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Southern/Central Plains Obs and Short Term Discussions


OKpowdah

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I figured we could use a thread to post general obs and short term discussion in the southern / central Plains area. Basically a thread to cover the garden variety slight risk days, so we don't clutter the long range thread with that stuff.

 

SPC has a slight risk up for most of Oklahoma for late today and tonight. Last update included a small 30% hail area.

DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1118 AM CDT FRI APR 26 2013
   
   VALID 261630Z - 271200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS LATE THIS AFTERNOON THROUGH
   TONIGHT ACROSS MUCH OF OK...
   
   ...OK...
   MORNING WATER VAPOR LOOPS SHOW A WELL-DEFINED SHORTWAVE TROUGH OVER
   EASTERN NM AND THE TX PANHANDLE.  THIS FEATURE WILL TRACK EASTWARD
   AND ACROSS THE SOUTHERN PLAINS TODAY INTO TONIGHT.  AHEAD OF THE
   TROUGH...SOUTHERLY LOW LEVEL WINDS ARE TRANSPORTING MOISTURE
   NORTHWARD ACROSS TX/OK WITH DEWPOINTS RISING THROUGH THE 50S.  LOW
   CLOUDS ARE SLOWLY ERODING OVER WESTERN OK AND WESTERN NORTH TX...BUT
   ARE LIKELY TO PERSIST MOST OF THE DAY OVER THE BULK OF OK.  THIS
   WILL LIMIT DAYTIME HEATING AND KEEP A SUBSTANTIAL CAPPING INVERSION
   IN PLACE THROUGH 00Z.
   
   BY EARLY EVENING...LIFT ASSOCIATED WITH THE NM/TX TROUGH WILL
   OVERSPREAD THE MOIST AXIS OVER OK.  LARGE SCALE ASCENT WILL LIKELY
   RESULT IN A RAPID WEAKENING OF THE CAP AND SCATTERED THUNDERSTORM
   DEVELOPMENT OVER NORTHWEST AND CENTRAL OK.  FORECAST SOUNDINGS SHOW
   STEEP MID LEVEL LAPSE RATES AND ELEVATED MUCAPE VALUES OF 1500+
   J/KG.  FAVORABLE EFFECTIVE SHEAR VALUES WILL PROMOTE SUPERCELL STORM
   STRUCTURES CAPABLE OF HAIL.  WHILE DAMAGING WINDS AND TORNADOES ARE
   NOT OUT OF THE QUESTION...IT APPEARS THAT LARGE HAIL WILL BE THE
   MAIN THREAT TODAY.
   
   THE SUITE OF STORM-SCALE MODEL SOLUTIONS THIS MORNING /NAM
   NESTS...NMM...NSSL...HRRR/ SHOW STRONG AGREEMENT IN A NARROW
   CORRIDOR OF GREATEST RISK OF SUPERCELL STORMS THIS EVENING AFTER
   00Z.  THIS AREA OF WESTERN/CENTRAL OK HAVE BEEN INCLUDED IN A 30
   PERCENT HAIL RISK.
   
   ..HART/GARNER.. 04/26/2013

Here's the impulse on water vapor:

 

post-128-0-65213300-1366998609_thumb.gif

 

12z sounding from Norman:

 

post-128-0-91184700-1366999067_thumb.gif

 

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I noticed that this morning. Seems like multiple hi-res models are focusing on OKC this evening. Another local chase seems to be in order!

By the way, congratulations on the promotion! It's great to have a severe-weather junkie on staff!

 

Yeah, the HRRR seems consistent across OKC the past handful of runs, too. 

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I noticed that this morning. Seems like multiple hi-res models are focusing on OKC this evening. Another local chase seems to be in order!

By the way, congratulations on the promotion! It's great to have a severe-weather junkie on staff!

 

NSSL WRF and HRRR both have at least some degree of this also, from a clear supercell to a kind in a line. Another local chase sounds good to me too

 

And thanks!!

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Latest OUN WRF shows a nasty updraft by 8 PM west of OKC on I-40. Looks to roll right into the city around 10 PM. I'll probably leave Norman by 4 to get out towards Clinton.

 

 

Sounds like a good plan. Cu field building back over the TX panhandle now.

 

RAP forecast soundings near Norman aren't half bad. Lots of elevated instability, and strong helicity

post-128-0-48988000-1367006595_thumb.png

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Another pic out of Edmond, from @lancewest on Twitter  -- 

 

934989_10151434769529200_1059097215_n.jp

 

Plains storms sure don't mess around, ha. 

 

We got 0.72" in 10 minutes here and gusted to 51MPH. Loving the rain though -- at this rate we'll possibly be officially out of drought next time the USGS updates! 

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So, Mr. Reimer. How did that 59 mph wind driven hail go over? I saw that LSR..

 

Pretty freaky actually! The storm was about three miles north of the front at the time I intercepted it. We had a sharp inversion with about two mile visibility. As the storm hit, it went from light, to pitch black (dead of night black), and then to bright green. Needless to say, it was a creepy experience and one I won't forget anytime soon. Hail remained around half-dollar size, but the wind made me think I was going to lose a few windows!

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It looks like the EdwardsPlateau and the Balcones Escarpment will be the areas to watch this afternoon into the overnight hours for strong storms with large hail and possibly damaging winds being the primary threat. I am somewhat concerned that training may become an issue along the sagging boundary across that Region with some flash flood potential developing.

 

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MESOSCALE DISCUSSION 0564
NWS STORM PREDICTION CENTER NORMAN OK
0336 PM CDT SAT APR 27 2013

AREAS AFFECTED...SRN EDWARDS PLATEAU INTO NRN PARTS OF SOUTH CENTRAL
AND SOUTH TX

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 272036Z - 272200Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...THE SRN EDWARDS PLATEAU INTO NRN PORTIONS OF SOUTH CENTRAL
AND SOUTH TX ARE BEING MONITORED FOR CONVECTIVE DEVELOPMENT THIS
AFTERNOON...AND THE POTENTIAL NEED FOR A ONE OR MORE WATCHES.
TRENDS WITH TSTM DEVELOPMENT OVER THE HIGHER TERRAIN OF COAHUILA
MEXICO WILL NEED TO BE MONITORED AS WELL FOR POTENTIAL SEVERE
WEATHER THREAT...IF ACTIVITY CAN REACH THE LOWER RIO GRANDE VALLEY
AREA OF S TX.

DISCUSSION...EARLY-MID AFTERNOON SURFACE ANALYSES INDICATED A FRONT
CONTINUED TO MOVE SLOWLY E/SEWD ACROSS ERN AND CENTRAL TX.  AT
20Z...THIS BOUNDARY EXTENDED FROM THE ARKLATEX REGION SWWD TO 50 S
OF KCRS...AND THEN WSWWD ACROSS THE SRN EXTENT OF THE EDWARDS
PLATEAU TO THE RIO GRANDE RIVER VICINITY OF WRN VAL VERDE COUNTY. A
MOIST/WARM BOUNDARY LAYER WITH SURFACE TEMPERATURES IN THE UPPER 70S
TO LOWER 80S ALONG AND S OF THE FRONT IS CONTRIBUTING TO MODERATE
INSTABILITY /MLCAPE 2000-2500 J PER KG/...GIVEN THE PRESENCE OF
STEEP MIDLEVEL LAPSE RATES.

OBJECTIVE ANALYSES INDICATED WEAK DEEP LAYER CONVERGENCE ALONG THE
FRONT WHICH APPEARS TO BE LIMITING THE DEVELOPMENT OF SURFACE BASED
CONVECTION THUS FAR ACROSS THE DISCUSSION AREA.  REGIONAL RADAR
IMAGERY SHOWED A COUPLE OF TSTMS HAD DEVELOPED WITHIN A PLUME OF
ELEVATED CONVECTION N OF THE FRONT THIS AFTERNOON.  THE MOST RECENT
STORMS COULD BE NEARLY SURFACE BASED IN WILLIAMSON AND TRAVIS
COUNTIES TX...GIVEN ITS LOCATION NEAR THE FRONT.  ADDITIONAL STORMS
LOCATED TO THE NW TO W OF THE HOUSTON METRO AREA SHOULD CONTINUE TO
PROPAGATE NWWD LATE THIS AFTERNOON INTO A MORE FAVORABLE CAPE/SHEAR
SPACE SUPPORTIVE OF MORE PERSISTENT/ORGANIZED UPDRAFTS THAT COULD
RESULT IN A HAIL THREAT.

MEANWHILE...IF GREATER COVERAGE OF CONVECTIVE DEVELOPMENT OCCURS
NEAR AND S OF THE FRONT...THE PRESENCE OF STRONG INSTABILITY AND
EFFECTIVE BULK SHEAR OF 30-40 KT WILL SUPPORT ORGANIZED STRONG TO
SEVERE STORMS.  THUS...THE DISCUSSION AREA IS BEING MONITORED FOR
THE POTENTIAL ISSUANCE OF ONE OR MORE WATCHES.

..PETERS/HART.. 04/27/2013

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...HGX...FWD...EWX...SJT...
 

 

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