922
FXUS10 KWNH 130418
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1117 PM EST SUN JAN 12 2020
VALID JAN 13/0000 UTC THRU JAN 16/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..LARGE SCALE PATTERN ACROSS THE CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH 36HRS THEN
18Z GEFS AND 12Z ECMWF/ECENS MEAN
EXCEPTION: NON-NAM BLEND FOR PACIFIC NORTHWEST END OF DAY 3
CONFIDENCE: AVERAGE
THE WELL ADVERTISED LARGE SCALE TROF HAS FINALLY TAKEN SHAPE WITH
THE COLD ARCTIC ANCHORING OVER THE BC/ALBERTAN ROCKIES IN THE NEXT
DAY OR SO. MULTIPLE FAST MOVING LOW AMPLITUDE SHORTWAVE PARADE
ACROSS THE NORTHERN US ROCKIES INTO THE PLAINS AND THEN THE GREAT
LAKES. THE GUIDANCE HAS COME INTO SOLID AGREEMENT WITH THE FIRST
TWO, MONDAY INTO GREAT LAKES AND SECOND BROADER BUT LESS DEFINED
NW-SE TROF THROUGH THE NORTHERN PLAINS INTO GREAT LAKES, THOUGH AS
THIS SYSTEM LINES THROUGH THE UPPER LAKES, THE NAM IS A BIT
GREATER AMPLIFIED AS IT CAN TYPICALLY GET BY THIS PERIOD IN ITS
CYCLE. THE 00Z GFS WHILE JUST A BIT NORTH/STRONGER THAN THE
UKMET/CMC/ECMWF, IT HAS SOME OF THE FLAVOR OF THE NAM WITHOUT
GOING ALL IN BY 60HRS AS IT COMES BACK TO THE ENSEMBLE SUITE
ACROSS THE NORTHEAST.
BY THIS TIME, THE 00Z GFS HAS BEEN CONTINUALLY PERSISTENT IN
WEAKENING THE CLOSED LOW AND SHIFTING IT EAST, THIS IS GENERALLY A
PROBLEM ALSO NOTED WITH THE SUBTROPICAL HIGH AND RETURN GULF
STREAM FLOW ACROSS THE SOUTH AND SO THE GFS IS LESS FAVORED AFTER
THIS TIME IN FAVOR OF THE GEFS SOLUTION WHICH IS MUCH MORE IN LINE
WITH THE ECMWF/ECENS SOLUTIONS. SO THE THIRD PACIFIC SHORTWAVE
THAT CROSSES INTO THE LOWER NORTHERN PLAINS BY EARLY WED AND
EVENTUALLY DEVELOPS A WEAK SURFACE WAVE THROUGH THE OHIO VALLEY,
THE GFS IS MUCH TO FAST, THOUGH THE CMC IS MUCH TOO FAST TOO AND
STRONG WHICH IS UNCHARACTERISTIC OF THAT GUIDANCE, SO A PREFERENCE
TOWARD THE ECMWF/ECENS/GEFS IS PREFERRED WITH LOWER CONFIDENCE
AFTER 60HRS EAST OF THE ROCKIES AND WITH THE REMAINING ARCTIC
CLOSED LOW THAT STARTS SHEARING INTO THE NORTHERN STREAM FLOW WED.
AS THE UPPER LOW LOSES INFLUENCE, A PATTERN CHANGING SHORTWAVE
AMPLIFIES OVER THE GULF OF ALASKA AND NORTHEAST PACIFIC OCEAN.
WITH A SLOWER CLOSED LOW (AS WELL AS NORTH), THE ECMWF PUMPS THE
DOWNSTREAM RIDGE ACROSS THE NORTHWEST AND RAPIDLY DEVELOPS A
CLOSED LOW/DEEP SURFACE CYCLONE ALONG THE PACIFIC NW COAST INTO
VANCOUVER ON DAY 3. WHILE, THE OPERATIONAL ECMWF IS ON THE FASTER
SIDE OF ITS OWN ENSEMBLE SUITE, GIVEN THE DOWNSTREAM INFLUENCES,
PREFER THE ECENS MEAN SOLUTION GREATEST THOUGH THE OPERATIONAL 00Z
GFS ARE FURTHER SOUTH/SLOWER NEAR THE CMC AND UKMET. THE
EVOLUTION AND SPREAD IS NOT TERRIBLE FOR THE END OF DAY 3 FOR SUCH
AN UPSTREAM WAVE THROUGH A RELATIVE DATA VOID THAT A NON-NAM BLEND
MAY WORK BEST WEIGHTED STRONGEST TO ECENS MEAN, THEN
ECMWF/CMC/UKMET.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
GALLINA
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