Eastern Idaho Forecast Discussion

Case: Archive (December 26 2003)

3:00 PM MST December 31 2018

Discussion Metrics

Forecast Period:

From: 5:00 AM MST (1200 UTC) December 26 2003

To: 1:00 AM MST (0800 UTC) December 27 2003

Satellite Imagery:

Large cloud shield on moisture imagery was associated with deep tropical moisture plume and upper-level low pressure system covering most of eastern Idaho.

Observations:

METAR observations and surface isobaric pattern support a 995 hPa surface cyclone moving from central Utah to central Wyoming by afternoon.

Operational Models:

NAM/AVN QPF: too dry over valleys.

WRF QPF (NARR initialization and WDM6 microphysics): wetter over valleys.

WRF suggests cyclone track favors widespread snow in cold sector and strong post-frontal winds over eastern Idaho, topographic convergence zone forming in Snake Plain by afternoon.

Forecast Challenges:

Locations of heaviest snowfall in lower plain and adjacent highlands.

Possible high surface winds in the valleys after cold front passage.

Final Predictions:

Event snowfall: 6 to 12 inches in Snake Plain with locally higher amounts in eastern foothills.

Example: WRF Forecast

Disclaimer:  Andretta Innovations LLC assumes no liability for application of these discussions in operational forecasting decisions.