Area Forecast Discussion
Issued by NWS Tulsa, OK

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FXUS64 KTSA 201950
AFDTSA

Area Forecast Discussion
National Weather Service Tulsa OK
250 PM CDT Fri Oct 20 2017

.DISCUSSION...
Main forecast concerns are the severe thunderstorm and heavy rain
potential, especially across eastern Oklahoma, tomorrow evening
and into early Sunday morning.

Early this afternoon, a few light showers continue across portions
of western Arkansas, in association with a fast moving disturbance
ahead of the main upper level wave currently located over the
western United States. Additional activity could develop later
tonight and into tomorrow morning as low level moisture continues
to increase across the region, along with the developing low
level jet. Steepening mid level lapse rates will provide an
isolated thunderstorm threat tonight. The low chance of showers
and thunderstorms will continue through most of the daylight hours
tomorrow.

Tomorrow afternoon, thunderstorms will develop along the
approaching cold front across parts of Kansas, southwestward into
western and central Oklahoma. The expected line of thunderstorms
may sneak into portions of northeast Oklahoma by early evening,
but most of the region will be affected toward mid to late evening
and into early Sunday morning. CAPE values ahead of the front
should be in the 2000-3000 J/kg range. Deep layer shear will be
sufficient for severe hail, especially with early, more isolated
development, but conditions remain more favorable for damaging
winds associated with more linear structures. While leading edge
QLCS tornado potential will be nonzero, forecast low level shear
parameters do not seem overly supportive of a large threat.
Overall, the severe thunderstorm threat should maximize across
portions of Oklahoma and diminish some once the line moves into
Arkansas.

Locally heavy rainfall will also be a concern, with storm totals
averaging between 1 and 2 inches and isolated amounts possibly
approaching the 3 to 4 inch range. Widespread flash flooding does
not look likely at this point, but rainfall amounts of this
magnitude could lead to an increased potential in a few locations.

Some showers and thunderstorms may linger across parts of far
eastern Oklahoma and western Arkansas into Sunday before the upper
trough and cold front finally clear the area later in the day.
A secondary cold front will move through the area late Monday and
into Tuesday, with no precipitation chances associated with it.

A stronger push of cold air is looking more likely toward the end
of the next work week and into next weekend. Some moisture
recovery may occur ahead of this system to produce a few showers
ahead of it on Friday. The bigger story, however, is the
potential for sub-freezing temperatures for portions of the area
into next weekend. We may be looking at Frost/Freeze Headlines at
this same time next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
TUL   67  78  54  70 /  20  20 100  10
FSM   64  79  60  69 /  20  20 100  40
MLC   67  78  56  68 /  20  20 100  20
BVO   65  77  53  69 /  20  20 100  10
FYV   63  75  57  62 /  20  20 100  40
BYV   61  77  57  63 /  20  20 100  50
MKO   65  77  55  68 /  20  20 100  20
MIO   66  78  53  67 /  20  20 100  20
F10   66  77  54  68 /  20  20 100  10
HHW   66  81  59  69 /  20  20 100  40

&&

.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...None.
&&

$$

LONG TERM....22



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