526
ACUS01 KWNS 311953
SWODY1
SPC AC 311951

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0251 PM CDT Thu Jul 31 2025

Valid 312000Z - 011200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THERE IS A SLIGHT
RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE MID-ATLANTIC STATES
AND FROM THE COLORADO FRONT RANGE INTO EASTERN AND NORTHERN
WYOMING...

...SUMMARY...
Severe thunderstorms capable of damaging winds are possible this
afternoon and early evening across the Mid-Atlantic region. Other
severe wind and hail producing storms are also possible across the
central/northern High Plains.

...20z Update...
The forecast remains largely on track with only minor adjustments
made based on recent convective trends. Low-end/5% risk
probabilities were expanded slightly across portions of the northern
Rockies where recent observed dewpoint depressions and short-range
forecast soundings show low-level thermodynamic environments
favorable for strong/severe downburst winds and GOES imagery shows
deepening convection. Elsewhere, the forecast remains on track. See
the previous discussion below and MCDs #1853 and #1854 for
additional details.

..Moore.. 07/31/2025

.PREV DISCUSSION... /ISSUED 1115 AM CDT Thu Jul 31 2025/

...Mid Atlantic Region...
Midday visible-satellite imagery indicates a moist airmass via a
swelling cumulus field from the upper OH Valley eastward into the
Mid-Atlantic states and Long Island.  Additional heating of an
extremely moist boundary layer (12 UTC raobs at IAD and WAL showing
17-18 g/kg lowest 100-mb mean mixing ratios), will result in
temperatures warming through the 80s deg F with 74-78 dewpoints to
the east of the Fall Line.

An upstream mid-level shortwave trough over WI/IL will continue to
progress eastward towards the region and promote the gradual
southward movement of a weak cold front.  Despite weak mid-level
lapse rates, the aforementioned warming/destabilization through mid
afternoon will promote scattered thunderstorms along/ahead of
the front.  Forecast hodographs will be elongated due to 50-70 kt
upper-level flow, which will support storm organization in the form
of multicell clusters and possibly a few weak supercell structures.
Weak low-level flow and a deep/moisture-rich profile will facilitate
water-loaded downdrafts with the stronger cores.  Widely scattered
50-65 mph gusts capable of wind damage will be the primary severe
concern before much of this activity moves east of the coast by mid
evening.

...High Plains...
No change from the previous forecast thinking.  Weak shortwave
ridging will reside across the central Rockies/plains northward into
the northern High Plains.  Surface observations and satellite data
depict a seasonably moist airmass abutted to the Front Range and
northward into the eastern WY.  Heating over the higher terrain and
along a residual frontal zone will aid in scattered storm
development this afternoon.  The strongest cells will pose some risk
of hail and gusty winds over the higher terrain before spreading
onto the plains by late afternoon.  Forecast soundings in this
region show moderately steep mid-level lapse rates, MLCAPE values of
1000-1500 J/kg, and sufficient vertical shear for transient
supercell structures.  Upscale growth into a linear cluster or two
may evolve (supported by recent HREF guidance), and this appears
most probable near the WY/CO/NE border during the early evening.  A
gradual transition from primarily a hail risk to a threat favoring
severe gusts may occur as outflow becomes more pervasive as storm
coverage and outflow increases during the evening.

...ID/Western MT...
A mid-level trough over northern NV will move slowly northward
through tonight into the northern Rockies.  Forcing for ascent
attendant to this upper feature coupled with orographic circulations
will likely result in scattered storms developing by mid to late
afternoon.  Very steep lapse rates and dry sub-cloud layers will
promote evaporative cooling and an isolated risk for severe gusts
(60-70 mph) with the stronger cores and outflow surges.

...AR/LA...
Scattered diurnally driven storms will likely evolve in the vicinity
of a weakness in the southern U.S. mid-level anticyclone.  A very
moist boundary layer amid moderate buoyancy may result in a few
stronger water-loaded microbursts capable of 50-65 mph gusts and
pockets of wind damage.

$$