Severe Weather Threat thru Aug 10

Sun Aug 3 Convective Outlook
Storm Prediction Center Norman Ok
Slgt Risk Svr Tstms for parts of the Northern Plains...

Scattered Thunderstorms Are Expected To Form This Afternoon From Upper Michigan And Northern Wisconsin Southwestward To Missouri And Possibly Eastern Kansas. Scattered Strong To Possibly Severe Thunderstorms Also Should Form Over Parts Of The Southwestern United States And The Northern Plains. Gusty Winds And Hail May Accompany Some Of The Storms.

Prev Discussion...

Slowly-Progressive Pattern Will Prevail Over The Conus Through Mon.

Cntrl/Srn Rckys Ridge Will Edge E To The High Plns As Nrn Baja Ca Upr Low Moves Nne Into The Lwr Co Vly. On The Nw Flank Of The Ridge...Disturbance That Crossed Ore Yesterday Will Continue Ene Across Nrn Mt.

Farther E...Satellite Suggests Presence Of Several Weaker Impulses Moving Ese To Se Across The Upr Ms Vly...And Another Disturbance Moving Se Across Ern Neb/Ks. Still Farther E... Larger-Scale Trough Should Further Weaken As Shortwave Impulse Now Over Wrn Pa/Wv Shears Enewd Into Downstream Confluent Flow.

The Main Sfc Feature Of Note Is Shallow Front Extending From Srn Ab/Sk Sewd Into Ern Mt/Wrn Sd. This Boundary Should Remain Qstnry As A Weak Sfc High Noses S Into The Upr Ms Vly.

Nrn Plns/Nrn High Plns Late Today Into Tngt...

Wdly Sctd Tstms Are Expected This Aftn/Eve With Sfc Heating Along And N Of Qstnry Front Over Nrn/Ern Mt.

A Few Storms Also May Form Farther S Over Cntrl/Ern Mt Along Lee Trough.

Potential For Development Throughout The Region May Be Enhanced By Upr Impulse Shearing Ene Across Nrn Mt...Although It Is Unclear Attm Where The Strongest Ascent With This Feature Will Materialize. At Any Rate...Pw Should Remain Sufficient /Aoa 1 Inch Per Current Observations/ Over Ne Mt And Adjacent Nd To Support Strong Updrafts Given Expected Persistence Of Existing Sely Low-Lvl Flow...Uplift Provided By Front...And Likely Mlcape Of 1000-1500 J/Kg.

Band Of 25-30 Kt Wly 500 Mb Accompanying The Upr Impulse Will Provide Ample W To Wnwly Deep Shear For Storm Organization / Sustenance... Including Possible Supercells. Hodographs Also Will Feature Sizable Near-Sfc Directional Shear. Coupled With Well-Mixed Subcloud Layer...Setup Could Yield A Few Storms With Svr Wind And Hail...Mainly Over Ne Mt And Wrn Nd Through Later Tngt.

A Tornado Cannot Be Ruled Out...Most Likely In Far Ern Mt And Wrn Nd Where Boundary Layer Will Remain Somewhat Cooler/More Moist.

Lwr Co Vly/Az...

Somewhat Anomalous Pattern With Upr Low Moving Nnewd Into Srn Ca Will Maintain 20-25 Kt... Unidirectional...Sly 700-500 Mb Flow Across Wrn/Cntrl Az And Adjacent Srn Ca.

Satellite Shows Well-Defined Mid-Lvl Dry Slot Overspreading Region Ahead Of Secondary Vort Max Now Near The Nrn Tip Of Baja Ca. As The Vort Max Continues Nnewd And Sfc Heating Occurs Within Dry Slot... Expect An Arc Or Two Of Strong Storms To Form In Dry Slot Over The Lwr Co Vly. Given Rich Moisture /Pw 1.75-2.00 Inches/...Setup May Yield Isold Wet Microbursts.

Upr Ms Vly This Aftn/Eve...

A Few Pulse Storms With Marginally Svr Hail May Occur Over Parts Of The Upr Ms Vly/Upr Grt Lks This Aftn And Eve As The Lower Levels Destabilize Ahead Of Weak Upr Disturbance/Seasonably Cool Mid-Lvl Temperatures.

Cntrl Plns Late This Aftn/Eve...

Despite Nva In Wake Of Passing Upr Impulse...Some Chance Will Exist For Storm Development Later Today With Sfc Heating Along Outflow Boundary Left By Overnight Mcs In The Ern Neb/Ks Region. Combination Of Modest Nnwly Deep Shear With Fairly Moist Lower Levels Suggests A Conditional Risk For A Couple Strong Or Possibly Briefly Svr Storms With Hail/Wind.

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Mon Aug 4 Convective Outlook
Storm Prediction Center Norman Ok
No Svr Tstm Areas Forecast...

Thunderstorms Are Expected Across Much Of The Interior West And Scattered Strong Storms May Produce Gusty Winds From Portions Of Northern Arizona Into Utah. Other Isolated Strong Storms Capable Of Hail And Wind Are Possible From The Northern High Plains To The Midwest.

Midwest And Middle/Upper Ms River Valley...

A Modestly Strong/Cool Belt Of Mid-Level Northwesterly Flow Will Coincide With A Weak Surface Low/Southeastward-Moving Cold Front On Monday.

Some Early-Day Precipitation/Cloud Cover Aside...The Boundary Layer Should Become Moderately Unstable /Generally 1000-2000 J Per Kg Mlcape/ By Afternoon Prior To At Least Widely Scattered Surface-Based Thunderstorm Development.

Vertical Shear/Mid-Level Lapse Rates Will Be Weak...But Steepening Low-Level Lapse Rates / Moderate Buoyancy In The Presence Of Wind Profiles That Strongly Veer With Height May Account For Some Stronger / Possibly Severe Storms. As Such...Episodic Bouts Of Marginally Severe Hail / Gusty Winds May Be Possible Monday Afternoon.

North-Central High Plains/Black Hills...

A Northwest-Southeast Oriented Frontal Zone Should Slowly Be Shunted / Refocused Generally Southwestward Across The Region As Lee-Side Surface Low Development Occurs In The Presence Of Falling Upper Heights.

Thunderstorm Development Monday Afternoon Should Especially Occur In Vicinity Of The Lee Trough And/Or Near/Southwest Of The Aforementioned Front...With A Subsequent Northeastward Expansion Possible Monday Night Via An Increasing Warm Advection Regime.

An Adequate Combination Of Vertical Shear/Buoyancy...Especially Near The Aforementioned Frontal Zone...May Account For At Least An Isolated/Marginal Severe Risk With Hail / Wind Possible Monday Afternoon/Evening.

Northern Mt...

A Weak/Slow-Moving Moving Upper Low Is Expected To Drift Southeastward Over Southeast British Columbia/Southern Alberta On Monday...With Isolated To Widely Scattered Thunderstorm Development / Intensification Likely Focused Near And Just East Of The Divide. As Much As 1000 J/Kg Of Mlcape And 35 Kt Of Effective Shear Contribute To Some Stronger Storms Capable Of Some Hail Monday Afternoon/Evening.

Interior West...

An Upper Low Currently Moving Over Far Southern Ca Will Continue A General North-Northeastward Progression Over The Great Basin/Interior West On Monday. Ample Moisture And A Modestly Strong Mid-Level South-Southwesterly Wind Field Will Accompany The Eastern Periphery Of The Upper Low.

While Consequential Destabilization Is Unlikely Owing To Extensive Cloud Cover / Precipitation ...Cloud Breaks And Pockets Of Locally Stronger Heating/Weak Buoyancy Could Contribute To Some Stronger/Sustained Thunderstorms Capable Of Downbursts.

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Tue Aug 5 Convective Outlook
Storm Prediction Center Norman Ok
No Svr Tstm Areas Forecast...

Scattered Strong Thunderstorms May Develop Across The Central Plains And Mid Mississippi Valley Tuesday. Isolated Large Hail And Damaging Winds Are Possible.

Cntrl Plains/Mid Ms Valley...

Upper Ridge Will Remain Anchored Over The Plains During The Day3 Period ... However Latest Short-Range Model Guidance Suggests A Weak Short-Wave Trough May Suppress Heights Across The Cntrl Plains Tuesday.

While Mid-Level Flow Is Not Expected To Be Particularly Strong...On The Order Of 20kt At 500mb...If Aforementioned Short Wave Tops The Ridge Over Neb At Peak Heating Then Convection Should Develop Along Trailing Frontal Zone. Models Are In Fairly Good Agreement Regarding The Sfc Boundary Draped Along The Mo/Ia Border...Wnwwd Into The Neb Panhandle At 05/18z.

Strong Heating Is Expected To Contribute To Robust Convective Development Along The Wind Shift After 21z...But Nocturnal Warm Advection Should Maintain Convection Well Into The Overnight Hours As Llj Shifts Into Sern Neb After Midnight.

Decided To Only Introduce 5 Percent Severe Probs To Account For Hail/Wind With This Convection ... Primarily Due To Modest Deep-Layer Shear. Additionally ... There Is Some Question To Validity / Timing Of Ejecting Short Wave Into The Cntrl Plains And This Feature Should Prove Instrumental In Potential Convective Organization.

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Aug 6-10 Convective Outlook
Storm Prediction Center Norman Ok

Latest Medium-Range Guidance Continues To Suggest Greatest Pockets Of Instability Will Remain Suppressed Across The Srn Conus And Weakly Sheared.

However...Steep-Lapse-Rate Plume Will Spread Across Much Of The Plains And Robust Convection May Develop At Times Along Ern Edge Of Cap Within Warm-Advection Zone Modulated By Nocturnal Llj.

While Stronger Flow Will Accompany Upper Trough Over The Nern U.S. During The Latter Half Of The Week...Meaningful Moisture/Instability Will Be Lacking Beneath This Feature.

Until Stronger Wlys Sag South Of The Canadian Border Into The Plains The Potential For Significant Organized Severe Thunderstorms Should Remain Low.


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