Baltimore, MD...Denver, CO...Cleveland, OH...Virginia Beach, VA...Omaha, NE...
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.)
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
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.
SPC AC 221955
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0255 PM CDT Tue May 22 2018
Valid 222000Z - 231200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
UPPER OHIO VALLEY AND THE MID-ATLANTIC REGION...
Isolated strong to severe thunderstorms remain possible this
afternoon and evening across parts of the Mid-Atlantic States and
Ohio Valley, as well as over portions of the High Plains and
...Upper OH Valley...
Recent surface analysis places a surface low across north-central OH
with a cold front extending southwestward into southern IL. This
cold front also extends northward from the low to another low over
Lake Ontario. A warm front extends southeastward from this second
low across eastern PA and into the northern Delmarva. Thunderstorms
have developed within the confluent warm sector ahead of the cold
front across the OH Valley. Damaging wind gusts remain possible with
the strongest storms in this region. More details are available in
Another area of thunderstorms is moving from the higher terrain of
VA into the more moist and unstable airmass across central VA.
Damaging wind gusts are also the primary threat in this area with
some isolated hail also possible.
Thunderstorms have developed across the higher terrain of the
Rockies Mountains while much of the downstream High Plains is
currently void of convection. Even so, strong heating will persist
with eventual airmass destabilization and convective initiation.
Vertical shear is relatively weak and supportive of predominately
outflow-dominant multicells. The exception may be across portions of
southeast WY/northeast CO where southeasterly upslope flow is
contributing to more favorable low-level shear and vertical
vorticity. In this area, an isolated supercell is possible.
.PREV DISCUSSION... /ISSUED 1128 AM CDT Tue May 22 2018/
...Upper Ohio Valley...
Visible imagery indicates thinning cloud cover over Indiana and much
of Ohio which will permit stronger diabatic heating and air mass
destabilization to occur this afternoon, in advance of a
southeastward moving cold front located from extreme northwest Ohio
into southwest Indiana. The decrease in cloud cover will spread
into western Pennsylvania with time and contribute to a gradual
increase in heating. MLCAPE is expected to reach 1000-1500 J/kg,
with greater instability expected with westward extent.
Short bands of mainly shallow convection are developing along/ahead
of the front from northwest Ohio into east central Indiana.
Updrafts within this activity are expected to strengthen with
several bands of northeast-southwest oriented thunderstorms forming
by early-mid afternoon. The storms will be located on the southern
edge of stronger westerly winds aloft, including the right entrance
region of an upper level jet, resulting in deep layer shear of 30-40
kt that will enhance storm organization and intensity. Stronger
cells will be capable of producing damaging wind gusts with isolated
hail also possible mainly with any storms that are able to develop
transient updraft rotation. The activity will spread eastward and
southeastward through the evening hours before storms gradually
weaken as boundary layer cooling and low-level stabilization occurs.
More extensive cloud cover over Pennsylvania and northern West
Virginia with fewer cloud to the south is creating a differential
heating zone along the southern edge of the thicker clouds.
Stronger heating to the south will enhance destabilization in
advance of storms beginning to develop over southern West Virginia
at this time. VAD winds at RLX and LWX exhibit westerly winds of
30-40 kt above 4 km which will provide sufficient shear to support
organized multi-cell storms and possibly an isolated supercell or
two. Storms are expected to develop eastward this afternoon with
potential for localized damaging wind gusts although isolated hail
will also be possible with stronger storms.
...Eastern New Mexico and West Texas...
Low-level moisture persists as far west as the upper Rio Grande
Valley of New Mexico in the wake of widespread storms on Monday. A
few strong storms are expected to develop this afternoon and
evening, initially over the mountains of central New Mexico, with
the activity spreading eastward with time. Other storms will
develop over southwest Texas as well. The region is on the edge of
stronger southwest winds aloft associated with the upper low that is
beginning to lift northeastward over the southern Great Basin. A
few stronger cells capable of producing hail and strong wind gusts
will be possible.
......North-central Rockies to middle Missouri Valley...
The Great Basin/southwest states-central upper low is beginning to
move northeastward, with a lead shortwave trough currently lifting
across northern Arizona expected to overspread the central
Rockies/Wyoming through the afternoon into tonight. Orographic lift,
increasing dynamic forcing for ascent coupled with adequate moisture
will allow for the development and intensification of storms this
afternoon initially across parts of Utah/western Colorado into
interior Wyoming where locally severe storms will be possible. As
forcing for ascent spreads northeastward by late afternoon, a
somewhat more moist and unstable environment across central/eastern
Wyoming could allow for more organized/sustained storm modes with
hail/severe wind gusts possible as storms spread east-northeastward.
Over the Plains, a nocturnally increasing low-level jet may help
sustain storms into South Dakota and western/northern Nebraska this
evening, in addition to an increase in storms farther east toward
the Missouri River late in the evening/overnight with some hail
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z