion may have cape, while cooler parcels lifted from below the inversion don't have cape. In this case, there may be little or no surface based cape, but significant most unstable cape. In situations where there is a lot of surface heating, the most unstable air parcels usually originate from the surface, so SBCAPE=MUCAPE in these situations.

make sense?

edit: ahh, you said "mixed layer", not "fixed layer".

I think mixed layer is the average cape through the well-mixed boundary layer - usually it is pretty close to surface based cape.

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NEC145-200200-

/O.CON.KGLD.TO.W.0027.000000T0000Z-110620T0200Z/

RED WILLOW NE-

829 PM CDT SUN JUN 19 2011

...A TORNADO WARNING REMAINS IN EFFECT FOR NORTHERN RED WILLOW COUNTY

UNTIL 900 PM CDT...

AT 825 PM CDT...TRAINED WEATHER SPOTTERS REPORTED A TORNADO. THIS

TORNADO WAS LOCATED 7 MILES NORTH OF MCCOOK...AND WAS MOVING EAST AT

30 MPH.

MULTIPLE BRIEF TORNADOES HAVE BEEN CONFIRMED BY STORM CHASERS.

LOCATIONS IMPACTED INCLUDE...

MAINLY RURAL AREAS OF NORTHERN RED WILLOW COUNTY.

THIS INCLUDES HIGHWAY 83 BETWEEN MILE MARKERS 20 AND 25.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TO REPEAT...A TORNADO HAS BEEN CONFIRMED BY TRAINED WEATHER SPOTTERS.

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The 80 I mentioned was a VIL. For a while, it seemed popular when the 88D was new for estimating hail stone size. Vertically integrated liquid, but ice is more reflective than water, so the name is a little inaccurate. Hail to VIL, from my understanding, is somewhat complex, for a while I used to see mention of VIL of the day, but now, not so much. I still see NWS give hail estimates based on radar, not sure if that is VIL based or something else.

MUCAPE is Most Unstable Cape. SB is surface based. I often prefer mixed layer myself. Quick Google find...

http://www.emc.ncep..../tip.jul02.html

One major reason why "VIL of the day" is not as popular (and you can count me as one of these people) is because is it vertically integrated you must wait for an entire volume scan to complete before getting the next image. Therefore you can lose lead time on an event. I try as often as I can to look at the real data when making warning decisions (i.e. reflectivity, velocity (base/SRM), and spectrum width), while the rest is more of safety net in case I miss something.

For instance, at GYX we still have VIL threshold alarms that trigger at certain levels to clue us in that a warning might be necessary. But it often false alarms for large amounts of small hail.

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The 80 I mentioned was a VIL. For a while, it seemed popular when the 88D was new for estimating hail stone size. Vertically integrated liquid, but ice is more reflective than water, so the name is a little inaccurate. Hail to VIL, from my understanding, is somewhat complex, for a while I used to see mention of VIL of the day, but now, not so much. I still see NWS give hail estimates based on radar, not sure if that is VIL based or something else.

MUCAPE is Most Unstable Cape. SB is surface based. I often prefer mixed layer myself. Quick Google find...

http://www.emc.ncep..../tip.jul02.html

the relationship for dbz goes something like dBz proportional to D^6, so larger objects reflect back enormously more power than smaller objects.

When VIL is calculated, (if memory serves me correctly from cloud physics), you basically solve the relationship between dBz and D in terms of D^3 on the LHS (which is proportional to mass) and other terms on the RHS. The integral of the resulting quantity is then taken through the vertical layer - hail must represent a more concentrated "storage" of liquid within air parcels than rain, so that high VIL correlates to large hail.

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Ok thank you for the information. So can dBz be like a reflectivity of like a debris ball as seen on radar as well as other things(hail, wind etc).

I don't get how you can always offer your opinions re: tornado ratings and follow severe wx constantly yet be asking these questions.

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Circulation increasing now, finally stopped sucking storms into itself.

SEVERE WEATHER STATEMENT

NATIONAL WEATHER SERVICE TOPEKA KS

902 PM CDT SUN JUN 19 2011

KSC061-127-197-200230-

/O.CON.KTOP.TO.W.0026.000000T0000Z-110620T0230Z/

MORRIS-GEARY-WABAUNSEE-

902 PM CDT SUN JUN 19 2011

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 930 PM CDT FOR WEST

CENTRAL WABAUNSEE...SOUTHEASTERN GEARY AND NORTH CENTRAL MORRIS

COUNTIES...

AT 857 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO

INDICATE A SEVERE THUNDERSTORM WITH STRONG ROTATION AND A WALL CLOUD

CAPABLE OF PRODUCING A TORNADO. THIS STORM WAS LOCATED 10 MILES

WEST OF DWIGHT...OR 12 MILES SOUTH OF JUNCTION CITY...MOVING EAST AT

15 MPH.

LOCATIONS IMPACTED INCLUDE...

DWIGHT.

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I assume the LLJ must be kicking in. Our KS supercell seems to be taking a more northward component having ingested a cell on its western edge, and there is an e-w line of storms starting to form south of Omaha now.

A few of which are tor warned, and others severe warned that have rotation/meso's.

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NAM is significantly cooler with H7 temps across nrn IL/IN tomorrow evening and breaks out convection along the warm front with a very unstable and highly-sheared atmosphere. ****.

you could say that again....huge difference from the 12z run.

With good mid-level westerly flow on the north side of the ridge coupled with backed sfc winds.

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you could say that again....huge difference from the 12z run.

With good mid-level westerly flow on the north side of the ridge coupled with backed sfc winds.

Lift mechanism is going to be the right-entrance region of the jet streak over WI/MI. If those H7 temps verify then we are up a creek w/o a paddle here tomorrow evening...

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What a weird evolution for the KS supercell...never seen one get stretched and destroyed that way

kinda struggled all along even if it was a giant too. warm sector ftl.

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