Severe Weather Threat thru May 3

Sat Apr 26 Convective Outlook
Storm Prediction Center Norman Ok
Slgt Risk Of Svr Tstms for S and Cntrl Plains Areas...

Isolated To Scattered Severe Storms Are Expected To Develop Across
The Southern And Central Plains Late Saturday Afternoon And Continue Into The Overnight. The Primary Threats Will Be Very Large Hail And Damaging Wind Gusts.

Vigorous Shortwave Trough Moving Esewd Through Ca Will Emerge Over The Srn-Cntrl High Plains Saturday Night.

A Lee Low Should Deepen Over The Cntrl High Plains Saturday Afternoon Within Zone Of Increasing Upper Divergence Downstream From This Feature.

At The Sfc A Dryline Will Become Established From Wrn Tx Nwd Through Wrn Ks.

Warm Front Will Develop Nwd And By Late Afternoon Will Extend Ewd
From The Low Through Neb Into The Middle Ms And Oh Valleys.

Pacific Cold Front Will Accompany The Shortwave Trough Into The Srn
Plains...Eventually Overtaking The Dryline Later Saturday Night.

Wrn Through Ncntrl Tx...Ok And Ks...

Strengthening Sly Llj Associated With Developing Lee Cyclone Will
Advect Richer Moisture Currently Residing Over Cntrl/Srn Tx Nwd
Through The Plains Warm Sector Beneath Eml Plume With Very Steep /8-9 C/Km/ Lapse Rates.

By Late Afternoon Near Sfc Dewpoints Should Range From The Low 60s Across Nrn Tx And Ok To Upper 50s Or Near 60 Farther North Through Ks.

As The Boundary Layer Warms An Axis Of 2000-3000 J/Kg Mlcape Will Likely Develop In This Region.

Plume Of Warmer Air At Base Of The Eml Should Contribute To A Substantial Cap Much Of The Day.

With Primary Upper Trough Remaining Far West Of The Dryline During The Afternoon...Any Upper Forcing For Deep Layer Ascent Will Remain Limited To Any Subtle Lead Impulses Ejecting Ahead Of Main Shortwave Trough.

However...Heating And Deep Mixing Along The Dryline Should Contribute To At Least Isolated Storms By Late Afternoon/Early Evening.

Any Storms That Can Initiate During The Late Afternoon Should Be
Somewhat Higher Based...Especially With Nwd Extent Through Warm
Sector Given 20+ Temperature-Dewpoint Spreads. This And Modest Flow Aloft Suggest Storms Will Probably Be Outflow Dominant.

Winds Aloft Will Increase And The Llj Will Strengthen During The Early Evening With Shear Profiles Becoming Supportive Of Supercell Structures.

Very Large Hail And Damaging Wind Will Be The Main Threats.

A Small Window May Also Exist For Isolated Tornadoes During The Early Evening As The Llj Strengthens And Before Boundary Layer Begins To Decouple.

Additional Storms May Develop Later In The Evening With Potential
For Upscale Mcs Growth As Deeper Forcing Attending The Ejecting
Shortwave Trough And Its Attendant Cold Front Begin To Interact With
Warm Sector.

This Activity May Be Slightly Elevated Above The Stable Boundary Layer But May Tap Into Sufficient Moisture For A Continued Threat For Large Hail And Damaging Wind As It Develops Newd Overnight.

Cntrl/Ern Neb...Sern Sd And Wrn Ia...

The Boundary Layer Will Moisten In Vicinity Of The Warm Front.

Ewd Advecting Eml Plume And Diabatic Warming Will Contribute To Further Destabilization...But The Atmosphere Will Likely Remain Capped Much Of The Day...Especially Given Proximity To Upper Ridge.

This Lends Considerable Uncertainty Regarding Thunderstorm Initiation Potential Saturday Afternoon.

Moderate Instability In The Presence Of Steep Lapse Rates And Veering Low-Level Wind Profiles Along/Just North Of The Warm Front Suggest A Conditional Threat For Severe Storms.

Should Storms Initiate Along This Boundary During The Afternoon / Early Evening...Supercells With Large Hail And Perhaps A Couple Tornadoes Will Be Possible.

Otherwise...Potential Will Exist For Elevated Storms To Develop During The Evening/Overnight North Of This Boundary With A Threat For Large Hail.

Ern Wy And Wrn Sd...

A Few Strong To Severe Storms Will Be Possible From Nern Wy Into The Black Hills Area Of Wrn Sd Where Ely Upslope Winds Will Exist
Beneath Increasing Upper Diffluent Flow Aloft.

Low-Level Moisture Will Remain Modest In The Presence Of Steep Lapse Rates...But The Thermodynamic And Kinematic Environment Appear To Support At Least A Modest Severe Threat As Storms Develop And Spread Newd Off The Higher Terrain.

This Area Might Need To Be Included In A Slight Risk In Later Updates.

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Sun Apr 27 Convective Outlook
Storm Prediction Center Norman Ok
Mdt Risk Of Svr Tstms for Ar...N La/Ne Tx/E Ok/Sw Mo...
Slgt Risk Of Svr Tstms for parts of Cntrl Conus...

An Outbreak Of Severe Storms Is Possible On Sunday Across Parts Of The Central States With Large Hail...Damaging Winds...And Tornadoes.

The Greatest Risk For Strong Tornadoes Appears Centered From The
Ark-La-Tex To The Lower Mississippi Valley.

A Vigorous Shortwave Trough Centered In The Lee Of The Srn Rockies At 12z/Sun Will Substantially Slow As It Progresses Towards Neb.

An Attendant Mid-Level Jet /Aoa 50 Kt At 500 Mb/ Will Persist From The Desert Sw...Curling Nwd From The Red River To The Mo Valley.

At The Surface...A Cyclone Should Drift Ewd Over The Cntrl Plains With A Warm Front Arcing Ewd Across The Corn Belt To The Lower Oh Valley.

A Dryline/Weakening Pacific Cold Front Should Reach Ern Ks/Ok Into Deep S Tx In The Late Afternoon.

Mo Valley To The Wrn Gulf Coast...

Overall Scenario Has Not Changed Much From Previous Outlook With
Gradually Increasing Confidence In A Possible Outbreak Amidst
Continued Limiting Factors.

The Warm Sector Will Be Increasingly Broad/Moist Beneath An Eml With Lower 60s Surface Dew Points Becoming Established Near The Warm Front And Middle To Upper 60s Into The Lower/Mid-Ms Valleys And Arklatex By Early Evening Sun.

This Combined With Initially Steep Mid-Level Lapse Rates And Moderate To Strong Deep-Layer Shear Will Support An Expansive Area Of Organized Severe Storms.

Areas Of Convection Should Be Ongoing At 12z/Sun From Parts Of Ia To Ok.

Although The Bulk This Activity Should Be Elevated...It Should Transition To Becoming Surface-Based As Downstream Diurnal Heating Ensues.

Clusters Of Isolated To Scattered Severe Storms Will Be Possible As This Lead Convection Likely Develops Ewd.

The Most Intense Severe Storms Should Develop Along The Dryline And Remnant Convective Outflows In The Warm Sector During The Afternoon.

In The Wake Of Early Day Convection...There Remains Substantial
Uncertainty In The Degree Of Destabilization /Especially With Nrn
Extent/.

Nam/Gfs Guidance Is Insistent On Developing At Least Moderate Buoyancy With Mlcape Aoa 1000 J/Kg Into Nern Ks As Insolation Occurs Along The Dryline Amidst Steep Mid-Level Lapse Rates.

If This Were To Occur...Robust Mid-Level Dcva Would Foster Scattered Storms Forming By Mid-Afternoon Invof Ks/Mo Border.

Although Deep-Layer Wind Profiles Should Be Largely Meridional
Here...Backed Low-Level Winds Would Aid In Sufficient Curvature To
The Low-Level Hodograph For Supercells.

Large Hail /Some Significant/ And At Least A Few Tornadoes Appear Possible.

Parts Of This Region May Be Upgraded To Moderate Risk In Later Outlooks If It Appears Stabilizing Effects Of Early Day Convection Will Not Be Too Detrimental To The Afternoon Threat.

Farther S...A More Volatile Thermodynamic Environment Should Exist S Of Any Early Day Convection /Invof The Arklatex/.

With Surface Temperatures Heating Into The 80s/90s Along/W Of The Dryline In Tx...Mlcape Should Reach 2500 J/Kg Just Ahead Of It.

Hodographs Appear Quite Conducive To Supercells...Capable Of Producing Very Large Hail And Strong Tornadoes.

Nam Forecast Soundings Remain The Most Robust With The Co-Location Of Strong Buoyancy And Large Curving Hodographs.

Other Guidance Suggests Stronger Kinematic Fields Will Be Displaced Farther East /Centered Over The Lower Ms Valley/.

But With The Dryline Stalling Or Slowly Moving Across Nern Tx Sun Night...Training Convective Clusters With Embedded Supercells May Continue Well Into The Night.

Parts Of This Region May Warrant An Upgrade To High Risk In Later Outlooks.

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Mon Apr 28 Convective Outlook
Storm Prediction Center Norman Ok
Mdt Risk Of Svr Tstms for N/Cntrl Ms...W Tn...Ne La/E Ar/Nw Al/Sw Ky...
Slgt Risk Of Svr Tstms for Midwest To Cntrl Gulf Coast...

An Outbreak Of Severe Storms Is Possible On Monday Across Parts Of The Lower Mississippi Valley And Mid-South. Large Hail... Damaging Winds...And Tornadoes Are Expected.

Broad Upper-Level Trough Will Remain Anchored Over The Cntrl Conus With An Intense Mid-Level Speed Max /Aoa 80 Kt At 500 Mb/ Rotating Through The Base Of The Trough And Ejecting Across Parts Of The Mid-South And Confluence Of Ms/Oh Rivers By Mon Afternoon.

Surface Cyclone Should Remain Centered Over The Mo Valley...With A Warm Front Draped Ewd Over The Midwest.

Composite Dryline/Pacific Cold Front Should Extend From The Lower Mo Valley To Tx Gulf Coast On Mon Afternoon.

Midwest To Cntrl Gulf Coast...

A Plume Of 60s Surface Dew Points Will Be Established From The Warm Front In The Midwest S/Swwd To The Wrn/Cntrl Gulf Coast And Persist Amidst Strong Low-Level S/Swlys.

Although Convection Will Likely Be Ongoing At 12z/Mon From Parts Of The Midwest To Mid-South...Robust Diurnal Heating Should Occur In Convective-Free Areas To Support At Least Moderate Buoyancy Over Much Of The Warm Sector By Afternoon.

Low/Deep-Layer Shear Will Be Quite Strong Owing To The
Aforementioned Speed Max.

This Co-Location With The Established Warm Sector Yields A Large Area Of Organized Severe Potential.

The Most Concentrated Corridor For High-End Severe Risk Appears
Centered Over Parts Of The Lower Ms Valley To Mid-South.

Widespread Storms Appear Probable During The Afternoon...Likely Emanating From Regenerative Convective Clusters Along The Dryline/Convective Outflows.

With Effective Shear Aoa 50 Kt And Surface Dew Points Into The Middle To Upper 60s...Setup Could Yield Several Supercells With Strong Tornadoes And Large Hail...Evolving Into Bows And Widespread Damaging Winds.

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Apr 29-May 3 Convective Outlook
Storm Prediction Center Norman Ok

The Multi-Day Severe Weather Episode Associated With The Persistent Upper-Level Trough Over The Cntrl Conus Should Continue Into D4/Tue As The Last In A Series Of Intense Mid-Level Speed Maxima Ejects Through The Base Of The Trough.

This Should Result In Strong Kinematic Fields Overspreading A Gulf Warm Sector Characterized By 60s Surface Dew Points.

The Breadth Of The Warm Sector Will Probably Be Confined By Widespread Antecedent Convection On D3.

However...Guidance Is Fairly Consistent With Diurnal Destabilization
Occurring Ahead Of The Pacific Cold Front/Effective Dryline.

The Cape/Shear Combination Appears Favorable For Higher-End Severe Risk Focused From The Cntrl Oh Valley To The Cntrl Gulf Coast.

Overall Kinematic Fields Should Be In A Weakening State On D5/Wed
And Become Increasingly Displaced From Greater Buoyancy As The Front Accelerates Ewd.

Nevertheless...Organized Severe Potential Is Evident From Parts Of The Cntrl Appalachians And Mid-Atlantic Swd To The Southeast... Likely Yielding Eventual Slight Risk Delineation.


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