SPC Jul 26, 2024 1300 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0749 AM CDT Fri Jul 26 2024

Valid 261300Z - 271200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHERN PLAINS...GREAT BASIN...AND SOUTHWEST...

...SUMMARY...
Isolated severe thunderstorms may occur today across the northern
Plains, Great Basin, and parts of the Southwest.

...Northern Plains/Upper Midwest...
A prominent upper-level trough will continue eastward today over the
northern Canadian Prairies, with peripheral height falls and a
strengthening of southwesterly winds aloft across the Dakotas and
northern Minnesota. This will largely overlie an eastward-shifting
front, that will be oriented northeast-southwestward across eastern
North Dakota and roughly bisect South Dakota by late afternoon.

Beneath a plume of very warm and capping elevated mixed-layer air,
which will continue to advect northeastward across the northern
Great Plains through the day, a seasonably moist boundary layer will
support a narrow corridor of strong buoyancy across the Red River
Valley vicinity by late afternoon, where forcing for ascent should
support isolated to widely scattered thunderstorm development by
early evening. In the presence of at least 30-40 kt deep-layer
shear, a couple of supercells appear possible to the south of the
international border, especially across northwest Minnesota, and
perhaps as far southwest as areas near/west of Grand Forks and
Fargo.

Additional severe storms may also develop near/behind the front
across western/central South Dakota and far eastern Wyoming into
western Nebraska.

...Arizona...
Cloud cover and outflows will abate across central/southern Arizona
early today after a couple of relatively active thunderstorm days.
This will be as the upper ridge over the Southwest further weakens
and shifts southward. While thunderstorms are expected to
develop/increase over the Rim this afternoon, and modestly stronger
north-northeasterly steering flow may remain across far southeast
Arizona, a less-active scenario seems likely as far as storms
reaching the desert floor. While some strong/severe-caliber winds
could occur, any such potential should remain relatively localized
with a diminished overall severe risk from prior days.

...Great Basin...
In the wake of a shortwave trough, storm coverage/intensity are not
expected to be as active as Thursday, but moderate diurnal
destabilization is expected especially across western/northern Utah,
with isolated/widely scattered thunderstorm development expected
this afternoon. A few of these storms could produce
strong/severe-caliber downbursts. A secondary round, and perhaps
somewhat greater coverage of storms, may occur tonight across Nevada
into western/northern Utah, influenced by the eastward transition of
the mid-level shortwave trough over northern California.

..Guyer/Grams.. 07/26/2024


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SPC Jul 26, 2024 0600 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook


Day 1 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
1231 AM CDT Fri Jul 26 2024

Valid 261200Z - 271200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE THIS
AFTERNOON AND EVENING ACROSS PARTS OF SOUTHEASTERN ARIZONA AND
ADJACENT SOUTHWESTERN NEW MEXICO...PARTS OF NORTHEASTERN NEVADA INTO
WESTERN UTAH...PARTS OF WESTERN NEBRASKA AND ADJACENT SOUTHEASTERN
WYOMING INTO CENTRAL SOUTH DAKOTA...AND PARTS OF EASTERN NORTH
DAKOTA INTO NORTHWESTERN MINNESOTA...

CORRECTED FOR GEN THUNDER LINE/NDFD GRAPHIC

...SUMMARY...
The risk for severe thunderstorms appears seasonably low across much
of the U.S. today through tonight.

...Discussion...
A significant inland migrating mid-level trough (and embedded low)
is now progressing east-northeast of the Canadian and northern U.S.
Rockies, and forecast to continue eastward across the Canadian
Prairies today through tonight. While stronger mid-level height
falls likely remain focused well to the north of the international
border area, models indicate that mid-level heights will continue to
fall across much of the West into the northern Great Plains, as weak
trailing troughing develops inland of the Pacific coast and
downstream ridging becomes increasingly suppressed. In lower
levels, to the south of a deepening surface cyclone associated with
the primary short wave perturbation, a modest cold front may advance
east of the northern Rockies, before stalling and weakening across
the northern Great Plains into northern portions of the Great Basin.

As this regime evolves, destabilization associated with strong
daytime heating and remnant monsoonal moisture appears likely to
support considerable thunderstorm development this afternoon and
evening across the higher terrain of eastern Arizona through the
southern Rockies, and near lee surface troughing across the north
central high plains. Additional, more widely scattered,
thunderstorm activity may focus near/just ahead of the surface front
across the northern Great Basin through portions of the northern
Rockies and northern Great Plains. Some of the stronger, more
persistent convection will probably overspread, or develop above,
more strongly heated and deeply mixed (with large developing surface
temperature-dew point spreads) lower elevations, accompanied by a
risk for strong to locally severe wind gusts.

...Eastern North Dakota/Northwestern Minnesota...
Beneath a plume of very warm and capping elevated mixed-layer air,
which will continue to advect northeastward across the northern
Great Plains through the day, models indicate that seasonably moist
boundary-layer air may support a narrow corridor of large potential
instability across the Red River Valley vicinity into the stalling
weakening frontal zone across northwestern Minnesota/southeastern
Manitoba/adjacent northwest Ontario by early evening. Downstream of
the base of the short wave perturbation crossing the Canadian
Prairies, forcing for ascent may support isolated to widely
scattered thunderstorm development. In the presence of at least
30-40 kt deep-layer shear, and modest clockwise-curved low-level
hodographs, one or two supercells appear possible to the south of
the international border, perhaps as far southwest as areas
near/west of Grand Forks and Fargo.

..Kerr.. 07/26/2024


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SPC Jul 23, 2024 1630 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1630Z Day 1 Outlook


Day 1 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
1241 PM CDT Tue Jul 23 2024

Valid 231630Z - 241200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF
NORTH CAROLINA AND VIRGINIA...IOWA INTO NORTHERN ILLINOIS...AND
WESTERN ARIZONA AND MOJAVE DESERT...

CORRECTED FOR THUNDERSTORM BOUND PLACEMENT OVER THE NORTHEAST

...SUMMARY...
Isolated severe storms are possible across parts of the Mid-Atlantic
states, portions of the Midwest, and parts of the Desert Southwest.

...Mid-Atlantic/Carolinas/Southeast States...
Visible-satellite imagery shows a building cumulus field over the
region amidst a very moist airmass located over the Carolina coastal
plain (mid to upper 70s deg F surface dewpoints). Strong heating
will contribute to moderate destabilization by early afternoon. A
belt of moderate west-southwesterly mid-level flow may aid in some
multicellular storm organization in the form of a few clusters.
Water-loaded downdrafts capable of an isolated risk for wet
microbursts (peak gusts 50-60 mph) appear to be the primary severe
hazard.

...IA into northern IL...
Thunderstorms are expected to redevelop along the northern front
from southern Wisconsin across Iowa and southern Minnesota this
afternoon, perhaps aided by a weak MCV from morning storms. Models
show the development of moderate buoyancy with deep-layer shear
around 25 kt. A few of the stronger storms may be capable of an
isolated risk for strong to locally severe gusts (50-60 mph) and
marginally severe hail. This activity will likely diminish by early
to mid evening.

...Western AZ into the Mojave Desert...
Thunderstorms are expected to develop over the Mogollon Rim of
Arizona again this afternoon, with relatively weak northeast
mid-level flow steering storms southwest into the lower elevations.
Widely scattered storms are forecast to develop late this afternoon
into the evening. The inverted-v thermodynamic profiles will
potentially support an isolated risk for severe gusts (60-70 mph)
with the stronger evaporatively cooled downdrafts.

..Smith.. 07/23/2024


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SPC Jul 23, 2024 1300 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0755 AM CDT Tue Jul 23 2024

Valid 231300Z - 241200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
MID-ATLANTIC STATES AND CAROLINAS...

...SUMMARY...
Today's overall risk for organized severe thunderstorms is expected
to remain relatively low, but a few severe storms may occur across
the Mid-Atlantic States/Carolinas.

...Mid-Atlantic/Carolinas/Southeast States...
The air mass over the region will remain very moist with
Precipitable Water values in excess of 2 inches, contributing to a
moderately unstable and minimally inhibited boundary layer this
afternoon. A modest increase in mid-level flow may occur today from
the southern Appalachians northeast across the mid-Atlantic, but
low-level winds will remain weak. While locally heavy rainfall will
be the most common hazard regionally, wet microbursts could cause a
few instances of localized wind damage this afternoon, with a
somewhat greater potential across parts of North Carolina and
Virginia.

...Midwest...
Thunderstorms are expected to redevelop along the northern front
from southern Wisconsin across Iowa and southern Minnesota this
afternoon, with the potential for multiple rounds of storms in some
locations. Moderate buoyancy should be in place near the front,
however deep-layer shear should generally remain at 25-30 kt (or
less) for much of the day. Some risk for hail and gusty winds will
exist with any stronger storm, but will defer any potential
introduction of low severe probabilities to subsequent outlooks.

...Arizona/Lower Colorado River Valley...
Thunderstorms are expected to develop over the Mogollon Rim of
Arizona again this afternoon, with relatively weak northeast
mid-level flow steering storms southwest into the lower elevations.
Despite very hot temperatures and a deep/well-mixed boundary layer,
overall confidence that storms will cluster and produce more than
localized strong/damaging gusts remains too low to introduce severe
probabilities.

..Guyer.. 07/23/2024


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