Severe Weather Threat Day 1 Sun Mar 10

Ongoing Forecast Remains On Track...With A Weak Convective Line Now Entering Wrn Tn/Wrn Ms And Crossing Central La. Despite Ample Shear Ahead Of The Line...A Lack Of Appreciable Instability Precludes Any More Than A Very Low-Probability Severe Threat.

Elsewhere...Any Appreciable Lightning Potential Remains Unlikely.

Prev Discussion...

Within A Separate Belt Of Westerlies Across Canada...One Vigorous
Short Wave Trough Is Beginning To Accelerate Northeastward Out Of
Northwestern Ontario...Away From The Central Plains Closed Low...
Which Is Embedded Within Large-Scale Troughing In A More Amplified Belt Of Westerlies Across The United States. However...In The Northern Stream...Another Strong Short Wave Trough Is Beginning To Dig Toward The Central Canadian/U.S. Border Area... And Models Suggest That This Will Contribute To The Northeastward Acceleration Of The Closed Low Toward The Upper Midwest/Upper Great Lakes Region Later Today And Tonight.

As This Occurs...An Associated Surface Low Over The Lower Missouri Valley Is Forecast To Redevelop Northeastward Into The Great Lakes Region By Late Tonight. A Trailing Surface Cold Front Should Surge Into The Lower Mississippi Valley Sometime Late This Evening Or Overnight...Overtaking An Initial Weak Cold Front Generated By Overnight Convection...Which Is Already Beginning To Advance Into The Lower Mississippi Valley.

At The Same Time...Upper Troughing Trailing To The Southwest Of The Mid-Level Low Appears Likely To Take On More Of A Neutral Tilt As It Pivots Across The Southern Plains Toward The Lower Mississippi Valley.

Lower Mississippi Valley...

The Latest Model And Observational Data Do Not Offer Much In The Way Of Any Greater Certainty Concerning Severe Weather Potential Today. A Window Of Opportunity Does Appear To Exist For Weak
Destabilization Along A Narrow Axis From South Central Louisiana
Coastal Areas Northward Along The Mississippi River...Through At
Least The Natchez/Vicksburg Areas By Early Afternoon. This May
Roughly Coincide With The Southerly 850 Mb Jet Axis...But Guidance
Suggests That The Stronger Jet Core Will Be In The Process Of
Shifting Northward Into The Lower Ohio Valley. Flow Could Still
Remain As Strong As 30-50 Kts...However Winds Are Expected To Become More Unidirectional With Height...Also Contributing To Shrinking Low-Level Hodograph Size. Mid/Upper Forcing For Upward Vertical Motion Also Remains An Uncertainty During The Period Of Peak Boundary Layer Destabilization. Upper Flow Is At Least Weakly
Difluent Across The Lower Mississippi Valley...But Forcing Associated With An Initial Impulse Pivoting Around The Central Plains Closed Low Will Continue To Generally Shift North Of The Region During The Day...While Stronger Mid-Level Height Falls Associated With The Upstream Impulse Do Not Occur Until After Dark.

It Is Possible That Boundary Layer Warming/Moistening Along The
Leading Edge Of Mid-Level Cooling /Around 700 Mb/...And Convergence Along The Eastward Advancing Surface Cold Pool...Could Contribute To The Regeneration Of A Narrow Line Of Thunderstorms Roughly By The 20-22z Time Frame. If This Occurs ...Some Risk For Potentially Damaging Wind Gusts May Exist... Mainly Due To Downward Momentum Transfer.

But The Severe Threat Still Seems Too Marginal/Uncertain For Slight Risk Probabilities At The Present Time.

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