MESOSCALE PRECIPITATION DISCUSSION 0391
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
836 PM EDT TUE JUN 28 2016
 
AREAS AFFECTED...WESTERN NE...FAR NORTHEAST CO...FAR NORTHERN KS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 290040Z - 290540Z
 
SUMMARY...A GROWING CONVECTIVE CLUSTER DROPPING SOUTHEAST WILL
TRANSFORM INTO A FLASH FLOOD THREAT DURING THE EVENING HOURS. 

DISCUSSION...REGIONAL RADARS ACROSS WESTERN NE/FAR SOUTHEAST WY
SHOWED A DEVELOPING CONVECTIVE CLUSTER DROPPING SOUTHEAST WITH THE
MID LEVEL FLOW. THE 00Z SOUNDING OUT OF KLBF SHOWED STEEP MID
LEVEL LAPSE RATES AND AN ABUNDANCE OF DRY AIR IN THE MID
LEVELS...AND NOT SURPRISINGLY THE COMPLEX IS OUTFLOW DOMINATED.
THE COMPLEX IS FOLLOWING THE MID LEVEL NORTHWEST FLOW...ALONG AN
AXIS OF 1500-2500 J/KG OF MLCAPE. 

REGIONAL VWP (AND SURFACE OBSERVATIONS) SHOWED THAT A 20 TO 25
KNOT SOUTHEASTERLY FLOW LEVEL INFLOW WAS FORMING AHEAD OF THE
COMPLEX IN A RIBBON OF 1.00 TO 1.25 INCH PRECIPITABLE WATER AIR
(PER THE LATEST BLENDED TPW PRODUCT AND RAP ANALYSIS). 

AS THE COMPLEX DROPS SOUTHEAST INTO THE STRENGTHENING INFLOW...IT
IS EXPECTED TO TRANSFORM INTO A HEAVY RAIN/FLASH FLOOD THREAT
LATER THIS EVENING. THE LATEST RAP SHOWED THE INSTABILITY
REMAINING IN PLACE...AND THE LOW LEVEL INFLOW INCREASING TO 20 TO
30 KNOTS AS IT VEERS TO THE SOUTHWEST. THE INCREASING MOISTURE IN
THE COLUMN SHOULD ALLOW WARM RAIN PROCESSES TO BECOME
IMPORTANT...AND THE STORMS SHOULD BECOME MORE EFFICIENT RAINFALL
PRODUCERS.

THERE IS SOME SPREAD IN THE CAM GUIDANCE CONCERNING WHERE THE
HEAVIEST RAINFALL WILL OCCUR. THE 12Z WRF ARW SUGGESTS THAT THE
HEAVIEST RAINFALL (WITH LOCAL 2-4 INCH AMOUNTS)WILL FALL OVER
WESTERN NE INTO FAR NORTHEAST CO/FAR NORTHWEST KS. THE HRRR SUITE
(INCLUDING THE PARALLEL HRRR) IS LIGHTER (WITH GENERALLY 1-2 INCH
RAINFALL AMOUNTS) AND FURTHER NORTHEAST (ACROSS CENTRAL NE).

IT SHOULD BE NOTED THAT MOST OF THE AVAILABLE HIGH RESOLUTION
GUIDANCE WAS TOO SLOW WITH THE FORMATION OF THE CONVECTIVE
COMPLEX...AND THE FLASH FLOOD THREAT AREA NEEDED TO BE ADJUSTED TO
COMPENSATE.

HAYES

ATTN...WFO...BOU...CYS...GID...GLD...LBF...TOP...

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

LAT...LON   41980216 41649982 40719864 40039804 39549788 
            39219856 39249964 40030151 40240182 40660252 
            41290326 41690326 41790301 41900289