ACUS02 KWNS 090520

SWODY2

SPC AC 090518



Day 2 Convective Outlook  

NWS Storm Prediction Center Norman OK

1218 AM CDT Fri May 09 2025



Valid 101200Z - 111200Z



...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SATURDAY ACROSS

PARTS OF CNTRL AND NORTHERN FL...SRN GA...AND WRN INTO CNTRL MT...



...SUMMARY...

Strong thunderstorms may impact parts of northern and central

Florida and adjacent southern Georgia on Saturday.  Additional

strong thunderstorms may impact parts of western into central

Montana.  Some of these storms may be accompanied by at least some

risk for severe weather.



...Discussion...

It appears that much of North America will remain under the

influence of split, amplified westerlies through this period and

beyond, with flow in the northern mid-latitudes remaining stronger

than in the southern mid- and subtropical latitudes.  Within this

regime, a significant mid-level trough is forecast to continue

digging offshore of the British Columbia coast toward the Pacific

Northwest, preceded inland by a less prominent, northeastward

accelerating perturbation into/across and east-northeast of the

Canadian Rockies.



Models indicate that the lead perturbation may be accompanied by

weak cyclogenesis to the lee of the Canadian and adjacent northern

U.S. Rockies, as it begins to progress around the western periphery

of large-scale mid-level ridging shifting across/east of the

Canadian Prairies, northern U.S. Great Plains and Upper Midwest.  



As the ridging overspreads the interior northern tier of the U.S.,

it appears that a broad mid-level low, initially centered just

inland of the north central Gulf coast, will move little or perhaps

retrograde to the west and southwest Saturday through Saturday

night.  An associated broad, weak low-level baroclinic zone may

remain quasi-stationary near/just offshore of the Carolina coast

through northern Florida, to a weak surface low near/offshore of the

southeastern Louisiana coast, but this remains a bit uncertain due

to model spread.  



Higher moisture content air will generally be confined to a corridor

focused above/to the cool side of the frontal zone, and within a

warm sector plume extending east of the mid-level low southward

toward the tropical latitudes.



...Southeast...

In additional to the uncertain details concerning the north central

Gulf frontal low and downstream frontal movement, spread evident in

model output concerning the sub-synoptic developments adds

uncertainty to the convective forecast.  However, while the

mid-level cold core remains well upstream, it does appear that much

of northern/central Florida and adjacent portions of the Gulf States

will remain under the influence of a broadly difluent, modest

southwesterly mid/upper flow regime.  



Although higher moisture content and more widespread convective

development may tend to remain focused well offshore, across the

northeastern Gulf, the front zone and inland advancing sea-breezes

might provide focus for widely scattered strong thunderstorm

development during the day.  Aided by modestly steep lower/mid-level

lapse rates, the environment may become conducive for a few of these

storms to pose a risk for severe hail and wind.  Some model output

suggests that low-level flow northeast of the surface low might

contribute to hodographs conducive to some risk for a tornado,

mainly across and west of the Florida Big Bend vicinity.



...Montana...

There is a notable signal within model output concerning the

potential for the initiation of thunderstorm activity across the

higher terrain of western Montana, and the subsequent evolution of

an upscale growing cluster into/across north central Montana

Saturday afternoon and evening.  Moisture/instability within

thermodynamic profiles characterized by the evolution of a deep and

well-mixed boundary is forecast to be weak.  But shear/momentum

associated with 40-50+ kt west-southwesterly mid/upper flow may

become conducive to a few storms initially posing a risk for small

to marginally severe hail, before strong to severe wind gusts become

the primary potential hazard until storms weaken Saturday night.



..Kerr.. 05/09/2025



$$