Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
345 PM EDT Fri Apr 05 2019
Valid 12Z Tue Apr 09 2019 - 12Z Sat Apr 13 2019
Somewhat ill-defined upper pattern, with low amplitude waves and
modest surface systems, will transition to a more amplified
pattern as the bulk of the Pacific becomes dominated by a
trough/ridge couplet through the mid-latitudes. This will be
instigated by a robust system crossing the Aleutians on Wednesday
and will move into the southern Bering Sea Thursday as a powerful
sub-960mb low (or perhaps deeper based on some models). This would
be near the low end of observed pressure values for April over the
central Aleutians. The models have wavered on the lead-up pattern
and thus modulated the timing of the more defined midweek system,
but overall remain in decent agreement. The 12Z GFS lied on the
southeastern side of the spread with the track of the low into the
Bering Sea and was only lightly weighted compared to the 00Z
ECMWF/ECMWF ensemble mean. Still expect the parent low to weaken
near the St. Lawrence Islands as the triple point moves through
the Gulf and into the Panhandle. Consensus approach should serve
well to minimize future shifts in the evolution.
Strong winds (40-50kts) around the low across the Aleutians may
stay mostly over the Bering as peak intensity will be realized
near the Aleutians. Precipitation will spread eastward through
Southcentral as the triple point moves eastward but focused along
the coast and especially southern/southeastern Kenai to Yakutat.
Fracasso
Bullet points from the WPC Days 3-7 Hazards chart can be found at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
Hazards
- Heavy precipitation across portions of the Alaska Panhandle,
mainland Alaska, and the Aleutians, Wed-Fri, Apr 10-Apr 12.
- High winds across portions of mainland Alaska and the Aleutians,
Wed-Thu, Apr 10-Apr 11.
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