MESO: Mesoscale Discussion 1868

ACUS11 KWNS 030248
SWOMCD
SPC MCD 030248
ALZ000-MSZ000-ARZ000-030345-

MESOSCALE DISCUSSION 1868
NWS STORM PREDICTION CENTER NORMAN OK
0948 PM CDT SUN SEP 02 2012

AREAS AFFECTED...NRN MS...NWRN AL

CONCERNING...TORNADO WATCH 609...

VALID 030248Z - 030345Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 609 CONTINUES.

SUMMARY...ENHANCED POTENTIAL FOR DAMAGING WIND DURING THE NEXT HOUR
AND THEN A GRADUALLY DIMINISHING THREAT AS THE MCS GRADUALLY
WEAKENS. A BRIEF TORNADO OR TWO IS ALSO POSSIBLE ALONG THE LEADING
EDGE OF THE SYSTEM.

DISCUSSION...MCS OVER NRN MS HAS EXHIBITED BOTH FORWARD-PROPAGATION
AND UPWIND PROPAGATION DURING THE PAST FEW HOURS. THE
FORWARD-PROPAGATING PORTION OF MCS QUICKLY PUSHED S FROM N-CNTRL IN
NERN MS /NEAR AND E OF/ DURING THE PAST HOUR WHILE THE SYSTEM SHOWED
SOME UPWIND PROPAGATION ACROSS NWRN MS. AS A RESULT...THE PRIMARY
SEVERE THREAT IS LOCATED ALONG AND AHEAD OF THE FORWARD-PROPAGATING
PORTION. RECENT GWX BASE VELOCITY DATA DEPICTED A LARGE AREA OF
ENHANCED VELOCITIES MOVING SWD ACROSS PONTOC...LEE...AND ITAWAMBA
COUNTIES IN MS INTO MONROE CO MS AND LAMAR CO AL. THE ENHANCED
DAMAGING WIND THREAT IS EXPECTED TO GRADUALLY DIMINISH AS THE
BOUNDARY LAYER CONTINUES TO COOL/DECOUPLE. GWX REFLECTIVITY DATA
SHOWS THE COLD POOL IS BEGINNING TO ACCELERATE AHEAD OF THE MAIN
LINE...ELEVATING CONFIDENCE IN THE ANTICIPATED WEAKENING TREND. AS
SUCH...A DOWNSTREAM WATCH IS NOT CURRENTLY ANTICIPATED BUT
CONVECTIVE TRENDS WILL BE MONITORED FOR ANY SIGNS THE THREAT WILL
EXTEND S OF THE CURRENT WATCH AREA.

FARTHER NW /NWRN MS/...THE UPWIND-PROPAGATING PORTION OF THE LINE
WILL CONTINUE TO POSE A FLASH FLOOD THREAT AS HEAVY RAIN REMAINS
OVER THE SAME AREA FOR A PROLONGED PERIOD OF TIME.

..MOSIER.. 09/03/2012

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

ATTN...WFO...BMX...HUN...MEG...JAN...LZK...

LAT...LON 34999026 34998819 34878811 34348816 34308711 34028716
33878704 33858694 33748699 33668708 33588717 33518729
33618738 33638763 33528768 33548827 33298829 33298910
33308935 33298969 33228976 33359021 33339077 33529077
33549120 33799109 34009096 34189083 34469068 34669054
34889037 34999026

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