Area Forecast Discussion
Issued by NWS Tulsa, OK

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418
FXUS64 KTSA 271129
AFDTSA

Area Forecast Discussion
National Weather Service Tulsa OK
629 AM CDT Thu Apr 27 2017

.AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG.
Areas of dense fog are reducing visibility at some of the NW
Arkansas terminals this morning. Conditions should improve after
14z. Otherwise, light winds today with low chance pops this
evening across northeast Oklahoma into northwest Arkansas.

&&

.PREV DISCUSSION... /Issued 306 AM CDT Thu Apr 27 2017/

..WIDESPREAD SIGNIFICANT FLASH FLOODING EXPECTED OVER PORTIONS
   OF E OKLAHOMA AND NW ARKANSAS FRI NIGHT THROUGH SAT NIGHT...

..MODERATE/MAJOR FLOODING ON SEVERAL MAIN-STEM RIVERS APPEARS LIKELY....

DISCUSSION...
Cold start this morning under mostly clear skies with some patchy
fog developing. Clouds will be on the increase today as initial
upper wave approaches from the west. Scattered showers/isolated
thunderstorms will be possible in association with feature across
northeast Oklahoma and northwest Arkansas late this afternoon into
the overnight hours. Rainfall amounts will generally be light.

Global models remain in good agreement with the likelihood of a
widespread/significant and potentially life threatening flood
event Friday night and continuing Saturday/Saturday night. As
discussed for the last several days, a potent upper level storm
system will move into the Four Corners region Friday night,
becoming highly amplified into the day Saturday with 100 knot
upper jet rounding base of trough. Low level moisture will surge
back north tonight into Friday with a warm front lifting to around
the I-40 corridor by Friday afternoon. Atmosphere will become
moderate to highly unstable along/south of boundary and with
limited MLCIN, strong to severe thunderstorms will rapidly develop
by early Friday evening and continue into the overnight hours
across NE OK/NW AR. Large hail, damaging winds and a few tornadoes
will be possible given instability/shear profiles.

Although the severe threat will persist into the day Saturday as
storms continue to develop along quasi-stationary front, it is
becoming apparent that flash flooding/river flooding will cause
the most impact. A flash flood watch will be issued for areas
along/south of I-44 Fri night through Sat night.

Antecedent soil conditions are favorable for excessive runoff
with the recent rainfall. Area lakes also remain above normal
with several main-stem rivers already in flood. Anomalous PWATs
of 2 to 3 standard deviations above normal is expected along and
south of boundary during this time. Thunderstorms with heavy rain
will likely persist Saturday evening before main convective line
shifts east Saturday night.

Widespread rainfall of 8 to 10 inches is expected over east-
central Oklahoma and northwest Arkansas with locally higher
amounts up to 15 inches given the instability available and
sustained updrafts. It should be noted that the axis of highest
rainfall could shift a few counties north or south and persons
should closely monitor the latest forecast as rainfall amounts
continued to be refined.

Main upper low will lift northeast Sunday with cool/breezy
conditions behind front. Brief warm expected on Tuesday before
precipitation chances return by Wednesday as upper wave dives
southeast out of the northern Rockies.

&&

.PRELIMINARY POINT TEMPS/POPS...
TUL   68  56  77  57 /  10  40  20  90
FSM   72  57  78  68 /  10  20  30  80
MLC   72  59  79  68 /  10  10  30  80
BVO   67  52  76  55 /  20  50  10  90
FYV   67  54  72  61 /  10  40  30  90
BYV   66  55  72  61 /  10  40  30  90
MKO   69  56  77  61 /  10  30  30  90
MIO   66  54  75  55 /  10  50  20  90
F10   70  58  78  62 /  10  20  30  90
HHW   73  57  80  70 /  10  10  30  70

&&

.TSA WATCHES/WARNINGS/ADVISORIES...
OK...Dense Fog Advisory until 9 AM CDT this morning for OKZ057-058-
     062-063-068-069.

     Flash Flood Watch from Friday evening through Sunday morning for
     OKZ049-057-058-060>076.

AR...Dense Fog Advisory until 9 AM CDT this morning for ARZ001-002-
     010-011-019.

     Flash Flood Watch from Friday evening through Sunday morning for
     ARZ001-002-010-011-019-020-029.

&&

$$

SHORT TERM...18
AVIATION...06

CORFIDI



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