ACUS02 KWNS 020503
SWODY2
SPC AC 020502

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1202 AM CDT Fri Aug 02 2024

Valid 031200Z - 041200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SATURDAY
AFTERNOON AND EVENING ACROSS PARTS OF EASTERN GEORGIA...SOUTH
CAROLINA...MUCH OF NORTH CAROLINA...CENTRAL AND EASTERN
VIRGINIA/MARYLAND...DELAWARE...SOUTHEASTERN PENNSYLVANIA...NEW
JERSEY...SOUTHEASTERN NEW YORK...SOUTHWESTERN CONNECTICUT...WESTERN
LONG ISLAND...AND NORTHWESTERN WISCONSIN...MUCH OF CENTRAL/SOUTHERN
MINNESOTA...EASTERN SOUTH DAKOTA AND ADJACENT SOUTHEASTERN NORTH DAKOTA...

...SUMMARY...
Scattered strong thunderstorms accompanied by potentially damaging
wind gusts may impact the Southeastern Piedmont and adjacent
portions of the coastal plain into northern Mid Atlantic Saturday
afternoon and evening.  Other widely scattered strong to severe
thunderstorms are possible across parts of the Upper Midwest into
adjacent portions of the northern Great Plains late Saturday
afternoon and evening.

...Synopsis...
Models continue to indicate that mid-level flow across the northern
mid-latitudes will undergo at least some amplification through this
period.  By Saturday night, this is forecast to include a building
ridge across the northeastern Pacific through Alaska and adjacent
portions of northwestern Canada.  Downstream, flow across the
Minnesota international border vicinity through the upper Great
Lakes may trend broadly cyclonic, to the southwest of a significant
deep-layer cyclone slowly progressing across the eastern shores of
Hudson Bay into northern Quebec.

In lower latitudes, a weak short wave perturbation may suppress
ridging across the northern Intermountain Region.  Otherwise,
ridging appears likely to remain prominent across much of the West
into the Great Plains, with an embedded high becoming centered over
the Four Corners states.  As downstream ridging across the
subtropical western Atlantic builds northwestward toward the Mid
Atlantic coast, troughing between the ridges is forecast to become
increasingly sheared across the southern Appalachians through
southern New England.  At the same time, a tropical perturbation
emerging from the Caribbean vicinity may begin impacting the Florida
Straits and southern Florida Peninsula late Saturday into Saturday
night.

Beneath this regime, some lower/mid-tropospheric drying appears
likely to continue spreading southward through the southeastern
Great Plains and lower Mississippi Valley, with seasonably high
moisture content (including a plume of precipitable water in excess
of 2 inches) largely confined to the southeast of the southern
Appalachians through the New England coast.  However, lingering
low-level moisture beneath an east-southeastward advecting plume of
warm elevated-mixed layer air may contribute large potential
instability ahead of a cold front advancing southward through the
northern Great Plains and Upper Midwest.

...Mid/Southern Atlantic Seaboard...
Although the approaching mid-level trough is forecast to become
increasingly sheared and weaken, the height gradient between the
troughing and the downstream building ridge may maintain modest
south-southwesterly mid-level flow (on the order of 20-30 kt) to the
lee of the Appalachians on Saturday.  Beneath this regime, within
the lee surface troughing, a moist boundary-layer including 70 F+
dew points appears likely to contribute to large CAPE in excess of
2000-3000 J/kg with daytime heating.  Given weak mid-level
inhibition, it appears that this will support considerable
thunderstorm development, with strongest storms posing a risk for
producing damaging wind gusts, aided by heavy precipitation loading
and downward mixing of momentum.

...Northern Great Plains/Upper Midwest...
Convective development appears likely to largely hinge on one or two
subtle perturbations progressing through northwesterly flow near the
base/southwestern flank of the large-scale mid-level troughing.
Substantive spread exists among the various model output, including
the convection allowing guidance.  While it appears that
thunderstorm development may remain isolated to widely scattered in
coverage, shear beneath the northwesterly mid-level regime will be
sufficient for supercells and one or two widely scattered upscale
growing clusters with potential to produce strong wind gusts may not
be out of the question Saturday evening.

...Florida...
Beneath a warm mid-level environment, models (NAM in particular)
suggest that precipitation preceding the developing tropical
perturbation may stabilize the boundary layer across much of the
interior peninsula Saturday through Saturday night.  While trends
will need to continue to be monitored, the risk for severe weather
through this period currently appears low.

..Kerr.. 08/02/2024

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