MD 1811 CONCERNING SEVERE POTENTIAL…WATCH POSSIBLE FOR SWRN INTO CNTRL IA / FAR NWRN MO / FAR SERN NEB / FAR NERN KS
MESOSCALE DISCUSSION 1811
NWS STORM PREDICTION CENTER NORMAN OK
0547 PM CDT THU SEP 17 2015
AREAS AFFECTED...SWRN INTO CNTRL IA / FAR NWRN MO / FAR SERN NEB /
FAR NERN KS
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 172247Z - 180045Z
PROBABILITY OF WATCH ISSUANCE...40 PERCENT
SUMMARY...THE POSSIBILITY FOR CONVECTIVE INITIATION WILL BE
MONITORED IN THE SHORT TERM AND UNCERTAINTY IS APPRECIABLY HIGH. IF
STORMS CAN DEVELOP AND SUBSEQUENTLY TAP THE UNSTABLE BOUNDARY
LAYER...THEN AN ISOLD SEVERE THREAT WILL PROBABLY EVOLVE.
DISCUSSION...VISIBLE SATELLITE TRENDS LATE THIS AFTERNOON SHOW A
SWELLING CU FIELD OVER SWRN IA INTO NERN KS. A FRACTURED FRONT HAS
BEEN ANALYZED EXTENDING FROM CNTRL IA SWWD INTO SERN NEB AND NRN KS
WHILE ANOTHER FRONTAL SEGMENT IS ANALYZED FROM S-CNTRL MN SSWWD INTO
W-CNTRL IA AND ERN NEB. IT APPEARS A CONSOLIDATION OF THE
BOUNDARIES WILL EVENTUALLY OCCUR THIS EVENING AND A BETTER LOW-LEVEL
FOCUS FOR ASCENT WILL MATERIALIZE AND BECOME BETTER CO-LOCATED WITH
A LLJ OVER SRN IA/NRN MO BY EARLY EVENING.
RAP-BASED OBJECTIVE ANALYSIS FIELDS SHOW A GRADUAL REDUCTION IN LFC
HEIGHTS THIS AFTERNOON OVER THE REGION WITH WEAK CINH. WHILE THE
PASSAGE OF A MID-LEVEL TROUGH TO THE ENE HAS DELAYED STORM
INITIATION...IT SEEMS PLAUSIBLE STORM INITIATION MAY OCCUR OVER THE
NEXT HOUR IN THE WARM SECTOR S OF AN OUTFLOW BOUNDARY OVER CNTRL AND
ERN IA. RECENT ITERATIONS OF THE OPERATIONAL HRRR ARE SUGGESTING
THE POSSIBILITY FOR STORMS MAY BE INCREASING AND IS AT LEAST
PARTIALLY SUPPORTED WITH A SWELLING CU FIELD.
IF/ONCE STORMS DEVELOP...THE ISOLD SEVERE THREAT WILL PARTIALLY BE
DEPENDENT ON THE ABILITY FOR STORMS TO ROOT IN THE BOUNDARY LAYER.
IF THIS OCCURS...AN ISOLD LARGE HAIL/DMGG WIND THREAT COULD DEVELOP
WITH THE STRONGER STORMS. GIVEN THE LARGE UNCERTAINTY AT THIS
TIME...WILL MONITOR OBSERVATIONAL TRENDS IN THE SHORT TERM.
..SMITH/EDWARDS.. 09/17/2015
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...DMX...EAX...OAX...TOP...
LAT...LON 39999669 41809417 41709327 41129309 39909436 39709560
39999669
from SPC Mesoscale Discussions http://1.usa.gov/1MtLxqC
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