MESOSCALE PRECIPITATION DISCUSSION 0418...CORRECTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
513 AM EDT SUN JUL 08 2018

CORRECTED FOR TYPO IN LAST SENTENCE

AREAS AFFECTED...ERN ND INTO NRN MN

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

VALID 080837Z - 081435Z

SUMMARY...FLASH FLOODING WILL BECOME A GROWING THREAT THROUGH THE
REMAINDER OF THE MORNING ACROSS PORTIONS OF EASTERN NORTH DAKOTA
INTO NORTHERN MINNESOTA. RAINFALL RATES OF 1-2 IN/HR AND STORM
TOTALS OF 2-3 INCHES WILL BE POSSIBLE.

DISCUSSION...GOES 16 INFRARED IMAGERY AND REGIONAL RADAR DATA AT
08Z SHOWED A SMALL CONVECTIVE CLUSTER PROPAGATING STEADILY
NORTHEASTWARD ACROSS CENTRAL NORTH DAKOTA. WHILE THE FORWARD
PROPAGATION OF THIS CLUSTER ALONE DOES NOT TRANSLATE TO A FLASH
FLOOD THREAT...LOCATIONS DOWNSTREAM ACROSS EASTERN NORTH DAKOTA
INTO NORTHERN MINNESOTA...COULD SEE REPEATING/SLOW MOVING
CONVECTION NEAR AND BEYOND 12Z. 00Z SOUNDINGS FROM BIS AND INL AND
THE LATEST SPC MESOANALYSIS SHOWED MODERATE TO LARGE CAPE VALUES
AHEAD OF A SURFACE COLD FRONT BUT WITH CIN DUE TO WARM
TEMPERATURES IN THE 700-850 MB LAYER. THE LATEST THINKING IS THE
CAP STRENGTH...WHICH IS WEAKER TO THE NORTH...WILL PREVENT
ADDITIONAL CONVECTION UNTIL A FLAT SHORTWAVE MOVING THROUGH
SOUTHERN CANADA AND ASSOCIATED HEIGHT FALLS ALLOWS FOR COOLING OF
700 MB TEMPERATURES BETWEEN 09-12Z...AND/OR FORCING AHEAD OF THE
FORWARD PROPAGATING STORMS IN NORTH DAKOTA AIDS IN CONVECTIVE
DEVELOPMENT. KMVX RADAR FROM 0830Z WAS BEGINNING TO SHOW A FEW
ECHOES ALIGNING FROM WEST TO EAST AHEAD OF THE LINE FROM
NORTHEASTERN NORTH DAKOTA INTO NORTHWESTERN MINNESOTA.

FLOW ALOFT IS DIFFLUENT ACROSS MINNESOTA WHICH IS EXPECTED TO AID
IN VERTICAL MOTIONS AS STRONGER FORCING FOR ASCENT ARRIVES LATER
THIS MORNING. GIVEN AREA PRECIPITABLE WATER VALUES ARE 1.6 TO 1.8
INCHES (PER GPS OBSERVATIONS) AND FLOW IS UNIDIRECTIONAL FROM
EASTERN NORTH DAKOTA INTO NORTHERN MINNESOTA...PARALLEL TO A
FORECAST 850 MB BOUNDARY AT 12Z...ANY CONVECTION THAT DEVELOPS IS
EXPECTED TO BE SLOW MOVING OR REPEATING...ALLOWING FOR 1-2 IN/HR
RAINFALL RATES AND POTENTIAL FOR 2-3 INCHES STORM TOTAL. GIVEN
FLASH FLOOD GUIDANCE BETWEEN 1 AND 2 INCHES PER HOUR ACROSS THE
REGION...FLASH FLOODING WILL BE POSSIBLE.

OTTO

ATTN...WFO...BIS...DLH...FGF...

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

LAT...LON   48829591 48809316 48379162 47109343 46789576
            46689742 46709866 47189932 47969916 48379826