Severe Weather Threat thru Apr 6

Sun Mar 30 Convective Outlook
Storm Prediction Center Norman Ok
No Svr Tstm Areas Forecast...

Ern Ut Into Wrn Co...

A Potent Shortwave Trough Continues To Bring Very High Winds To Much Of The Four Corners States Where Steep Lapse Rates And Strong Mixing Exist.

High-Based Showers And A Few Embedded Thunderstorms Currently Exist Over Far E-Cntrl Ut Into Wrn Co.

These Storms May Locally Augment Wind Gusts...But In General... Severe Wind Gusts Are Being Observed Over Much Of The Area Even Apart From The Precipitation.

Rapid Drying In The Wake Of This Trough And Loss Of Heating Should Result In An Abrupt End To The Lightning Activity Later This
Evening...But Will Maintain A Small 5 Percent Severe Wind Area For
The Current Activity.


Mon Mar 31 Convective Outlook
Storm Prediction Center Norman Ok
No Svr Tstm Areas Forecast...

A Progressive Quasi-Zonal Mid-Upper Level Flow Regime Will Persist
Into Day 2.

A Shortwave Trough...Currently Moving Into The Great Basin Per Water Vapor Imagery...Is Expected To Track Enewd From The Central High Plains Toward The Mid-Upper Ms Valley On Monday...And Likely Reach The Upper Great Lakes By 12z Tuesday.

A Surface Low Attendant To This Trough Will Move From Central Neb Into Central/Srn Mn By 01/00z...And Reach Upper Mi/Lake Superior By 12z Tuesday.

A Trailing Cold Front Is Forecast To Sweep Ewd Through The Central
Plains And Mid-Upper Ms Valley Region...And Be The Focus For Late
Afternoon Tstm Development From Srn Mn To Nrn Mo.

This Front Should Extend From The Upper Great Lakes Swd Through Ern Il...And Then Swwd Through The Ozarks To The Red River Valley And W/Nw Tx By The End Of Day 2.

The Rest Of The General Tstm Area Across The Central U.S. Is
Expected To Have Mainly Elevated Storms Located Within The Warm
Conveyor Belt.

Farther West...A Closed Mid-Upper Level Low Will Move Steadily Sse
Toward The Ore/Nrn Ca Coast...With A Lead Impulse On Its Srn
Periphery Expected To Move Into Central Ca Late Monday Afternoon Or
Early Evening.

There Will Be The Potential For Tstms Generally Confined To The Coastal Areas Of Nrn/Central Ca.

Srn Mn/Ia/Nrn Mo...

A Dry Slot Attendant To The Progressive Shortwave Trough Moving
Toward The Mid-Upper Ms Valley On Monday Should Allow For Surface
Heating In The Wake Of Any Elevated Tstms/Associated Cloudiness
Expected Across This Region Monday Morning To The Early Afternoon.

This Corridor Of Surface Heating Should Be Relatively Narrow Just
Ahead Of The Cold Front And Co-Located With A Similar Breadth Of
Weak Moisture Return /Surface Dewpoints Ranging From 45-50 F/.

Although Instability Will Be Rather Weak /Mlcape 100-250 J Per
Kg/...The Timing Of Strong Forcing For Ascent Attendant To 1/ Around
100 Meter 500-Mb Height Falls...2/ Exit Region Of A 60-70 Kt Swly
500-Mb Jet And 3/ Frontal Forcing During Peak Heating Suggest A
Narrow Line Of Surface-Based Tstms Will Be Possible.

This Combined With Effective Bulk Shear Of 35-40 Kt And Cooling 500-Mb Temperatures/Steepening Midlevel Lapse Rates Should Allow For A Few Strong To Severe Storms.

The Weak Instability /Limiting The Overall Severe Threat/ And The Narrow Window For The Stronger Storms To Develop /Late Afternoon Into The Early Evening/ Suggest A Low Severe Probability Is Warranted At This Time.

The Greatest Threats Should Be Marginally Severe Hail And/Or Locally Strong Wind Gusts.


Tue Apr 1 Convective Outlook
Storm Prediction Center Norman Ok
No Svr Tstm Areas Forecast...

Tuesday...Swly Flow Aloft And Very Low-Amplitude Ridging Will
Prevail Over The Plains In Wake Of A Shortwave Trough Moving Through The Great Lakes And An Upper Low Moving Ssewd Along The Ca Coast.

A Cold Front Extends From A Surface Low Over The Great Lakes Swwd Into Nrn Tx At The Start Of This Period.

The Swrn Extension Of The Front Across Nrn Tx Will Lift Nwd Into Srn Ok During The Day...While A Dryline Becomes Established From Swrn Through Nwrn Tx Where It Will Intersect The Warm Front.

Nwrn Tx Through Swrn Ok...

Strengthening Sly Llj East Of Developing Lee Trough Will Advect
Richer Moisture Nwd Through The Srn Plains Warm Sector With Low 60s Dewpoints Reaching As Far North As Srn Ok Later In The Day.

Meanwhile Plume Of Warm Air At Base Of The Eml Will Advect Newd
Above The Moistening Warm Sector...Promoted By Swly Winds Aloft And Will Serve To Effectively Cap The Boundary Layer Most Of The Day.

Best Chance For An Isolated Surface-Based Storm Or Two Will Probably Be Near The Intersection Of The Dryline And Warm Front Across Nwrn Tx Or Extreme Swrn Ok By Late Afternoon.

An Isolated Storm Or Two Could Also Initiate Some Distance Down The Dryline As Mixing Gets Underway.

Should These Storms Develop...Steep Lapse Rates And Strong
Vertical Shear Will Promote Supercell Structures With Very Large
Hail And Perhaps A Tornado Possible.

However...Activity Will Likely Dissipate Toward Sunset With The Onset Of Nocturnal Cooling And Increasing Convective Inhibition.

Given Potential For Sparse Coverage And Initiation Concerns In General...Will Introduce 5% Severe Probabilities But Continue To Monitor For A Possible Slight Risk In Later Outlooks.

Elsewhere Across Tx It Appears The Warm Sector Will Remain Capped To Surface-Based Storms.

However...Weak Impulses Embedded Within The Swly Flow Regime And Steep Mid-Level Lapse Rates May Promote Elevated Convection Rooted Above The Capping Inversion.

Nrn Ok Through The Cntrl Plains And Mid Ms Valley Areas...

Theta-E Advection And Isentropic Ascent Associated With
Strengthening Llj Will Likely Promote The Development Of Elevated
Storms North Of The Warm Front With Activity Likely Increasing In
Coverage Over The Cntrl Plains And Mid Ms Valley Overnight.

Instability May Become Sufficient For A Threat Of At Least Marginally Severe Hail Given Steep Mid-Level Lapse Rates.


Apr 2-6 Convective Outlook
Storm Prediction Center Norman Ok

Day 4-5/

Models Appear To Be Converging Toward A Slower...More Amplified
Solution Regarding The Upper Trough Forecast To Move Through The
Cntrl And Srn Plains And Mid Ms Valley Area By Thursday /Day 5/ With
Ecmwf Also Trending Slower...But Still Remains The Faster Model.

Preceding This Feature...Richer Gulf Moisture /Low-Mid 60s
Dewpoints/ Will Advect Through The Warm Sector Underneath Steep
Mid-Level Lapse Rates Resulting In Moderate-Strong Instability Over
The Srn Plains And A Portion Of The Lower Ms Valley By Wednesday
/Day 4/.

It Still Appears A Few Severe Storms Could Develop Along The Dryline Day 4 Over The Srn Plains And Near The Dryline/Front Intersection Over Nwrn Ok/Swrn Ks.

However...Capping Will Be A Concern For Severe Storm Coverage Along The Dryline As Well As Farther East In Warm Sector.

Confidence In Where To Place A 30% Or Greater Severe Area Remains Low For Day 4...But A Categorical Risk Area Will Probably Be Needed For The Next Day 3 Update.

Given Model Trends...It Now Appears A More Substantial Severe Threat Might Develop From The Srn Plains Into The Lower-Mid Ms Valley Region Thursday /Day 5/ As The Shortwave Trough Ejects Enewd Resulting In Height Falls Across The Warm Sector And A Strengthening Llj.

Storms May Develop Along The Dryline And Dryline/Pacific Front
Merger Over The Srn Plains As Well As Farther East In The Warm

Severe Threat Will Likely Spread Ewd Into The Lower Ms Valley Area By Later Thursday Afternoon And Evening.

Day 6/

Severe Threat Will Probably Develop Farther East Into The Oh And Tn
Valleys As Well As A Portion Of The Sern States By Friday /Day 6/.

If Current Trends Persist...A Portion Of This Region May Be Included
In A Categorical Risk In The Next Update.

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