- Day Three
acus02 kwns 260552
Storm Prediction Center ac 260551
Day 2 convective outlook
National Weather Service Storm Prediction Center Norman OK
1251 am CDT Tuesday Jul 26 2016
Valid 271200z - 281200z
..there is a marginal risk of severe thunderstorms from the middle-MO valley into
parts of the central and northern plains...
..there is a marginal risk of severe thunderstorms for parts of southern Virginia and northern
Isolated severe thunderstorms are possible across parts of the Great
Plains and the middle-Atlantic region Wednesday afternoon and evening.
A shortwave trough will gradually amplify across the middle-MS valley
into the upper Great Lakes...loosely associated with a deep-layer
low over eastern Canada. A separate midlevel speed maximum will move
across the Central High plains during the afternoon...along the northestern
periphery of anticyclonic flow aloft centered over the western Great
Basin. A surface cold front will slowly spread southward across the
Dakotas and northern Minnesota...while a weak nearly stationary
front extends from the middle-Atlantic region westward into the Central
..mid-MO valley into parts of the central/northern plains...
Early morning convection is forecast to weaken by the early portion
of the Wednesday/d2 period...and a boundary /potentially modified by
convection/ should extend from southeastern South Dakota southwestward into northestern Colorado by late
morning. Reservoir of low 60s f dewpoints will exist across the
middle-MO valley into eastern portions of neb/KS...with drier low-level air
/50s f dewpoints/ extending to the west and north into the northern High Plains.
Timing of individual impulses remains somewhat uncertain...but
general consensus is a midlevel speed maximum will move into the Central
High plains during the afternoon...and encourage thunderstorm development
along the boundary across parts of central Nebraska. Despite weak low-level
winds...northwesterly midlevel flow should be sufficient /20-30 knots/ to
support evolution of a couple clusters propagating generally southeastward
into eastern Nebraska and northern Kansas during the evening. Given uncertainty
related to the timing of impulses...and somewhat marginal
boundary-layer moisture...confidence remains too low for slight risk
delineation at this time.
Additional thunderstorms are possible within an upslope regime along the
Front Range into the parts of southeastern Montana. A few strong wind gusts
and/or small hail will be possible with convection across the
central/northern High Plains.
..srn Virginia and northern NC...
A band of moderate westerlies aloft /20-25 knots at 500 mb/ will persist
along the southern periphery of an eastern Canada trough across the central
Appalachians to the middle-Atlantic region. Rich moisture will be in
place to the S of a stalled boundary across southern Virginia...and strong
diurnal heating should yield MLCAPE values approaching 2000
j/kg...despite relatively warm middle-tropospheric temperature
profiles. Deep-layer shear may be sufficient to sustain a few
multicell clusters capable of damaging wind gusts from the higher
terrain eastward to the coast.