Valid 161200Z – 171200Z
…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
NORTHERN AND CENTRAL UTAH THIS AFTERNOON INTO TONIGHT…
…SUMMARY…
A few thunderstorms with locally strong wind gusts may impact
portions of northern and central Utah this afternoon into tonight.
…Utah/Great Basin Vicinity…
A shortwave trough approaching the Pacific coast early this morning
will continue to progress eastward across the Great Basin through
the forecast period. Residual midlevel moisture should be sufficient
for a few diurnally driven thunderstorms across eastern AZ/UT as
forcing increases with the approach of the upper trough. However,
effective shear will remain weak despite increasing speed shear for
much of the period. This will limit severe potential for much of the
day, though a well-mixed sub-cloud layer producing inverted-v type
thermodynamic profiles could support some locally gusty winds.
Overnight, shear profiles will improve as the trough impinges on the
area and a surface cold front sweeps southeast across ID/NV/CA and
into UT after around 06z. Instability will be limited, but guidance
continues to suggest a weak convective line associated with the
front moving across parts of northern/central UT overnight. Given
the strength of the background wind field and the dry sub-cloud
layer, some downward momentum transport could result in a couple of
severe wind gusts associated with weak convection.
..Leitman/Bentley.. 09/16/2019
$$