#3186 Postby Portastorm » Thu Jan 15, 2015 4:19 pm
Interesting comments from the Climate Prediction Center today in its 8-14 day forecast discussion:
8-14 DAY OUTLOOK FOR JAN 23 - 29 2015
DESPITE THE AFOREMENTIONED UNCERTAINTY DURING THE 6-10 DAY PERIOD, THE WEEK-2
FORECAST IS ISSUED WITH FAIRLY HIGH CONFIDENCE. MODEL AGREEMENT REMAINS GOOD
WITH RESPECT TO THE EVOLUTION OF THE RIDGE OVER FAR WESTERN NORTH AMERICA,
WHICH IS FORECAST TO ALLOW MORE ARCTIC AIR TO INFLUENCE THE CONUS WITH TIME.
THE 528 DM HEIGHT LINE LOCATED OVER THE GREAT LAKES IN THE MANUAL BLEND FINDS
ITS ORIGIN OVER THE ARCTIC OCEAN, A SURE SIGN OF AN ANOMALOUSLY COLD PATTERN.
IN FACT, THE FORECAST PATTERN BEARS MANY SIMILARITIES TO THE EXTREME COLD
PERIODS THAT HAVE OCCASIONALLY IMPACTED PARTS OF THE CONUS OVER THE PAST TWO
WINTERS.
THE ENSEMBLE MEANS ARE IN FAIRLY GOOD AGREEMENT ON THIS PATTERN, THOUGH SOME
UNCERTAINTY REMAINS WITH RESPECT TO TEMPERATURES OVER THE NORTHERN ROCKIES. THE
GFS REMAINS FARTHER EAST WITH THE MEAN RIDGE POSITION OVER WESTERN NORTH
AMERICA, AND SO HAS A MILDER SOLUTION OVER THAT REGION. HOWEVER, THE ECMWF AND
CANADIAN ENSEMBLES ARE IN GOOD AGREEMENT ON A COLDER SOLUTION WITH A RIDGE
CENTERED FARTHER WEST, SIMILAR TO THE DISAGREEMENT IN THE 6-10 DAY PERIOD. HERE
AGAIN THE ECMWF SOLUTION IS FAVORED, SINCE IT HAS GOOD SUPPORT FROM THE
TELECONNECTIONS, ANALOGS, AND THE CANADIAN ENSEMBLES.
THE PRECIPITATION OUTLOOK IS GENERALLY DRIER ACROSS MUCH OF THE CONUS COMPARED
TO THE 6-10 DAY PERIOD, DUE TO SOME EASTWARD PROGRESSION RESULTING IN ANOMALOUS
NORTHERLY FLOW ACROSS MOST OF THE CONUS. SOME SLIGHT PROBABILITIES FAVORING
ABOVE-MEDIAN PRECIPITATION ARE INDICATED OVER THE IMMEDIATE EAST COAST
EXTENDING TO SOUTHWEST TEXAS BASED ON THE FORECAST POSITION OF THE MEAN FRONTAL
ZONE.
THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 10% OF TODAY'S 0Z GFS ENSEMBLE
MEAN CENTERED ON DAY 11, 20% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY
11, 50% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11, AND 20% OF
TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 11
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: ABOVE AVERAGE, 4 OUT OF 5, DUE
TO GOOD AGREEMENT ON THE OVERALL PATTERN, OFFSET SLIGHTLY BY MODEL DISAGREEMENT
NEAR THE ROCKIES.
FORECASTER: STEPHEN BAXTER
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