MESOSCALE PRECIPITATION DISCUSSION 0868
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
424 PM EDT FRI OCT 06 2017

AREAS AFFECTED...CENTRAL PLAINS/LOWER MO VALLEY

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

VALID 062023Z - 070223Z

SUMMARY...THUNDERSTORMS ARE EXPECTED TO EXPAND IN COVERAGE NEAR
SURFACE BOUNDARIES ACROSS THE REGION.  HOURLY RAIN TOTALS TO 2"
WITH LOCAL AMOUNTS TO 4" ARE EXPECTED.

DISCUSSION...A SHORTWAVE MOVING THROUGH WESTERN NE AND EASTERN CO
HAS LED TO THUNDERSTORMS FORMING ACROSS THE HIGH PLAINS A COUPLE
HOURS AHEAD OF SCHEDULE WHEN COMPARED TO RECENT RAP RUNS. 
PRECIPITABLE WATER VALUES OF ~1.75" EXIST HERE.  INFLOW AT 850 HPA
IS SOUTHWEST AT 30-40 KTS PER VAD WIND PROFILES, NEAR THE
MAGNITUDE OF THE 850-400 HPA WIND.  THE LOW LEVEL WIND IS
IMPORTING ML CAPE VALUES OF 500-2000 J/KG INTO THE REGION.  RECENT
RADAR IMAGERY SHOWS THE SHARPENING OF A FINE LINE BETWEEN
MCCRACKEN AND DIGHTON KS WHICH SHOULD BECOME A FOCUS FOR
CONVECTIVE INITIATION SHORTLY.  NEW SHOWERS AND THUNDERSTORMS HAVE
FORMED DOWNSTREAM ALONG THIS BOUNDARY FROM RUSSEL TOWARD BELOIT
AND GLASCO KS.

EFFECTIVE BULK SHEAR OF 40-50 KTS EXISTS HERE, WHICH ALONG WITH
NEARLY UNIDIRECTIONAL FLOW WITH HEIGHT SHOULD ALLOW FOR THE
FORMATION OF TRAINING CONVECTIVE BANDS IN THE NEAR FUTURE.  THE
DEGREE OF BULK SHEAR SUPPORTS MESOCYCLONE FORMATION, WHICH COULD
LEAD TO HIGHLY EFFICIENT RAIN RATES/TOTALS.  THE MOST LIKELY
LOCATION FOR ISSUES WOULD BE ON THE NORTHERN PERIPHERY OF THE
INSTABILITY POOL AND NORTHWEST OF THE 9C ISOTHERM AT 700 HPA WHICH
SHOULD ACT AS THE EFFECTIVE CAP FOR BROADER CONVECTIVE COVERAGE. 
HOURLY RAIN TOTALS UP TO 2" ARE EXPECTED, WITH LOCAL AMOUNTS UP TO
4" FORECAST BY THE AVAILABLE MESOSCALE GUIDANCE.  THESE AMOUNTS
WOULD EXCEED THE RELATIVELY LOW FLASH FLOOD GUIDANCE VALUES ACROSS
THE REGION.  THE BEST MODELS PLACEMENT-WISE APPEAR TO BE THE 12Z
WRF NSSL AND 18Z RAP BASED UPON THE LOCATION OF THE CURRENT
SURFACE BOUNDARIES AND THEIR EXPECTED LOCATIONS OVER THE NEXT
SEVERAL HOURS.

ROTH

ATTN...WFO...DDC...DMX...EAX...GID...GLD...ICT...OAX...TOP...

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

LAT...LON   42299491 41949315 41119309 40519377 39829537
            38699773 37670071 38490116 40029951