MESOSCALE PRECIPITATION DISCUSSION 0069
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
430 PM EDT SAT MAY 09 2015
 
AREAS AFFECTED...EASTERN CO 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 092029Z - 100229Z
 
SUMMARY...THUNDERSTORMS ARE EXPECTED TO CONTINUE TO GROW IN
INTENSITY AND COVERAGE THIS AFTERNOON, WITH THE FLASH FLOOD RISK
SHIFTING FROM NORTH TO SOUTH THROUGH CO WITH TIME.  RAIN RATES UP
TO 1.5" AN HOUR SHOULD CAUSE FLASH FLOODING OVER SATURATED SOILS.

DISCUSSION...WINDS ACROSS THE REGION ARE BEGINNING TO BACK AS A
SURFACE LOW SPINS UP ACROSS SOUTHERN CO.  BOTH THE SURFACE FRONT
AND AN INVERTED TROUGH ACROSS THE HIGH PLAINS HAVE BEEN ACTING AS
FOCI FOR CONVECTIVE ACTIVITY.  HEAVY RAINS HAVE CONTINUED ACROSS
THE REGION, THOUGH THEY ARE BEGINNING TO EXPAND IN COVERAGE ACROSS
EASTERN CO.  MIXED CAPE VALUES ARE BETWEEN 500-1000 J/KG WHILE
SURFACE BASED VALUES CLOSE TO 2000 J/KG.  SOUTHEAST WINDS OF 30
KTS WERE RECENTLY REPORTED FROM PUEBLO CO AT 700 HPA, WHICH IS
ROUGHLY NEAR CLOUD BASES.  PRECIPITABLE WATER VALUES REMAIN NEAR
0.75", WHICH IS BETWEEN THE 75TH AND 95TH PERCENTILE FOR EARLY
MAY. 

THE CHANGE IN THE SURFACE WINDS, ALONG WITH THE ADVENT OF SNOW IN
SOUTHEAST WY, ALLOWED US TO SHIFT THE FLASH FLOOD RISK FARTHER
SOUTHWARD OUT OF WY INTO CO.  NOW THAT WINDS ARE BEGINNING TO VEER
IN AREA WIND PROFILES, FORWARD PROPAGATION TO THE EAST IS POSSIBLE
ACROSS NORTHEAST CO PER THE 1000-500 HPA THICKNESS PATTERN, WHICH
HAS BEEN SHOWING UP SOMEWHAT AS OF LATE.  THE 12Z SSEO
NEIGHBORHOOD PROBABILITIES SUGGEST THE THREAT FOR FLASH FLOODING
MAXIMIZES BETWEEN NOW AND 01Z BEFORE FADING THEREAFTER, LIKELY DUE
TO THE LOW-LEVEL FLOW NO LONGER ADVECTING IN THE INSTABILITY FROM
SOUTHERN CO AND SOUTHWEST KS.  THE THREAT OF FLASH FLOODING SHOULD
SHIFT FROM NORTH TO SOUTH THROUGH CO BEFORE FADING.  THE SIGNAL IN
THE MESOSCALE GUIDANCE IS FOR AN ADDITIONAL 1-2" OF RAINFALL
LOCALLY, WHICH COULD FALL IN AN HOUR BASED ON OCCASIONAL RAINFALL
ESTIMATES FROM RADAR AND SURFACE OBSERVATIONS.  CONSIDERING THE
SATURATED SOILS, FLASH FLOODING IS CONSIDERED LIKELY.    

ROTH

ATTN...WFO...ABQ...BOU...DDC...GLD...LBF...PUB...

ATTN...RFC...ABRFC...CBRFC...MBRFC...WGRFC...

LAT...LON   40990452 40990276 40990210 40990209 40990209 
            40650202 38620201 37060204 37040206 37040206 
            37000287 36990379 37000480 37220530 37990581 
            39160611 39990593 40440559 40860496