Area Forecast Discussion
Issued by NWS Little Rock, AR

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FXUS64 KLZK 211124

Area Forecast Discussion
National Weather Service Little Rock AR
624 AM CDT Wed Mar 21 2018

Isolated areas of MVFR visibility due to fog will clear by 14z. A
northwesterly near surface flow of 09-15 kts will prevail between
14 and 23z.



.PREV DISCUSSION...(ISSUED 405 AM CDT Wed Mar 21 2018)
SHORT TERM...Today Through Thursday Night
07z subjective surface analysis indicates a pressure ridge extending
from southeast Nebraska, to central Texas.  This feature will slide
eastward through this period.

The ridge axis will be east of the forecast area by late in this
period.  The developing low level flow pattern will promote some
isentropic upglide, most pronounced across northeastern sections.
However, substantial condensation pressure deficits will need to
be overcome to produce more than trace rainfall amounts late
Thursday night.

LONG TERM...Friday Through Wednesday
To begin the period, the overall synoptic flow pattern will be
characterized by large-scale upper troughing across the western and
eastern coasts with upper ridging through the central CONUS. A
developing shortwave trough will cross the Rockies late Friday into
Saturday, spurring surface cyclogenesis in the Central Plains by
early Saturday.

Southerly flow locally will advect modest boundary layer moisture
northward, with a plume of 60+ F dewpoint temperatures becoming
established by Saturday afternoon. With the best upper energy
progged to remain well north of the forecast area, not expecting
significant rain or thunder chances for most areas, but some showers
and perhaps a rumble of thunder are possible in far northern zones
during the day Saturday.

Upper flow begins to flatten late weekend and transitions to
southwesterly by Monday as the upper ridge shifts east. At this
time, operational and ensemble guidance suggest the large west coast
trough will migrate southeastward into the Four Corners region
heading into the mid-week time frame. Given this scenario, expecting
large-scale upper divergence to overspread the area with increasing
southwest flow aloft early next week. Showers and thunderstorms are
expected to increase as a result, with multiple scales of lift
providing sufficient forcing for ascent. That said, there is
significant disagreement with the placement of frontal boundaries
and mesoscale impulses aloft through the end of the period.
Confidence is higher-than-average concerning the overall synoptic
pattern, but low concerning the placement of the highest
rain/thunder probabilities. Kept PoPs capped at high-end chance due
to this uncertainty; however, the likelihood of prolonged rainfall
over at least portions of the area is increasing through next week.

Expecting temperatures to exhibit a gradual cooling trend with
plenty of cloud cover and precipitation. That said, not anticipating
significantly unseasonable temps through the period.


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


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