MESOSCALE PRECIPITATION DISCUSSION 0449
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
539 PM EDT SUN JUL 10 2016
 
AREAS AFFECTED...PORTIONS OF WESTERN AND CENTRAL ND 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 102138Z - 110338Z
 
SUMMARY...THUNDERSTORMS ARE BEGINNING TO EXPAND IN COVERAGE NEAR
THE MT/ND BORDER.  WITH HOURLY RAIN RATES UP TO 2" POSSIBLE, FLASH
FLOODING IS POSSIBLE.

DISCUSSION...THUNDERSTORMS WITH OVERSHOOTING TOPS ARE DEVELOPING
AND BEGINNING TO FORWARD PROPAGATE INTO ND FROM EASTERNMOST MT
WITHIN THE TROWAL REGION OF A DEEPENING SURFACE LOW ACROSS FAR
NORTHWEST SD.  TO ITS EAST, A FIELD OF CUMULI ARE ASCENDING NEAR
THE CAP EDGE FROM SOUTHWEST INTO SOUTH-CENTRAL ND.  MLCAPES SOUTH
OF THE THUNDERSTORMS/CUMULUS FIELD ARE 1000-3000 J/KG PER SPC
MESOANALYSES.  THE CAP EDGE APPEARS TO BE APPROXIMATED BY THE 15C
ISOTHERM AT 700 HPA IN THE HIGH PLAINS AND 12C ISOTHERM NEAR/EAST
OF THE 100TH MERIDIAN.  PRECIPITABLE WATER VALUES ARE 1.1-1.25" IN
THE AREA PER A RECENT SPECIAL SOUNDING FROM BISMARCK ND AND GPS
VALUE NEAR BELFIELD ND.  INFLOW AT 850 HPA IS SOUTH-SOUTHEAST AT
20-30 KTS PER AREA VAD WIND PROFILES, NEAR THE MAGNITUDE OF THE
MEAN 850-400 HPA WIND BUT AT NEARLY A RIGHT ANGLE.

THE MESOSCALE/CAM GUIDANCE WHICH HAS THIS HANDLED THE BEST ARE THE
12Z SPCWRF, 20Z HRRR, 12Z WRF NSSL, AND THE 18Z HRRR
EXPERIMENTAL/VERSION 2.  OTHER GUIDANCE SUCH AS THE 18Z CANADIAN
REGION APPEAR TOO SLOW WITH THE FORWARD PROPAGATION.  THE BREADTH
AND MAGNITUDE OF THE LOW-LEVEL INFLOW ARE EXPECTED TO EXPAND WITH
TIME, WHICH COULD ALLOW FOR A WARM ADVECTION THUNDERSTORM BAND TO
DEVELOP.  WITH THE LOW-LEVEL INFLOW BECOMING MORE NORMAL TO THE
BOUNDARIES IN THE REGION, FORWARD PROPAGATING CONVECTION WITHIN
SUCH A BAND COULD LEAD TO CELL TRAINING.  EASTWARD MOVEMENT
TOWARDS 30 KTS IS EXPECTED PER FORWARD PROPAGATING CONVECTIVE
VECTORS AND THE 1000-500 HPA THICKNESS PATTERN IN THE REGION. 
WITH LESS ORGANIZED ACTIVITY MOVING MORE NORTHEASTWARD, CELL
MERGERS ARE ALSO OF CONCERN.  WITH PRECIPITABLE WATER VALUES
FORECAST BY THE RAP TO INCREASE TO 1.75", HOURLY RAIN RATES UP TO
2" ARE POSSIBLE.  THE PREFERRED MESOSCALE GUIDANCE HAS A MODEST
SIGNAL FOR LOCAL AMOUNTS IN THE 2-4" RANGE, WHICH WOULD EXCEED THE
LOW FLASH FLOOD GUIDANCE IN THE REGION.  FLASH FLOODING IS
CONSIDERED POSSIBLE, PARTICULARLY WITHIN URBAN AREAS.

ROTH

ATTN...WFO...ABR...BIS...BYZ...FGF...GGW...UNR...

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

LAT...LON   48030301 48030215 47900159 47930116 47939981 
            47879898 47729914 47429887 47399847 47239834 
            46919821 46679891 45850190 45660307 45630401 
            45910452 46330467 47320459