Severe Storm Outlook Narrative (AC)
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8
ACUS03 KWNS 200631
SPC AC 200630

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0130 AM CDT Sun May 20 2018

Valid 221200Z - 231200Z


Isolated strong thunderstorms are expected across eastern New Mexico
and west Texas Tuesday afternoon.

...Eastern NM/Western TX...

Upper low that is expected to drift into the lower CO River Valley
is forecast to weaken and lift northeast into the Great Basin during
the latter half of the period. As a result, weak height rises are
expected across the southern High Plains as primary corridor of
stronger mid-level flow extends across southern AZ into central CO.
Model guidance suggest strong boundary-layer heating will be noted
across eastern NM/west TX such that convective temperatures should
easily be breached by late afternoon. Favorable low-level
trajectories will maintain adequate moisture across this region for
ample instability required for robust updrafts. Even so, deep-layer
shear will be seasonally weak but likely sufficient for isolated
severe thunderstorms capable of generating hail/wind. This activity
will be strongly diurnal in nature.


Unusually weak steering currents for mid may are expected to persist
across much of the CONUS outside of the northeastern US. This flow
regime leads to low predictability regarding organized severe
thunderstorms despite the likelihood for isolated severe in various
locations across the country, primarily east of the Rockies. Late
evening guidance suggest low-level warm advection may induce deep
convection across the northern Plains late and conceivably this
activity could generate some hail.

Another region where a few severe thunderstorms could evolve will be
across portions of the OH Valley along the southwestern flank of
stronger flow associated with a short-wave trough. If adequate
instability can develop across portions of OH/western PA/western NY
there is some concern for robust convection. However, predictability
is just too low at this time to issue severe probabilities.

..Darrow.. 05/20/2018

$$ is the U.S. government's official web portal to all federal, state and local government web resources and services.