EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD
1026 AM EST MON JAN 07 2013
VALID 12Z THU JAN 10 2013 - 12Z MON JAN 14 2013
THE 7/00Z ECMWF/GEFS ENSEMBLE MEANS WERE IN REASONABLE AGREEMENT
THROUGH DAY 7...WITH AN AMPLIFYING RIDGE ALONG 130W-140W (IN THE
EAST PAC). AND AN AMPLIFYING TROUGH OVER THE CENTRAL PORTION OF
THE NORTH AMERICAN CONTINENT BY DAY 7.
THE FORECAST CHALLENGE AND TROUGH AMPLIFICATION STARTS
CONTENTIOUSLY WITH A DAY3-4 SYSTEM/CYCLONE IN THE SOUTHERN PLAINS
MIGRATING NORTH-NORTHEASTWARD THROUGH THE MIDWEST. A 'KICKER'
SHORTWAVE ORIGINATING IN THE EAST PAC AND COLD FRONT
STARTS/FINISHES THE PROCESS OF AMPLIFICATION ON DAY 5/6 OVER THE
CENTRAL PLAINS WITH ADDITIONAL EMBEDDED H5 ENERGY CONTINUING TO
CARVE THE WESTERN (UPWIND) PORTION OF THE TROUGH (DAYS 6/7) ACROSS
THE INTERMOUNTAIN WEST/CENTRAL ROCKIES. FOR THE MOST PART...THE
SURFACE AND H5 GRAPHICS UTILIZED SOME OPERATIONAL ASPECTS OF THE
7/00Z GFS/ECMWF DETERMINISTIC RUNS...THOUGH CONFIDENCE IS ON THE
LOW SIDE REGARDING THE DEVELOPMENT/INTENSIFICATION AND TRACK OF A
MID-LEVEL SHORTWAVE EXITING THE CENTRAL ROCKIES ON FRI NIGHT/SAT
MORNING. THIS SHORTWAVE SHOULD DEVELOP A CLOSED SURFACE CYCLONE IN
THE NORTH CENTRAL PLAINS/UPPER MISSISSIPPI VALLEY (ALONG THE
DOWNWIND SIDE OF THE TROUGH AXIS) ON SATURDAY AND SATURDAY NIGHT.
THIS BODES WELL FOR A DECIDEDLY WARMER/MILDER AND MOISTURE-LADEN
AIRMASS TO SET UP ACROSS NEW ENGLAND...THE MID ATLANTIC STATES
(DAY 4-7) AND EASTERN GREAT LAKES/MID-UPPER OHIO VALLEY (DAY 4-5).
AND THE RETURN OF COLDER CANADIAN AIR TO THE PACIFIC
NORTHWEST...GREAT BASIN...NORTHERN ROCKIES AND NORTHERN PLAINS
THROUGH DAY 6.
VOJTESAK
Source:
http://www.hpc.ncep.noaa.gov/discussions/hpcdiscussions.php?disc=pmdepd