Severe Weather Threat thru Aug 16

Sat Aug 9 Convective Outlook
Storm Prediction Center Norman Ok
Slgt Risk Svr Tstms for parts of Neb/Ks And Vicinity...

Isolated To Widely Scattered Severe Thunderstorms Are Expected To Affect Portions Of Nebraska And Kansas This Afternoon Into Tonight. Large Hail And Damaging Straight-Line Winds Will Be The Primary Hazards.

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Ks/Neb Area This Afternoon Into Tonight...

An Outflow Boundary From Overnight Convection Extends From S Central Ks Nwwd To Nw Ks And Wrn Neb...Where The Boundary Intersects A Weak Lee Cyclone. The Background Flow Regime Aloft Consists Of A Series of Weak Mid-Upper Troughs Moving Slowly Ewd Over Ern Sd/Neb...And Srn Wy / Nrn Co. The Wrn Wave Will Interact With The Remnant Outflow/Lee Trough This Afternoon. Thus ... Weak Background Ascent Will Coincide With Diurnally Increasing Cape And Weakening Cin... That Will Support Scattered Thunderstorm Development By Mid-Late Afternoon for Wrn Neb and Ks.

Mlcape Will Increase To Near 2500 J/Kg By Mid Afternoon...And While Wind Profiles Will Not Be Particularly Strong...Effective Bulk Shear Near 30 Kt Will Favor Some Organized Clusters And Marginal Supercell Structures With The Initial Storms. Substantial Pw And Buoyancy Will Favor Heavy Precipitation Loading...Which Combined With Steep Low-Level Lapse Rates And Large Dcape ...Will Support A Risk For Strong Downdrafts And Damaging Outflow Winds. Isolated Large Hail Will Also Be Possible With The More Organized/Persistent Cells...Before Convection Likely Grows Upscale Into One Or Two Clusters That Will Move Sewd Toward Central Ks And Persist Into Tonight.

Ern Ok To Coastal Sc This Afternoon...

Multiple Outflow Boundaries From Prior/Ongoing Convection...And Debris Clouds...Will Modulate Afternoon Strong Thunderstorm Occurrence. Low-Mid 70s Boundary Layer Dewpoints And Surface
Heating Will Drive Mlcape To 2000-2500 J/Kg Along The Sc Coast... And To 3000-3500 J/Kg From Central Ms To Ern Ok. Vertical Shear Will Be Weak Across This Entire Area...But A Few Downbursts Will Be Possible With The Strongest Storms This Afternoon.

Wrn Nd Area This Afternoon...

Thunderstorm Development Is Possible Along A Surface Cold Front Later This Afternoon...Where Surface Heating Will Be Strongest To The Nw Of A Persistent Stratus Deck In Nd. Though Moderate
Instability Is Expected Immediately Ahead Of The Front...The Stronger Vertical Shear Will Remain Post-Frontal In Association With A Weakening Midlevel Wave Moving Enewd From N Central Mt. Thus ... Only A Marginal Wind/Hail Risk Is Expected With Storms Along The Front For A Few Hours This Afternoon.


Sun Aug 10 Convective Outlook
Storm Prediction Center Norman Ok
No Svr Tstm Areas Forecast...

A Few Strong Storms Will Be Possible From The Central And Southern Plains Into The Middle And Lower Mississippi Valley Region With A Threat For Locally Strong Wind Gusts And Small To Marginally Severe Hail.

Generally Weak Flow Field Aloft Will Prevail Across The U.S. This Period...Though Some Amplification Of A Central Canada Trough Is Progged To Expand Sewd Across The Great Lakes/Midwest Later In The Period. In The Mean Time...A Short-Wave Trough Moving Esewd From the Central Plains Toward The Mid Ms/Lower Oh Valley Region Will Be Associated With An Area Of Convective Potential/Low-Probability Severe Risk.

The Weak Upper Pattern Will Yield Similarly Benign Surface Features ... With Weak/Convectively Reinforced Baroclinic Zones Extending From Srn Ks/Ok/N Tx Ewd Into The Mid Ms Valley Focusing Convective Development During The Afternoon And Evening.

Ern Ks/Ern Ok Ewd Into The Mid And Lower Ms Valley Area...

Small Clusters Of Weak Convection May Be Ongoing At The Start Of The Period Across Parts Of Ks/Ok/Mo/Ar Vicinity...With Associated Outflows Serving As Possible Foci For New/Afternoon Storm Development As The Airmass Diurnally Destabilizes. Uvv Associated With The Weak Upper Feature Progged To Be Crossing The Nwrn Mo/Ern Ks Vicinity During The Afternoon Should Aid In Convective Development...While Modestly Enhanced Mid-Level Wnwlys Add To Somewhat Greater Convective Intensity/Longevity. A Few Stronger Storms Will Traverse This Region Thus Capable Of Producing Marginal Hail/Locally Stronger Wind Gusts...Will Maintain 5% Severe Risk Across The Area For Peak Afternoon/Evening Convective Cycle.


Mon Aug 11 Convective Outlook
Storm Prediction Center Norman Ok
No Svr Tstm Areas Forecast...

A Few Storms With A Threat For Mainly Locally Strong Wind Gusts Will Be Possible From Northern California To Western Oregon. Storms With Gusty Winds May Occur From Southwestern And Central Texas Through The Lower Mississippi Valley Into The Southeast States.

The Upper Pattern Will Undergo Amplification As A Shortwave Trough Drops Sewd Into The Upper Ms Valley And Great Lakes Region Along Swrn Periphery Of The Synoptic Upper Trough. Farther West A Cutoff Upper Low Is Forecast To Persist In The Ca Vicinity With An Upper Ridge Across The Rockies And High Plains.

At The Sfc A Cold Front Will Accompany The Amplifying Nrn Stream Trough Sewd Into Great Lakes And Ms Valley Region. A Convectively Reinforced Front Should Advance Farther South Into Tx And The Lower Ms Valley.

Nrn Ca Into Western Oregon...

Plume Of Subtropical Moisture Will Be Drawn Nwwd In Association With The Circulation Around Cutoff Upper Low...And Storms Should Develop During The Afternoon Over The Higher Terrain. Inverted-V Boundary Layers And Steep Lapse Rates Will Support A Threat Of Isolated Locally Strong Wind Gusts Through Early Evening.

Cntrl Tx Through The Lower Ms Valley Area...

Outside Of Convective Debris...Diabatic Warming Will Contribute To A Corridor Of Moderate /1500-2000 J/Kg/ Mlcape In Vicinity Of The Front From Cntrl Tx Into The Lower Ms Valley Where Multicell Storms Will Likely Redevelop During The Day. Mid-Level Lapse Rates And Vertical Shear Will Remain Weak. However...Steepening Lapse Rates Within The Boundary Layer May Support A Modest Threat For Locally Strong Wind Gusts With Some Of The Storms.


Aug 12-16 Convective Outlook
Storm Prediction Center Norman Ok

Model Consensus Is That A Blocking Pattern Will Continue To Evolve Through At Least Day 4-6 As An Upper Low Closes Off Over The Nern U.S. And Great Lakes Region With An Upstream Trough Also Over The Wrn States.

Tuesday /Day 4/ Severe Threat With The Amplifying Ern U.S. Upper Trough Is Expected To Remain Low Due Mainly To Likelihood Of A Very Marginal Thermodynamic Environment Ahead Of Attendant Cold Front. The Cold Front Will Eventually Occlude With The More Unstable Warm Sector Residing South Of Another Boundary Over The Sern States. The Pre-Frontal Environment Across The Oh Valley And Nern U.S. Will Be Characterized By Widespread Clouds And Areas Of Precipitation Which Will Result In Moist Adiabatic Lapse Rates... Limiting The Severe Potential.

Days 6-8 Some Severe Potential Will Likely Evolve Over The Cntrl And Nrn Plains As Richer Low-Level Moisture Returns Nwd And A Series Of Vorticity Maxima Advances Ewd And Interacts With The Destabilizing Boundary Layer. However...Confidence In Where To Place A 30% Or Greater Coverage Severe Threat Area Is Not Particularly High At This Time.

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