SPC MD 1634

MD 1634 CONCERNING SEVERE POTENTIAL…WATCH LIKELY FOR CENTRAL SD

MESOSCALE DISCUSSION 1634
NWS STORM PREDICTION CENTER NORMAN OK
0401 PM CDT SUN SEP 04 2016

AREAS AFFECTED...CENTRAL SD

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 

VALID 042101Z - 042230Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...A NEW SEVERE-WEATHER WATCH WILL LIKELY BE NEEDED TO THE
EAST/NORTHEAST OF WW 465 ACROSS MAINLY CENTRAL SD THROUGH THIS
EVENING.  IF CURRENT TRENDS OF INCREASING STORMS/INTENSITY PERSIST
ACROSS THE NORTH AND NORTHEAST PORTIONS OF WW 465...THEN THIS WATCH
ISSUANCE WILL NEED TO OCCUR SOONER THAN PREVIOUSLY EXPECTED.

DISCUSSION...TRENDS IN MOSAIC RADAR IMAGERY...SINCE 20Z...SHOWED AN
INCREASE IN STORM DEVELOPMENT/INTENSITY...WHILE IR SATELLITE IMAGERY
INDICATED RAPIDLY COOLING CLOUD TOPS WITH THESE STORMS IN OGLALA
LAKOTA TO JACKSON COUNTIES SOUTH DAKOTA.  THESE STORMS WERE LOCATED
IN VICINITY OF A SURFACE BOUNDARY EXTENDING SOUTHWESTWARD FROM AN
AREA OF LOW PRESSURE IN CENTRAL SD /NEAR PIR/...WITH THIS SAME
BOUNDARY EXTENDING TO THE NORTHEAST INTO NORTH-CENTRAL SD TO EASTERN
ND.  THE AIR MASS FROM CENTRAL/WESTERN NEB THROUGH CENTRAL SD HAS
BECOME MODERATELY UNSTABLE WITH SOME INCREASE IN BULK SHEAR
EXPECTED.  GIVEN THE LIKELIHOOD FOR ONGOING STORMS AND ADDITIONAL
STORM DEVELOPMENT TO SPREAD INTO CENTRAL SD THROUGH THIS EVENING...A
NEW WW WILL BE NEEDED...WITH THAT ISSUANCE POSSIBLE SOONER...IF
STRONGER STORM INTENSITIES IN NORTHERN PART OF 465 ARE SUSTAINED IN
THE SHORT TERM.  SEVERE HAIL AND DAMAGING WINDS WILL BE THE PRIMARY
THREATS DOWNSTREAM OF WW 465.

..PETERS/HART.. 09/04/2016

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

ATTN...WFO...FSD...ABR...UNR...

LAT...LON   44720114 45939946 45889878 45919784 44749809 43659849
            43359888 43169928 43630037 44040109 44720114 

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