ZCZC SPCSWOMCD ALL
ACUS11 KWNS 012050 
SPC MCD 012050 
MNZ000-IAZ000-NEZ000-SDZ000-KSZ000-012245-

MESOSCALE DISCUSSION 0177
NWS STORM PREDICTION CENTER NORMAN OK
0350 PM CDT WED APR 01 2015

AREAS AFFECTED...NRN KS...CNTRL/ERN NEB...FAR SERN SD...NWRN
IA...SWRN MN

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 012050Z - 012245Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...THE POTENTIAL FOR WIDESPREAD TSTM INITIATION IS BEING
MONITORED ALONG A COLD FRONT... WHICH MAY OCCUR WITHIN THE NEXT 1-2
HRS. DESPITE A MARGINAL THERMODYNAMIC ENVIRONMENT...THE POTENTIAL
WILL EXIST FOR STRONG-SVR WIND GUSTS AND INSTANCES OF LARGE HAIL.
TRENDS ARE BEING MONITORED FOR A POSSIBLE WW.

DISCUSSION...WEAK CU DEVELOPMENT HAS RECENTLY BEEN NOTED BENEATH
SCATTERED MID-HIGH LEVEL CLOUDS ACROSS NERN NEB INTO SERN SD...ALONG
A SEWD PROGRESSING COLD FRONT WHICH EXTENDS SWWD TO A SFC LOW OVER
NWRN KS. A FEW LIGHTNING STRIKES HAVE ALSO BEEN NOTED IN ASSOCIATION
WITH CONVECTION DEVELOPING NEAR A WEAK SFC LOW OVER NWRN KS. TRENDS
IN SFC OBS SHOW WEAK LOW-LEVEL MOIST ADVECTION BEING OFFSET BY DEEP
BOUNDARY-LAYER MIXING...WITH DEW POINTS ONLY IN THE UPPER 30S TO MID
40S F AHEAD OF THE COLD FRONT. ALSO OF NOTE...MODEL GUIDANCE HAS HAD
DIFFICULTY ACCURATELY DEPICTING THE MAGNITUDE OF BOUNDARY-LAYER
MOISTURE...WITH THE NAM AND GFS TOO MOIST...AND THE RAP TOO DRY. 

LATEST THINKING IS THAT WIDESPREAD CONVECTIVE INITIATION COULD OCCUR
BY 23Z AS WEAK ASCENT/MIDLEVEL HEIGHT FALLS ALONG THE SRN PERIPHERY
OF A NRN ROCKIES/PLAINS SHORTWAVE OVERSPREADS THE AREA. DESPITE
MEAGER BOUNDARY-LAYER MOISTURE...VERY STEEP MIDLEVEL LAPSE RATES
/OVER 8 C/KM/ ARE STILL YIELDING MLCAPE VALUES OF 500-800 J/KG.
GIVEN THE HIGH-BASED NATURE OF CONVECTION...COMBINED WITH 20-30 KT
OF AMBIENT LOW-LEVEL FLOW...STRONG TO SVR WIND GUSTS SHOULD BE THE
PRIMARY THREAT. HAIL MAY ALSO ACCOMPANY MORE ROBUST DISCRETE
DEVELOPMENT INITIALLY...BUT THE DEGREE OF LOW-LEVEL FRONTAL FORCING
SHOULD EVENTUALLY RESULT IN CONSOLIDATION INTO A MORE LINEAR MODE. 

TRENDS WILL CONTINUE TO BE MONITORED FOR SIGNS OF INCREASING TSTM
DEVELOPMENT...WHICH COULD PROMPT ISSUANCE OF A WW...POSSIBLY BY 23Z.

..ROGERS/HART.. 04/01/2015

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

ATTN...WFO...MPX...DMX...FSD...OAX...TOP...GID...LBF...DDC...
GLD...

LAT...LON   43979413 41689524 40039774 38920031 38730102 38890136
            39660060 41739857 43599668 44549630 44849559 44659496
            43979413 

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