LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1245 AM CDT Sun Jul 30 2023
Valid 301200Z - 311200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHERN AND CENTRAL HIGH PLAINS...
...SUMMARY...
Scattered severe thunderstorms are expected across portions of the
northern and central High Plains. Very large hail and damaging winds
are expected. More isolated strong to severe storms are possible
Sunday across parts of the Southeast and lower deserts region of the
Southwest.
...Northern/Central High Plains...
Dominant upper ridge is anchored over the southern Rockies/Four
Corners region early this morning. Latest water-vapor imagery
suggests several weak short-wave troughs are ejecting northeast
around the western/northern periphery of this feature. One such
short wave is located over western ID with another prominent vort
located over northeast CA. 00z model guidance suggests these
features will top the ridge over central MT by 31/00z then dig
southeast across the western Dakotas Sunday evening. In response to
the short wave, lee surface trough should remain oriented from
southeast WY into north-central MT. This will ensure favorable
easterly boundary-layer component across the northern Plains where
strong surface heating is forecast during the afternoon.
As temperatures warm into the lower 90s, CINH will weaken such that
deep convection is expected to develop. Initial updrafts will likely
evolve over the higher terrain of southwest MT into northern WY.
Forecast soundings exhibit substantial surface-6km shear with at
least 2km southeasterly low-level flow. Current thinking is
supercells will develop then mature as they propagate across the
lower elevations of southern/eastern MT into northeast WY. Very
steep lapse rates and MLCAPE in excess of 2000 J/kg should aid the
production of potentially very large hail (in excess of 2"). Some
increase in LLJ during the evening is expected to aid upscale growth
of this activity as it propagates southeast toward the Black Hills.
...Elsewhere...
Southern influence of OH Valley trough will contribute to scattered
robust convection across the Southeast later today. Latest model
guidance suggests strong/potentially severe thunderstorms should
evolve from central MS to central GA. This activity will propagate
slowly southeast with an attendant threat for gusty winds.
Notable short-wave trough is currently located over northwest
Mexico. Northern extent of this feature will result in 500mb flow
strengthening near the international border. Additionally,
seasonally high PW values will extend across the Gulf of CA into the
lower CO River Valley. High-based convection that develops across
this region could produce gusty winds, potentially in excess of
50kt.
..Darrow/Bentley.. 07/30/2023
Read more CHECK UPDATE ZOOM GRAPHIC
http://dlvr.it/SsxKjl
