MESOSCALE PRECIPITATION DISCUSSION 0388
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
924 PM EDT MON JUL 02 2018

AREAS AFFECTED...SOUTHEAST ND...NORTHEAST SD...WEST CENTRAL MN

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

VALID 030125Z - 030730Z

SUMMARY...ENVIRONMENT FOR SOLID MOISTURE FLUX, TRAINING AND
BACKBUILDING LEADS TO  POSSIBLE FLASH FLOODING THROUGH THIS
EVENING/EARLY OVERNIGHT PERIOD.

DISCUSSION...GOES-WV SUITE DEPICTS A SMALL COMPACT SHORTWAVE
SHIFTING THROUGH NW SD WITH A NICELY ANTICYCLONICALLY CURVED JET
80KT 250MB JET ACROSS THE US/CANADIAN BOARDER WITH THE RIGHT
ENTRANCE REGION IN THE VICINITY OF THE AREA OF CONCERN IN SE ND/NE
SD AND WEST CENTRAL MN.  IN RESPONSE TO THE APPROACHING
SHORTWAVE...A WEAK SURFACE INFLECTION CAN BE ANALYZED ALONG THE
ND/SD BORDER WITH FAIRLY CONVERGENT LOW LEVEL FLOW ACROSS NE SD. 
VISIBLE IMAGERY SHOWS THIS CONVERGENCE BAND WELL FROM THE
INFLECTION TOWARD THE NORTHEAST TOWARD CASS COUNTY MN...WHERE
SCATTERED ELEVATED CONVECTION IS CURRENTLY BLOSSOMING.  STILL VWP
NETWORK SHOWS LL SOUTHERLY FLOW OF 40KTS CONVERGING TO 20KT FROM
KFSD TO KABR. THESE ELEVATED CELLS ARE LIKELY TO CONTINUE TO
DEVELOP WITH THE INCREASED DPVA AS WELL AS STRENGTHENING UPPER
LEVEL JET OVER 90KTS OVER NIGHT. LOW LEVEL VEERING OF THE LLJ WILL
ALSO SUPPORT CONVERGENCE ALONG THE BAND BUT ALSO SUPPORT INCREASED
UNIDIRECTIONAL CLOUD BEARING FLOW ACROSS THE SD/ND BORDER INTO
WEST CENTRAL MN OVERNIGHT ALLOWING FOR A TRAINING ENVIRONMENT BUT
ALSO SUPPORT BACKBUILDING WITH THE UPGLIDE/ISENTROPIC ASCENT AFTER
DARK.  MOISTURE FLUX WILL SUPPORT TPWS TO INCREASE FROM THE 1.5"
VALUES OBSERVED ON THE 00Z ABR SOUNDING TOWARD THE 1.75"
INCREASING RAINFALL EFFICIENCY WITH RAIN RATES OF 1.75-2"/HR AND
2-4" POSSIBLE THROUGH 08Z.  THE LIMITING FACTOR WILL BE RELATED TO
SOUTHERN CONVECTION THAT HAS THE POTENTIAL TO ROB BEST
CONVERGENCE/MST FLUX...LEADING TO SOME UNCERTAINTY.  STILL
UPSTREAM DEVELOPMENT OVER CENTRAL ND NEARER THE S/W CENTER MAY
HELP TO OFFSET THIS REDUCTION OR FURTHER EXACERBATE THE POTENTIAL
FF RISK FROM 04-08Z.

AS FOR THE SOUTHERN CONVECTION... SFC AND VISIBLE IMAGERY ALSO
DELINEATE A N-S CONVERGENCE LINE FROM HUGHS/HYDE COUNTIES TO THE
INFLECTION IN BROWN COUNTY SD...A WEAK SW TURN HAS ALLOWED FOR
INCREASED SFC CONVERGENCE TO DEVELOP A GROWING CLUSTER OF CELLS
WHERE RADAR VELOCITIES DEPICT SOLID MESOCYCLONE ROTATION.  THESE
CELLS ALREADY SHOW A SLOWING TO THE MEAN FLOW AND BUNKERS RIGHT
MOVING PROPAGATION VALUES ARE IN THE 15KT RANGE ALLOWING FOR
COMPOUNDING RAIN TOTALS.  AS MENTION PRIOR...LLJ IS QUITE STRONG
INTERSECTING WITH THIS CONVECTION AND WITH SBCAPES IN THE
3000-3500 J/KG RANGE SUPPORT STRONG UPDRAFTS THAT MAY MANIPULATE
THE LOCAL ENVIRONMENT SUPPORTING SOME INCREASED LONGEVITY TO THE
CLUSTERS EVEN THOUGH BEST DYNAMICS REMAIN FURTHER NORTH.  STILL
SIMILAR MOISTURE ENVIRONMENT WITH MID-60S TDS AND 40KT UNABATED
FLUX WILL SUPPORT RAIN RATES OVER 2"/HR.  VISIBLE IMAGERY ALSO
DENOTES THAT THE CELLS ARE DEEP IN THE SMOKE LAYER FROM COLORADO
FIRES...AND WHILE TYPICALLY REDUCING CONVECTIVE
INITIATION/INSTABILITY THERE WILL BE INCREASED WARM CLOUD RAINFALL
EFFICIENCY FROM THE INGESTION OF NUMEROUS ADDITIONAL NUCLEATION
AGENTS FROM THE SMOKE...POTENTIALLY AS MUCH AS .5-1"/HR...FURTHER
SUGGESTING FLASH FLOODING RISK. 

GALLINA

ATTN...WFO...ABR...BIS...DLH...FGF...FSD...MPX...

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

LAT...LON   47269567 47219367 46569367 46269436 45609486
            44549520 44339559 44219620 44219747 44209929
            44449954 45059917 45729909 46099877 46599812
            46979694