Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
132 PM EDT Thu Jul 18 2019
Valid 12Z Mon Jul 22 2019 - 12Z Fri Jul 26 2019
A more amplified pattern with time is forecast across the region,
driven by a deep layer cyclone/upper trough progressing slowly
across Siberia. Downstream of this feature, a stable Rex Block
pattern takes hold extending from Alaska/Yukon (closed deep layer
high) into the northeast Pacific (closed deep layer low).
Broadly, the guidance is agreeable but detail issues continue to
cloud the picture. A compromise of the 00z ECMWF, 00z UKMET, 06z
GFS, 12z GFS, 00z ECMWF ensemble mean, and 00z NAEFS mean was used
through the period, with increasing weight of the ensemble means
with time to help deal with the forecast uncertainty. Confidence
is increasing in this scenario, but remains no better than average
where uncertainty is greatest near the Bering Sea/Aleutians/AK
peninsula mid next week.
Mild to warm temperatures are forecast for the state this period
-- temperatures remain on pace for record warmth for the month of
July across south-central AK. North and Northwest AK have the
highest rain chances this weekend (where moderate to heavy
rainfall is expected) before the low moving eastward through the
northeast Pacific increases rain chances for southwest AK
Sunday/Monday and southeast AK and the AK panhandle Tuesday into
next Thursday. One to two inches of rainfall, with locally higher
amounts in preferred topography, is expected in association with
the northeast Pacific cyclone.
Roth
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
No significant hazards are expected over Alaska during this
forecast period.
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