MESOSCALE PRECIPITATION DISCUSSION 0314
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
442 PM EDT FRI JUN 09 2017

AREAS AFFECTED...PORTIONS OF ND

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

VALID 092041Z - 100241Z

SUMMARY...LOW-LEVEL CONVERGENCE IS STRENGTHENING IN AN AREA WITH A
WEAKENING MID-LEVEL CAP ACROSS ND.  HOURLY RAIN RATES UP TO 2",
WITH LOCAL AMOUNTS UP TO 4", ARE POSSIBLE IN BACK BUILDING
CONVECTION AND CELL MERGERS.

DISCUSSION...EXPERIMENTAL GOES-16 VISIBLE IMAGERY SHOWS
INDICATIONS OF A WEAKENING MID-LEVEL CAP ACROSS ND.  SHORTWAVES
UPSTREAM ACROSS MT AND NEAR THE MT/ND/SASKATCHEWAN BORDER, ALONG
WITH INCREASING INSTABILITY, ARE HELPING IN THE EROSION. 
STRATOCUMULI IN WESTERN ND HAVE BECOME MORE CONGESTED IN THE PAST
HOUR.  A WARM FRONT IN THE REGION IS SHOWING INCREASED CUMULUS
DEVELOPMENT AS WELL.  THE MINOT ND RADAR INDICATES SHARPENING FINE
LINE ECHOES TO THEIR SOUTHWEST.  BELIEVE CONVECTIVE DEVELOPMENT IS
IMMINENT WITHIN THE HOUR.  PRECIPITABLE WATER VALUES OF 1.25-1.5"
EXIST HERE.  INFLOW AT 850 HPA IS SOUTHERLY AT 35 KTS PER VAD WIND
PROFILES.  EFFECTIVE BULK SHEAR OF ~50 KTS EXIST IN THIS REGION,
IMPLYING THAT MESOCYCLONES WOULD BE POSSIBLE.  UPSTREAM MLCAPES
ARE 1000-3000 J/KG.

THE EXPECTATION IS FOR THUNDERSTORMS TO FORM BETWEEN NORTH-CENTRAL
AND CENTRAL ND SHORTLY.  ALTHOUGH THE FLOW VEERS SLIGHTLY THROUGH
THE PERIOD, STRENGTHENING LOW-LEVEL INFLOW IS EXPECTED TO CAUSE
BACK BUILDING WITH ANY DEVELOPING THUNDERSTORMS.  THERE IS AN
INCREASING SIGNAL WITHIN THE MESOSCALE GUIDANCE FOR LOCAL AMOUNTS
UP TO 4" WITHIN CENTRAL AND NORTHERN ND, AN AREA WHERE FLASH FLOOD
GUIDANCE VALUES ARE MODEST.  PER RECENT SATELLITE IMAGERY AND THE
MLCAPE FIELD, BELIEVE THE GUIDANCE IS DISPLACED A BIT TO THE NORTH
OF WHERE CONVECTION WOULD FORM/MOVE.  AVAILABLE MOISTURE SUPPORTS
HOURLY RAIN RATES UP TO 1.75".  FORWARD PROPAGATION TO THE
SOUTHEAST AT 30+ KTS IS EXPECTED TO TAKE HOLD 3-4 HOURS AFTER A
COLD POOL FORMS WITH THE ANTICIPATED THUNDERSTORM ACTIVITY.  UNTIL
FORWARD PROPAGATION CAN OCCUR, HEAVY RAIN-RELATED ISSUES WOULD BE
POSSIBLE, PARTICULARLY IN URBAN AREAS.  UNCERTAINTY ON CONVECTIVE
INITIATION TIMING KEEPS THE CATEGORY AS POSSIBLE AND STRETCHED THE
HORIZON OF THIS MPD TO SIX HOURS.

ROTH

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

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

LAT...LON   48910179 48900021 48379815 47029683 45969673
            45939809 46830001 48260217