Convective Outlook

Day 4-8 Outlook

Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0311 AM CDT Sun Mar 29 2020

Valid 011200Z - 061200Z

...DISCUSSION...
A seemingly quiescent period for organized severe thunderstorms will
begin on Wednesday (day 4) and perhaps extend through Saturday (day
7) according to medium-range guidance.  A progressive upper-air
pattern will characterize the extended outlook until some signals in
models imply an amplification of a western U.S. trough next weekend.
Although low-level moisture from the Gulf will likely infiltrate the
southern Great Plains later this work week, the overall combination
of predictability and potential appear low for an organized severe
risk.

Updated 29 March 2020 | 3:15 am

SPC 0730Z Day 3 Outlook

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0211 AM CDT Sun Mar 29 2020

Valid 311200Z - 011200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR SOUTHERN
ALABAMA AND GEORGIA AND INTO THE FLORIDA PANHANDLE AND FAR NORTH
FLORIDA...

...SUMMARY...
Isolated to scattered severe thunderstorms are possible Tuesday over
the northeast Gulf Coast states and southern Georgia.  Damaging
gusts and perhaps a tornado are the primary severe threats.

...Southeast...
A mid-level shortwave trough is forecast to move from the lower MS
Valley across the Southeast and into the western Atlantic during the
Day 3 period.  An eastward-moving surface low will translate along a
northward-advancing maritime front.  A cold front attendant to the
low will push east across the Gulf Coast during the day.  

A cluster of showers/thunderstorms, possibly strong to severe, will
likely be ongoing during the morning over parts of MS and AL.  The
northward penetration of a moist/maritime airmass into the coastal
plain will gradually destabilize downstream of the ongoing
convection.  Model forecast soundings show weak mid-level lapse
rates, but moist low levels and some heating will probably result in
250-750 J/kg MLCAPE.  Strong westerly flow, increasing with height
above the boundary layer, will result in long hodographs and the
potential for organized storm structures.  The main threats with the
stronger storms will be damaging gusts and perhaps a tornado or two.
This activity will push east off the coast into the western Atlantic
during the evening.

..Smith.. 03/29/2020

Updated 29 March 2020 | 2:13 am

SPC 0600Z Day 2 Outlook

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1234 AM CDT Sun Mar 29 2020

Valid 301200Z - 311200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR NORTHERN
LOUISIANA INTO WEST-CENTRAL MISSISSIPPI...

...SUMMARY...
Isolated to scattered severe thunderstorms are possible across parts
of the lower Mississippi Valley during the evening and overnight.

...Synopsis...
A mid-level disturbance will move from AZ/NM eastward during the
period and reach the OK/AR border by early Tuesday morning.  A
frontal zone initially in the northern Gulf of Mexico will advance
northward through parts of TX during the day as a surface low
develops over west-central TX by early evening.  An inverted surface
trough will extend northwest through the TX Panhandle into the
central High Plains during the day.  After dark, a cold front will
sweep east across much of TX as the surface low develops eastward
into MS at daybreak Tuesday.  

...Southern Great Plains into the lower MS Valley...
Strengthening southerly low-level flow and increasing moisture from
the northwest Gulf will spread north through TX during the day. 
Considerable cloud cover will likely limit destabilization across
east TX within a moist/marginally unstable warm advection zone. 
Farther west over the TX Panhandle, isolated storms are forecast by
late afternoon within a northwest-southeast corridor.  Steepening
tropospheric lapse rates will support a few strong to severe
thunderstorms potentially capable of a hail/wind risk.  This
diurnally driven activity will likely weaken by sunset.  Farther
south over northwest and into central TX, uncertainty remains
whether a few storms can manage to form during the late afternoon. 
Wind profiles would support updraft rotation but a paucity of storm
coverage implied by model convective schemes, casts doubt whether
more than a storm or two will develop.  

During the evening into the overnight, increasing mid-level height
falls will overspread east TX into the lower MS Valley.  Storm
coverage will likely increase concurrent with a strengthening warm
conveyor and mid-level DCVA.  Forecast soundings show a relatively
deep/moist boundary layer with strong deep shear.  The more vigorous
storms may organize into a few small clusters/bands with an
accompanying damaging wind hazard being the primary concern near and
south of the warm front.  This activity will likely spread east
across the MS River late Monday night into early Tuesday morning.

..Smith.. 03/29/2020

Updated 29 March 2020 | 1:00 am

SPC 1200Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1255 AM CDT Sun Mar 29 2020

Valid 291200Z - 301200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM A PORTION
OF THE OHIO VALLEY INTO THE MIDDLE ATLANTIC REGION...

...SUMMARY...
A few strong to severe storms are possible today over a portion of
the Ohio Valley into the Mid-Atlantic.

...Synopsis...

Upper trough will continue to advance slowly northeast through the
Great Lakes and OH Valley this period. Attendant occluded low will
move from WI to southeast Ontario. An occluded front will stretch
from the surface low in WI eastward into MI, then trail southward as
a cold front through western OH, the TN Valley and into the western
Gulf by 12Z today. Warm front will extend from central VA
northwestward through western PA. The cold front will advance east
and off the Atlantic seaboard during the evening.

...Upper Ohio Valley and lower Great Lakes region...

Leading band of convection along warm conveyor belt will likely
continue weakening as it moves into a more stable atmosphere. In
wake of this activity, a narrow corridor of weak instability may
develop from eastern OH into western and central PA, within the
mid-upper dry slot region and just ahead of the cold front, where up
to 500 J/kg MLCAPE is possible. A few storms might initiate in this
strongly sheared, but weakly unstable environment by late morning or
towards noon. Low-topped supercells and bowing segments are possible
with threat for mainly locally strong wind gusts and perhaps a brief
tornado. If it becomes more apparent instability will be sufficient
for sustained robust updrafts, a slight risk may be warranted in
later updates.

...Mid Atlantic region...

Convection will likely weaken during the morning as it moves through
the central and southern Appalachians. Farther downstream diabatic
heating is expected in the pre-frontal warm sector and up to 1000
J/kg MLCAPE is possible during the afternoon. However, mid-level dry
slot, presence of an inversion around 700 mb along with tendency for
the low-level winds to veer to southwesterly ahead of the front
suggest thunderstorm initiation might be problematic. Nevertheless,
at least a few thunderstorms are possible in this environment with
mostly unidirectional flow suggesting a few updrafts could develop
mid-level rotation, posing a risk for mainly strong downdrafts and
possibly some hail.

..Dial/Dean.. 03/29/2020

Updated 29 March 2020 | 12:59 am