858
AWUS01 KWNH 210255
FFGMPD
COZ000-NMZ000-AZZ000-UTZ000-210845-

Mesoscale Precipitation Discussion 0476
NWS Weather Prediction Center College Park MD
1055 PM EDT Thu Jun 20 2024

Areas affected...Four Corners of UT, CO, NM, AZ...

Concerning...Heavy rainfall...Flash flooding possible

Valid 210255Z - 210845Z

SUMMARY...Increased convective activity with near record low level
moisture flux pose potential for efficient rainfall producing
thunderstorms across complex terrain with spots of 1.5-2.5" totals
resulting in possible localized scattered incidents of flash
flooding.

DISCUSSION...GOES-E WV suite and 00z RAOB analysis denote two
subtle shortwaves moving north-northeastward along the western
edge of the larger scale ridge nosing across the Southern Plains.
The lead wave is crossing western CO with a favorable anticyclonic
arch of cirrus with transverse banding across WY demarcating solid
divergence aloft and favorable sloped ascent pattern across the
central Rockies.  The second wave is starting to lift north
through the eastern San Francisco Plateau of northeast AZ.  This
shortwave is providing solid DPVA and isallobaric increased wind
response of 850-500mb flow.  CIRA ALPW denotes strong moisture
flux into an axis of enhanced moisture across Western NM into a
deeper overlapped axis from west-central AZ to the four-corners
with 1.25-1" total PWat values with the axis.  CIRA ALPW 850-700mb
flux percentiles are at the maximum range/percentile for this time
of year indicating the anomalous nature to the rainfall potential.

RADAR and GOES-E EIR along with GLM lightning loops suggest a few
convergence zones along and downstream of the shortwave; a SW to
NE axis from N Cibola/SE McKinley to Los Alamos appears to be
feeding upon best orthogonal convergence from the responding low
level flow.  A few cells appear to be anchored near along favored
terrain delaying forward propagation and likely to result in
increased rainfall totals.   Given the deep moisture of .75"
through rugged terrain and strong flux and axis of slowly eroding
instability up to 1000 J/kg of MUCAPE should support rates of
1.0-1.25"/hr and spots of 2" are possible (perhaps higher if
terrain locked).

Further west into the Plateau, stronger thunderstorms appear to be
aligned parallel and downstream of the DPVA lifting northeastward,
suggesting short-term training/repeating could be a problem...so
with similar 1"+/hr rates and 1-2 hours duration spots of 2-2.5"
totals may be possible with risk area slowly drifting
northeastward into CO providing some instability advection into SW
CO through the overnight period.  As such, scattered incidents of
flash flooding are considered possible.

Gallina

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...ABQ...FGZ...GJT...PUB...

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

LAT...LON   38480814 38390642 36870546 35760584 35080772
            34650893 35151028 35821066 36441056 37170991
            37980922