Areas affected…Far Western NM…Eastern/Northern AZ…Southern
UT
Concerning…Heavy rainfall…Flash flooding possible
Valid 031920Z – 040120Z
SUMMARY…Scattered monsoonal showers and thunderstorms may cause
a few instances of flash flooding this afternoon and into the
early evening hours.
DISCUSSION…The latest GOES-16 GeoColor satellite imagery shows a
well-defined MCV over south-central IT which is drifting slowly
off to the northeast early this afternoon. This compact piece of
energy in conjunction with diurnally driven surface-based
instability and orographics is leading to an increase in shower
activity across southern UT and extending southeast down across
northeast AZ. SBCAPE values are approaching 1000 j/kg across
southern UT, and 1500 j/kg across northeast AZ. The low-levels of
the column are relatively dry, but there is a fair amount of
mid-level moisture noted as per the 12Z KFGZ RAOB sounding and
more recent CIRA-LPW data.
Going through the afternoon hours, an increase in shower and
thunderstorms will be expected as additional diurnal heating
drives increased instability parameters. This will include the
Mogollon Rim and areas of western NM which will see favorable
orographics/terrain-induced circulations, but will be more removed
from any MCV-driven forcing. Additionally, there is expected to
some additional increase in the PWATs as deep layer southerly flow
around the western periphery of the deep layer ridge over the Four
Corners allows for more monsoonal moisture transport north out of
northwest Mexico.
The morning hires model suite supports isolated storm totals
amounts through early evening of as much as 2 inches, but the
recent runs of the HRRR have been actually notably lower. However,
with the forcing associated with the MCV over southern UT, a
gradual uptick in monsoonal moisture and slow cell motions, it is
feasible that some locally heavier totals in the 2 to 3 inch range
will be possible.
Widely scattered areas of flash flooding will be possible with the
monsoonal convection, with the more sensitive dry washes,
slot-canyons and burn scar areas seeing the greatest threat.
Orrison
…Please see www.wpc.ncep.noaa.gov for graphic product…
ATTN…WFO…ABQ…EPZ…FGZ…GJT…PSR…SLC…TWC…VEF…
ATTN…RFC…CBRFC…WGRFC…
LAT…LON 39221136 38751073 38601019 38700965 38640915
38230900 37230901 36710881 36160820 35850779
35420738 34650737 34190728 33710733 33390759
33160792 33100853 33310931 33791044 34331130
34891205 35291236 35661238 36121237 36751255
37331289 38041301 38771250 39151210