Area Forecast Discussion
Issued by NWS Little Rock, AR

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036
FXUS64 KLZK 221140
AFDLZK

Area Forecast Discussion
National Weather Service Little Rock AR
640 AM CDT Fri Sep 22 2017

.AVIATION...
Patchy dense FG occasionally producing bouncy IFR to LIFR vsby,
but most terminals MVFR or better this morning. FG dissipating
after 22/13-14Z, giving way to prevailing VFR through the day with
SCT 5 kft cumulus and S/SEly winds less than 10 kts. Winds will
subside and back to easterly through evening and into tonight,
especially central/southern terminals. Some BR possible during the
early morning hours Saturday, although confidence is low.

&&

.PREV DISCUSSION...(ISSUED 323 AM CDT Fri Sep 22 2017)
SHORT TERM...Today Through Saturday Night
Practically a rinse and repeat persistence forecast. Elongated upper
ridge remains anchored overhead, nearly stacked atop broad surface
high pressure across the eastern half of the CONUS. No
significant weather expected through the period aside from
diurnally-driven cumulus once deep mixing commences after sunrise.
H850 temps of 18C+ keeping temps above average in the upper 80s
and low 90s, although NAM guidance tries to knock those values
down into the 16-17C range by tomorrow afternoon, so perhaps a
degree or two cooler, especially in higher terrain across northern
AR.

Southerly flow relaxes a bit today as the tight pressure
gradient across the High Plains is buffered by the ridge. Continued
influx of moisture in a stagnant atmosphere will keep dewpoints
uncomfortably high and overnight low level moisture pooling will
promote patchy fog and/or haze. Models in good agreement slowly
nudging an upper low our way as the period ends, which would
predominantly result in increased cloud cover across the southern
counties. Little to no thunder expected through Sat night with
continued strong subsidence aloft.

Used a blend of hi-res and global guidance with preference for
the HRRR/NAM through tomorrow evening, then a more general blend
thereafter.

LONG TERM...Sunday Through Thursday
Initially, presence of an upper low in the vicinity of the midsouth
region will keep diurnally-driven convection in the forecast.

However, by late Monday and into Tuesday, the system will dampen out
and get absorbed into the mean flow. Irritating ridge which has been
our predominant weather feature will continue to break apart, and
the southern remnant of it will flatten out. This will allow a
stalled frontal boundary out in the plains to move southeast and
into the region, with rain chances increasing.

By the end of the week, troughing digging down into the central
CONUS will push the front out of the region, with cooler air
following. Heck, it may even start to feel like fall again.

&&

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

$$


Aviation...COOPER



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