MD 1883 CONCERNING WINTER MIXED PRECIPITATION FOR MUCH OF KS AND FAR NORTHWESTERN OK
Mesoscale Discussion 1883
NWS Storm Prediction Center Norman OK
0400 AM CST Tue Dec 29 2020
Areas affected...Much of KS and far northwestern OK
Concerning...Winter mixed precipitation
Valid 291000Z - 291600Z
SUMMARY...Freezing rain should occur this morning before gradually
turning to rain from south to north. Freezing rain rates may exceed
0.05 inch per 3 hours. Some snow/sleet may also mix with the
freezing rain, mainly across parts of northern Kansas.
DISCUSSION...A 40-50+ kt southerly low-level jet will continue to
transport moisture northward across the southern/central Plains this
morning. Strong forcing for ascent associated with this low-level
jet has encouraged the development of scattered to numerous showers
across northern OK and much of central/eastern KS. An initially dry
sub-cloud layer across these areas is gradually becoming saturated
as precipitation continues. Evaporative cooling to the surface wet
bulb temperature should result in a period of freezing rain for at
least a few hours this morning across far northwestern OK and much
of KS, where surface air temperatures are or will soon fall below
freezing. The light to moderate and showery precipitation should
support freezing rain rates around 0.05 inch per 3 hours, with
locally higher rates possible with convection that may produce
isolated lightning flashes with very weak elevated instability.
Still, ice accretion may remain limited to elevated surfaces for
most locations due to the marginal surface temperatures. The best
potential for ice accretion appears to be across parts of
north-central into northeastern KS, where surface temperatures
should generally remain below freezing this morning.
Continued robust low-level warm advection is expected to gradually
erode the near-surface sub-freezing layer from south to north across
this region through the morning, as surface winds veer from easterly
to southeasterly. Accordingly, a transition from freezing rain to
rain should occur across far northwestern OK and parts of
southern/central KS by 16Z (10 AM CST). A mix of freezing rain,
sleet, and/or snow also appears possible across mainly northern KS,
where the low-level warm nose will not be as pronounced compared to
locations farther south.
..Gleason.. 12/29/2020
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...EAX...TOP...ICT...OUN...GID...DDC...GLD...AMA...
LAT...LON 37899794 37419871 36699916 36439964 36670051 37430083
38250072 39129999 39889814 39959681 39879573 39489508
38759494 38309587 38109708 37899794
from SPC Mesoscale Discussions https://bit.ly/2Mh5Qio
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