MESOSCALE PRECIPITATION DISCUSSION 0513
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
200 AM EDT THU SEP 24 2015
 
AREAS AFFECTED...SOUTHEASTERN SD/EASTERN NEB/FAR WESTERN IA... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 240559Z - 241059Z
 
SUMMARY...MODERATE TO HEAVY RAINFALL AHEAD OF A SLOW-MOVING UPPER
LOW WILL FOSTER A THREAT FOR FLASH FLOODING DURING THE OVERNIGHT
HOURS. THIS WILL PARTICULARLY BE THE CASE ALONG THE NEB/IA BORDER
WHERE 3 TO 6 INCHES OF RAIN FELL IN THE PAST 24 HOURS. 

DISCUSSION...WATER VAPOR IMAGERY INDICATED A STAGNANT MID/UPPER
LOW CENTER TRACKING ACROSS FAR NORTH-CENTRAL NEB. IN ADVANCE OF
THIS FEATURE...THE BLENDED-TPW PRODUCT AND GPS DATA SHOWED
ABUNDANT TROPOSPHERIC MOISTURE RISING NORTHWARD THROUGH THE LOWER
PLAINS. THE MOST RECENT DATA INDICATES 1.50 TO 1.75 INCH PWATS IN
PLACE ACROSS THE MPD AREA. THE PAST COUPLE HOURS OF RADAR IMAGERY
SHOWS A BROAD AREA OF MODERATE TO OCCASIONALLY HEAVY RAINFALL
SPREADING EASTWARD ACROSS THE STATE. ALTHOUGH FORECAST SOUNDINGS
GENERALLY SHOW THERMODYNAMIC PROFILES LACKING MUCH
INSTABILITY...STRONG DYNAMICAL LIFT HAS BEEN PLENTY SUPPORTIVE OF
SUSTAINED UPDRAFTS WHICH HAS LED TO AN UPTICK IN CG LIGHTNING.
EXPECT THIS TREND TO CONTINUE AS THE CONVECTION MOVES INTO A
BETTER ENVIRONMENT CONTAINING STRONGER LOW-LEVEL INFLOW AND BETTER
MOISTURE PROFILES. THESE ARTIFACTS COUPLED WITH SLOW FORWARD CELL
MOTIONS SHOULD SUPPORT LOCALIZED THREATS FOR FLASH FLOODING.

IT APPEARS A MAJORITY OF THE RECENT CAMS HAVE FOCUSED TOO MUCH OF
THE HEAVY RAINFALL FARTHER NORTH ALONG THE NEB/SD AND SD/IA/MN
BORDER REGIONS. SO DID NOT PUT TOO MUCH FAITH INTO THE GUIDANCE
AND LEANED MORE ON RECENT RADAR/SATELLITE TRENDS AND OBSERVATIONAL
DATA.

RUBIN-OSTER

ATTN...WFO...ABR...FSD...GID...LBF...OAX...UNR...

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

LAT...LON   44559816 44489720 43719671 43029624 42189596 
            41209609 40619674 40549766 40989863 42039923 
            43320005 44069924