Graphic for MPD #0625

MESOSCALE PRECIPITATION DISCUSSION 0625
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
445 AM EDT SAT AUG 05 2017

AREAS AFFECTED...SOUTHEAST NE & EASTERN KS

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

VALID 050843Z - 051443Z

SUMMARY...SHOWERS AND THUNDERSTORMS ARE DEVELOPING ACROSS A REGION
WITH STRENGTHENING WARM AIR ADVECTION.  HOURLY RAIN RATES TO 1.75"
WITH LOCAL AMOUNTS TO 4" ARE POSSIBLE.

DISCUSSION...A NEGATIVELY TILTED UPPER TROUGH EXTENDS
SOUTH-SOUTHEAST DOWN THE BORDERS OF SD/WY INTO EASTERN CO, WHICH
HAS INCREASED DIVERGENCE ALOFT. INCREASING LOW-LEVEL INFLOW -- 25
KTS PER RECENT VAD WIND PROFILES -- HAS IMPORTED MU CAPES VALUES
OF 1000-2000 J/KG AND INCREASED PRECIPITABLE WATER VALUES TO
1-1.3" PER RECENT GPS DATA.  THE LOW LEVEL INFLOW IS GREATER THAN
THE MEAN 850-400 HPA WIND.  THUNDERSTORMS ARE DEVELOPING WITHIN
THIS AIR MASS AND SHOWING SOME BACKBUILDING CHARACTER.  SHOWERS
AND THUNDERSTORMS NEAR THE CENTRAL KS/NE BORDER ARE MIGRATING OUT
OF THE MIDDLE OF THE INSTABILITY POOL, MOVING EAST-NORTHEAST AT 25
KTS.

SCATTERED THUNDERSTORMS ACROSS CENTRAL NE ARE EXPECTED TO ROB
INSTABILITY FROM ACTIVITY ACROSS NORTHEAST NE OVER THE NEXT COUPLE
HOURS, WHICH SHOULD LEAD TO THEIR COLLAPSE WITH TIME.  ACTIVITY
SHOULD ATTEMPT TO MOVE SOMEWHAT EASTWARD, BUT THERE ARE COMPETING
FACTORS -- THE EATING AWAY OF THE EASTERN SIDE OF THE INSTABILITY
POOL BY THE DEVELOPING CONVECTION AND THE EASTWARD SHIFT OF THE
850 HPA SLICE OF THE WARM FRONT.  CELL MERGERS BETWEEN THE
ACTIVITY MOVING IN FROM THE WEST AND BACKBUILDING SHOULD CONTINUE
TO RAMP UP HOURLY RAIN RATES, WHICH ARE EXPECTED TO PEAK NEAR
1.75".  LOW-LEVEL INFLOW IS EXPECTED TO NEARLY DOUBLE THE MEAN
850-400 HPA WIND WITH TIME AS PRECIPITABLE WATER VALUES ECLIPSE
1.5", WHICH SHOULD MAKE THUNDERSTORMS EFFICIENT RAINFALL-WISE. 

THE MESOSCALE GUIDANCE APPEARS 2-3 HOURS DELAYED IN THE FORMATION
OF THIS ACTIVITY, WITH THE NEIGHBORHOOD PROBABILITIES SUGGESTING
INITIATION WAS EXPECTED AFTER 11Z.  SO FAR, IT APPEARS THAT THE
00Z NAM CONEST AND 00Z WRF NSSL ARE DOING THE BEST, ALTHOUGH THEIR
CELL COVERAGE IS UNDERDONE AT THE MOMENT.  DUE TO THIS, BELIEVE
THEIR QPF OUTPUT IS TOO LOW.  LOCAL AMOUNTS UP TO 4" ARE POSSIBLE
WHERE CELLS MERGE AND/OR IN AREAS OF BACKBUILDING CONVECTION.

ROTH

ATTN...WFO...EAX...GID...ICT...OAX...SGF...TOP...TSA...

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

LAT...LON   41109822 41079692 40319570 38999468 37149446
            36859577 36999663 37629718 38239740 40629836
           


Last Updated: 445 AM EDT SAT AUG 05 2017