Severe Weather Threat thru May 17

Sat May 10 Convective Outlook
Storm Prediction Center Norman Ok
Slgt Risk Of Svr Tstms for Mid Ms Valley Sw to Wrn Ok...

Isolated Severe Thunderstorms Should Form During The Heat Of The Day Across The Mid Mississippi Valley...Southwest Across Eastern Kansas Into Portions Of Western Oklahoma.

Large Hail Is The Primary Severe Threat With This Activity.

Mid Ms Valley To Wrn Oklahoma...

30-60m 12hr Mid-Level Height Rises Will Develop Across The Mid-Ms
Valley Saturday As Short-Wave Ridging Builds Ahead Of Strong Upper
Low Digging Into The Great Basin.

At The Sfc...Warm Front Is Expected To Advance Nwd Across Ks/Mo To A Position Near I-70 By 11/00z.

Intense Boundary Layer Heating Across The Cntrl/Srn Plains Should Allow The Dryline To Initially Establish Itself From Swrn Ok...Newd Into Nern Ks Before Late Day Pressure Falls In The Lee Of The Cntrl Rockies Results In Flow Backing Across Ks And The Dryline Retreating Wwd.

In The Absence Of Meaningful Large Scale Ascent It Appears Diurnal
Heating Will Prove Instrumental In Convective Initiation...Both Along The Dryline And Along Warm Front.

Early In The Period Weak Subsidence Should Be Noted In The Wake Of Ejecting Short-Wave Trough.

Tstms May Not Develop Until After 21z Along The Warm Front/Dryline Intersection When Readings Breach Convective Temperatures.

Low Level Convergence Should Be Maximized Across Mo And This Should Prove More Supportive Of Sustaining Potentially Organized Supercell Development.

Forecast Soundings Across This Region Exhibit Substantial Deep Layer Shear Along With Sbcape In Excess Of 3000 J/Kg.

Additionally...Low Level Shear Will Be Maximized Along The Warm Front And This Could Enhance Tornado Threat From Late Afternoon Through Mid Evening.

Otherwise...Very Large Hail Can Be Expected With Supercells That Evolve Within Warm Advection Regime.

As Llj Increases During The Overnight Period Additional Convection May Evolve Within Warm Advection Belt...Thus A Few Severe Tstms May Linger Well Into The Overnight Hours.

Farther Sw...Strong Heating Along The Dryline Will Allow Sfc Temperatures To Warm Into The Lower 90s And Isolated High-Based
Convection Is Expected To Develop Across Parts Of Ks/Ok.

Deep Layer Shear Should Support Storm Rotation And Supercell Structures Are Possible.

Large Hail And Gusty Winds Are The Primary Threats Across This Region.

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Sun May 11 Convective Outlook
Storm Prediction Center Norman Ok
Slgt Risk Of Svr Tstms for Upper Ms Valley to Srn Plains...

At Least Scattered Severe Storms Appear Probable Beginning Sunday
Afternoon From Iowa To Western Oklahoma.

Severe To Very Large Hail...Damaging Winds...And Tornadoes Will Be Possible.

A Vigorous Shortwave Impulse Embedded Within An Amplified Upper-Level Trough Will Track From The Srn Great Basin To The Srn
Rockies.

Attendant Mid-Level Speed Max Will Become Centered From The Srn High Plains To The Cntrl Plains Early Mon.

At The Surface...A Cyclone Will Diurnally Deepen In The Lee Of The Srn Rockies With A Dryline Mixing Towards The Ern Tx Panhandle / Wrn Ok Border S/Swwd Across The Permian Basin.

Guidance Continues To Differ On The Acceleration Of A S/Sewd-Progressing Cold Front Over The Cntrl/Srn Plains.

Modest Cyclogenesis Should Occur Along A Portion Of This Front From The Cntrl Plains To Upper Midwest On Sun Night.

Upper Ms Valley To Cntrl Plains...

Considered A Moderate Risk For Portions Of Ks To Ia Where Scattered
To Numerous Storms Are Expected Within A Strong Combination Of
Instability/Shear.

But Uncertainties With Regard To Frontal Placement...Deep-Layer Flow Generally Paralleling The Front And Effects Of Early-Day Convection Preclude An Upgrade This Outlook.

Strengthening Swlys At 700 Mb Will Result In An Expanding Eml Plume And Attendant Capping Inversion Early Sun...With Increasingly Rich Boundary Layer Moisture Amidst Poleward Advection From The Wrn Gulf.

Middle To Upper 60s Surface Dew Points Should Become Established From At Least The Lower Mo Valley Swd...Yielding A Broad Strongly Unstable Air Mass With Mlcape Reaching 2500-3500 J/Kg In The Afternoon Ahead Of The Cold Front And Dryline.

Low-Level Waa On The Leading Edge Of The Richer Moisture Return / Capping Inversion Should Aid In Regenerative Clusters Of Elevated Storms Sun Morning Into Afternoon From Parts Of The Lower Mo To Upper Ms Valley.

How Exactly This Convection Will Play Out Is Unclear...But There Is Potential For An Effective Warm Front/Outflow Boundary To Become Established From Parts Of Ia To Il.

Should This Occur...Hodographs During Late Afternoon And Evening Along This W/E-Oriented Boundary Would Become Quite Favorable For Supercells As The Llj Strengthens.

This Suggests A Risk For Strong Tornadoes May Develop In Ia.

The Ecmwf/Ukmet Remain Consistently Slower With Cold Front
Progression Compared To The Nam/Gfs In Neb/Ks.

Even So...Strong Convergence Along This Front Will Yield Increasingly Numerous Storms Late Afternoon Into Evening.

Large Hail /Some Significant/ And A Few Tornadoes Will Be Possible Initially.

The Potential For Undercutting By The Front Appears More Likely In Ks With Weak Cyclogenesis Expected To Occur Towards The Mo Valley.

With Mid-Level Winds Generally Paralleling The Front...Cluster/Linear Modes Should Become Dominant As Convection Should Tend To Zipper S/Swwd Along The Front.

Severe Hail/Wind Hazards Should Persist Into Sun Night.

Srn Plains...

Intense Surface Heating Along With Strengthening Convergence Near
The Lee Cyclone/Dryline Intersection Should Yield Isolated Storms
Developing Late Afternoon.

Although Hodographs Should Not Be Overly Large Initially...Cross-Boundary Deep-Layer Flow Will Be Favorable For Discrete Supercells Given Strong Instability.

Very Large Hail Will Likely Be The Primary Initial Hazard With Convection Probably Forming Amidst Moderately Large Surface Temperature/Dew Point Spreads.

Spreads Will Lower During The Early Evening As A Sly Llj Strengthens ... Likely Maximizing Potential For A Couple Tornadoes During This Time Frame Invof Wrn Ok.

Greater Convective Coverage Should Occur Sun Night As The Front Impinges On The Still Strongly Buoyant Air Mass...With Attendant Severe Hail/Wind Hazards.

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Mon May 12 Convective Outlook
Storm Prediction Center Norman Ok
Slgt Risk Of Svr Tstms for Cntrl Great Lakes to Srn Plains...

Isolated Severe Storms Are Possible From The Central Great Lakes To The Southern Great Plains Through Monday Evening.

A Srn-Stream Speed Max Ejecting Out Of The Base Of An Amplified
Upper-Level Trough Late D2 Should Progress Across The Cntrl Plains
Into The Upper Ms Valley By Early Tue.

Attendant Surface Cyclone Along A Meridional Cold Front Should Track Across The Upper Ms Valley To Near Lk Superior.

Trailing Portion Of The Front Will Push E/Sewd Across The Mid-Ms Valley And Srn Plains...With Differences In Boundary Placement Among Guidance Most Pronounced During The First Half Of The Period.

Central Great Lakes To Srn Plains...

Scattered To Widespread Convection Is Anticipated To Be Ongoing At
12z/Mon Along Both The Cold Front Over The Great Plains And
Downstream Waa Regime Over The Great Lakes.

With A Residual Eml Plume Likely Across Undisturbed Portions Of The Warm Sector...Diurnal Heating Should Support At Least Moderate Buoyancy Developing Ahead Of This Activity From The Ozark Plateau To S Tx.

However...Wind Profiles With Srn Extent Will Be Weaker And Probably
Characterized By Veer-Back Signatures In The Mid-Levels...Given The
Track Of The Plains Shortwave Impulse.

Although Storm Clusters Will Likely Increase In Coverage During The Day...Small Hodographs Suggest Convection Would Struggle To Organize And Generally Remain On The Margins For Bouts Of Severe Wind/Hail.

Farther N From The Mid-Ms Valley To Cntrl Great Lakes...

Wind Profiles Will Be More Conducive To Rotating Updrafts.

However...Extensive Ongoing Convection Will Probably Have Deleterious Effects On Instability...Especially With Any Potential Redevelopment Along The Front During Peak Heating.

For Now...Will Broad-Brush With Low-End Slight Risk Probabilities.

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May 13-17 Convective Outlook
Storm Prediction Center Norman Ok

Consensus Of Guidance Suggests A Broad Upper-Level Trough Will Be Present From S-Cntrl Canada To Nm At 12z/Tue.

Poor Predictability Persists With The Evolution Of This Trough... Especially With The Potential Amplification Of An Embedded Srn-Stream Shortwave Impulse.

The 00z Ecmwf/Ukmet Are Most Pronounced With This Scenario Evolving Across The Lower Ms Valley To Southeast On D6/Thu.

This Could Induce Strengthening Wind Profiles Across A Residual Warm Sector Over Parts Of The Ern Conus.

But With Meridional Wind Profiles And Extensive Convective Overturning Through At Least D2-3 Over The Cntrl States...Mid-Level Lapse Rates Should Be Limited.

Even So...Given The Potential Robustness Of Wind Profiles...At Least A Marginal Severe Risk Could Develop.


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