MESOSCALE PRECIPITATION DISCUSSION 0577...CORRECTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
623 PM EDT THU JUL 27 2017

CORRECTED FOR TYPOS IN THE SECOND AND THIRD PARAGRAPHS

AREAS AFFECTED...CENTRAL AND SOUTHEAST AZ...WESTERN NM

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

VALID 272215Z - 280315Z

SUMMARY...SLOW MOVING CELLS TIED TO THE TERRAIN IN A HIGH MOISTURE
ENVIRONMENT COULD RESULT IN A LOCAL FLASH FLOOD THREAT INTO THE
EVENING HOURS.

DISCUSSION...REGIONAL RADARS INDICATED THAT THE COVERAGE OF
CONVECTION TIED MAINLY TO THE TERRAIN ACROSS CENTRAL AND SOUTHEAST
AZ AND NEARBY WESTERN NM HAS INCREASED. A LOW TO MID LEVEL EAST TO
SOUTHEAST FLOW CONTINUES TO FEED 1.25/1.50 INCH PRECIPITABLE WATER
AIR IN AN UPSLOPE FLOW ACROSS THE REGION...WHERE THE LATEST RAP
ANALYSIS SHOWED AXES OF 500-1000 J/KG OF MLCAPE.

THE EXPERIMENTAL GOES-16 CLEAN IR CHANNEL SHOWED COOLING TOPS WITH
THE CONVECTION... PARTICULARLY OVER WESTERN NM. BOTH THE KFSX AND
KABX RADAR SHOWED HOURLY RAINFALL RATES BETWEEN 1.50 AND 2.00
INCHES...THOUGH THE HCA PRODUCTS FROM THESE RADARS SUGGEST SOME OF
THIS COULD BE HAIL CONTAMINATED.

THE COMBINATION OF MOISTURE AND INSTABILITY IS FEEDING CONVECTION
THAT HAS BECOMES TIED TO THE TERRAIN IN THE LOW TO MID LEVEL
EASTERLY FLOW ON THE SOUTH SIDE OF THE MID LEVEL RIDGE. THE 700 MB
FLOW OVER EASTERN AZ AND WESTERN NM IS GENERALLY UNDER 10
KNOTS...AND PROPAGATION VECTORS ARE ALSO GENERALLY WEAK. THIS
SUGGESTS THAT THE STORMS WILL REMAIN TIED TO THE TERRAIN THROUGH
PEAK HEATING...THEN MOVE WESTWARD WITH THE MEAN 850-300 MB FLOW.

THE RELATIVELY SLOW MOVEMENT IN THE HIGH MOISTURE ENVIRONMENT
COULD RESULT IN A FLASH FLOOD THREAT...PARTICULARLY WHERE CELL
MERGERS OR SHORT TERM TRAINING OCCURS. THIS COULD RESULT IN HOURLY
RAINFALL RATES NEAR 1.50 INCHES...WITH LOCAL 3.00 INCH STORM
TOTALS POSSIBLE. ONE HOUR FLASH FLOOD GUIDANCE VALUES ARE AS LOW
AS AN INCH...AND ANY STORM COULD PRODUCE RAINFALL AMOUNTS THAT
EXCEED THESE VALUES. 

AS THE CELLS MOVE OUT OF THE TERRAIN...THE THREAT FOR TRAINING OR
MERGERS SHOULD DECREASE...ALLOWING THE FLASH FLOOD THREAT TO WANE
LATER THIS EVENING.

HAYES

ATTN...WFO...ABQ...EPZ...FGZ...PSR...TWC...

ATTN...RFC...CBRFC...WGRFC...

LAT...LON   36540806 36010770 34850770 34220753 33560738
            32950742 32050746 31450761 31260809 31330876
            32791055 33821179 34221219 34691244 35091240
            35271199 34841106 34611038 35890887