Prognostic Meteorological Discussion
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FXAK02 KWNH 201820
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
219 PM EDT WED AUG 20 2014

VALID 12Z SUN AUG 24 2014 - 12Z THU AUG 28 2014


THE GLOBAL NUMERICAL MODELS HAVE TRENDED STRONGLY OVER THE PAST
FEW DAYS WITH THE PROJECTED FLOW ACROSS THE NORTHEAST PACIFIC AND
NORTH AMERICA AT THE MEDIUM RANGE. ALASKA IS ONE OF THE REGIONS
WITH THE MOST VOLATILE FORECASTS, THOUGH THAT DISTINCTION IS NOT
SINGULAR TO THE CURRENT SITUATION. BOTH THE GFS AND ECMWF HAVE
EXHIBITED POOR RUN-TO-RUN CONTINUITY, SO CHOSE AN ENSEMBLE MEAN
APPROACH FOR THIS FORECAST. OF COURSE, USING AN ENSEMBLE MEAN AS A
BASE SUBSTANTIALLY WEAKENS GRADIENTS AND DIRECTIONAL SHEAR ACROSS
FRONTS; SOME BOUNDARIES GET LOST ALTOGETHER. STILL, THIS APPROACH
IS SURELY MORE SERVICEABLE THAN FLIP-FLOPPING OR JUMPING FROM ONE
MODEL CAMP TO ANOTHER.

AFTER THE PASSAGE OF THE SPLITTING CYCLONE EARLY IN THE PERIOD,
THE MEANS DEPICT A REGIME NOT FAVORABLE TO LARGE STORM
DEVELOPMENT, WITH TEMPERATURES AVERAGING NEAR NORMAL FOR MUCH OF
THE STATE.


CISCO

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