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fxus64 kmeg 120546 

Area forecast discussion
National Weather Service Memphis Tennessee
1146 PM CST Mon Dec 11 2017


Updated for 06z taf discussion


Previous discussion... /issued 947 PM CST Mon Dec 11 2017/

9 PM / 03z surface map showed a cold front over north MS, dropping
south. Not typically seen with cool season cold fronts, a thermal
ridge was evident on Arkansas and southern MO obs this evening. The
combination of very low dewpoints and warm Post frontal temps led
to a continuation of elevated fire danger well past sunset.
However, the Post frontal temps were finally cooling at midevening,
with the the cross-frontal thermal gradient almost nil.

Forecast was updated to reprofile overnight temperature and
dewpoint curves a bit. Overnight lows also tweaked up, with cold
advection lagging and wind expected to stay up overnight. The
winds will lead to wind chills dropping into the 20s by sunrise.


Previous discussion... /issued 324 PM CST Mon Dec 11 2017/

a Rex block over the western Continental U.S. Will result in little change
in the synoptic pattern through Thursday, maintaining a mean
trough over the east and a ridge across the southwest. Closer to
home, a potent shortwave trough continues to dive southeast across
the western Ohio Valley this afternoon. The attendant surface low
has moved into northern Illinois with a trailing cold front extending
south-southwest across southeast MO into central Arkansas. The resultant pressure
gradient has helped produce gusty southwest winds across the mid-
south, with the strongest winds found over northeast Arkansas into the
bootheel. Relative humidity generally remains above 25% in most
areas, but has dropped slightly lower in a few locations. Winds
will veer westerly as 00z approaches, gradually shifting from the
northwest as a dry cold front moves across the mid-south. Winds
are expected to remain up in the 8-14 mph range and may be gusty
at times throughout the night. No changes are anticipated to the
ongoing red flag warning.

Northwest winds will increase again Tuesday morning but are
expected to slowly wane during the afternoon hours as the surface
gradient relaxes. Temperatures will take a big hit tomorrow with
afternoon highs only in the 40s. Mostly clear skies and a
decoupled boundary layer will result in cold temperatures across
the County Warning Area for Wednesday morning. Expect sub-freezing temperatures
area wide with some locations dipping into the lower 20s. The
surface anticyclone remains south of the area, causing winds to
back southwesterly on Wednesday. Temperatures will be a bit
warmer, but most areas should top out in the low to mid 50s.

Another shortwave trough will swing across the region Thursday
into Thursday night. This will drive another cold front through
the area along with a bit of mid/upper-level moisture. A few
sprinkles and/or snow flurries aren't out of the question Thursday
night, but confidence remains rather low at this time. Will
continue to monitor this potential over the coming days. This
Thursday cold front will reinforce the Continental polar airmass
over the mid-south, maintaining highs ranging from the mid 40s to
mid 50s.

A pattern shift is anticipated by the weekend as the east Continental U.S.
Trough moves east and a trough digs over the west. There remains
significant model disparity regarding the evolution of this
pattern, especially pertaining to the available moisture. At this
time, it appears that a cold front will move across the area on
Sunday as a relatively deep, positively tilted trough swings
through the plains. The GFS continues to indicate a good amount of
quantitative precipitation forecast along this front while the European model (ecmwf) remains quite dry across the
region. Given this uncertainty, pops will be capped at 30-40% for
Sunday. This system will be a quick hitter with dry weather
expected early next week.



06z tafs

VFR conditions prevail for the majority of the period, with
several hours of MVFR cigs expected at kmem and kmkl in the early
morning hours. Less confidence that kmem gets these cigs as it
will be on the western edge of the cloud deck. Northerly winds
will become gusty today behind the front, but will quickly taper
off after sunset and become light or calm overnight.



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