Area Forecast Discussion
Issued by NWS Little Rock, AR

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FXUS64 KLZK 230952

Area Forecast Discussion
National Weather Service Little Rock AR
452 AM CDT Fri Mar 23 2018

...Prolonged rainfall likely with flooding possible next week...

.SHORT TERM...Today Through Saturday Night

Not many significant changes will be forth coming this morning with
the overall pattern slightly on the unsettled side and supportive of
only minimal precipitation chances. The latest surface analysis and
radar data indicate some light precipitation ongoing over the
northeast part of the state but moving towards the southeast.

Northwest flow aloft will continue today with another upper level
impulse moving through which will result in minimal chances of
precipitation across the north. Surface high pressure will slip off
to the east with southerly winds helping to pull temperatures back
int the upper 60s to upper 70s across the forecast area. Meanwhile,
surface cyclogenesis will be initiating over the Texas and Oklahoma
panhandles with the pressure gradient tightening in response. Wind
speeds are expected to be in the 10 to 20 mph range with higher
gusts so no headlines will be needed at this time.

As the aforementioned low passes to the north of the state during
the day Saturday, it will drag a cold front through the state. The
front is rather weak with barely a wind shift to mark its presence
and little if any temperature change. Once again, precipitation
chances will generally be minimal with light amounts.

Lingering rain chances will be confined to the south Saturday night
with the overall flow becoming more zonal with time. Attention will
then be turn to a large trough that will be sitting over the Pacific
northwest by the end of the period. This feature will will have a
significant impact on our sensible weather and will be discussed in
the extended period.


.LONG TERM...Sunday Through Thursday Night

The axis of an upper ridge will shift across and then east of the
area to begin the period. In its wake, large-scale upper divergence
in a southwesterly flow regime will increase as a significant West
Coast trough comes ashore. Guidance hints at shortwave trough energy
crossing through the day Sunday as a weak frontal boundary settles
into central AR. With modest moisture in place and a stalling
frontal boundary draped west-to-east across central portions of the
state, expecting showers to develop, with the greatest probability
centered along and either side of the front. Some instability will
be present, but with forecast soundings showing non-negligible CIN,
restricted thunder chances mainly to southern AR, where the best
deep moisture and instability will reside. By Monday, the front
quickly lifts north with ample moisture advection commencing ahead
of the next system, which will be poised off the Pacific Northwest

Through the early/mid-week time frame, the western upper trough will
dig rapidly into the Four Corners region. Resultant southwesterly
flow at H500 will amplify considerably as a surface front shifts
into northwest AR by late Tuesday or possibly early Wednesday.
Persistent surface ridging invof the Mid-Atlantic should slow the
forward progression of this front as it pushes across the state. The
boundary is expected to act as a focusing mechanism for the most
prolific rainfall, but timing and placement differences remain among
operational model guidance. In any case, an array of guidance,
including standardized anomalies and analogs, continue highlighting
excessive moisture profiles characterized by 1.25+ inch PWAT values
(2 standard deviations above the climatological mean). The
interaction of several upper waves, a well-defined frontal wave at
the surface, and multiple scales of dynamic forcing with the
anomalously moist atmosphere in place will yield widespread rainfall
on the order of 2+ inches for much of the state. Still not confident
defining a storm total max, but would not be surprised to see 4 to 6
inches in at least some portions of the area, and that estimate may
be conservative. All modes of flooding appear possible if not
likely, including flash and areal flooding, as well as river
flooding. Stay tuned for more details on hazard magnitude and timing
as forecast details become better-resolved over the coming days.

The frontal boundary and rainfall will linger through at least early
Thursday before kicking out as the parent upper trough finally
ejects to the northeast. Surface ridging and dry air advecting in
will end precipitation west-to-east by late Thursday into Friday.
Despite the unsettled weather through the week, expecting temps to
remain close to or slightly above average through Thursday.



Batesville AR     70  58  78  46 /  20  30  20  10
Camden AR         78  61  77  59 /   0  20  20  20
Harrison AR       70  59  74  43 /  20  30  10   0
Hot Springs AR    74  60  77  54 /  10  20  10  20
Little Rock   AR  74  59  76  52 /  10  20  20  10
Monticello AR     76  60  74  57 /   0  20  20  20
Mount Ida AR      73  61  77  54 /  10  20  10  10
Mountain Home AR  69  56  76  42 /  30  30  20   0
Newport AR        69  58  76  47 /  20  30  30  10
Pine Bluff AR     74  59  75  54 /  10  20  20  20
Russellville AR   73  60  79  51 /  10  20  10   0
Searcy AR         71  58  77  48 /  10  30  20  10
Stuttgart AR      73  59  74  52 /  10  20  20  20

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


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