Severe Weather Threat thru Apr 18

Fri Apr 11 Convective Outlook
Storm Prediction Center Norman Ok
No Svr Tstm Areas Forecast...

Broadly Cyclonic Large-Scale Flow Positioned Across North America
Will Feature A Series Of Shortwave Impulses.

The Lead Wave...Currently Situated Over The Cntrl Plains...Will Translate Ewd Towards The Oh Valley...While A Trailing Impulse Will Move Across The Nrn Plains Into The Upper-Ms Valley By Early Sat Morning.

Farther W...A Srn-Stream Upper Low Will Approach The Ca Coast...But
Moisture Associated With This System Remains Quite Limited.

At The Sfc...A Cold Front Is Forecast To Become Quasi-Stationary Over The Srn Ozarks Enewd Along The Oh Valley.

The Air Mass S Of This Boundary Will Continue To Modify Throughout The Day...Before Returning Nwd Towards The Upper-Ms Valley As Low-Level Flow Strengthens Across The Plains.

Ozark Plateau Into The Mid-Atlantic...

Low-Level Moisture Axis /Characterized By Low-Mid 50s F Sfc
Dewpoints/ Is Centered Over The Ern Great Plains As Of Early Fri
Morning...With Drier Air Noted E Of The Ms Valley.

A Plume Of Moderately Steep Midlevel Lapse Rates Will Extend Ewd From The Srn Plains Towards The Mid-Atlantic Region...Which Will Be Sufficient To Support Marginal Instability Invof The Stalling Cold Front.

The Timing Of A Shortwave Trough Moving Through The Mid-Upper Oh Valley During The Afternoon Should Focus Shower/Tstm Development Along The Weakly-Convergent Front...Mainly From Portions Of Sern Mo And The Mid-Ms Valley And Points Ewd.

A Few Strong Wind Gusts And Instances Of Hail Will Be Possible Invof The Mid-Ms Valley As Low-Level Lapse Rates Steepen As Temperatures Warm Into The 70s F...But A Greater Risk Appears Limited By Meager Instability And Boundary-Layer Moisture...And Weak 0-3 Km Agl Flow.

W Of The Mid-Ms Valley...Modest Midlevel Height Rises In The Wake Of The Aforementioned Shortwave Trough...Along With The Presence Of Cinh And Weakening Frontal Convergence...Will Limit Prospects For Convective Development...Despite Slightly More Favorable Low-Level Moisture.

Cntrl/Nrn Sierra And Coastal Ranges Of Nrn Ca...

Marginal Buoyancy Via Strong Diurnal Heating And Midlevel Moistening Will Support Isolated Afternoon Tstms Over The Higher
Terrain...Ahead Of An Approaching Offshore Low.

Upper Ms Valley Early Sat...

Low-Level Waa Will Occur As A Modified Air Mass Returns Nwd Into The Upper Ms Valley. While Weak Elevated Buoyancy May Develop And Support Isolated Shower Development Early Sat Morning...Better
Potential For Tstms Appears To Reside Beyond The 12/12z Time Period.


Sat Apr 12 Convective Outlook
Storm Prediction Center Norman Ok
Slgt Risk of Svr Tstms for parts of Ks/Neb to S Ia/N Mo...

Portions Of Ks/Southeast Neb To Ia/Northern Mo...

A Split Upper Pattern Will Yield To Some Phasing With Increasingly
Cyclonic Upper Flow Over The Rockies/Plains On Saturday.

Surface Cyclogenesis Is Expected Across The Central High Plains Into Saturday Evening...With Steady But Modest Northward Moisture Return To The East-Southeast Of A Dryline/Accelerating Cold Front.

In The Wake Of Early Day Tstms Across The Upper Midwest...Current
Thinking Is That Near Surface-Based Tstms Should Develop Saturday
Afternoon/Early Evening Across The Upper Ms Valley And Parts Of
Ia/Northern Mo In Vicinity Of The East-Southeastward Moving Cold

With Upper 50s/Perhaps Around 60 F Surface Dewpoints...Sufficient Instability/Vertical Shear Collocated Near The Front May Allow For Some Tstms Capable Of Severe Hail/Wind.

Farther Southwest...Other Storms May Form As Early As Late Saturday
Afternoon...But More So Saturday Evening Across Parts Of Central / Northeast Ks And Far Southern Neb In Areas Near And East-Northeast Of The Surface Triple Point.

While The Extent Of Surface-Based Development Is Uncertain Given Relatively Modest Boundary Layer Moisture And A Very Strong Elevated Mixed Layer...Supercells Would Be Possible Given At Least Moderate Instability And Around 35-45 Kt Of Effective Bulk Shear.

Large Hail Would Be The Primary Hazard...With A Nocturnal Expansion Of Mainly Elevated Tstms /Some Capable Of Severe Hail/ Likely Saturday Night.

Southwest Ks/Far Western Ok And E Tx Panhandle/Northwest Tx...

Near The Nne-Ssw Oriented Dryline Across The South-Central High
Plains...It Is Possible That Sufficient Mass Convergence/Mixing May
Exist For The Development Of A Few High-Based Tstms Late Saturday Afternoon/Early Evening.

Should Such Development Occur...A Risk For Severe Hail/Strong Winds Would Exist Given Strong/Veering Wind Profiles And Very Steep Lapse Rates/Moderate Instability.


Sun Apr 13 Convective Outlook
Storm Prediction Center Norman Ok
Slgt Risk of Svr Tstms for S Plains/Ozarks to Mid/Low Ms River Valley...

Longwave Trough Amplification With Broad Cyclonic Upper Flow Is
Expected To Evolve Sunday Over The Central Conus...With Multiple
Shortwave Impulses Overspreading The Region.

A Cold Front Will Accelerate South-Southeastward Across Much Of The South-Central Plains And Lower Mo Valley/Ozarks Through Sunday Night.

Southern Plains/Ozarks To Middle/Lower Ms River Valley...

Given The Large-Scale Evolution As Previously Described...It Seems
Likely That A Lead/Southern Stream Impulse And Associated Speed Max Will Spread East-Northeastward From The Southern Plains To The Middle Ms River Valley Sunday/Sunday Night. Ahead Of The Cold
Front/Surface Low.

Persistently Strong Southwesterly Low-Level Winds Will Continue To Transport Moisture North-Northeastward Within An Increasingly Broad Warm/Moist Sector From East-Central Parts Of Ok/Tx To The Ozarks/Lower-Middle Ms River Valley.

As The Air Mass Destabilizes Through Afternoon...Ample Forcing For
Ascent Tied To The Aforementioned Shortwave Trough And Cold Front
Should Influence Increasing Tstm Development Particularly Sunday

Greater Certainty For Stronger Deep Convective Development Will Be Near The Advancing Cold Front Across Parts Of Ok/Southeast Ks And Adjacent Mo/Ks.

However...Other More Discrete Strong/Severe Storms Including Supercells Will Be Possible Across Additional Parts Of East-Central Tx/Arklatex Within The Pre-Frontal Warm Sector And Near The Dryline Extending Southward Across South-Central Ok Into North-Central / Central Tx.

Favorable Wind Profiles Will Support Initial Supercells...Although
Increasingly Unidirectional Winds /Veer-Back-Veering Winds With
Height/ And The Influence Of The Cold Front Suggest That Multicells / Line Segments Should Evolve During The Evening In Most Areas... With Near-Cold Frontal Storms Steadily Being Undercut By The Cold Front /From Northwest To Southeast/.

Large Hail Is Expected To The Primary Hazard Overall...Although Damaging Winds And Some Tornadoes May Be Possible As Well.


Apr 14-18 Convective Outlook
Storm Prediction Center Norman Ok

00z-Based Medium Range Guidance Suggest That A Longwave
Trough/Associated Cold Front Will Shift Generally Eastward Across
The Eastern Conus Early Next Week.

Initially On Day 4/Monday...Clusters Of Showers/Tstms Should Be Ongoing In The Morning Across The Gulf Coast States/Tn Valley Ahead Of The East-Southeastward Advancing Cold Front.

While Some Severe Risk May Be Possible Monday In Areas Such As The Central Gulf Coast States Given Sufficient Moisture/Vertical Shear...The Likelihood/Magnitude Of Such A Risk Is Uncertain Especially Given Unknowns Related To Early Day Convection/Cloud Cover And Subsequent Destabilization.

As The Southern Stream Trough Amplifies/Spreads Eastward On Day
5/Tuesday...Some Strong Storms May Be Possible Across Portions Of Fl And The Coastal Southeast States.

Thereafter...In The Absence Of Meaningful Moisture...A Relatively
Quiet Pattern Should Result In A Limited/Below-Average Severe
Potential Much Of The Remaining Week.

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