Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
334 PM EDT Wed Jul 11 2018

Valid 12Z Sun Jul 15 2018 - 12Z Thu Jul 19 2018

The guidance was in decent agreement in principle, but was split
in timing even before the medium range period over the
AKPen/Southcentral. The 00Z ECMWF/ECMWF ensembles (and 00Z UKMET)
were slower/stronger with the upper low dropping southward in the
western Bering over the next couple of days while the other models
and GEFS/Canadian ensembles moved it bodily eastward with not
trailing/deepening energy on its back side. As the 12Z UKMET
switched camps to the GFS-led consensus, opted to rely on that
cluster to form the forecast -- essentially the 12Z/06Z GFS and
06Z GEFS mean -- as the ECMWF-led cluster trailed behind the GFS
cluster until about next Wed/Thu.

To the north, models/ensembles were in better agreement and the
forecast was more consistent bringing in an upper trough across
the North Slope. This would take a sfc front through from NW to SE
to about 65N before another wave over northeastern Russia lifts
the front back to the north mid-week next week. Temperatures will
rise and fall ahead of and behind, respectively, the front.
Precipitation will be fairly widespread across the interior thanks
to the height falls and also along the coast from Southcentral to
the Panhandle.

Uncertainty rises near the Aleutians with the next system (likley
of low amplitude) as it crests the upper high to its south and
sinks southeastward next Wed/Thu.

Fracasso


WPC medium range Alaskan products including 500mb, surface
fronts/pressures progs and sensible weather grids can be found at:

http://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif
http://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml
http://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html