Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 212213
SWOMCD
SPC MCD 212212
INZ000-ILZ000-220015-

MESOSCALE DISCUSSION 1596
NWS STORM PREDICTION CENTER NORMAN OK
0512 PM CDT THU AUG 21 2014

AREAS AFFECTED...NERN IL...NRN INDIANA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 212212Z - 220015Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...CLUSTERS OF STORMS COULD ORGANIZE FURTHER FROM NRN IL INTO
INDIANA THIS EVENING...WITH AN INCREASING THREAT OF STRONG TO
DAMAGING WINDS AND MARGINALLY SEVERE HAIL.

DISCUSSION...A CLUSTER OF STORMS IS SLOWLY INCREASING IN SIZE SOUTH
OF THE CHICAGO AREA...WITH A MARKED INCREASE IN LIGHTNING ACTIVITY
AND ECHO TOPS. THESE STORMS ARE NEAR THE INSTABILITY GRADIENT ALONG
THE WARM FRONT...AND APPEAR TO BE SUPPORTED BY A WEAK DISTURBANCE
ALOFT WITH VEERING WINDS BEHIND THE SYSTEM.

AMPLE MOISTURE AND INSTABILITY EXISTS TO FUEL THESE CELLS...WITH
30-40 KT MID TO UPPER-LEVEL FLOW ATOP WEAK SELY SURFACE WINDS
HELPING TO ELONGATE HODOGRAPHS NEAR THE BOUNDARY. CURRENT TRENDS
SUGGEST FURTHER STRENGTHENING. THE PRIMARY HAZARD WILL BE LOCALLY
STRONG WINDS DEVELOPING AS A COLD POOL FORMS. HOWEVER...HAIL MAY
OCCUR WITH THE STRONGEST CORES GIVEN SUFFICIENT SHEAR FOR PERHAPS
SHORT-LIVED SUPERCELL STRUCTURES WITHIN THE CLUSTER.

..JEWELL/THOMPSON.. 08/21/2014

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

ATTN...WFO...ILN...IWX...IND...LOT...ILX...

LAT...LON   40558823 40838846 41248845 41438821 41528731 41728679
            41458573 40998522 40118485 39728486 39378530 39358597
            39578693 40208773 40558823



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