Severe Weather Threat thru May 29

Thu May 22 Convective Outlook
Storm Prediction Center Norman Ok
Slgt Risk Svr Tstms for parts of Mid Atl & Nern States...
Slgt Risk Svr Tstms for parts of Tn Valley & Mid Ms Valley...
Slgt Risk Svr Tstms for parts of Cntrl High Plains...
Slgt Risk Svr Tstms for parts of Srn High Plains...

Strong To Isolated Severe Storms Should Develop Thursday Afternoon And Evening Across Parts Of The Central To Southern High
Plains...And From Parts Of The Mid-Atlantic States To Tennessee
Valley. Large Hail And Damaging Winds Will Be The Primary Hazards.

Cutoff Upper Low Will Remain Over The Wrn States And Slowly Drop A
Bit Farther Swd...Becoming Centered Over Srn Ca And Swrn Az Later In The Period.

Downstream Of This Feature...An Upper Ridge Will Build Across The Cntrl Plains.

Farther East...An Upper Trough Will Amplify Over The Great Lakes Region.

A Shortwave Trough Embedded Within This Feature And Currently Moving Into The Great Lakes Will Continue Through The Nern States Thursday Morning Into Early Afternoon.

Cold Front Will Move Into The Nern U.S. And Mid Atlantic In Association
With This Feature...While Trailing Portion Of This Boundary Settles
Into The Tn Valley Then Wwd As A Quasi-Stationary Front Across Ks
Into Co.

Mid Atlantic Area...

Modest Instability With 500-1000 J/Kg Mlcape Should Develop In Pre-Frontal Warm Sector Across The Mid Atlantic Region And A Portion
Of The Nern States By Late Morning.

While Low To Mid-Level Flow Will Remain Weak...Belt Of Stronger Flow Aloft With 50 Kt At 500 Mb Associated With The Progressive Shortwave Trough Will Result In 40-45 Kt Unidirectional Wly 0-6 Km Shear.

Frontal Convergence Should Remain Limited Due To Weak And Veered Low-Level Winds.

However...Weak Capping Should Promote The Redevelopment Of Storms Along And Ahead Of The Front By Early Afternoon As The Boundary Layer Warms And Destabilizes.

Sufficient Unidirectional Shear Will Be Present For Some Supercell Structures With A Threat For Isolated Large Hail And Damaging Wind Gusts.

Tn Valley Through Mid Ms Valley...

Plume Of Steep Mid-Level Lapse Rates Are Already In Place Across
This Region Above Modest Low-Level Moisture.

Boundary Layer Dewpoints Should Rise Into The Mid 60s In Vicinity Of The Front As It Settles Swd Through Mo And Tn.

This Region Should Become Moderately To Strongly Unstable /2000-2500 J/Kg Mlcape/ As The Sfc Layer Warms During The Afternoon.

Low-Mid Level Winds Will Remain Weak...But The Front Will Persist Along Srn Periphery Of The Upper Trough With Moderate Winds Aloft Supporting 30-40 Kt Effective Bulk Shear.

Given Capping Inversion Associated With Eml Plume And Weak
Low-Level Winds Which Will Limit Convergence Along The Front... Thunderstorm Coverage In This Region Might Be Sparse. This
Makes Overall Severe Potential Somewhat Conditional...But Any Storms That Initiate Could Acquire Supercell Structures With A Threat For Large Hail And Damaging Wind Through Early Evening.

Cntrl High Plains...

Building Upper Ridge Downstream From Swrn U.S. Upper Low Will Result In Weaker Flow Aloft And Vertical Shear Compared To Wednesday.

Nevertheless...The Atmosphere Is Expected To Become Moderately
Unstable With Steep Lapse Rates And Ample Sfc Heating.

Storms Will Likely Develop Over The Higher Terrain And Spread Newd Into The High Plains.

Low-Level Veering Will Be Present Across Nern Co Into Nwrn Ks North Of The Stationary Front...But Weak Flow Aloft Will Result In Only 25-30 Kt Deep Shear.

Storms Will Likely Remain Multicell In Character And Eventually Consolidate Into Clusters Posing A Threat For Gusty Winds And Hail.

Srn High Plains...

Srn High Plains Will Stay Removed From The Stronger Flow Aloft Associated With The Cutoff Upper Low. Modest But Deep Sly Flow Will
Exist In This Region Downstream From The Upper Low With 20-25 Kt
Vertical Shear.

An Axis Of Moderate Instability Will Develop From Wrn Tx Into Ern Nm Where Steep Mid-Level Lapse Rates Overlap The Wrn Edge Of Upper 50s Dewpoints.

Plume Of Deeper Subtropical Moisture May Also Be Advected Nwd Through This Region Ahead Of The Upper Low.

Storms Will Likely Redevelop Over And East Of The Higher Terrain As
The Boundary Layer Destabilizes.

Despite Modest Vertical Shear...A Few Storms May Become Capable Of Producing Strong To Damaging Wind Gusts As Outflows Merge And Storms Evolve Into Clusters As They Develop Nwd.


Fri May 23 Convective Outlook
Storm Prediction Center Norman Ok
Slgt Risk Svr Tstms for Far West Tx & Sern Nm...

Scattered Severe Thunderstorms Will Develop Across The High Plains Of Far West Texas And Southeast New Mexico.

Isolated Strong Storms May Also Develop Across Parts Of The Southeast And Northern High Plains.

West Tx/Sern Nm...

Slow-Moving Upper Low Is Expected To Shift East Of The Lower Co
River Valley Into Sern Az By The End Of The Period.

While Strong Flow Will Rotate Through The Base Of The Trough Into The Ern Hemisphere Of This System Late...Mid-Level Speed Max Will Only Glance Far West Tx By 24/12z.

As A Result...Somewhat Marginal Deep Layer Shear Will Be Noted Across The Srn High Plains With Roughly 20kt Expected Across The Slgt Risk Region At 500mb.

Even So...Strong Heating Will Be Noted Across This Region And Lapse Rates Will Steepen Prior To Convective Initiation.

Minimal Cinh Is Expected This Region Due To Relatively Cool 700mb Temperatures And Thunderstorms May Develop By Late Morning Within Moist Upslope Regime.

Veering Wind Profiles With Height Suggest Weak Supercells Are Possible And Large Hail Is The Most Likely Severe Threat.

Other Isolated Strong Storms Could Develop Across Much Of The
Srn/Cntrl High Plains From The Edwards Plateau Of Tx...Nwd Into Ern
Co/Wrn Ks.

Will Maintain 5 Percent Severe Probs Due To Weak Deep Layer Shear.


Strong Heating Across The Nrn High Plains Of Mt Will Allow Sfc Parcels To Reach Their Convective Temperatures...Lower-Mid 80s...By

As A Result...Isolated Thunderstorms Should Develop Along A Weak Low Level Confluence Zone Along Wrn Fringe Of Flattening Upper Ridge.

This Activity Should Struggle To Organize Due To Weak Large Scale Forcing And Marginally Severe Hail/Wind Gusts Are The Primary Threats.

Sern U.S...

Strong Mid-Level Speed Max Will Dig Sewd Across Wv And Off The Nc
Coast During The Evening Friday.

Deep Nwly Flow Will Continue Across The Oh Valley Into The Sern U.S. In The Wake Of This Feature Which Should Force Synoptic Front To A Position From Wrn Tn...Sewd Into The Carolinas By 18z.

Strong Heating And Weak Convergence May Allow A Few Thunderstorms To Develop Along This Wind Shift.

Latest Nam Suggests A Cluster Of Storms Could Develop Near The Sc Coast...Possibly Aided By Sea Breeze Interactions.

If Confidence Increases In An Active Sea Breeze Then Severe Probs Will Need To Be Adjusted As Steep Lapse Rates/Buoyancy Will Be More Than Adequate For Organized Updrafts Given 40kt+ Sfc-6km Shear.

Otherwise...Hail/Wind Could Accompany Convection That Manages To
Evolve Along The Front.


Sat May 24 Convective Outlook
Storm Prediction Center Norman Ok
Slgt Risk Svr Tstms for Srn High Plains...

Numerous Thunderstorms Should Develop Across The Southern High Plains Saturday;

Several Storms May Produce Severe Hail And Damaging Wind Gusts.

Isolated Thunderstorms...A Few Strong...May Develop Across The Northern High Plains And Over The Southeastern Us Into The Florida Peninsula.

Southern High Plains...

Slow-Progressing Upper Low Will Shift Into The Srn Rockies During
The Day3 Period.

In Response To This Feature Sely Low Level Flow Will Be Maintained Across West Tx Into Ern Nm.

While Typical Steep Lapse Rate Environment Will Not Reside Across This Region Saturday...Mostly Due To Layered Cloud Cover And
Precipitation...Sufficient Buoyancy Should Exist For Robust Convection.

Strongest Heating Will Be Confined To Far West Tx And Srn Nm...But Rather Moist Sely Boundary Layer Flow Should Prevent Much Of The Tx South Plains Into Ern Nm From Warming Significantly.

Negligible Cinh And Low Convective Temperatures Will Allow Tstms To Develop Early In The Period Along Leading Edge Of Stronger Flow

Strong Deep Layer Shear Should Support Organized Updrafts... Perhaps Embedded Supercells Within Larger Convective Clusters.

Risk Of Tstms Will Exist Through The Period As Influence Of Upper Low Slowly Drifts Toward West Tx.

Nrn High Plains...

Isolated Thunderstorms May Develop Across The Nrn High Plains From Ern Mt Into Wrn Nd.

Intense Boundary Layer Heating Should Allow Sfc Temperatures To Warm Into The 80s...Enough For High-Based Convection By Late Afternoon.

Gusty Winds/Marginally Severe Hail May Accompany This Diurnally-Driven Activity.

Sern U.S./Fl...

Mid-Level Flow Will Gradually Veer Into The Nw Across The Sern U.S./Fl As East Coast Trough Moves Offshore.

This Will Allow Steep Lapse Rates To Develop Along A Corridor From The Nrn Gulf States...Sewd Into The Fl Peninsula.

While Large Scale Forcing Will Prove Negligible...Various Sea Breeze Interactions And Weak Forcing Along Synoptic Front Should Allow At Least Isolated Thunderstorms To Develop Across This Region.

Large Hail/Damaging Winds Are The Primary Threats.


May 25-29 Convective Outlook
Storm Prediction Center Norman Ok

Slow-Moving Upper Low Is Forecast To Eject Across The Srn Rockies
Into The Cntrl/Srn Plains Early Next Week.

A Considerable Amount Of Convective-Overturning Is Expected Across The High Plains Which Should Limit Lapse Rates / Instability...Except For Meso-Scale Pockets Which Can Not Be Deduced 4-6 Days In Advance.

Despite The Likelihood For Robust Storms...Predictability Is Too Low To Warrant A Severe Outlook This Period.

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