ACUS02 KWNS 210452
SWODY2
SPC AC 210450

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1150 PM CDT Wed Mar 20 2024

Valid 221200Z - 231200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FRIDAY THROUGH
FRIDAY NIGHT NEAR THE NORTHEASTERN GULF COAST AND ACROSS PARTS OF
SOUTHERN FLORIDA AND THE FLORIDA KEYS...

...SUMMARY...
One or two clusters of strong thunderstorms may impact portions of
southern Florida and the Keys Friday into Friday evening,
accompanied by at least some risk for damaging winds and a tornado
or two. More isolated strong to severe thunderstorm development may
impact northeastern Gulf coastal areas into Friday night.

...Synopsis...
It appears that blocking centered over the northeastern Pacific will
generally persist through this period, but guidance continues to
indicate at least some weakening, as a more progressive regime
gradually develops across the central toward eastern mid-latitude
Pacific. There remains variability within and among the model
output concerning the extent of this weakening, and the eastward
acceleration of an associated mid-level low toward the northern U.S.
Pacific coast. This may have at least some impact on downstream
synoptic developments within the broadly confluent split flow across
North America.

In the higher-latitude branch, one significant occluding cyclone is
forecast to continue migrating northeast and east of the Canadian
Maritimes. An elongating upstream cyclonic circulation may become quasi-stationary near the southwestern shores of Hudson Bay, with a
series of lower amplitude perturbations digging to its west through
south, across the international border. In lower levels, the
leading edge of another significant cold intrusion is forecast to
nose as far south as the Texas Panhandle and Red River vicinity, and
as far east as the lower Great Lakes and Ohio Valley by 12Z
Saturday.

In lower latitudes, mid-level troughing is still forecast to
progress slowly across and east of the lower Mississippi Valley and
north central Gulf of Mexico. One smaller-scale perturbation may
emerge from its base and become increasingly sheared across and to
the east of the southern Appalachians, while another digs across the northwestern through north central Gulf of Mexico by late Friday
night. Models continue to differ concerning these features, and the larger-scale troughing will be preceded by a subtropical
perturbation which is likely to be in the process of progressing
into and across the Florida peninsula by early Friday.

It does appear that a broad area of deepening surface low pressure
will develop northeastward across much of the eastern Gulf and South
Atlantic Coast states. However, sizable spread is evident within
the model output concerning sub-synoptic through convective-scale
developments across the Southeast, Gulf of Mexico and offshore
Atlantic.

...Southeast...
Even with the aforementioned uncertainties, it does appear that an
initially dry/potentially cool low-level environment, across much of
the Florida peninsula through eastern Gulf Coast region, will tend
to maintain generally stable conditions inland of coastal areas as
initial convection supported by warm advection overspreads it.
However, based on various model output, including some
convection-allowing guidance, there appears potential for at least
one initially organized convective cluster to overspread the Florida Keys/southern Florida peninsula vicinity, coincident with a warm
front off the southeastern Gulf of Mexico early Friday. Given
sufficient boundary-layer destabilization in the presence of strong
deep-layer shear, this may be accompanied by a risk for damaging
wind gusts and perhaps a tornado or two.

Thereafter, it appears that widespread convective development,
perhaps including organizing clusters, may continue along trailing
convective outflow gradually advancing across and east-southeast of
the southeastern Gulf of Mexico through early Saturday. Convective
potential to the north of this outflow remains unclear. However,
models do indicate that substantive boundary-layer destabilization
is possible across much of the northeastern Gulf of Mexico by late
Friday night, ahead of a weak southeastward advancing cold front.
Still ahead of the mid-level troughing axis, this environment may
support additional scattered strong thunderstorm development which
might spread inland across coastal areas before weakening.

..Kerr.. 03/21/2024

$$
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ACUS02 KWNS 220558
SWODY2
SPC AC 220556

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1256 AM CDT Fri Mar 22 2024

Valid 231200Z - 241200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
SOUTH FLORIDA/THE KEYS...AND EASTERN NORTH CAROLINA...

...SUMMARY...
Isolated strong to severe thunderstorms may occur Saturday across
parts of south Florida and the Keys, along with eastern North
Carolina/the Outer Banks.

...Synopsis...
Two upper troughs will advance across the eastern states on
Saturday, with the southern-stream upper trough progressing over the
Southeast and eventually the western Atlantic through Saturday
evening. An initially weak surface low over GA should redevelop
along/near the Outer Banks of NC by Saturday afternoon. Multiple
surface lows will probably form through Saturday evening along the
length of a cold front given the split-flow pattern aloft and
various sources of large-scale ascent. Greater low-level moisture
should remain confined to parts of south FL and the Keys, along with
eastern NC/the Outer Banks.

...South Florida and the Keys...
A parade of thunderstorm clusters over the Gulf of Mexico will
likely impact parts of the FL Peninsula and the Keys in the Day 1
period. This convection should tend to hamper daytime heating and
related destabilization across south FL Saturday morning as a
southern-stream upper trough moves eastward. An effective
front/convectively reinforced outflow boundary will probably be
located over the Keys/FL Straits at the start of the period. The
potential for weak to moderate instability to develop north of this
boundary remains questionable. Still, some guidance suggests this
may occur, especially if an overnight/early Saturday morning MCS
from the Day 1 time frame remains farther north towards the
east-central Gulf and central FL Peninsula.

Enhanced mid-level flow of 50-70 kt attendant to the upper trough
and related strong deep-level shear will conditionally support
robust/severe thunderstorms, should they develop across south FL and
the Keys. Isolated damaging winds appear to be the greatest threat
with any thunderstorm clusters that can persist and remain surface
based. But, sufficient low-level shear should also be present
Saturday morning to pose some risk for a tornado. This isolated
severe threat will shift quickly offshore by Saturday afternoon in
tandem with an eastward-moving cold front.

...Eastern North Carolina...
At least low 60s surface dewpoints will attempt to advance inland
across parts of eastern NC Saturday in tandem with a developing
surface low. Greater instability is generally expected to remain
offshore, but weak MLCAPE may develop over this region with filtered
daytime heating behind early-day convection. This morning convection
will be in a strongly sheared, but only modestly unstable
environment. If additional thunderstorms can form along/ahead of the
cold front, they could become strong to severe while posing an
isolated threat for damaging winds and perhaps a tornado.

..Gleason.. 03/22/2024

$$
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