Severe Weather Threat thru Aug 17

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

Isolated Strong Storms With Gusty Winds Will Continue To Develop This Afternoon And Evening From The I-44 Corridor In Oklahoma And Missouri To The Ark-La-Miss. Other Isolated Strong Storms Likely The Next Few Hours Across Parts Of Interior Northern New England.

Risk For Severe Weather Will Remain Limited Through The Period... With Only Local/Marginally Severe Storms Expected.

Prev Discussion...

Ok/Mo/Ar This Afternoon/Evening...

A Surface Cold Front Will Move Sewd Across Ia/Mo/Ok In Association With A Weak Midlevel Trough Progressing Sewd From Nern Ks. Surface Heating In Advance Of The Front Will Boost Mlcape Values To 1500-2500 J/Kg Over Ern Ok/Wrn Ar With Minimal Convective Inhibition...Per Modified 12z Soundings.

Thus...Thunderstorm Development Is Expected By Mid Afternoon Near The I-44 Corridor From Central/Sw Mo Into Ok...With Storms Likely To Spread Ewd/Esewd Through Early Evening. Vertical Shear Will Be A Bit Stronger Toward Sw Mo In Proximity To The Weak Midlevel Wave /Effective Bulk Shear Approaching 30 Kt/...Though The Stronger Buoyancy Will Likely Remain Farther To The Sw Into Ok.

As A Result...Semi-Organized Clusters/Cells Will Be Possible Into Srn Mo...But Poor Lapse Rates Will Limit The Hail Threat. Thermodynamic Profiles Will Be More Favorable For Downbursts Farther To The Sw Into Ok...Where Vertical Shear Will Be Weak. Overall... Risk For Damaging Winds Is Marginal Across Ok/Mo/Ar.

Interior Nrn New England This Afternoon...

A Mid-Upper Speed Max Will Rotate Swd From Quebec To Nrn New England This Afternoon. Weak Ascent With This Feature Will Combine With Surface Heating/Destabilization And Some Increase In Vertical Shear To Support A Marginal Wind/Hail Risk For A Few Hours This Afternoon.

Se/S Central Az This Afternoon/Evening...

15-20 Kt Ely Midlevel Flow Will Be Maintained Across Srn Az...Around The Periphery Of A Diffuse Four Corners High. Though The More Favorable Thunderstorm Environment Will Likely Remain Near And S Of The Mexican Border...There Will Be Low Potential For Gusty Outflow Winds With Storms Moving Over The Lower Valleys From The Higher Terrain In Se Az.

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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. Other Storms With Gusty Winds May Occur From The Midwest/Ohio Valley Southwestward Across The Tennessee And Lower Mississippi Valleys Into East Texas.

Some Amplification Of The Flow Field Aloft Is Expected This Period... As Troughing/Cyclonic Flow Expands Over The Ern U.S. And An Upper Low Off The Ca Coast Drifts Onshore.

In Between... Amplification Of The Ridge Over The Intermountain West/Rockies Will Result. At The Surface...A Cold Front Will Shift Ewd/Sewd As The Ern Upper Trough Expands...With This Front To Remain A Focus For Convective Development Through The Period.

Oh/Tn/Lower Ms Valleys And Wwd To E Tx...

Diurnal Destabilization Of The Moist Pre-Frontal Boundary Layer Combined With Gradual Ewd/Sewd Advance Of The Surface Front Will Result In Development Of Scattered Showers And Thunderstorms In An Arcing Band From The Great Lakes/Mid And Upper Oh Valley Swwd Across The Tn And Lower Ms Valleys Into Tx.

While Greater Destabilization Is Forecast From The Tn Valley Area Swwd...Flow Aloft Is Expected To Be Progressively Weaker With Swwd Extent Along The Front.

Meanwhile...Though Slightly Stronger /20 To 25 Kt/ Mid-Level Wlys Are Expected From The Tn/Ky Area Nwd...Destabilization Potential Will Likely Remain Limited By More Widespread Cloudiness / Ongoing Convection.

Thus...Will Maintain A Large 5% Risk Area Ahead Of The Front...But Will Extend It Farther Nwd Into The Oh Valley Area Where Stronger Flow Aloft Should Reside...While Removing Parts Of Central And Wrn Tx Given The Very Weak Flow Forecast Across This Area.

Nrn Ca/Parts Of Oregon...

As The Offshore Upper Low Drifts Newd Toward The Nrn Ca Coast... Slightly Cooler Air Aloft Combined With Diurnal Heating Will Allow Ample Destabilization To Support Scattered Storm Development Through The Afternoon And Evening Hours.

With This Area On The Wrn Fringe Of A Stronger Belt Of Flow Aloft Centered Over The Great Basin...Cape/Shear Combination May Become Sufficient To Support A Few Stronger/Marginally Severe Storms Capable Of Hail And Gusty Winds Through Mid Evening.

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Tue Aug 12 Convective Outlook
Storm Prediction Center Norman Ok
No Svr Tstm Areas Forecast...

Severe Thunderstorm Prospects Will Remain Somewhat Limited Tuesday. A Few Strong Storms With A Threat For Isolated Downburst Winds Will Be Possible From Northern California And Oregon Into The Northern Rockies. A Marginal Risk For A Strong StormWill Also Exist From The Tennessee Valley Into A Portion Of The Ohio Valley.

A Blocking Synoptic Upper Pattern Will Continue To Evolve Tuesday. Shortwave Trough Will Advance Through Base Of The Ern U.S. Synoptic Trough And Into The Oh Valley In Wake Of A Lead Impulse Moving Through The Nern States.

Sfc Low Will Consolidate Over The Great Lakes In Response To The Shortwave Trough With Trailing Occluded Front Continuing Through The Oh Valley. The Southwest Extension Of This Boundary Will Move Sewd As A Cold Front Into The Lower Ms Valley And Sern States. A Warm Front Will Lift Nwd Through The Mid-Atlantic Region.

Farther West A Shortwave Trough Initially Over Nrn Ca Will Eject Newd Into The Nrn Rockies In Response To An Upper Low Approaching The Pacific Nw.

Nrn Ca Through Ern Oregon And The Nrn Rockies...

Thunderstorms Will Once Again Develop Within Plume Of Subtropical Moisture And Steep Lapse Rates Over The Higher Terrain And Within Belt Of Stronger Flow Aloft Ahead Of The Ejecting Upper Trough. Instability Will Remain Marginal Due To Modest Low-Level Moisture. But...A Few Storms Will Become Capable Of Producing Isolated Downburst Winds Promoted By Inverted-V Boundary Layers.

Oh Valley Area...

Widespread Clouds And Areas Of Ongoing Rain Along Warm Conveyor Belt Will Limit Destabilization Potential Over Much Of This Region. However...Low Clouds May Mix Out In Dry Slot Region West Of This Activity And Just Ahead Of The Occluded Front Where Mlcape From 400-800 J/Kg Will Be Possible Depending On Degree Of Boundary Layer Warming.

A Few Thunderstorms May Redevelop During The Afternoon As Zone Of Dpva And Stronger Mid-Upper Flow Attending The Shortwave
Trough Overtakes Occluded Front. A Conditional Risk For Isolated Strong Wind Gusts Exists...But Marginal Thermodynamic Environment Should Limit Overall Severe Potential.

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Aug 13-17 Convective Outlook
Storm Prediction Center Norman Ok

Model Consensus Is That Synoptic Regime Will Remain Dominated By A Blocking Pattern With Upper Lows Over The Ern And Wrn U.S. Through At Least Day 5...After Which A Transition To A More Progressive Regime Is Expected To Evolve.

Any Severe Threat In Association With The Ern U.S. Upper Low Day 4 Will Be Very Limited Due To A Marginal Thermodynamic Environment.

Severe Potential May Increase By Day 6-7 As A Corridor Of Modified Cp Air Returns Nwd Through The Nrn High Plains Ahead Of The Ejecting Wrn U.S. Shortwave Trough.

Models Have Not Shown Good Run-To-Run Consistency Regarding Details Of The Amplitude And Timing Of This Feature... Therefore Predictability Is Too Low To Introduce A Severe Risk Area At This Time.


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