Area Forecast Discussion
Issued by NWS Tulsa, OK

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473
FXUS64 KTSA 211755
AFDTSA

Area Forecast Discussion
National Weather Service Tulsa OK
1155 AM CST Wed Feb 21 2018

.DISCUSSION...

The discussion for the 18Z TAF forecast can be found below.

&&

.AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG.
More issues for aviation ops over the next 24 hours. After a
relative lull in the activity early this afternoon, another round
of precipitation will move across the region this afternoon and
into the evening hours. The NE OK and far NW AR sites will see a
wintry mix of sleet/fzra, while KFSM/KFYV/KMLC will likely see
just plain rain. Some patchy freezing drizzle is expected after
the wave of precip is over, mainly after midnight tonight, for the
NE OK and NW AR TAF sites. MVFR/IFR conditions will gradually
deteriorate overnight to sub-IFR.

Lacy

&&

.PREV DISCUSSION... /Issued 929 AM CST Wed Feb 21 2018/

UPDATE...

There were no major changes to the forecast this morning. PoPs
have been nudged north a bit this morning across E OK, and
sleet/ice amounts have been tweaked during the day today. The
configuration of the current winter weather advisory has not been
changed. See discussion below.

DISCUSSION...

An upper level wave ejecting north out of old Mexico this morning,
on the eastern side of broad western CONUS trough, will bring the
next round of precip to the region, while round 1 gradually comes
to an end down in far SE OK. The models are in agreement that
light precip will gradually spread northeast over the region
mainly this afternoon and tonight in association with the
ejecting wave. Thermal profiles from the 12Z NAM suggest a mix of
sleet and frz rain for precip types, where temps are expected to
remain at or below frz. The latest obs from MLC suggest that light
sleet may be falling there currently. The current winter weather
advisory covers areas that are expected to receive the wintry mix
either now or later today, and thus no changes are planned at this
time. Updated text products have been sent.

Lacy

PREV DISCUSSION... /Issued 531 AM CST Wed Feb 21 2018/

AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG.
Overall flight conditions will remain in the IFR category through
this forecast cycle. Widespread rain has largely shifted
southeast of the area for the time being, however some additional
light rain or freezing rain will spread back north across
southeast OK and possibly west central AR later this morning, with
another round of ice accumulating expected to impact northeast OK
by around 00z.

PREV DISCUSSION... /Issued 349 AM CST Wed Feb 21 2018/

DISCUSSION...

Cloud cover along with surface ridging to our west/persistent
northeasterly surface winds will keep the shallow cold air in
place today, with much of eastern OK and far northwest AR
remaining near or below freezing. Morning precipitation will be
mainly confined to areas near or a little above freezing (far
southeast OK/western AR), although precipitation is expected to
lift back north through western/central OK later this morning and
into portions of eastern OK during the afternoon and into the
evening hours. RAP/NAM soundings suggest a mix of freezing rain
and some sleet, with the greatest accumulations generally along
and west of a McAlester to Vinita line. The risk of wintry
precipitation across northwest AR may hold off until beyond 00Z,
with the better chances arriving later Wednesday night.

While there are obvious uncertainties with how quickly
precipitation redevelops and areal extent, feel its prudent to go
ahead with another winter weather advisory for a large portion of
eastern OK and into far northwest AR beginning this afternoon and
continue through Wednesday night. Precipitation looks to taper off
later tonight/early Thursday morning although later shifts will
need to monitor the ending of the advisory.

The active southwesterly flow will continue, with additional
periods of showers/isolated storms expected later Thursday
afternoon into early Saturday. Rainfall axis looks to set up
across southeast OK into northwest AR during this period, with
additional heavy rainfall expected across areas that have received
2-4 inches of rain over the past few days. We`ll likely need flood
headlines, but will hold off for now.

A more pronounced trof axis will swing through the region later
Saturday, with a drying/warming trend expected going into next
week.

&&

.PRELIMINARY POINT TEMPS/POPS...
TUL   31  30  47  38 /  40  60  60  60
FSM   41  39  53  47 /  60  50  50  90
MLC   34  32  50  41 /  60  50  60  80
BVO   32  30  43  34 /  40  70  60  50
FYV   36  34  53  43 /  40  40  50  80
BYV   33  32  53  45 /  40  40  40  80
MKO   34  32  50  41 /  40  50  60  70
MIO   32  31  49  39 /  20  50  50  60
F10   31  30  47  39 /  60  50  60  70
HHW   41  37  53  48 /  90  50  70  80

&&

.TSA WATCHES/WARNINGS/ADVISORIES...
OK...Winter Weather Advisory until 6 AM CST Thursday for OKZ054>067-
     070-071-073.

AR...Winter Weather Advisory until 6 AM CST Thursday for ARZ001-002.

&&

$$


AVIATION.....30



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