Prognostic Meteorological Discussion
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FXAK02 KWNH 222012
PMDAK

Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
311 PM EST Thu Feb 22 2018

Valid 12Z Mon Feb 26 2018 - 12Z Fri Mar 02 2018

...Guidance/Predictability Assessment and Weather
Highlights/Threats...

Models and ensembles offer reasonably compatable larger scale
patterns into medium range time scales, but have more substantial
smaller scale system variance that grow over time that limit
predictability of associated weather system focus. This pattern is
highlighted into next week at high latitudes by an entrenched cold
Arctic closed trough/low aloft. Timing differences emerge with the
flow of energetic lows and frontal systems working underneath from
the north Pacific northeastward to Alaska. Recent GFS and
GEFS/NAEFS means have been more progressive with mid-upper level
trough/jet energies that more quickly break through a lead Gulf of
AK to southern/southwestern interior ridge aloft than recent ECMWF
and ECMWF ensemble mean. The less progressive ECMWF and ECMWF
ensemble mean seem more reasonable considering the lead-in
amplified/blocky nature of the flow. In this scenario, an
initially deep Bering Sea low and heavy weather/seas focusing
frontal system Monday crashes inland across western Alaska and the
interior into Tuesday as a secondary low/front works precipitation
from the Gulf of Alaska into southern/southeastern Alaska. The
pattern reloads upstream mid-later next week with development of
another deep Bering Sea low and downstream rebuilding/amplified
Gulf of Alaska to southern/southwestern Alaska mid-upper level
ridge. This would eventually threaten western/southwestern Alaska
with organized late period weather.
This overall solution maintains good WPC continuity from yesterday
and WPC has re-established access to most guidance that was
limited from recent computer issues.

Schichtel

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