MESOSCALE PRECIPITATION DISCUSSION 0409
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
256 PM EDT THU JUL 05 2018

AREAS AFFECTED...COLORADO...NRN NEW MEXICO...FAR SE WYOMING

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

VALID 051855Z - 060045Z

SUMMARY...THUNDERSTORMS WERE BEGINNING TO DEVELOP AROUND MIDDAY IN
AREAS OF HIGHER TERRAIN FROM COLORADO INTO NORTHERN NEW MEXICO.
THESE SLOW-MOVING STORMS SHOULD CONTINUE TO BUILD IN THESE AREAS
FOR ANOTHER COUPLE HOURS...BEFORE EXPANDING EAST. THE SLOW-MOVING
STORMS MAY PRODUCE RAIN RATES AROUND 1 IN/HR WHICH MAY LEAD TO
FLASH FLOODING. AREAS AROUND RECENT BURN SCARS WOULD BE MOST
LIKELY TO EXPERIENCE FLASH FLOODING.

DISCUSSION...GOES SATELLITE IMAGERY SHOWS CONVECTION BLOSSOMING
ACROSS MUCH OF THE FOUR CORNERS REGION IN AREAS OF HIGHER TERRAIN
AS INSTABILITY GROWS AND CONVERGENCE OF DIURNAL UPSLOPE FLOW
INCREASES. THE MOST CONCENTRATED AREA OF COOLING CLOUD TOPS WAS
FROM CENTRAL COLORADO INTO NORTHERN NEW MEXICO. THIS CONVECTION
SHOULD BE SLOW-MOVING GIVEN THE WEAKNESS IN MID-LEVEL FLOW
CENTERED ON COLORADO. 12Z RAOBS SHOWED ANTICYCLONIC FLOW AROUND
COLORADO AT 500MB (ONLY 8 KNOTS AT DNR). THIS SHOULD ALLOW
CONVECTION INTO THE EARLY AFTERNOON TO BE LARGELY CONCENTRATED
ALONG TERRAIN RIDGES...AND WITH SLOW STORM MOTIONS COULD PRODUCE
LOCALIZED HEAVY RAINFALL AND FLASH FLOODING.

AS THE AFTERNOON PROGRESSES...CONVECTION MAY BEGIN TO BUILD INTO
SOME OF THE ADJACENT VALLEYS AND EAST INTO THE FRONT RANGE AND
HIGH PLAINS IN EAST-CENTRAL COLORADO. STRONGER INSTABILITY AND
HIGHER PWATS ARE CONCENTRATED FURTHER EAST (PARTIALLY AS A
FUNCTION OF ELEVATION)...BUT A BROAD AREA OF EASTERLY 15-20 KNOT
LOW-LEVEL (850MB) INFLOW ALSO EXISTS PER REGIONAL RADAR VWPS. THIS
MAY PLACE SOME OF THE CONVECTION INTO MORE POPULATED AREAS...AND
ALSO INTO SOME PLACES WITH RECENT WILDFIRE BURN SCARS...WHICH MAY
INCREASE THE THREAT OF FLASH FLOODING AND ALSO POTENTIAL IMPACTS.

MODEL ANALYZED PRECIPITABLE WATER VALUES ARE JUST ABOVE THE 90TH
PERCENTILE FOR JULY IN THIS REGION...AND PARTICULARLY FROM THE
EASTERN HALF OF COLORADO INTO SOUTHEAST WYOMING. THE VALUES AROUND
1 INCH ALONG THE EASTERN EDGE OF THE HIGHER TERRAIN WOULD BE
SUPPORTIVE OF RAIN RATES AROUND 1 IN/HR IN THE STRONGER
CONVECTION...AND PERHAPS LOCALLY HIGHER IF STORM MERGERS AND/OR
MOTION CAN FAVORABLY STALL HEAVY RAIN FOR AN EXTENDED PERIOD OF
TIME IN A GIVEN LOCATION. RAIN RATES SUCH AS THIS WOULD BE CAPABLE
OF PRODUCING SOME LOCALIZED FLASH FLOODING ACROSS THE REGION...AND
WOULD BE MORE THAN SUFFICIENT TO PRODUCE FLASH FLOODING AND DEBRIS
FLOWS AROUND BURN SCARS.

THROUGH 00Z...THE STRONGEST HI-RES MODEL QPF SIGNAL IS FROM AROUND
LEADVILLE CO ENE TO THE DENVER METRO AREA (ALSO VERY CLOSE TO THE
CENTER OF THE 500MB ANTICYCLONIC CIRCULATION)...AS WELL AS IN FAR
NC NEW MEXICO FROM NEAR TAOS TO NEAR DES MOINES...PER THE 12Z HREF
AND 16Z HRRR.

LAMERS

ATTN...WFO...ABQ...BOU...CYS...GJT...PUB...

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

LAT...LON   41600671 41600573 40770453 39650336 37450300
            36380357 35430479 35510623 36280745 37560814
            38560731 39430697 40420704