Severe Weather Threat 01/24/23-01/25/23

i000

FXUS64 KLIX 211321

AFDLIX



Area Forecast Discussion

National Weather Service New Orleans LA

721 AM CST Sat Jan 21 2023


Still looking at increasing potential for a significant weather

event Tuesday afternoon and night. This storm system has the

potential to produce severe weather, excessive rainfall and

windy conditions.


As low level flow becomes southerly Tuesday morning, low level

moisture ramps up quickly, with precipitable water values climbing

from near 0.5 inch around sunrise, to 1.5 inches or higher by

sunset. The upper low will track from near El Paso Tuesday morning

to near Memphis Wednesday morning as it deepens. The surface low

will develop over east Texas and track just to the northwest of

our area into West Tennessee by Wednesday morning. This is usually a

rather favorable track for severe weather along the central Gulf

Coast. Forecast soundings show rather strong wind fields with

30-40 knot winds just off the surface (500 feet), and winds in

excess of 50 knots at 925 mb (2000 feet). If nothing else, a Wind

Advisory is a pretty decent bet in later forecasts for a good

segment of the area. Won`t get deep into specific severe weather

parameters at this point, as specifics will change each model run,

but moisture and shear aren`t expected to be problems. Looks to

be a high shear, low CAPE setup, with some question whether

convection will become fully surface based. Current timing would

indicate a late afternoon through the evening event. People across

the area should monitor the latest information on this system

over the next few days. Once that system exits the area Wednesday

morning, dry weather anticipated through the end of the week, with

the next significant chance of precipitation late next weekend.

iDay 3 Convective Outlook

NWS Storm Prediction Center Norman OK

0228 AM CST Sun Jan 22 2023



Valid 241200Z - 251200Z



...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TUESDAY EVENING

THROUGH TUESDAY NIGHT ACROSS MUCH OF SOUTHEASTERN

LOUISIANA...SOUTHEASTERN MISSISSIPPI...SOUTHERN ALABAMA AND THE

WESTERN FLORIDA PANHANDLE...



...SUMMARY...

Severe thunderstorms are possible, perhaps near mid to upper Texas

coastal areas early Tuesday afternoon, but more likely across

southeastern Louisiana and Mississippi through southern Alabama and

the western Florida Panhandle Tuesday night. These may become

capable of producing tornadoes and locally damaging wind gusts.


Aside from the NCEP SREF (with the 22/03Z run remaining a notable

slower outlier), most model output indicates that the perturbation

will rapidly progress across the southern Great Plains into the Mid

South by late Tuesday night, accompanied by significant surface

cyclogenesis near mid/upper Texas coastal areas into and through the

lower Mississippi Valley and Mid South. As this occurs, an intense

west-southwesterly mid/upper jet (including 90-100 kt around 500 mb)

is forecast to develop across the lower Mississippi through

Tennessee Valleys by 12Z Wednesday. In association with the

developing cyclone, a southerly low-level jet may include speeds

increasing in excess of 50-70 kt to the east of the lower

Mississippi Valley during a period of more rapid deepening Tuesday

evening. A similar earlier period of cyclone deepening and wind

field intensification is also appearing increasingly probable near

mid/upper Texas coastal areas early Tuesday afternoon.



...Texas coastal areas through central Gulf Coast states...

Given the synoptic forcing, the presence of an initially cool/stable

boundary layer across much of the Gulf Coast region is the primary

limiting factor to the development of a more substantive risk for

severe thunderstorms Tuesday through Tuesday night. The boundary

layer across much of the northern Gulf of Mexico will also still be

in the process of modifying from prior frontal intrusions, but it

does appear that mid/upper 60s F surface dew points may rapidly

advect toward northwestern through north central Gulf coastal areas.



Boundary-layer destabilization near, if not inland of, mid into

upper Texas coastal areas may contribute to an environment conducive

to supercell development around midday into early afternoon.

Thereafter, boundary-layer moistening within at least a narrow

inland corridor across southeastern Louisiana into south central

Alabama still seems probable Tuesday evening through Tuesday night.

Beneath a plume of modestly steepening lapse rates, this is expected

to contribute to a corridor of boundary-layer destabilization

sufficient to support organized convective development. This may

include a developing line of storms along a pre-frontal confluence

zone, perhaps preceded by more discrete supercells.



While it appears possible that moist adiabatic to more stable

near-surface lapse rates could tend to minimize the number of

potentially severe storms, even with only somewhat better

boundary-layer modification than currently forecast, a more

substantive severe weather threat may still develop. Very large and

clockwise-curved low-level hodographs forecast to develop within the

warm sector will contribute to wind profiles potentially supportive

of strong tornadoes in supercell storms.



..Kerr.. 01/22/2023