Dallas, TX...Columbus, OH...Fort Worth, TX...Portland, OR...Kansas City, MO...
Probabilistic Tornado Graphic
Probability of a tornado within 25 miles of a point. Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point.
Day 1 Tornado Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
2 %
31,093
2,192,544
Omaha, NE...Des Moines, IA...Cedar Rapids, IA...Iowa City, IA...Council Bluffs, IA...
Probabilistic Damaging Wind Graphic
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Day 1 Wind Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
5 %
420,008
48,311,118
Dallas, TX...Columbus, OH...Fort Worth, TX...Portland, OR...Kansas City, MO...
Probabilistic Large Hail Graphic
Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
Day 1 Hail Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
5 %
179,543
12,885,073
Portland, OR...Kansas City, MO...Omaha, NE...Tulsa, OK...Des Moines, IA...
SPC AC 200540
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1240 AM CDT Wed Jun 20 2018
Valid 201200Z - 211200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE PACIFIC NW AND FROM THE SOUTHERN PLAINS TO THE MID ATLANTIC...
...SUMMARY...
Scattered strong thunderstorms, possibly severe, are expected to
develop from portions of the southern Plains/Mid-Mississippi Valley
to the Middle Atlantic. Other strong/severe storms are possible
across parts of the Pacific Northwest.
...Southern Plains/Mid MS Valley...
Early-morning water-vapor imagery depicts a well-defined short-wave
trough over the central High Plains ejecting east in line with
latest model guidance. This feature is forecast to shift into the
eastern part of the central Plains by 18z then drift into the MS
Valley by the end of the period. Considerable amount of convection
has evolved over NE/KS ahead of this feature at 05z and an expansive
MCS should propagate southeast and weaken toward daybreak. In all
likelihood this complex of storms will be more disruptive than late
evening guidance , and CAM solutions suggest. For this reason have
shunted 5% severe probs to a position where convective outflow is
most likely to exist by 18z. If the air mass over IA is not
overturned by early afternoon there is some concern that a few
supercells could evolve immediately ahead of the upper low. This
area will be favorably sheared for perhaps a few weak tornadoes and
a SLGT risk may be needed if buoyancy is adequate. However,
confidence is low regarding this scenario given that the leading
edge of the MCS is already into western IA. Otherwise, strong
boundary-layer heating is expected to aid convection along the
remnant outflow/front by mid-late afternoon. Hail/wind are the
primary threats.
...OH Valley/Middle Atlantic...
Remnant convective debris field will drift across the OH Valley
early in the period. Heating along the leading edge of this activity
is expected to result in destabilization necessary for renewed
thunderstorm development. Isolated strong wind gusts could accompany
convection that develops ahead of this disturbance from southern OH
into the Middle Atlantic.
...Pacific Northwest...
Exit region of a strong mid-level speed max will advance into
northern CA/OR during the afternoon ahead of a short-wave trough off
the Northwest Coast. Cool 500mb temperatures and steep lapse rates
will ensure sufficient buoyancy for robust convection as
temperatures warm. 20/00z NAM is a bit too aggressive with surface
dew points/instability across this region but isolated severe
thunderstorms are nonetheless expected due to favorable dynamics and
aforementioned lapse rates.
..Darrow/Squitieri.. 06/20/2018
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z