SPC MD 1647



MD 1647 CONCERNING WINTER MIXED PRECIPITATION FOR SOUTHERN OHIO…CENTRAL APPALACHIANS…AND MID ATLANTIC

MD 1647 Image

Mesoscale Discussion 1647
NWS Storm Prediction Center Norman OK
0218 AM CST Thu Nov 15 2018

Areas affected...Southern Ohio...central Appalachians...and Mid
Atlantic

Concerning...Winter mixed precipitation 

Valid 150818Z - 151415Z

SUMMARY...Precipitation will continue to move north and east through
the morning. Although precipitation may start as light rain, a
relatively quick transition to snow is expected. As precipitation
continues to move northward, snow should transition to sleet, then
freezing rain or rain from north to south.

DISCUSSION...A strong, broad, moist warm-conveyor belt has
established an extensive precipitation shield across much of the
eastern United States. As the precipitation shield moves northward
-- on the nose of said warm-conveyor belt -- it is overspreading a
cool/dry airmass with surface temperatures in the 30sF and surface
dew point temperatures in the teens and low 20sF. The result is
wet-bulb temperatures below 32F/0C. Thus, even though precipitation
may begin as rain, evaporative cooling should quickly allow the
precipitation type to transition to snow as the vertical profile of
wet-bulb temperatures remains below 32F/0C.

Strong warm-air advection within the warm-conveyor belt will allow
for a gradual increase in temperatures within the 700-850-millibar
layer, eventually resulting in temperatures greater than 32F/0C in
the vertical column. Thus, precipitation should eventually
transition from snow to sleet to freezing rain or rain with time.
Although initial precipitation rates may be limited owing to
evaporation, rates should increase with time as low-level saturation
occurs.

..Marsh.. 11/15/2018

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

ATTN...WFO...PHI...AKQ...CTP...LWX...RNK...PBZ...RLX...CLE...
JKL...ILN...LMK...

LAT...LON   39418428 40248361 40648177 40617974 40117745 39017622
            38357766 36947944 36468128 38318149 38638222 38428416
            39418428 

Read more



Source link

Editor

Leave a Reply

Your email address will not be published. Required fields are marked *