Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
335 PM EDT Wed Mar 13 2019
Valid 12Z Sun Mar 17 2019 - 12Z Thu Mar 21 2019
The latest guidance persists in showing a multi-day signal of
several inches of QPF along the southern coast of the Mainland and
northern portions of Southeast Alaska as a series of lows lift
northward through the Gulf of Alaska. The air mass will quickly
lose its moisture content farther inland, however, with relatively
dry conditions expected to persist across the Interior and the
North Slope. The continuous track of storm systems across the Gulf
into southern Alaska, and the persistent deep southerly flow will
make for a period of widespread and occasionally heavy
precipitation for many areas from southern mainland Alaska to
Southeast Alaska. Additionally, the weekend system may bring the
potential for high wind gusts to southern mainland Alaska,
particularly for coastal areas.
Confidence remains fairly high that multiples systems within the
atmospheric river will result in well above normal amounts of
precipition - daily totals averaging 2 to 4 inches with 5-day
totals of 10 to 20+ inches possible. Days 4/5 blend consisted of a
multiple model approach given the waviness of the pattern. The CMC
and UKMET were not overly useful for Days 6 and beyond so
therefore they were not utilized. The later peiods had heavier
weighting of the ensemble means with some of the ECWMF/GFS
incorporated.
Campbell
Bullet points from the WPC Days 3-7 Hazards chart:
https://www.wpc.ncep.noaa.gov/threats/threats.php
- Heavy precipitation across portions of the Alaska Panhandle and
mainland Alaska, Sat-Tue, Mar 16-Mar 19.
- High winds across portions of the Alaska Panhandle and mainland
Alaska, Sat-Tue, Mar 16-Mar 19.
WPC medium range Alaskan products including 500mb, surface
fronts/pressures progs and sensible weather grids can 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