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WPC Met Watch

Mesoscale Precipitation Discussion: #0775
(Issued at 211 PM EDT Wed Aug 17 2022 )

MPD Selection

Graphic for MPD #0775

Mesoscale Precipitation Discussion 0775...Corrected
NWS Weather Prediction Center College Park MD
211 PM EDT Wed Aug 17 2022

Corrected for wording at the end of the first discussion paragraph

Areas affected...portions of the Southwest & Great Basin

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

Valid 171807Z - 180007Z

Summary...An east-west trough moving northward through the region
along with well above average moisture should lead to hourly rain
totals to 2.5" and local amounts to 4".  This would be most
problematic in burn scars, urban areas, slot canyons, and dry

Discussion...Sunny skies have led to an increase in ML CAPE
values, currently in the 500-2500 J/kg range across portions of
southeast CA, southern NV, southwest UT, and a good portion of AZ
per SPC mesoanalyses.  Precipitable water values of 1.5-2.2" lie
across the region per GPS data.  CIN is eroding across the region
which is leading to shower and thunderstorm development at this
time.  A surprisingly well-defined tropical disturbance
approaching the Bootheel of NM is inducing easterly mean flow
across southern and eastern portions of the area.

A trough noticable at 700 hPa is forecast to drift north from
southeast CA into Sierra Nevada, while its eastern portion pivots
across southern NV and the UT/AZ border which should aid/focus
convection across the region.  Activity across AZ should prefer
development along the terrain which will then drift south to
southwest following the 700 hPa flow ahead/west of the tropical
disturbance while also showing a tendency to develop towards the
higher instability in the Southwest Deserts.  Hourly rain totals
to 2.5" with local amounts to 4" are expected.  This degree of
rainfall would be most problematic in area burn scars, slot
canyons, dry washes, and urban areas. 




LAT...LON   38760921 37780909 36980929 34561059 31721165
            32191427 32161580 32231633 33751706 34381830
            35941792 37411574 38111265 38181126 38071018

Last Updated: 211 PM EDT Wed Aug 17 2022

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Page last modified: Saturday, 01-Jan-2022 07:08:48 GMT