US Final Extended Weather thru Apr 14

...Overview And Preferences...

Most Guidance Expects Mean Flow To Become Less Amplified Over The Conus During The Course Of The Period But A Few Individual
Model/Ensemble Solns Display Significant Amplitude/Phase Diffs
Over The Ern Pac/Wrn Noam By Next Weekend.

For The Sfc Low/Frontal System Fcst To Cross The Ern Half Of The Conus Mid-Late Week... There Is Decent Clustering From Wed Into Early Thu But Guidance Spread Increases Rapidly Thereafter.

In General A 06z Gefs/00z Ecmwf Ensemble Mean Represents Consensus Well For Large Scale Flow Through The Period. Prefer To Lean About 2/3 Toward The 00z Ecmwf Mean Late Thu Into Sat As It Provides A Slightly Less Extreme Change From Continuity For The Ern System.

...Guidance Evaluation...

Over Wrn Noam And The Ern Pacific... A Deep Closed Low Over Alaska And Surrounding Flow Is Fcst To Settle Swd/Sewd During The Period. While Hgts Within This Feature Are Fcst To Rise Gradually A
Decent Core Of Low Hgts Is Still Fcst To Reaching The Vicinity Of
Vancouver Island Or Slightly Newd By Day 7 Sun. The 00z Cmc
Tracks The Closed Low Farther Swd Than Other Solns While The Past Two Ecmwf Runs Bring An Upstream Ridge Farther Ewd Than Consensus.

The 00z Ecmwf Is Not An Outlier Relative To The Full Ensemble
Spread By Day 7 Mon Into Day 8... But Has Support From A Steadily
Decreasing Percentage Of What Is Already A Minority Of Ensemble
Members With Time. The 00z Canadian Mean Is Similar To The
Gefs/Ecmwf Ensemble Means Aside From Reflecting Some Of The
Greater Ern Pac Trough Amplitude Seen In The 00z Cmc Run. Some
Aspects Of The 00z/06z Gfs Runs May Be Reasonable Given Comparison To The Ensemble Means... Though The 00z Gfs/Gefs Mean May Be A Tad Fast To Bring Lower Sfc Pressures Into The Upr Ms Vly Late In The Period.

Over The East... Ecmwf Mean Runs Have Been More Stable Than Gefs Means With Sfc Low Pressure And Assoc Fronts Through Late This Week.

However By Day 5 Fri The 00z Ecmwf Mean Has Adjusted A Little Newd With The Primary Sfc Low And Nwd Toward Most Other Solns With The Front Extending E/Ne From The Low To The East Coast.

At That Time The 00z Ukmet/Cmc/Canadian Mean Are Still Farther Newd With The Sfc Low. Further Complicating The Fcst Is Uncertainty Over Handling Of The Srn Part Of The Mid Lvl Shrtwv.

The 00z Ecmwf Is In The Slower Half Of The Spread With This Mid
Lvl Feature And Assoc Sfc Wave. The 06z Gfs Has Adjusted Toward A
Defined Srn Wave But With Faster Timing Than The 00z Ecmwf.
Diverse Ensemble Sfc Low Plots After Thu Reflect The Detail Spread
Seen In Operational Solns Near The East Coast.

Once Solns Diverge From Late Thu Onward... Prefer A 70/30 Weighting Of The 00z Ecmwf Mean/06z Gefs Mean Since The 00z Ec Mean Has A Less Significant Trend From Continuity With Its Sfc Low While The 06z Gefs Mean Component Is Favored Over The 00z Run As The 06z Version Adjusted A Little Swwd From The 00z Cycle.

...Sensible Weather Highlights...

Over The West Expect Multiple Periods Of Pcpn Confined To The Nrn
Third To Half Of The Region... With Best Focus Over Favored
Wwd-Facing Terrain.

Near To Above Normal Temps Over Most Of The West Around Midweek Should Trend Below Normal Over Nrn Areas While Warm Readings Relative To Normal Should Persist Over The Desert

Meanwhile Ample Gulf Inflow Ahead Of The System Crossing The Ern States... And Moderately Slow Movement... Will Likely Support Some Areas Of Hvy Rnfl From The Ms Valley To The East Coast In The Wed-Fri Time Frame. Consult Spc Outlooks For Latest Info Regarding Severe Weather Threats.

Some Snow May Be Possible In The Extreme Nrn Periphery Of The Pcpn Shield.

Behind This System Daytime Highs Will Be Much Below Normal Over A Majority Of The Plains On Wed-Thu. Then Most Of The Plains Should Moderate While The Cool Air Passes Through The East In Less Extreme Form.

The Nrn Tier May See Some Mstr Spread Across The Region From The West By Next Weekend With The Full Array Of Guidance Showing A Wide Spread In Pcpn Totals From This Activity.

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