FXUS64 KLZK 121745

Area Forecast Discussion
National Weather Service Little Rock AR
1145 AM CST Wed Dec 12 2018

MVFR conditions prevailing across northern AR at the moment, with
VFR conditions south. CIGs will continue to deteriorate throughout
the day at all locations. Conditions should deteriorate to IFR
around or after 06Z. Sfc winds have been predominantly W/SW at
most sites, but will be veering to S/SE thru the period.


.PREV DISCUSSION...(ISSUED 544 AM CST Wed Dec 12 2018)

For the 12Z TAFs, low clouds will continue to build eastward into
the forecast area, and impact most terminals later this morning.
MVFR conditions are expected for the majority of the period. Light
drizzle will precede rain later this afternoon, but light rain
will move into the state through the evening and overnight hours.
Low clouds will linger, with conditions approaching IFR late in
the period. Winds will be a little breezy today, but stronger winds
just off the surface could cause llws at most terminals.

SHORT TERM...Today Through Thursday Night

An upper low to our north moving across the Midwest and Great Lakes
region can be seen on the latest water vapor satellite imagery, as
well as an upper level low over the Pacific Southwest and developing
trough over the Pacific Northwest.

The upper low to our north will push east through the day, providing
little impacts to the state. However, as the areas of low pressure
across the West push eastward, they will bring rain showers and
thunderstorms to the region through the period. The shortwave trough
across the Pacific Northwest will develop as it plunges
southeastward through the Desert Southwest region and eastern New
Mexico/West Texas, providing the primary focus for the active

The best chances for widespread rainfall will be late Wednesday
night, with chances increasing through the day Thursday as the stout
upper level low nears and moves across the state. Thunderstorms will
be possible across the southern half of the state on Thursday,
however at this time organized severe weather chances are low.

A cold front associated with the upper level low will move through
the state Thursday night into Friday morning, shifting our southerly
surface winds to the north. Colder air will begin to filter in
behind the front during the long term portion of the forecast, but
for now temperatures will be mild, with highs in the 50s and lower
60s, and lows in the 40s and lower 50s.

LONG TERM...Friday Through Tuesday

All the active weather looks to take place early in the extended
period with dry weather expected from Sunday night through its
conclusion. Much like the past few nights, the models remain in good
agreement in the synoptic scale but rather significant timing and
intensity differences in the finer details are apparent. The only
model that is showing any run to run consistency is the ECMWF and
will lean the forecast in the direction of that solution.

A deep upper level low will be located over far east Texas when the
period initiates with surface reflection located just to the east of
the upper system. Plenty of moisture will be in place with periods
of showers continuing Friday and into Friday night as system moves
off to the east/northeast. Center of circulation will be located
over the Tennessee Valley early Sunday with just enough wrap around
moisture to warrant precipitation chances over the east and
northeast during the day. Dry conditions are expected through the
remainder of the period as the overall trend is to bring in higher
pressure. However, confidence is not very high as model differences
remain fairly large.

Thunderstorm chances look limited at this point and while a rumble
of thunder can not be discounted, Friday its probability is to low
to be included in the forecast. Cooler air does move into the state
behind the departing system but moisture will be all but gone by the
time that happens. As such, no winter precipitation is expected at
this time.

Temperatures will be very cool on Friday as the system moves through
with northwest flow aloft in its wake. Temperatures do moderate with
time and look at average a little above normal. Overall the MAV/MEX
numbers look reasonable and are generally accepted.


.LZK Watches/Warnings/Advisories...NONE.

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