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About the Alaska Medium Range Forecast
The Weather Prediction Center's (WPC) Alaska Medium Range forecasts are part of
a National Centers for Environmental Prediction (NCEP) commitment to providing meteorological support for
areas outside of the contiguous U.S. (OCONUS). The Alaska Medium Range product suite has
been developed to mimic that which is currently available for the CONUS.
Differences between the product suites are primarily the result of addressing problems specific to the
National Weather Service Alaska Region (e.g., highly varied terrain).
The Alaska Medium Range product suite consists of:
One meteorologist is dedicated to Alaska Medium Range forecasting each day, and the shift
is scheduled from 1500 UTC to 0000 UTC. The Alaska forecaster utilizes data from recent deterministic and
ensemble model output and collaborates with the CONUS Medium Range forecaster before beginning graphical
composition.
Deterministic and ensemble model output available to forecasters at NCEP/WPC include the GFS,
Global Ensemble Forecast System (GEFS), Canadian GEM Global, Canadian GEM Ensembles, ECMWF,
ECMWF Ensembles, Navy NAVGEM, UKMET, and the North American Ensemble Forecast System (NAEFS) in addition to the
National Blend of Models (NBM).
Graphical forecasts for 500 hPa heights and surface fronts and pressures are generated using blending
tools available to WPC forecasters. Gridded forecasts for maximum/minimum temperature,
probability of precipitation, and dewpoints, etc. are also created using blending tools available
to WPC meteorologists via the Graphical Forecast Editor (GFE) software. These tools allow the
forecaster to blend preferred solutions from any of the aforementioned deterministic and ensemble forecasts.
Generally, the same blends will be used to generate graphics and grids for consistency,
but the blend tools do allow forecasters to add a climatology bias to forecasts, which should limit
inconsistencies in forecasts with less predictable features. Consequently, the amount of
climatology added is generally a function of forecast confidence and predictability.
The Alaska Medium Range Discussion complements the graphical products by
outlining the model forecast preference, communicating forecast confidence, conveying areas of
uncertainty and providing a catalyst for collaboration between WPC and NWS Alaska Region Weather
Forecast Offices (WFOs).
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