MESO: Mesoscale Discussion 1335

ACUS11 KWNS 171933
SWOMCD
SPC MCD 171933
SDZ000-NDZ000-172100-

MESOSCALE DISCUSSION 1335
NWS STORM PREDICTION CENTER NORMAN OK
0233 PM CDT SAT JUL 17 2010

AREAS AFFECTED...SERN ND...NERN SD THROUGH CNTRL MN

CONCERNING...TORNADO WATCH 483...

VALID 171933Z - 172100Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 483 CONTINUES.

THREAT FOR LARGE HAIL...DAMAGING WIND AND ISOLATED TORNADOES WILL
PERSIST NEXT SEVERAL HOURS WITH STORMS DEVELOPING SEWD THROUGH CNTRL
AND TOWARD SERN MN. WW 483 MAY NEED TO BE LOCALLY EXTENDED TO
INCLUDE THE MINNEAPOLIS METRO AREA. OTHER STORMS ARE EXPECTED TO
DEVELOP PRIOR TO 21Z FROM SERN ND INTO NERN SD AND MOVE INTO WW 483.

A CONVECTIVELY REINFORCED WARM FRONT EXTENDS ACROSS CNTRL MN NWWD
INTO SERN ND. A PRE-FRONTAL CONVERGENCE BOUNDARY STRETCHES FROM
E-CNTRL ND SWD THROUGH CNTRL SD. A RESERVOIR OF 3000-4000 J/KG
MLCAPE EXIST IN WARM SECTOR BETWEEN THESE BOUNDARIES. STORMS
CONTINUE DEVELOPING WITHIN ZONE OF ISENTROPIC LIFT ASSOCIATED WITH A
SSWLY LOW-LEVEL JET INTERSECTING THE WARM FRONT ACROSS CNTRL AND
E-CNTRL MN. STORMS ARE SUBSEQUENTLY MOVING SEWD ALONG INSTABILITY
GRADIENT TOWARD SERN MN. SUPERCELLS WITH LARGE HAIL...DAMAGING WIND
AND ISOLATED TORNADOES WILL REMAIN A THREAT INTO THE EVENING.

FARTHER WEST...VISIBLE IMAGERY SHOWS CUMULUS INCREASING WITHIN
PRE-FRONTAL CONVERGENCE ZONE FROM SERN ND INTO N-CNTRL SD. THE 18Z
RAOB FROM ABERDEEN STILL SHOWED A CAPPING INVERSION AROUND 850 MB.
HOWEVER...DEEPER FORCING FOR ASCENT WILL INCREASE IN ASSOCIATION
WITH SHORTWAVE TROUGH MOVING EWD THROUGH SASKATCHEWAN AND NRN ND
WHICH WILL FORCE A BAROCLINIC ZONE SEWD THROUGH THE DAKOTAS.
EFFECTIVE SHEAR OF 40-50 KT WILL SUPPORT SUPERCELLS WITH INITIAL
STORMS THAT DEVELOP...BUT SOME OF THE STORMS MAY EVENTUALLY GROW
UPSCALE INTO AN MCS. TORNADOES...LARGE HAIL AND DAMAGING WIND WILL
BE POSSIBLE AS ACTIVITY DEVELOPS ESEWD.

..DIAL.. 07/17/2010

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

ATTN...WFO...FGF...ABR...BIS...

LAT...LON 45129923 45889881 46629846 46359750 45169823 44859886
45129923

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