MESOSCALE PRECIPITATION DISCUSSION 0684
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
802 PM EDT WED SEP 21 2016
 
AREAS AFFECTED...SOUTHERN TO SOUTHEASTERN MN/NORTHERN IA/WESTERN
WI... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 220002Z - 220502Z
 
SUMMARY...A COMPLEX SITUATION UNFOLDING ACROSS SECTIONS OF THE
UPPER MIDWEST/MIDDLE MS VALLEY THIS EVENING. MODELS CONTINUE TO
SUGGEST A WEST-EAST TRAINING EVENT UNFOLDING OVERNIGHT. GIVEN
MODERATE/HEAVY RAINFALL IN THE PAST 24 HOURS OVER SECTIONS OF THE
MPD AREA...FLASH FLOODING WILL BE POSSIBLE.

DISCUSSION...THE LAST FEW SCANS OF THE VISIBLE SATELLITE IMAGERY
SHOWED A PAIR OF COMPLEXES AFFECTING THE REGION. TO THE
NORTH...GENERALLY ELEVATED CONVECTION HAS PERSISTED ACROSS FAR
EAST-CENTRAL MN INTO CENTRAL WI WITH LOCALIZED HEAVY RAINFALL
OCCURRING. TO THE SOUTH...THE ACTIVITY HAS BEEN ROOTED IN THE
BOUNDARY LAYER ALONG THE NORTHWESTERN FLANK OF A REMNANT OUTFLOW
BOUNDARY FROM EARLIER THIS AFTERNOON. OVER THIS REGION...A NEARLY
STATIONARY SUPERCELL DEVELOPED WHICH HAS DROPPED HEAVY AMOUNTS OF
RAINFALL THE PAST FEW HOURS. SANDWICHED IN BETWEEN THESE TWO AREAS
HAS BEEN A PATCH OF CLEARING WHICH HAS IGNITED A FEW CLUSTERS OF
STORMS OVER SOUTHEASTERN MN. MODELS CONTINUE TO FOCUS THE MOST
CONCENTRATED ACTIVITY OVER SOUTHERN MN INTO WESTERN WI WHICH IS
POSITIONED ALONG THE 850-MB BOUNDARY. THIS IS FAIRLY CONSISTENT
WITH WHAT THE 00Z MPX SOUNDING SHOWED WHICH MAINTAINED THE BEST
INSTABILITY ABOVE 775 MB GIVEN ISOTHERMAL PROFILES BELOW.

WHILE THE EVOLUTION IS FAIRLY UNCERTAIN...A PRONOUNCED SHORTWAVE
LIFTING OUT OF FAR NORTHEASTERN NEB SHOULD LEAD TO STRONGER ASCENT
DOWNSTREAM ACROSS THE WESTERN EXTENT OF THE MPD AREA. THERE IS
PLENTY OF INSTABILITY POOLING NORTHWARD FROM A REGION OF 3000 TO
4000 J/KG OF MUCAPE ACROSS IA/MO. SUFFICIENT MOISTURE ADVECTION
INTERCEPTING THE WEST-EAST THERMAL/MOISTURE GRADIENT SHOULD LEAD
TO A REASONABLY ORGANIZED THUNDERSTORM COMPLEX OVERNIGHT.

THE LATEST CAMS CONTINUE TO BE TOO FAR NORTH WITH THE ONGOING
CONVECTION. THUS...TRUSTED REAL-TIME SATELLITE/RADAR/OBSERVATIONAL
TRENDS AND NOTED SOME OF THE HRRR/EXPERIMENTAL-HRRR SOLUTIONS. ALL
SEEM TO FAVOR THIS WEST-EAST TRAINING SCENARIO UNFOLDING BEFORE
THE ACTIVITY GRADUALLY SHIFTS SOUTHWARD LATER IN THE NIGHT.


RUBIN-OSTER

ATTN...WFO...ARX...DMX...GRB...MKX...MPX...

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

LAT...LON   45209176 44758987 43278906 42638994 42709150 
            42559333 42879429 43979480 44979380