800
FXAK02 KWNH 072211
PMDAK

Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
610 PM EDT Sun Jul 07 2024

Valid 12Z Thu Jul 11 2024 - 12Z Mon Jul 15 2024

Multi-day heavy rain pattern from West/Southwest through
Southern Alaska


...Overview and Guidance Evaluation/Preferences...

Forecast spread has decreased through medium range time scales,
bolstering forecast confidence given larger nature of main weather
focusing systems with time. Prefer a blend of best clustered
guidance of the 12 UTC GFS/ECMWF and GEFS/ECMWF/Canadian ensemble
means with emphasis on the GFS/ECMWF valid Thursday/Friday
increasingly shifting to the ensemble means next weekend/Monday
along with manually applied edits to better depict surface systems
with favorable mean upper support as an offset to inherent
smoothing from a blending process.

...Weather/Hazards Highlights...

A slow moving surface front may linger across the Interior and
provide a weakening focus for local precipitation next week. Much
of the rest of Alaska should remain quite wet and unsettled, which
should also help bring some relief to wildfire activity. Despite
guidance variances recently, models and ensembles continue to show
an amplified and slowly evolving larger scale pattern with a major
closed upper low/trough centered over the Bering Sea and an
emerging upper trough over the Gulf of Alaska as ample energy
fuels cyclogenesis and frontogenesis. In this scenario, heights
rise at least temporarily overtop into the eastern Interior to
moderate short range cooling before retreating. Around the
periphery of the ridge, this pattern favors a continued wet and
storm system active period out from the Arctic Ocean to the Bering
Sea, with inland impacts from West/Southwest Alaska through the
Alaska Peninsula/Kodiak Island, SouthCentral and then Southeast
Alaska later week through next weekend. Storm systems will remain
prone to develop and evolve/linger over the eastern Bering and
downstream into the Gulf of Alaska. This portends a protracted
period with potential for cummulative heavy rain, with some 1-2"+
daily totals set to steadily add up over the course of this
forecast period to monitor for any runoff issues, especially over
favored terrain.

Schichtel


Additional 3-7 Day Hazard Information can be found on the WPC
medium range hazards outlook 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

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