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Severe Weather: April 2, 2015


natecast

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Thought it was appropriate to add a new thread about the threat tonight.  SPC has added a 10% tornado risk contour and is mentioning the risk for a strong tornado in their latest update this afternoon:

 

...SUMMARY...
   SEVERE THUNDERSTORMS WITH LARGE HAIL...DAMAGING WINDS AND A COUPLE
   OF TORNADOES ARE EXPECTED FROM THE OZARKS EASTWARD ACROSS THE LOWER
   OHIO VALLEY THIS AFTERNOON AND INTO THE OVERNIGHT PERIOD. A SMALL
   WINDOW EXISTS EARLY THIS EVENING FOR A FEW STORMS TO PRODUCE VERY
   LARGE HAIL AND POSSIBLY A STRONG TORNADO ESPECIALLY FROM NORTHEAST
   OKLAHOMA...SOUTHEAST KANSAS...SOUTHWEST MISSOURI INTO NORTHWEST
   ARKANSAS.

 

 

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Didn't seem like there was a huge tornado threat today. Been outta the loop, what changed?

 

There had previously been capping concerns and timing of the cold front, but progression of the front has slowed.  Now, with a boundary in the area, and SBCAPE of 2,000-2,500 on current SPC mesoanalysis, and shorter term models firing convection, seems to be a bigger threat.  SPC pulled the trigger on an Enhanced Risk with the first D1 outlook this morning.

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Deep layer shear and MLCAPE values in the 1200-1800 J/kg range will

initially be supportive of supercells...especially across

southeastern Kansas and northeastern Oklahoma where Bunkers right-

moving vectors will have a stronger cross-component to the surface

boundary. Any supercells will then tend to move east into southern

Missouri this evening. Given the presence of steeper mid-level

lapse rates and increasing deep layer shear with an approaching

speed max, we will be increasing our maximum potential hail size

to tennis balls. We will also be increasing the tornado threat to

elevated across portions of extreme southeastern Kansas and

southern Missouri as short term models have increased low level

helicities into the overnight period. This is due to a rather

veered low level jet and the potential for some localized backing

of winds due to terrain effects across southern Missouri.

Additionally, storms that develop along the front across the

Missouri Ozarks may also have a tendency to track along this

feature and ingest low level vorticity.

 

Here is part of the SGF discussion of note related to the backing of the winds.

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MESOSCALE DISCUSSION 0189
NWS STORM PREDICTION CENTER NORMAN OK
0447 PM CDT THU APR 02 2015

AREAS AFFECTED...SERN KS / SWRN MO / EXTREME NWRN AR / NERN OK

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

VALID 022147Z - 022315Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...THE CAP IS WEAKENING ALONG A FRONTAL ZONE OVER SERN KS AND
STORM INITIATION IS PROBABLE IN THE NEXT 1-2 HOURS. SEVERE STORM
DEVELOPMENT IS FORECAST.

DISCUSSION...VISIBLE SATELLITE IMAGERY SHOWS AN AGITATED CU FIELD
ACROSS SERN KS EWD INTO SWRN MO ALONG AND S OF A STATIONARY FRONTAL
ZONE. A LEAD MID-LEVEL SPEED MAX IS MOVING INTO THE CNTRL HIGH
PLAINS THIS AFTERNOON AND SHOULD PROGRESS TOWARDS THE I-35 CORRIDOR
TOWARDS EARLY EVENING.

STRONG HEATING AND LOW-LEVEL MOIST ADVECTION INTO THE REGION IS
ACTING TO FURTHER DESTABILIZE THE AIR MASS AND IS CONTRIBUTING TO
1500-3000 J/KG SBCAPE. THE MOIST/UNSTABLE BOUNDARY LAYER COUPLED
WITH BACKED LOW-LEVEL FLOW VEERING AND STRENGTHENING WITH HEIGHT
WILL FAVOR SUPERCELL DEVELOPMENT. LARGE TO VERY LARGE HAIL AND
ISOLD SEVERE WIND GUSTS WILL BE THE EARLY THREATS WITH THIS ACTIVITY
BEFORE LOW-LEVEL HODOGRAPHS ENLARGE TOWARDS EVENING IN PARTIAL
RESPONSE TO THE EJECTING MID-LEVEL SPEED MAX. LOWERING LCL/S AND
STRONG SHEAR WILL BECOME MORE SUPPORTIVE FOR LOW-LEVEL MESOCYCLONES
AND AN ATTENDANT SUPERCELL TORNADO RISK.

..SMITH/MEAD.. 04/02/2015


ATTN...WFO...LZK...SGF...TSA...ICT...OUN...

LAT...LON 37039743 37519744 37719698 37879456 37719325 37099291
36069355 36229536 37039743

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Once the Low-Level Jet kicks up around sundown the Tornado risk will increase significantly. RAP forecast hodographs are supportive or strong tornadoes in far NE OK / Joplin area. The surface low is currently centered just east of the Stillwater area with a quasi-warm front extending NEward into SE KS. Watch out along that front NE of the low center. Line of tornadic supercells possible. 

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The MD simply expired and we'll see a tornado watch issued soon. The 0Z sounding up in springfield shows backing low level winds and only a 5 J/Kg CIN remaining. Slight moistening and increased instability also noted compared to the 20Z sounding.

Lots of convection attempting to get going in SE KS as well... Should fire soon.
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As others have said we'll really see a ramp up in convective intensity after dark as the low level jet increases. The HRRR has been fairly constant in showing a substantial severe weather risk tonight in NE OK, SE KS, and SW MO. Hopefully we can keep the tornado threat out in the rural areas but I do believe we're going to have problems. LCLs will also lower after dark. A dangerous situation for sure. 

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Longggg time lurker, first time poster, decided to join in on the fun this year. If I was chasing today I would be watching the developing shower/cell near cherryvale. Very near the intersection of the wf and a boundary visible on radar that runs roughly west of Tulsa to near Independence 

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The MD simply expired and we'll see a tornado watch issued soon. The 0Z sounding up in springfield shows backing low level winds and only a 5 J/Kg CIN remaining. Slight moistening and increased instability also noted compared to the 20Z sounding. 

 

 

Gotcha, typically I feel like they go up pretty quick after the MD is gone. Appreciate the clarification; any predictions in regards to probs?

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50/20 tornado probs

URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 17

NWS STORM PREDICTION CENTER NORMAN OK

705 PM CDT THU APR 2 2015

THE NWS STORM PREDICTION CENTER HAS ISSUED A

* TORNADO WATCH FOR PORTIONS OF

NORTHWEST AND NORTH-CENTRAL ARKANSAS

SOUTHEAST KANSAS

SOUTHWEST AND SOUTH-CENTRAL MISSOURI

NORTHEAST OKLAHOMA

* EFFECTIVE THIS THURSDAY NIGHT AND FRIDAY MORNING FROM 705 PM

UNTIL 200 AM CDT.

* PRIMARY THREATS INCLUDE...

A FEW TORNADOES POSSIBLE

SCATTERED DAMAGING WINDS LIKELY WITH ISOLATED SIGNIFICANT GUSTS

TO 80 MPH POSSIBLE

SCATTERED LARGE HAIL LIKELY WITH ISOLATED VERY LARGE HAIL EVENTS

TO 3 INCHES IN DIAMETER POSSIBLE

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 55 STATUTE

MILES NORTH AND SOUTH OF A LINE FROM 65 MILES WEST NORTHWEST OF

BARTLESVILLE OKLAHOMA TO 40 MILES NORTHEAST OF WEST PLAINS

MISSOURI. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR

TORNADOES AND 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.

&&

DISCUSSION...RAPID THUNDERSTORM DEVELOPMENT IS UNDERWAY WITH

SUPERCELLS EXPECTED TO QUICKLY EVOLVE WITH A RISK FOR VERY LARGE

HAIL AND A FEW TORNADOES. A TRANSITION TO BOWING LINE SEGMENTS

MIXED WITH SUPERCELLS WILL LIKELY OCCUR TONIGHT WITH A CONTINUED

RISK FOR TORNADOES...LARGE HAIL...AND CORRIDORS OF WIND DAMAGE.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL

SURFACE AND ALOFT TO 3 INCHES. EXTREME TURBULENCE AND SURFACE

WIND GUSTS TO 70 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO

550. MEAN STORM MOTION VECTOR 27035.

...MEAD

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