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April 14-17th Severe Weather (Day 3 Mod)


Chicago Storm

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MESOSCALE DISCUSSION 0493   NWS STORM PREDICTION CENTER NORMAN OK   0109 PM CDT WED APR 17 2013      AREAS AFFECTED...SERN TX PANHANDLE/NWRN TX INTO   SWRN...CENTRAL...NERN OK...AND SERN KS      CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY       VALID 171809Z - 171945Z      PROBABILITY OF WATCH ISSUANCE...80 PERCENT      SUMMARY...A TORNADO WATCH WILL BE COORDINATED THIS AFTERNOON FOR   AREAS INCLUDING NORTHWEST TX INTO SWRN...CENTRAL TO NERN OK AND SERN   KS.      WEST THROUGH NORTHWEST OF THE TORNADO WATCH THREAT AREA...ELEVATED   TSTMS WILL CONTINUE TO DEVELOP ACROSS W THROUGH NW OK AND SPREAD   INTO SRN KS.  HAIL WILL BE THE PRIMARY THREAT WITH THIS ACTIVITY.      DISCUSSION...TRENDS IN SURFACE MESOANALYSES INDICATED THE SURFACE   FRONT ORIENTED FROM SW-NE ACROSS OK HAS BECOME QUASI-STATIONARY...   EXTENDING FROM INVOF KLTS TO 10 N KOKC TO 35 N KCQB TO 20 W CNU.    THE SRN EXTENSION OF THIS BOUNDARY EXTENDED SWD INTO NWRN TX...AND   THEN NWWD AS A COLD FRONT INTO THE SRN TX PANHANDLE. ALTHOUGH THE   DRY LINE WAS LOCATED FARTHER W ACROSS WEST TX...BOUNDARY LAYER   MODIFICATIONS THROUGH THE AFTERNOON SUGGEST THE DRY LINE WILL MIX   EWD WITH THE TRIPLE POINT EVENTUALLY BECOMING ESTABLISHED IN NWRN   TX.      STRONG SURFACE HEATING ALONG AND S OF THE FRONTS IN NWRN TX AND E OF   THE DRY LINE ARE QUICKLY ERODING SURFACE INHIBITION FOR CONVECTIVE   INITIATION LIKELY OCCURRING INVOF HASKELL/STONEWALL COUNTIES WHERE   CU HAS BEEN GROWING DEEPER.  MODIFIED 12Z SOUNDINGS SUGGEST   CONVECTIVE TEMPS IN THE UPPER 80S WILL BREACH THE CAP AND SUPPORT   TSTM INITIATION ACROSS NWRN TX SOON.  THIS SCENARIO IS SUPPORTED BY   THE 15Z RAP.  STRONG TO VERY STRONG INSTABILITY AND STRENGTHENING   WIND FIELDS/DEEP LAYER AND LOW LEVEL SHEAR WILL SUPPORT SUPERCELLS   WITH ALL FACETS OF SEVERE WEATHER LIKELY...INCLUDING TORNADOES.      FARTHER W/NW...TSTMS WILL CONTINUE TO DEVELOP W OF THE SURFACE FRONT   IN OK...WITH THIS ACTIVITY REMAINING ELEVATED.  THIS ACTIVITY IS   BEING SUPPORTED BY LOW LEVEL WAA AND DEEP LAYER ASCENT WITHIN THE   ENTRANCE REGION OF A SWLY MIDLEVEL JET.  WW ISSUANCE FOR THE AREAS W   THROUGH NW OF THE FRONT IS UNCERTAIN.      ..PETERS/KERR.. 04/17/2013

 

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URGENT - IMMEDIATE BROADCAST REQUESTED
   TORNADO WATCH NUMBER 116
   NWS STORM PREDICTION CENTER NORMAN OK
   120 PM CDT WED APR 17 2013
  
   THE NWS STORM PREDICTION CENTER HAS ISSUED A
  
   * TORNADO WATCH FOR PORTIONS OF
     CENTRAL AND EASTERN OKLAHOMA
     NORTHWEST TEXAS TEXAS
  
   * EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 120 PM
     UNTIL 1100 PM CDT.
  
   * PRIMARY THREATS INCLUDE...
     SEVERAL TORNADOES WITH A FEW INTENSE TORNADOES POSSIBLE
     SEVERAL VERY LARGE HAIL EVENTS TO 2.5 INCHES IN DIAMETER
       POSSIBLE
     SEVERAL DAMAGING WIND GUSTS TO 70 MPH POSSIBLE
  
   THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 75 STATUTE
   MILES EAST AND WEST OF A LINE FROM 15 MILES NORTH OF BARTLESVILLE
   OKLAHOMA TO 30 MILES SOUTH SOUTHWEST OF WICHITA FALLS TEXAS.  FOR
   A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
   OUTLINE UPDATE (WOUS64 KWNS WOU6).
  
   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.
 

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OK/TX watch probs don't really jive with 15% hatched on the outlook. If anything, a downgrade to 10% may be possible on the 20 UTC outlook down S. The watch text reflects the concerns hinted at by the last few runs of the RAP/HRRR of the front advancing southward much earlier than previously expected and undercutting nearby storms. Really thinking we'll need something to come off the DL in NW TX for a big event.

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OK/TX watch probs don't really jive with 15% hatched on the outlook. If anything, a downgrade to 10% may be possible on the 20 UTC outlook down S. The watch text reflects the concerns hinted at by the last few runs of the RAP/HRRR of the front advancing southward much earlier than previously expected and undercutting nearby storms. Really thinking we'll need something to come off the DL in NW TX for a big event.

Doesn't jive with the hail probs either, only 40/40, and hail has always been a huge threat, hence the 45% hatched. So I don't know if I would put too much into the lower probs at this point.

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OK/TX watch probs don't really jive with 15% hatched on the outlook. If anything, a downgrade to 10% may be possible on the 20 UTC outlook down S. The watch text reflects the concerns hinted at by the last few runs of the RAP/HRRR of the front advancing southward much earlier than previously expected and undercutting nearby storms. Really thinking we'll need something to come off the DL in NW TX for a big event.

 

I feel like based on the outlook wording that they expect the most significant tornadic storms to form this evening when the LLJ really kicks in.  Based on the previous outlook, at least.  Although, the newer outlook also seems to infer the more substantial risk also lingering into the night.

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SGF special 18z sounding says Yikes.

 

 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
149 PM CDT WED APR 17 2013

.MESOSCALE DISCUSSION...
ISSUED AT 135 PM CDT WED APR 17 2013

18Z SPECIAL WEATHER BALLOON RELEASE SHOWING A VERY UNSTABLE
ATMOSPHERE PRIMED FOR STRONG TO SEVERE CONVECTION DEVELOPMENT.
CAPE VALUES APPROACHING 3000 TO 3500 J/KG ACROSS SOUTHERN
MISSOURI. SURFACE TEMPERATURES HAVE WARMED UP INTO THE LOWER 80S
WITH DEWPOINTS IN THE MIDDLE 60S. THE CAP IS WEAKENING AND WAS
AROUND -20 J/KG. 0-3KM STORM RELATIVE HELICITY VALUES ARE 250
M2/S2. PW VALUES AROUND 1.25 INCHES. STEEP LAPSE RATES ON THE
ORDER OF 8C/KM. WATER VAPOR IMAGERY IS SHOWING A WEAK MID LEVEL
WAVE OVER NORTHERN OKLAHOMA MOVING NORTHEAST AND WILL MOVE ACROSS
OUR WESTERN HALF OF THE AREA THIS AFTERNOON WHICH WILL HELP IN THE
DEVELOPMENT OF CONVECTION.

RADAR IS CURRENTLY SHOWING AN AREA OF STRONG CONVECTION ACROSS
WEST CENTRAL MISSOURI MOVING TOWARDS CENTRAL MISSOURI AT THIS
TIME. FOR THE NEXT COUPLE OF HOURS...EXPECT SCATTERED SHOWERS AND
THUNDERSTORMS TO CONTINUE TO DEVELOP MAINLY OVER SOUTHEAST KANSAS
AND FAR WESTERN MISSOURI THROUGH MID AFTERNOON. THERE WILL BE A
CONCERN FOR AN ISOLATED SUPERCELL POTENTIAL WHICH WILL BE ABLE TO
PRODUCE VERY LARGE HAIL...DAMAGING WIND GUSTS UP TO 70 MPH...AND
ISOLATED TORNADOES THROUGH THE REST OF THE AFTERNOON.

 

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I feel like based on the outlook wording that they expect the most significant tornadic storms to form this evening when the LLJ really kicks in.  Based on the previous outlook, at least.  Although, the newer outlook also seems to infer the more substantial risk also lingering into the night.

I also simply wouldn't be surprised if the bigger threat ends up in MO.  The low-levels are primed and once the better UL support moves it, it could be a hell of an evening up there.

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OK/TX watch probs don't really jive with 15% hatched on the outlook. If anything, a downgrade to 10% may be possible on the 20 UTC outlook down S. The watch text reflects the concerns hinted at by the last few runs of the RAP/HRRR of the front advancing southward much earlier than previously expected and undercutting nearby storms. Really thinking we'll need something to come off the DL in NW TX for a big event.

Give the issues with the forecast, I wouldn't give that a second thought at this point.  I've seen them upgrade watches to PDS in the past or reissue the watch when more substantive data becomes available.  They could downgrade the Tor probs at 3pm but I doubt we see that at this point.

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BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE NORMAN OK

155 PM CDT WED APR 17 2013

 

THE NATIONAL WEATHER SERVICE IN NORMAN HAS ISSUED A

 

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTHEASTERN GREER COUNTY IN SOUTHWEST OKLAHOMA...
  NORTHEASTERN JACKSON COUNTY IN SOUTHWEST OKLAHOMA...
  NORTHWESTERN KIOWA COUNTY IN SOUTHWEST OKLAHOMA...
  SOUTHWESTERN WA****A COUNTY IN WESTERN OKLAHOMA...

 

* UNTIL 245 PM CDT

 

* AT 153 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
  SEVERE THUNDERSTORM LOCATED NEAR BLAIR...MOVING NORTHEAST AT 45
  MPH.
 
HAZARDS IN THE WARNING INCLUDE...
LARGE HAIL UP TO PING PONG BALL SIZE...
DAMAGING WINDS IN EXCESS OF 60 MPH...
                                                                                                                                               
* LOCATIONS IMPACTED INCLUDE...
  HOBART...GRANITE...BLAIR...MOUNTAIN VIEW...SENTINEL...LONE WOLF...
  GOTEBO...MARTHA...ROCKY...WARREN...ALTUS-LUGERT LAKE AND HESTER.

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No, it's the actual front.

 

Those cells are gone-rs already.

 

The one S of the Red initiated in the open warm sector away from the front, so if it can turn right a bit over the next hour, it may not be a goner. Time will tell. Still suspect the best potential will be with storms that fire in the same region (and slightly S) but a couple hours from now.

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Can we not start with this before the first storm even forms in OK/TX?

 

Meh, we get this all the time. Moderate risk doesn't equal tornadoes. The hail probabilities still support the moderate risk, but sometimes the thought is that SPC exists solely to point chasers in the right direction.

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