MESOSCALE PRECIPITATION DISCUSSION 0256
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
826 PM EDT FRI JUN 01 2018

AREAS AFFECTED...ND...NORTH CENTRAL SD

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 020100Z - 020500Z

SUMMARY...CELLS TRAINING ALONG CONVECTIVE LINES CROSSING WESTERN
AND CENTRAL ND THIS EVENING COULD POSE A FLASH FLOOD THREAT.

DISCUSSION...REGIONAL RADARS CONTINUE TO SHOW CONVECTIVE LINES
SLOWLY CROSSING WESTERN AND CENTRAL ND LATE THIS AFTERNOON AND
EARLY THIS EVENING. THE CONVECTION IS ALIGNED WITH AN AXIS OF
1500-2000 J/KG OF MLCAPE CENTERED OVER WESTERN AND NORTHERN ND.
AHEAD OF A LONG WAVE TROUGH APPROACHING FROM EASTERN MT...CELLS
ALONG THE LINES ARE TRACKING NORTH NORTHWEST...AS THE LINES
THEMSELVES MOVE EASTWARD.

MODEL SOUNDINGS ACROSS WESTERN AND NORTHERN ND INDICATED THAT MUCH
OF THE INSTABILITY WAS ELEVATED NORTH OF THE SURFACE WARM FRONT.
SOUNDINGS ALSO SHOWED STEEP MID LEVEL LAPSE RATES (GREATER THAN
7.0 C/KM) OVER THE AREA...AND LOCAL RADARS HAVE SHOWN HAIL CORES
IN MANY OF THE INDIVIDUAL CELLS. THIS IS SUPPORTED BY THE HCA
PRODUCTS FROM THE KBIS RADAR.

HOWEVER...A 40 TO 50 KNOT LOW LEVEL SOUTH SOUTHEAST FLOW CONTINUES
TO SUPPLY 1.50 INCH PRECIPITABLE WATER INTO THE CONVECTION.
DESPITE THE HAIL PRODUCERS...
SPOTTER REPORTS HAVE INDICATED RAINFALL AMOUNTS GREATER THAN 1.50
INCHES OVER WESTERN AND CENTRAL ND WITH THE CELLS.

AS THE CELLS TRACK NORTH NORTHWEST ALONG THE LINES OF CONVECTION
AS THEY MOVE EAST THIS EVENING...THE POTENTIAL EXISTS FOR LOCAL
1.50/2.00 INCH RAINFALL AMOUNTS AMONG THE HAIL PRODUCING STORMS.
THREE HOUR FLASH FLOOD GUIDANCE VALUES ARE AS LOW AS 1.00/1.50
INCHES ACROSS PORTIONS OF CENTRAL ND...SO DESPITE THE PRESENCE OF
THE HAIL PRODUCING STORMS...FLASH FLOODING IS A CONCERN. TRAINING
CELLS COULD RESULT IN LOCAL RAINFALL AMOUNTS IN EXCESS OF 2.00
INCHES...ESPECIALLY OVER CENTRAL ND.

THE 850-300 MB FLOW SHOULD CONTINUE TO PUSH THE CONVECTIVE LINES
EASTWARD...EVEN AS THE CELLS TRACK NORTH NORTHWEST. THE LINE
MOVEMENT COULD MITIGATE THE FLASH FLOOD THREAT TO A DEGREE (OR AT
LEAST LIMIT THE EXTENT OF A MORE WIDESPREAD FLASH FLOOD PROBLEM).
AS THE STORMS MOVE INTO EASTERN ND AFTER 02/05Z...THE THREAT FOR
FLASH FLOODING SHOULD DIMINISH...AS THE CONVECTION BECOMES MORE
OUTFLOW DOMINATED.

HAYES

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

ATTN...RFC...MBRFC...NCRFC...

LAT...LON   49100058 49099958 48669853 47169796 45779829
            45169903 45590088 46950218 48640234