Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 042219
SWOMCD
SPC MCD 042218
SDZ000-NEZ000-COZ000-050015-

MESOSCALE DISCUSSION 1298
NWS STORM PREDICTION CENTER NORMAN OK
0518 PM CDT SAT JUL 04 2015

AREAS AFFECTED...PORTIONS OF SWRN SD...WRN NEB...AND NERN CO

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 042218Z - 050015Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...WHILE COVERAGE OF STORMS REMAINS IN QUESTION...THE SEVERE
POTENTIAL IS INCREASING...WITH LARGE HAIL AND DAMAGING WINDS THE
MAIN THREATS. WW ISSUANCE IS POSSIBLE.

DISCUSSION...VISIBLE SATELLITE IMAGERY AND AREA RADARS SHOW A
THUNDERSTORM WHICH HAS RECENTLY DEVELOPED OVER THE WRN NEB
PANHANDLE...WITH ADDITIONAL CUMULUS DEVELOPMENT OCCURRING WWD INTO
E-CNTRL WY AND OVER THE BLACK HILLS OF WRN SD. A FAVORABLE
THERMODYNAMIC AND KINEMATIC ENVIRONMENT CHARACTERIZED BY MLCAPE OF
1500-3000 J/KG AND 40-50 KT OF EFFECTIVE BULK SHEAR WILL SUPPORT
SUPERCELL THUNDERSTORM STRUCTURES ACROSS THE MCD AREA. RELATIVELY
STEEP MID-LEVEL LAPSE RATES OF 7.0 TO 7.5 DEG C/KM PER RAP
MESOANALYSIS AND MODERATE TO STRONG INSTABILITY SHOULD SUPPORT LARGE
HAIL..SOME POSSIBLE GREATER THAN 2 INCHES IN DIAMETER...WITH THE
STRONGEST CORES. A WELL-MIXED BOUNDARY LAYER WITH NEAR-DRY ADIABATIC
LOW-LEVEL LAPSE RATES PER FORECAST SOUNDINGS SHOULD ALSO ENCOURAGE
THE DEVELOPMENT OF STRONG TO SEVERE DOWNDRAFT WINDS. GIVEN SLY
LOW-LEVEL WINDS VEERING WITH HEIGHT TO WLY/NWLY...EFFECTIVE SRH OF
100-150 M2/S2 ACROSS THE WRN NEB PANHANDLE AND INCREASING WITH EWD
EXTENT MAY BE ENOUGH TO SUPPORT AN ISOLATED TORNADO THREAT AS WELL
WITH ANY DISCRETE STORMS.

SYNOPTIC-SCALE ASCENT ASSOCIATED WITH AN UPPER LEVEL TROUGH MOVING
OVER CANADA REMAINS GENERALLY DISPLACED TO THE N...WITH OROGRAPHIC
FORCING THE MAIN FOCUS FOR CONVECTIVE DEVELOPMENT THUS FAR. EVENTUAL
CONVECTIVE COVERAGE ACROSS THE MCD AREA THIS EVENING REMAINS
UNCLEAR...WITH SOME SHORT-TERM CONVECTION ALLOWING MODEL GUIDANCE
SUGGESTING STORMS WILL REMAIN TOO ISOLATED FOR A WW...AND OTHERS
SHOWING MORE SCATTERED COVERAGE AND EVENTUAL UPSCALE GROWTH INTO AN
MCS ACROSS SWRN NEB/NERN CO LATER THIS EVENING. DEPENDING ON
CONVECTIVE TRENDS OVER THE NEXT TWO HOURS...WW ISSUANCE IS POSSIBLE.

..GLEASON/THOMPSON.. 07/04/2015

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

ATTN...WFO...ABR...LBF...UNR...GLD...BOU...CYS...

LAT...LON   41030394 42540395 44220346 44420232 44310104 41690090
            40710108 40170199 40360336 41030394



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