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US Extended Forecast thru Nov 15

Short Range Forecast Discussion

...Temperatures will be 10 to 15 degrees above average for the Central High Plains...

...Snow and snow showers anticipated across the Great Lakes...

A front extending from the Northern High Plains to the Great Basin will
move eastward to the Great Lakes while extending southward to the Middle Mississippi Valley. The system will produce light snow over parts of the Northern Plains into the Upper Great Lakes by Saturday. Rain will also develop over parts of the Upper Great Lakes on Saturday. Onshore Pacific flow will produce scattered snow over parts of the Northern Rockies and the higher elevations of the Cascades on Friday.

A new front will come onshore over the Pacific Northwest on Saturday
moving to the Northern High Plains by Saturday evening. The storm will produce coastal rain and higher elevations snow over the Northwest and snow in parts of the Northern Rockies on Saturday.

Meanwhile, counter-clockwise upper-level flow will aid in producing lake effect snow downwind from the Great Lakes on Friday until the Northern Rockies low nears the Great Lakes on Friday night.

Easterly flow off the Atlantic will aid in producing showers and thunderstorms over parts of the southeastern portion of Florida Friday afternoon into Saturday.

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Extended Forecast Discussion
Valid 12z Mon Nov 11 2013 - 12z Fri Nov 15 2013

...Overview...

The Northern Pacific Ocean Is Forecast To Become Quite Amplified
Next Week With A Nw To Se Oriented Trough/Ridge/Trough/Ridge
Pattern Near Japan/Aleutians/N Of Hawaii/West Of The Baja...
Respectively. Standardized Anomalies Of The Forecast 500mb Heights Average -4 And +3 Or So Which Is Not Unusual But The Combination Of Four Such Anomalies Is Notable.

Downstream Over The Conus... A General Ridge/Trough Pattern Is Expected Until The End Of Next Week When Troughing May Dig Into The West As The Pacific Pattern Begins To Break Down. The Transition Out Of Highly Amplified Flow Is Often Met With Inconsistent Forecasts... Which Have Only Recently Started To Fall Into More Agreement In A Synoptic Sense.The Details Within The Forecast Remain Less Clear.

...Model/Ensemble Preferences...

The Models And Ensembles Have Settled On Keeping The Ne Pac Upper Low Well Offshore... But Seem To Have Nudged A Bit Farther West Over The Past 24 Hrs... Which Dictates Where The Pw Plume And High Qpf Axis Sets Up. The Gefs/Ecens Means Offer Pretty Good Agreement While Their Deterministic Runs Largely Follow Their Parent Ensemble. Gfs Runs Continue To Be On The Nw Side Of The Best Clustering Though The Ongoing Westward Trend In The Guidance Would Not Rule Them Out Completely. Stuck Close To The Idea Of The Ecens Mean For The Forecast Though The Gefs Mean Most Certainly Cannot Be Ruled Out Either.

In The Central/Eastern Conus... Building Ridging Over The Rockies
In Response To The Amplified Upstream Pattern Should Send A Cold
Airmass Southward And Then Eastward Behind Digging Troughing
Through The Ohio Valley Tue/D4 And Into The Southeast Wed/D5.

The Past Several Days Of Model/Ensemble Cycles Have Seen Various Degrees Of Cutting Off The Sw Portion Of The Mid-Level Energy Somewhere In The East... But Continue To Show A Large Amount Of Spread As To Where That May Occur.

The 00z Ecmwf Represents One Of The Slower/Deeper Solutions Which Closes Off The Upper Low Over Va/Nc And Move It Towards The 40/70 Benchmark Late Thu/D6 While The 00z Ukmet/Canadian Close Off The Energy Much Farther To The Northeast Near New England Late Wed/D5. The Gfs Has Shown Anything And Everything Recently From A Slower/Closed System Yesterday To A Much More Progressive Open Wave To A Separate But Weak System Breaking Off Over Nc/Sc. The Ensemble Members Also Show These Various Solutions With The Ecmwf Members Slower/Deeper Than The Gefs Members.

Prefer To Stay Near The 00z Ecens Mean With This Updated Forecast... Which Still Indicates The Potential For A System To Develop Just Offshore The Coast. It Has Offered Better Consistency Over The Past Several Runs Compared To The Gefs Mean And Maintains Better Wpc Continuity While Leaving Room To Modify
Future Forecasts.

By Fri/D7... Ensembles Show Troughing Pushing Southward Through
The Rockies As Heights Rebound In The East... Though How The
Upstream Pattern Breaks Down Will Be Crucial To Its Trajectory.
Multi-Ensemble Spread Maximizes Over The Gulf Of Alaska Indicating
Downstream Details /I.E. Over The Pac Nw/ Make Take A Few More
Days To Become Clearer.

..Sensible Weather Highlights...

In The West... Sw Flow At 500mb With Embedded Shortwaves Should
Produce Light To Moderate Precip Especially Over Coastal Wa/Or And
Into Norcal. Lighter Precip Should Filter Through The Rockies Later In The Week Should Troughing Push Southward As Currently Forecast.

In The East... Light To Moderate Precip Should Accompany The Strong Front Moving Southward And Eastward With Some Lake-Effect
Snows Likely In Its Wake.

Most Noticeable Change Will Be The Dramatic Cool Down For Areas Along And East Of 100w.

24-Hr Temperature Changes Could Be 20-30 Degrees With High Temperatures About 10-20 Degrees Below Normal.

Front Should Clear Florida Though The Degree Of Cooling Depends On How Deep The Troughing Is To The North.

Precipitation Details Associated With Possible Oceanic Cyclogenesis Remains Elusive At This Point... Ranging From
Nothing To More Than Two Inches. Ec Mean Lies Near The Lower Half
Of That Range... Which Is Reasonable At This Point.


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