Forecast Discussion

FXUS64 KMEG 180312

Area Forecast Discussion
National Weather Service Memphis TN
912 PM CST Thu Jan 17 2019


A cold front is slowly moving across the Mid-South this evening.
At 03z the front stretched from the TN River into NW MS. There are
some patches of light rain/drizzle along and ahead of the front
along with some areas of fog. Front will continue to push east
overnight though clouds and patchy fog will remain with the best
chance for drizzle across NE MS after midnight. Expect lows from
the upper 30s north to mid 40s south.



PREV DISCUSSION... /issued 250 PM CST Thu Jan 17 2019/

Currently skies were cloudy over the Midsouth with patches of
light rain and/or drizzle still affecting the region. Temperatures
were seasonal...ranging from the upper 40s to low 50s. Light fog
was also being reported at several locations with winds generally
southwest at 5-15 mph. Presently a cold front was tracking through
northeast Arkansas and the Bootheel of Missouri.

For tonight...the low level westerly flow over the region will
weaken and becoming northeasterly with the passage of the
aforementioned front. This will likely lead to clouds sticking
around with either a few lingering light showers or patchy
drizzle. Light fog will also be present...though fog may become
thicker across the southeast counties after midnight. Low
temperatures will drop into the upper 30s to mid 40s.

Friday into Saturday...weak shortwave ridging will influence the
region through the day surface winds turn more
southeasterly. Skies will remain mostly cloudy with milder high
temperatures in the 50s to near 60F for most. The approach of the
next Pacific system will quickly ramp up rain chances in the
evening and overnight hours as 850mb winds increase from the
southwest and the current front lifts back north into the mid
Mississippi Valley. Despite the light to moderate precipitation
WAA will keep Friday night lows closer to average high
temperatures. Increasing instability lifting out of Texas ahead
the approaching trough and next cold front will bring the threat
for some thunder to the area through Saturday afternoon. Models
show CAPE values up to around 500 j/kg by noonish...with the GFS
more bullish on this coverage. For now plan on leaving the
current wording for a few strong storms across northeast
Mississippi in the afternoon HWO. Storm total rainfall amounts
will range from an inch in the 2+ inches in the east.
Models are also getting closer in agreement with this storm`s
evolution and exit Saturday night...specifically the depth of
trailing moisture changing over to wintry precipitation. Best
guess for now shows rain changing over to snow by the late
afternoon hours across the northwest counties...then early evening
in the Memphis metro and near midnight at
TUP...which by then should just be some spotty flurries and/or
a trace of freezing drizzle. Snow accumulations of a dusting...up
to one inch are most feasible along and north of I-40. It would
be more if the dendritic zone were more saturated...but the open
nature of the trough has this moisture exiting fairly rapidly
as the low level cold air infiltrates the low levels. Forecasted
Skew-Ts support patchy freezing drizzle along with the light snow
that may cause some road problems. For that reason plan on
issuing an SPS to address the impact to elevated surfaces. There
is still a few more model runs that could easily change this
thinking. Wind chill values will fall into the teens for most
after midnight with northwest winds of 10-15mph and higher gusts.

Sunday and Monday...below normal temperatures will be the rule
Sunday with highs in the 30s and 40s. The sun will return to the
area but midlevel clouds cresting the fast approaching upper ridge
will spill into the northern counties in the afternoon and evening
hours. The ridge will warm temperatures and further dry the region
for Monday.

Mid-week...Rain chances will increase Tuesday into Wednesday with
the next storm to cross the Plains. A more northerly upper flow
behind this system suggests a pattern change...with arctic air
keeping temperatures below normal through the week.



00Z TAF cycle

Low clouds will remain over the region for the entire forecast
period. Some areas of drizzle and fog will be possible tonight
into early Friday morning. Winds will be light and variable for
much of the forecast period.