- Day Three
acus01 kwns 011258
Storm Prediction Center ac 011256
Day 1 convective outlook
National Weather Service Storm Prediction Center Norman OK
0756 am CDT Wednesday Apr 01 2015
Valid 011300z - 021200z
..there is a slight risk of severe thunderstorms this afternoon/evening from northern
Kansas northeastward to SW Minnesota...
..there is a marginal risk of severe thunderstorms surrounding the slight risk and
extending southward into OK/North Texas/western Arkansas...
..there is a marginal risk of severe thunderstorms this afternoon for NE Florida/southeast
A few strong to severe storms...capable of producing large hail and
damaging winds...are expected this afternoon and evening from
northern Kansas northeastward to southwest Minnesota. A more
isolated risk of severe storms will extend southward across Oklahoma
into western Arkansas and North Texas...with a separate area across
northeast Florida and southeast Georgia.
A midlevel trough will progress eastward from the northern rockies to the northern
plains through tonight...as a surface cyclone near the ND/South Dakota border
develops northeastward to southeast Manitoba/western Ontario. In response to the
cyclogenesis...the moist sector will be drawn northward as far as Iowa/southern
Minnesota. Farther S...a series of embedded speed maxima will move northeastward
from central/North Texas across eastern OK/western Arkansas in advance of the weak southern
stream trough exiting NE Mexico...along with an mesoscale convective vortex from overnight
convection moving northeastward from NE OK toward SW/central MO today.
..wrn OK/KS/neb/IA/MN this afternoon into early tonight...
The cold front /trailing the primary northern plains cyclone/ will move
southeastward across Nebraska/SD/IA/MN today...and across Kansas/MO tonight.
Low-level moisture will be drawn northward from OK/Texas in advance of the
front...with the western edge of the moist sector demarcated by a Lee
trough/dryline extending southward from a secondary/Lee cyclone in western Kansas
this afternoon. The low-level moisture field has been disrupted
across OK as a result of overnight convection...so northward moisture
transport will likely be delayed/reduced some compared to the more
aggressive model forecasts. This will likewise reduce buoyancy from
earlier expectations...though MLCAPE of 1000-2000 j/kg is still
probable given the plume of 8-9 c/km midlevel lapse that has
overspread the Central Plains.
Thunderstorm initiation is expected along the cold front by 21-00z
from SW Minnesota southwestward into Nebraska...within the narrow corridor of moderate
buoyancy. Given deep-layer shear that will be marginal for
supercells...and shear vector orientations parallel to the
boundary...a rather quick upscale growth to linear convection is
likely. A few damaging gusts and large hail will be possible with
the stronger embedded storms for a few hours late this afternoon
through late evening. Farther SW...the degree of storm development
is unclear along the dryline this afternoon from SW Kansas southward near the
Texas/western OK border. Deep mixing will probably reduce boundary layer
dewpoints east of the dryline...and the moisture influx may also be
interrupted by the ongoing convection in North Texas. Given the likely
high-based nature of any storms that form...and only
marginally-favorable wind profiles for supercells...will maintain
only 5% hail/wind probabilities.
..TX to eastern OK/western Arkansas/MO today...
Clusters of thunderstorms should persist and develop northeastward through
the day in association with the subtle speed maxima and the mesoscale convective vortex
ejecting northeastward from NE OK. Lapse rates are not as steep as
yesterday...and vertical shear has also weakened. Still... remnant
instability and several clusters of storms suggest a marginal
wind/hail risk with the stronger embedded storms. Areas farther S
into central Texas may have some risk for strong storms later
today...though clouds will tend to slow surface heating. This area
may need to be re-evaluated in later updates.
..se Georgia/NE Florida this afternoon...
A shortwave trough over NE Alabama/central Georgia will move east-southeastward through
this afternoon...brushing the NE Florida/southeast Georgia area. The 12z jax
sounding shows sufficient vertical shear and potential buoyancy to
support a risk for isolated damaging gusts and marginally severe
hail for a few hours this afternoon.
acus11 kwns 010616
sels mesoscale discussion
Storm Prediction Center mesoscale discussion 010616
Mesoscale discussion 0174
National Weather Service Storm Prediction Center Norman OK
0116 am CDT Wednesday Apr 01 2015
Areas affected...east central Oklahoma
Concerning...Severe Thunderstorm Watch 14...
Valid 010616z - 010745z
The severe weather threat for Severe Thunderstorm Watch 14
Summary...the risk for severe winds/hail probably is becoming
focused in an increasingly narrow corridor...but may persist into
the 08-10z time frame across parts of east central
Oklahoma...roughly near/ northwest through northeast of
McAlester...toward areas southwest of Fort Smith. Parts of ww 14
probably will need to be extended locally another couple of hours.
Discussion...thermodynamic profiles in areas not yet impacted by
convection remain characterized by very steep middle-level lapse rates
and sizable cape...on the order of 1000-2000 j/kg for most unstable
lifted parcels. And this continues to compensate for rather
marginal kinematic parameters...to support thunderstorm development
capable of producing severe hail and surface gusts. It currently
appears that severe potential could persist another few hours...with
strongest storms generally focused where outflow ... with
the evolving ongoing convective cluster...tracks along a weak
front/low-level convergence zone extending roughly from
Ardmore/Spencer through areas southwest of Fort Smith...between now
..please see www.Spc.NOAA.Gov for graphic product...
Latitude...Lon 35529638 35469542 35289474 35089421 34829383 34409427
34479484 34489552 34399624 34549659 34929637 35529638