FXUS64 KMEG 162046
Area Forecast Discussion
National Weather Service Memphis TN
246 PM CST Sun Dec 16 2018
Skies were partly sunny across the Midsouth this afternoon.
Temperatures were in the mid and upper 50s this hour with winds
westerly at 5-10 mph.
For tonight and tomorrow...weak shortwave dropping southeast from
the Midwest will have minor influences on the Midsouth tonight.
This feature will scour out the current cirrus overhead and shift
westerly winds more northerly for tomorrow. With ground surfaces
remaining moist and radiational cooling tonight short term model
guidance and BUFKIT soundings suggest areas of dense fog...mainly
across the southern two thirds of the CWA. A dense fog advisory
is in effect beginning late this evening through late tomorrow
morning. The NAM MOS guidance has also picked up on the fog
formation forecasting highs tomorrow as much as twelve degrees
cooler than other guidance is depicting. For now have dropped
forecast highs for Monday a few degrees as fog dissipation should
occur before noon.
Monday night and Tuesday...a narrow but well amplified ridge with
a negative tilt will pass across the Mississippi Valley this
period. Mid level moisture though will be right on the ridge
axis's heels late Tuesday as the upper flow becomes southwest.
Dry weather is expected with slightly above normal temperatures.
Wednesday through Friday...models depict a split in jet energy
across the west...with a gradual merging of the southern and
northern branches over the central U.S. by late Thursday. This
will lead to the formation of a new 500mb closed low somewhere
over the Ozarks or Midsouth. The GFS then tracks the low eastward
across the Midsouth...while the Euro now takes it southeast
towards the Gulf Coast. Either way rain chances appear likely for
the area...with temperatures cooling by Friday behind a passing
cold front. Changes in the forecast this period...add thunderstorm
chances Wednesday night into Thursday over the south as elevated
energy lifts northward...add a slight chance for a rain and snow
mix over the northern counties Friday morning before the system
pulls east...and finally linger wrap around low level moisture
east of the Mississippi River into Friday afternoon. Highs will
start off slightly above normal this period...but will fall below
normal by Friday. Lows will generally be in the 30s and 40s.
Saturday and Sunday...extended models show a dry start this
period...with increasing clouds and a slight chance for rain
returning Sunday with the passage of a weaker shortwave trough.
Temperatures both days will appear seasonal.
VFR conditions are expected to persist through at least early
evening. However, relatively clear skies, light/nearly calm winds,
and temperatures cooling to near surface dewpoints is expected to
result in the development of fog overnight and subsequent IFR/LIFR
conditions. Lowest forecast visibility in this set is down to
3/4SM. However, its plausible that visibilities may drop down to
1/4SM late tonight towards daybreak, then gradually improve
throughout the rest of Monday morning. Additional adjustments to
TAFs may be necessary if this trends looks more certain for
AR...Dense Fog Advisory from 10 PM this evening to 10 AM CST Monday
for Craighead-Crittenden-Cross-Lee AR-Mississippi-Phillips-
MS...Dense Fog Advisory from 10 PM this evening to 10 AM CST Monday
for Alcorn-Benton MS-Calhoun-Chickasaw-Coahoma-DeSoto-
TN...Dense Fog Advisory from 10 PM this evening to 10 AM CST Monday
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