Mesoscale Discussion 1864

Issued

Sep 2, 2012, 6:35 PM CDT (23:35 UTC)

Expired

Sep 2, 2012, 8:00 PM CDT

In force

85 min

Issued by

the Storm Prediction Center

The Nashville radar (KOHX), 40 km from the middle of the area, began a volume at 23:37 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

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467 
ACUS11 KWNS 022335
SWOMCD
SPC MCD 022335 
KYZ000-TNZ000-ALZ000-MSZ000-030100-

MESOSCALE DISCUSSION 1864
NWS STORM PREDICTION CENTER NORMAN OK
0635 PM CDT SUN SEP 02 2012

AREAS AFFECTED...CNTRL KY...MIDDLE TN...NRN AL

CONCERNING...TORNADO WATCH 608...

VALID 022335Z - 030100Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 608 CONTINUES.

SUMMARY...AN ELEVATED THREAT FOR DAMAGING WINDS AS WELL AS A TORNADO
OR TWO CONTINUES ACROSS TOR WATCH 608. MOST ROBUST ACTIVITY REMAINS
CONFINED TO THE SRN PORTION OF THE WATCH AREA /ACROSS MIDDLE TN AND
NRN AL/.

DISCUSSION...EARLIER ACTIVITY ACROSS NRN AL HAS GROWN UPSCALE INTO A
FORWARD-PROPAGATING MCS WITH A PRIMARY THREAT OF DAMAGING WINDS.
MOST OF THE THIS ACTIVITY SHOULD MOVE S OF THE WATCH AREA AND INTO
ADDITIONAL WATCHES DURING THE NEXT HOUR. ADDITIONAL ACTIVITY HAS
DEVELOPED ACROSS MIDDLE TN AMIDST MODEST LOW-LEVEL CONVERGENCE
/EVIDENCED BY SLY WINDS AT KTHA AND WLY WINDS AT KMQY/. MID TO UPPER
LEVEL WIND FIELDS HAVE CHANGED LITTLE OVER THE PAST FEW HOURS AND
SFC WINDS ACROSS MOST OF MIDDLE TN REMAIN SLY. AS A
RESULT...LOW-LEVEL SHEAR AND SRH STILL REMAIN FAVORABLE FOR A FEW
CELLS TO EXHIBIT TRANSIENT ROTATION WITH THE POSSIBILITY OF A BRIEF
TORNADO. HOWEVER...THE LOSS OF SFC HEATING WILL CONTINUE TO REDUCE
THE INSTABILITY ACROSS THE AREA AND REDUCE OVERALL THE SEVERE
THREAT. PRIMARY THREAT APPEARS TO BE DAMAGING WINDS ASSOCIATED WITH
PRECIPITATION LOADING AND BRIEF ORGANIZATION ALONG ASSOCIATED COLD
POOLS.

FARTHER N /CNTRL KY/...THE THREAT IS BECOMING INCREASINGLY MARGINAL
AS VEERING WINDS REDUCE LOW-LEVEL SHEAR AND THE LOSS OF DAYTIME
HEATING REDUCES INSTABILITY.  

IN ADDITION TO THE SEVERE THREAT...A VERY MOIST ATMOSPHERIC PROFILE
/PWATS AROUND 2 INCHES/ WILL PROMOTE HEAVY RAINFALL WITH RAIN RATES
IN EXCESS OF 2 INCHES PER HOUR. SOME CELL TRAINING IS POSSIBLE WITH
THE POTENTIAL FOR ISOLATED FLASH FLOODING.

..MOSIER.. 09/02/2012

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

ATTN...WFO...RLX...MRX...JKL...ILN...LMK...OHX...HUN...MEG...

LAT...LON   34368830 38388508 38378324 34348655 34368830

Mesoscale Discussions in Kentucky, 2012Mesoscale Discussions in Tennessee, 2012Mesoscale Discussions in Alabama, 2012Every mesoscale discussion in 2012

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.