Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 210858
SWOMCD
SPC MCD 210858
WIZ000-MNZ000-IAZ000-211030-

MESOSCALE DISCUSSION 1592
NWS STORM PREDICTION CENTER NORMAN OK
0358 AM CDT THU AUG 21 2014

AREAS AFFECTED...PORTIONS OF CENTRAL/SOUTHERN MN AND FAR NORTHERN IA

CONCERNING...SEVERE THUNDERSTORM WATCH 470...

VALID 210858Z - 211030Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 470
CONTINUES.

SUMMARY...ISOLATED SEVERE HAIL AND LOCALIZED STRONG WIND GUSTS
REMAIN A POSSIBILITY ACROSS PORTIONS OF CENTRAL/SOUTHERN MN AND
EXTREME NORTHERN IA OVERNIGHT. SEVERE THUNDERSTORM WATCH 470
CONTINUES ACROSS PORTIONS OF MN UNTIL 12Z.

DISCUSSION...EARLIER SEMI-DISCRETE STRONG/OCCASIONALLY SEVERE
THUNDERSTORMS HAVE TENDED TO MERGE OVER THE PAST 1-2 HOURS...A TREND
THAT SHOULD GENERALLY CONTINUE THROUGH THE EARLY MORNING HOURS WITH
AT LEAST A SEMI-ORGANIZED MESOSCALE CONVECTIVE SYSTEM EVOLVING.
POTENTIALLY SEVERE HAIL...MAINLY IN A MARGINAL SENSE...WILL REMAIN A
POSSIBILITY PRIMARY ON THE SOUTHERNMOST FLANK OF THE EVOLVING MCS
ACROSS FAR SOUTHERN MN/FAR NORTHERN IA...IN PROXIMITY TO AN
RESERVOIR OF UNSTABLE AIR ABOVE THE BOUNDARY LAYER. AFOREMENTIONED
UPSCALE QUASI-LINEAR GROWTH SHOULD CONTINUE TO OCCUR IN VICINITY OF
A NORTHWARD-SHIFTING WARM FRONTAL SEGMENT ACROSS SOUTHERN MN...WHERE
A CORRIDOR OF 2+MB/2-HOUR PRESSURE FALLS ARE NOTED. THIS SCENARIO
WILL LIKELY BE AIDED BY AN MCV AND CONVECTIVELY ENHANCED WIND FIELD
AS EVIDENCED BY 40-50 KT LOW/MID TROPOSPHERIC WINDS AS PER WSR-88D
VWP DATA FROM SIOUX FALLS/ABERDEEN SD. WHILE THE STABILITY OF THE
BOUNDARY LAYER SHOULD LARGELY PRECLUDE SUCH...SOME STRONG DOWNDRAFTS
REACHING THE SURFACE CANNOT BE ENTIRELY DISCOUNTED IN VICINITY OF
THE WARM FRONT AS ADDITIONAL UPSCALE QUASI-LINEAR GROWTH OCCURS.

..GUYER.. 08/21/2014

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

ATTN...WFO...ARX...MPX...DMX...FSD...ABR...

LAT...LON   45539608 45829542 45349379 44459218 43739238 43119491
            43349570 44279560 44799635 45539608




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