Severe Thunderstorm Warning 99, NWS Norman, OK

Area Forecast Discussion
National Weather Service Norman OK
1058 PM CDT Wed May 2 2018

.AVIATION...
Most of the convection that formed this afternoon and evening
has moved east of all TAF sites at 4Z. Strong wake low winds
across north central Oklahoma will diminish by 6z. VFR ceilings
at 4Z should lower to MVFR overnight with breezy southeast winds.
Meanwhile, additional storms have formed across southwest Texas
this evening. At least scattered thunderstorms should move across
SPS/LAW/OUN/OKC from roughly 6Z through 12-13Z.

&&

.PREV DISCUSSION... /issued 709 PM CDT Wed May 2 2018/

AVIATION...
A line of strong to severe storms will move across most terminal
sites between 00z and 4z. The stronger storms may lower visibility
to around 1sm with mainly MVFR ceilings. More storms may develop
and move across the southern half of Oklahoma and western north
Texas mainly between 6z and 12z. After 12-13Z, mainly VFR
conditions are expected with a south to southwest wind.

PREV DISCUSSION... /issued 210 PM CDT Wed May 2 2018/

DISCUSSION...
Latest surface observations and satellite show enhanced cumulus
and some glaciation along a sharpening dryline now across the
eastern Texas Panhandle. Deeper convection has been ongoing for an
hour or so further north, near a weak surface front across the far
northern Texas Panhandle into the Oklahoma Panhandle. NSSL mobile
sounding at Elk City from 18z shows a weak capping EML and this
should continue to errode as forcing for ascent increases from
approaching deep closed low and embedded minor shortwave trough.

Latest RAP mesoanalysis shows moderate to strong instability has
already developed across western Oklahoma and western north Texas
with MLCAPE as high as 3,000 J/kg and effective shear of 50-60
knots. This parameter space, along with nearly perpendicular shear
vectors to the sharpening dryline, is more than favorable for
supercells. Other concerns include climatologically low LCL
heights. One mitigating factor to a potentially higher-end tornado
threat will be somewhat weak low level shear. Our bigger tornado
events tend to have larger 0-1km bulk shear and SRH values.
Nevertheless, 15-20 kt 0-1km shear and low LCLs with the
aforementioned parameter space is concerning and tornadoes,
including a few significant tornadoes are possible given the
proper storm evolution. Some cold pool expansion and resulting
consolidation may occur with the ongoing convection across
northeast Texas Panhandle and the Oklahoma Panhandle. This could
evolve into a cluster or line of convection that posses mainly a
damaging wind threat later in the evening across northern
Oklahoma. This evolution is uncertain at the moment and we'll
continue to monitor trends.

Suite of CAMs have varied some from run to run and model to
model. The spectrum of solutions generally supports the above
thinking, and we'll continue to watch the trends in observations
through the late afternoon and evening and add more detail to the
forecast when we can.

Regardless of how early on more discrete supercells evolve, some
tornado threat will persist into the night given such a moist
boundary layer with only modest stabilization. The threat could
persist into the early morning hours and some localized flooding
could occur particularly across eastern and southern sections of
the area once shear vectors become a little more parallel to a
potential cluster or line of convection. Depending on the extent
of convection and magnitude/breadth of convective overturning,
some thunderstorm threat and severe potential will persist across
roughly the southeast half of the area into tomorrow afternoon.

The rest of the forecast is relatively unchanged. Northwesterly
flow will gradually back and become more zonal with at least one
or two minor shortwaves resulting in convection by early next
week.

BRB

FIRE WEATHER...
Elevated fire weather conditions could occur tomorrow afternoon
across far western Oklahoma and portions of north Texas. Greenup
may limit the threat of significant spread however. ERC-G values
are on the high end of normal currently.

BRB

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  68  83  56  75 /  80  30  10   0
Hobart OK         66  86  55  77 /  50  20   0   0
Wichita Falls TX  69  86  60  75 /  70  40  10  10
Gage OK           61  81  50  76 /  20   0   0   0
Ponca City OK     69  85  54  75 /  50  30  10   0
Durant OK         70  78  66  73 /  60  70  40  30

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&

Hazardous Weather Outlook
National Weather Service Norman OK
728 PM CDT Wed May 2 2018

OKZ004>048-050>052-TXZ083>090-040030-
Harper-Woods-Alfalfa-Grant-Kay-Ellis-Woodward-Major-Garfield-
Noble-Roger Mills-Dewey-Custer-Blaine-Kingfisher-Logan-Payne-
Beckham-Washita-Caddo-Canadian-Oklahoma-Lincoln-Grady-McClain-
Cleveland-Pottawatomie-Seminole-Hughes-Harmon-Greer-Kiowa-Jackson-
Tillman-Comanche-Stephens-Garvin-Murray-Pontotoc-Coal-Cotton-
Jefferson-Carter-Johnston-Atoka-Love-Marshall-Bryan-Hardeman-
Foard-Wilbarger-Wichita-Knox-Baylor-Archer-Clay-
728 PM CDT Wed May 2 2018

This hazardous weather outlook is for portions of northern...
western...central...and southern Oklahoma...and western north
Texas.

.DAY ONE...Tonight...

.Thunderstorms...
There is an enhanced risk for severe thunderstorms across parts
of central and southern Oklahoma, and northern Texas.

Location...
The enhanced risk area is along and east of a line from Okarche,
to Fort Cobb, to Loveland, Oklahoma, to Lake Kickapoo, Texas, and
west of a line from near Shawnee, to Ada, to Madill, Oklahoma.

Timing...
A line of severe thunderstorms will continue to move east across
central and southern Oklahoma, and northern Texas from 700 PM to
1100 PM.

Impacts...
The most common impacts will be large hail up to the size of
golf balls, and wind gusts up to 80 mph. Tornadoes will also
remain possible through about 900 PM, especially near and just
north of the Red River. Overnight, the most common impact will be
damaging wind gusts although embedded tornadoes cannot be ruled
out.

Discussion...
A line of severe thunderstorms will move across north Texas, and
central and southern Oklahoma through at least 1100 PM tonight.
The most likely impact from this storms will be damaging wind
gusts, although hail up to the size of golf balls and embedded
tornadoes will remain possible.

.SPOTTER AND EMERGENCY MANAGEMENT STATEMENT...
Storm spotter groups and emergency management personnel across
the Oklahoma and northern Texas should prepare for severe weather
operations today and tonight.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday...

.Thunderstorms...
Thunderstorms will be ongoing Thursday morning in central and
southern Oklahoma. As a dry line and front arrive, new
thunderstorms are expected across southeastern Oklahoma. Any of
these will be potentially severe. The most common impact will be
damaging wind gusts in the morning and damaging wind gusts and
large hail later in the day. Locally heavy rainfall will also be
possible. There is a low chance for non- severe thunderstorms in
southeastern Oklahoma Friday.

There is also a chance for thunderstorms next Tuesday.

.Fire Weather.
Near-critical fire weather conditions are expected to the west of
an advancing dry line over western Oklahoma and adjacent parts of
northern Texas during the day Thursday.

Get graphics and more details at weather.gov/norman...and follow
our weather forecast office on Twitter and Facebook.

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORMAN OK
1051 PM CDT WED MAY 2 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0415 PM     HAIL             GRANITE                 34.96N 99.38W
05/02/2018  E1.75 INCH       GREER              OK   LAW ENFORCEMENT

            TIME APPROXIMATED.

&&

RBARNES

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORMAN OK
1105 PM CDT WED MAY 2 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0800 PM     TORNADO          5 S POCASSET            35.12N 97.95W
05/02/2018                   GRADY              OK   TRAINED SPOTTER

            LOFTED DEBRIS VISIBLE. PERHAPS CORRUGATED ROOFING.
            TORNADO STARTED AT OR JUST EAST OF HWY 81, MOVING NE.
            PRESENT FOR 2-3 MINS.

&&

RBARNES

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE Norman OK
1119 PM CDT WED MAY 2 2018

OKZ046-047-050-051-030445-
Love OK-Carter OK-Johnston OK-Marshall OK-
1119 PM CDT WED MAY 2 2018

...SIGNIFICANT WEATHER ADVISORY FOR Love...southern Carter...
southwestern Johnston and northwestern Marshall Counties Until 1145
PM CDT...

AT 1117 PM CDT, a strong thunderstorm was located 9 miles north of
Burneyville, moving northeast at 55 MPH.

HAZARDS INCLUDE...
Hail up to the size of nickels...
Wind gusts to 50 MPH...

LAT...LON 3386 9746 3389 9745 3391 9747 3392 9750
      3391 9754 3392 9756 3403 9754 3438 9726
      3433 9697 3418 9679 3391 9720 3392 9721
      3391 9724 3386 9727 3389 9731 3385 9733
      3388 9733 3382 9738
TIME...MOT...LOC 0417Z 226DEG 47KT 3404 9731

MAD

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE Norman OK
1154 PM CDT WED MAY 2 2018

OKZ041>043-046>048-051-030530-
Coal OK-Atoka OK-Carter OK-Johnston OK-Pontotoc OK-Marshall OK-
Murray OK-
1154 PM CDT WED MAY 2 2018

...SIGNIFICANT WEATHER ADVISORY FOR southwestern Coal...western
Atoka...southeastern Carter...Johnston...southeastern Pontotoc...
northwestern Marshall and southeastern Murray Counties Until 1230 AM
CDT...

AT 1153 PM CDT, a strong thunderstorm was located near Mill Creek,
moving northeast at 50 MPH.

HAZARDS INCLUDE...
Hail up to the size of nickels...
Wind gusts to 50 MPH...

LAT...LON 3408 9701 3426 9716 3475 9665 3463 9645
      3440 9629
TIME...MOT...LOC 0453Z 228DEG 43KT 3439 9680

MAD