US Final Extended Forecast thru Aug 24

...Overview And Preferences...

Fast Low Amplitude Flow Along/N Of 50n Latitude Is Fcst To Trend A
Little More Amplified With Time... Evolving Toward An Ern Pac Trough/ Cntrl Noam Ridge/East Coast Trough. Hgt Falls Approaching The West Coast Will Help To Eject The Closed Low Initially Near The Ca Coast While Lingering E-Cntrl Conus Energy Will Drift Toward The East Coast/Wrn Atlc.

The Most Significant Fcst Uncertainties Today Involve Shrtwv Details Of The Progressive Srn Canada Flow And Impact On The Assoc Sfc Front Over The Nrn Third Of The Conus... And To A Lesser Extent Ejection Of The Ca Closed Low. Latest Guidance Shows Enough Spread For Most Of The Period To Favor A Blend Of The 06z Gefs/00z Ecmwf Means As The Starting Point For Days 3-7 Tue-Sat. This Soln Represents Consensus For The Ca Coast Upr Low.

...Guidance Evaluation...

Newest Guidance As A Whole Shows A Somewhat Faster/More Amplified Trend With Leading Hgt Falls Crossing The Ern Half Of Canada By Wed-Fri... Leading To A Farther Sewd Extent Of The Sfc Front Reaching Into The Nrn Portions Of The Lower 48 Relative To

Operational Models Show Variations Aloft With Lower Confidence Than The Ensemble Means. By Days 4-5 Wed-Thu The 00z Ecmwf Brings A Shrtwv Into Wrn Canada While Consensus Shows A Mean Ridge Over That Area... With This Diff Leading The Ecmwf To Become
A Fast Extreme With The Trough Reaching Ern Canada. 00z/06z Gfs
Runs Bring More Hgt Falls Than Consensus Into The Pac Nw/Wrn
Canada Around Thu-Fri And The 00z Gfs In Particular Is Fairly
Amplified With Its Nern Conus Trough Thu Onward... Albeit Remaining Within The Ensemble Spread. The 06z Gefs Mean Is A Tad Weaker Than The 00z Version With The Leading Trough Reaching Ern Canada And The 00z Cmc Mean Is Weaker As Well So The 06z Gefs Mean Is Blended With The 00z Ecmwf Mean. This Fcst Still Pushes The Nrn Tier Sfc Front S/E Of Continuity But To A Lesser Extent Than The More Extreme Side Of The Envelope. Continuity Changes/Spread Seen In Guidance Over The Past 1-2 Days Argue For A Conservative Approach At This Time.

For The Closed Low Initially Near The Ca Coast... The 06z Gfs Is The Primary Outlier With Faster Ejection Than Other Solns. The 00z Gfs Is Close To Consensus Into Early Day 5 Thu But It Also Trends Faster Once Its Stronger Ern Pac Hgt Falls Approach.

Weak Nature Of The Mid Lvl Energy Drifting From The E-Cntrl Conus
Toward The East Coast Leads To Low Confidence In Exact Details...
With Some Dependence On Amplitude Of Flow To The N As Well. Would Recommend The Ensemble Means Until The Operational Models Display Better Agreement.

Regardless Of Details Aloft There Is Reasonable Agreement That The Persistent Sfc Front Along The Gulf/Sern Coast Should Weaken And Eventually Dissipate.

...Sensible Weather Highlights...

Weak Mid Lvl Energy Over The E/Se And Gradually Weakening Sfc
Bndry Along The Gulf/Sern Coast Will Continue The Potential For Sct Shwrs/Tstms Over Srn/Ern Areas Of The Lower 48 But Likely With
Lower Max Amts Than Fcst In The Short Range Time Frame.

The Cold Front Expected To Progress From The Nrn Plains Into The Northeast Will Serve As Another Focus For Sct Convection.

Meanwhile Gradual Movement Of The Mean Ridge Aloft From The Rockies Into The Plains May Help To Increase The Flow Of Monsoonal Mstr Into The West Next Week... And Newd Ejection Of The Compact Upr Low Near The Ca Coast May Lead To A Period Of Enhanced Convection Over Nrn Portions Of The Interior West/Rockies After Wed.

Expect Warmest Temps Relative To Normal... With Some Locations Seeing Plus 10-15f Anomalies For Daytime Highs On One Or More Days... Over Nrn Conus Areas To The S Of The Sfc Front.

Clouds And Occasional Rnfl Should Keep Highs Near To Below Normal Across Srn Tier States.

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