SPC MD 1699


MD 1699 Image

Mesoscale Discussion 1699
NWS Storm Prediction Center Norman OK
0506 AM CST Sat Dec 08 2018

Areas affected...Portions of northern AR

Concerning...Winter mixed precipitation 

Valid 081106Z - 081600Z

SUMMARY...Light freezing rain will be possible this morning,
especially across the locally higher terrain of the Ozarks. Freezing
rain rates in excess of 0.05 inch per 3 hours may occur. A
transition to sleet and eventually snow should occur later this

DISCUSSION...11Z observations across northern AR show surface
temperatures around/just below freezing, with several RAWS sites in
the higher terrain of the Boston Mountains reporting 28-31F.
Low-level warm air advection and a related area of moderate to heavy
rain is occurring ahead of a lead shortwave trough over much of LA
and southern/central AR. Generally light rain or freezing rain has
been reported thus far across northern AR. Additional precipitation
will likely develop over the next several hours across this region
as the primary upper trough/low over the southern High Plains
develops eastward this morning. 09Z RAP forecast soundings show
around a +1.5 C warm nose in the 850-750 mb layer over northern AR
and a very shallow sub-freezing layer near the surface, which should
support light freezing rain in the short term. Rates may exceed 0.05
inches per 3 hours, especially in the higher terrain where surface
temperatures will be slower to warm this morning. The modest warm
nose aloft is forecast to slowly erode and eventually fall below
freezing, with a corresponding transition to light sleet and then
snow possible around 15-16Z.

..Gleason.. 12/08/2018

...Please see www.spc.noaa.gov for graphic product...


LAT...LON   35629441 35919441 36169391 36369314 36469162 36309082
            35999048 35619047 35409086 35279177 35309305 35629441 

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