Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
424 PM EST Sat Jan 04 2020
Valid 12Z Wed Jan 08 2020 - 12Z Sun Jan 12 2020
...Weather/Hazards Highlights...
It remains the case that upper ridging is forecast to build over
the southern Arctic Ocean early next week and heights rise
underneath over the North Slope/Interior to end the recent cold
snap. Active and fairly progressive flow cuts underneath into a
stormy Bering/Aleutians and Gulf of Alaska. Models and ensembles
continue to struggle with embedded system timing in the flow, but
overall still align adequately with the larger scale flow
evolution. This will carry a couple areas of low pressure toward
and into the Panhandle early-mid next week. As these systems exit
into British Columbia, the main focus shifts to the Aleutians and
Bering Sea as a series of deep lows with a threat of high
winds/waves and heavy precipitation feed into the region all next
week, with weather working with some vigor into the
western/southwestern mainland into next weekend. Renewed lead
triple point low developments will meanwhile work downstream into
an unsettled Gulf of Alaska again, with renewed risk later next
week then again next weekend to threaten maritime interests and
onshore into the southern/southeastern Alaskan tier.
...Guidance/Predictability Assessment...
The 12 UTC GFS/ECMWF and GEFS/NAEFS/ECMWF ensembles offer more
embedded system variance than preferable, but forecast spread has
improved compared to yesterday. These guidance pieces though do
seem sufficiently clustered at mid-larger scales to allow
preference for a composite blend along with the 19 UTC National
Blend of Models to maintain good WPC continuity. Manual
adjustments were applied to trend to deeper Aleutian/Bering Sea
low developments with an increased maritime and coastal threat
considering favorable support aloft and trend of decreasing
uncertainty.
Schichtel
Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
WPC medium range Alaskan products including 500mb, surface
fronts/pressures progs and sensible weather grids can also be
found at:
https://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml
https://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html