Area Forecast Discussion
Issued by NWS Tulsa, OK

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FXUS64 KTSA 181744
AFDTSA

Area Forecast Discussion
National Weather Service Tulsa OK
1244 PM CDT Thu May 18 2017

.DISCUSSION...

The 18Z TAF discussion is included below.

&&

.AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG.
VFR conditions will prevail this afternoon, with storm potential
increasing this evening and overnight across E OK/NW AR. Used
tempo groups to try and pinpoint the most favorable time at any
given site, but this could change and amendments would be needed.
MVFR possibly even IFR conditions are possible with any storms,
along with strong wind gusts. MVFR conditions will prevail Friday
morning.

Lacy

&&

.PREV DISCUSSION... /Issued 1114 AM CDT Thu May 18 2017/

DISCUSSION...

The 12Z soundings across the region, along with goes16 water vapor
imagery, show a stout EML in place over the region, in advance of
an approaching upper level low over the southern Rockies. Rich low
level moisture is returning north beneath the cap, with 70
dewpoint air lifting north into eastern Oklahoma to the south of a
warm front over southern Kansas. A dryline is taking shape
south of surface low across far western Oklahoma.

Hi-res CAM models have shown for several runs now that a north-
south band of elevated convection could form by early afternoon
across western Oklahoma. Some of this convection could congeal
into clusters and pose a wind threat into the evening across
portions of eastern Oklahoma.

Otherwise the focus remains to the west, where surface based
storms are expected to fire along the dryline and near the warm
front by mid to late afternoon out in western Oklahoma. These
storms will pose the greatest risk of severe weather as they track
generally to the northeast. The area with the greatest potential
for discrete storms, and thus the highest tornado and largest hail
risk, will be to the northwest of Tulsa closest to where surface
based storms are expected to initiate. Eventually, storms are
expected to evolve into clusters or lines and pose a damaging wind
threat tonight into eastern Oklahoma. Isolated tornadoes could
occur with any bowing line segments as well.

Lacy

PREV DISCUSSION... /Issued 648 AM CDT Thu May 18 2017/

AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG.
Surging low-level moisture overnight has moved in an MVFR sct/bkn
cloud deck this morning. This deck should scour out a bit later this
morning with cloud deck rising to VFR by late morning. Focus turns
to timing of convection tonight. A line of convection will fire
across western Oklahoma and move east with time. Hi-res models have
the line nearing the far eastern terminals between 03-05Z, however,
models aren`t in very good agreement as to the overall evolution and
extent of the convective line and timing will likely be adjusted in
a future issuance.

PREV DISCUSSION... /Issued 337 AM CDT Thu May 18 2017/

DISCUSSION...
As expected...surface dryline has quickly retreated west tonight
with mainly mid/upper 60s dewpoints across the region at this
time. The atmosphere will become quite unstable this
afternoon...and while there are some signals that a few storms
could develop across southeast OK late today...the main concern
will come from storms developing well to our west. Expect
explosive development by late afternoon near the triple point
across southwest KS southward along/ahead of the dryline across
far western OK. Several clusters of storms will likely organize
into the evening/overnight hours...with strong/severe storms
tracking east into northeast OK and possibly northwest AR late
Thursday night.

The active weather continues into Friday...as additional storms
are expected to fire along the eastward advancing dryline.
Forecast shear profiles appear more than sufficient for rotating
storms...with all modes of severe weather possible Friday
afternoon and into the evening hours. Convection should
eventually evolve into a more linear mode Friday night as the cold
front overtakes the dryline and surges into the forecast area.
Showers/storms will linger into Saturday...especially across
southeast OK and western AR...with the activity finally pushing
south by Saturday night. Will also need to monitor the heavy rain
potential through Saturday night.

Sunday and into early next week is looking cooler and drier...with
showers/storms returning to the forecast Monday night as another
front moves through the region.

&&

.PRELIMINARY POINT TEMPS/POPS...
TUL   71  81  62  73 /  60  50  90  40
FSM   71  87  68  78 /  30  40  70  80
MLC   71  84  65  75 /  50  30  90  60
BVO   67  82  59  72 /  60  60  90  40
FYV   67  82  64  74 /  50  30  70  70
BYV   69  83  65  75 /  50  30  70  70
MKO   68  83  64  73 /  50  40  90  60
MIO   68  82  63  73 /  60  40  90  50
F10   68  80  61  74 /  50  50  90  50
HHW   70  86  69  76 /  50  40  70  80

&&

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

$$

AVIATION...30



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