Area Forecast Discussion
Issued by NWS Little Rock, AR

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FXUS64 KLZK 181101
AFDLZK

Area Forecast Discussion
National Weather Service Little Rock AR
501 AM CST Tue Dec 18 2018

.AVIATION...

Areas of fog remain possible this morning, particularly over the
southern terminals with brief ifr conditions possible. Once the
fog does burn off, low to mid level moisture will remain in place
across the central and south with just high level moisture over
the north. Overall VFR to occasional MVFR conditions will prevail.
Winds will be light and generally from the south to southeast.

&&

.PREV DISCUSSION...(ISSUED 250 AM CST Tue Dec 18 2018)
DISCUSSION...

Short term...Today through Wednesday night

Cirrus shield continues to overspread the forecast area which is
helping to limit radiational cooling somewhat. In spite of this,
high res models are continuing to show dense fog developing through
the early morning hours and will hold on to the dense fog advisory
in its current form.

Meanwhile, upper level ridging currently over the area will begin to
lose its grip. A weak upper wave moving through the prevailing flow
aloft is responsible for the aforementioned high clouds. Clouds will
likely continue through the early afternoon. High temperatures today
will be in the upper 50s to lower 60s with light southeast winds.

Meanwhile, water vapor imagery is showing upper level troughing over
the desert southwest. As trough progresses to the east, low pressure
develops in its base and eventually becomes detached from the
prevailing flow. Southerly surface flow will pull moisture into the
developing system with scattered showers and isolated thunderstorms
developing Wednesday. Temperatures will be just a degree or two
cooler versus what will be seen today.

Upper pattern amplifies significantly on Wednesday night as a strong
piece of energy drops into the advancing upper trough which will be
located over west Arkansas as the period concludes.

Precipitation chances will be increased as a result but overall
rainfall amounts will not be overly high. Winds on the back side of
the system will be increasing over the west late in the period but
the main effects of this system will be felt in the long term.

Long Term...Thursday through Monday

While the surface system will be shifting eastward on Thursday, a
cutoff upper low will be moving through behind it, and rainfall will
linger into the day. Given elevated instability present, will
continue to mention isolated thunderstorms in the forecast. As the
upper low shifts southeast late in the day, rain should come to an
end fairly quickly as dry air is drawn in on the back side of the
system. Pressure gradient behind the surface system will remain
significant into the day Thursday, with gusty winds continuing.
Winds will decrease during the evening as the gradient relaxes, and
high pressure moves in.

The high will shift through the region fairly quickly, with another
cold front approaching by the weekend. However, there shouldn`t be
much of an opportunity for large-scale moisture return ahead of the
boundary, so precip chances will be minimal initially.

The upper level flow will flatten out by late in the weekend, with
the front stalling out south of Arkansas. Longwave pattern will
amplify early next week, with a trough digging down into the
Rockies. Southwest upper flow will develop, which will push the
stalled front back to the north. Uplift north of the front will
allow for precip to develop...possibly as soon as late Sunday night
or early Monday morning.

Through the period, temperatures will largely remain above seasonal
averages.

&&

.LZK Watches/Warnings/Advisories...
Dense Fog Advisory until 10 AM CST this morning FOR Arkansas-
Bradley-Calhoun-Clark-Cleveland-Dallas-Desha-Drew-Garland-Grant-
Hot Spring-Jefferson-Lincoln-Montgomery-Ouachita-Pike-Polk.

&&

$$


Aviation...GOUDSWARD



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