SPC Jul 24, 2024 1630 UTC Day 1 Convective Outlook

[NorthGeorgiaWX]

SPC 1630Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1128 AM CDT Wed Jul 24 2024

Valid 241630Z - 251200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS
AFTERNOON/EVENING FOR WESTERN/CENTRAL NY INTO NORTHWEST PA...AND
FROM EASTERN OR/ID INTO WESTERN MT...

...SUMMARY...
Strong to severe thunderstorms may produce damaging wind gusts
across western/central New York and vicinity this afternoon/evening,
as well as across southern Arizona.

...Western/central NY and northwest PA this afternoon/evening...
A midlevel trough will progress eastward from the upper Great Lakes
toward NY as an associated surface cold front likewise moves
eastward into western NY and southeastward into OH/northwest PA
through this evening.  Surface heating is underway in a corridor
ahead of the cold front from northern OH into western NY where
boundary-layer dewpoints are in the mid-upper 60s with surface
temperatures warming into the lower 80s, and a band of convection
has already developed from Lake Erie to western Lake Ontario.  These
storms may persist into the afternoon while spreading eastward, with
additional development possible along convective outflow, a
pre-frontal confluence zone and/or local lake breeze boundaries. 
Midlevel lapse rates will remain modest (roughly 6.5 C/km), but the
low-level moisture/warming temperatures will drive MLCAPE in the
1000-1500 J/kg range.  Deep-layer vertical shear/hodograph length
will be on the lower margins for organized clusters/cells per local
VWPs now sampling 30-40 kt midlevel flow, while steepening low-level
lapse rates will support the potential for occasional wind damage
with strong thunderstorm outflow in the 50-60 mph range.

...Southern AZ this afternoon/evening...
Strong surface heating is underway near and south of the Rim, and
late afternoon temperatures will peak near or above 110 F across the
lower deserts into southern AZ.  Moisture will be sufficient for
thunderstorm development this afternoon along the Rim and the
mountains in southeast AZ, while northeasterly midlevel flow of
15-20 kt will steer outflows southwestward toward the lower deserts.
 MLCAPE will increase to the 1000-1500 J/kg with deep inverted-V
profiles favoring strong downdrafts and outflow winds of 60-75 mph
capable of producing wind damage and substantial blowing dust.  The
relatively greater severe threat will be with the stronger/deeper
convection driven by outflow mergers.

...Northern Rockies area this afternoon/evening...
A plume of mainly midlevel moisture with PW values of 0.75-1 inch
(per BOI and LKN 12z soundings) will persist around the northern
periphery of a midlevel high over the Great Basin, and southeast of
a midlevel trough approaching WA.  High-based thunderstorms are
expected in a few loosely organized clusters within this plume,
where deep inverted-V profiles will support the potential for a few
strong-severe outflow gusts 50-65 mph.

...Mid-Atlantic into NC this afternoon...
Modest surface heating within small cloud breaks and boundary-layer
dewpoints of 72-74 F will contribute MLCAPE approaching 1500 J/kg to
the east of the Blue Ridge, though midlevel lapse rates will remain
poor.  Still, the southern extent of 30-40 kt midlevel flow will
support a low-end wind damage threat with the stronger storm
clusters this afternoon.

..Thompson/Karstens.. 07/24/2024

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