633
FXUS10 KWNH 091835
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
235 PM EDT MON MAR 09 2020
VALID MAR 09/1200 UTC THRU MAR 13/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..CLOSED LOW AFFECTING THE SOUTHWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z NAM/ECMWF/CANADIAN
CONFIDENCE: ABOVE AVERAGE
A CLOSED LOW OFF SOUTHERN CALIFORNIA WILL BE SLOW TO MOVE
EASTWARD, INTERACTING WEAKLY WITH THE NORTHERN STREAM AND ITS
GREATER WESTERLY FLOW COMPONENT BRUSHING ACROSS THE TOP. OUR
PREFERENCE IS WEIGHTED MORE TOWARD THE ECMWF. ENSEMBLE SPAGHETTI
PLOTS VIEWED OVER SEVERAL CONSECUTIVE MODEL CYCLES SHOW A CLEAR
TREND OF THE GEFS MEMBERS AND MEAN TRYING TO MOVE BACK TOWARD THE
SLOWER AND MORE PRONOUNCED CLOSED SIGNATURE OF THE ECMWF MEMBERS.
THE 00Z AND 12Z CANADIAN MODEL AND NOW THE 12Z NAM ALSO MATCH
QUITE WELL TO THE ECMWF AND ITS ENSEMBLE. THERE IS A SHORTWAVE IN
THE NORTHERN STREAM THAT WILL TUG A BIT AT THE CLOSED LOW TUESDAY
NIGHT/WEDNESDAY, DRAWING IT TO THE COAST. BUT THE 12Z GFS GOES
FARTHER WITH THIS INTERACTION, AND LEAVES A MORE STRUNG OUT TROUGH
HANGING OFF THE COAST WITH NO DISTINCT LOW UNTIL IT REFORMS
RAPIDLY ON THURSDAY. THESE SMALL SCALE SHORTWAVE DETAILS DO NOT
SHARE ANY SUPPORT FROM OTHER MODELS AND ARE A PRETTY SUBSTANTIAL
CHANGE FROM EARLIER GFS RUNS. THAT BEING THE CASE, WE RECOMMEND
CAUTION WITH THE GFS HERE AFTER MARCH 11/12Z.
..NORTHERN STREAM FLOW
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z ECMWF/UKMET/CANADIAN, WITH NAM/GFS
VIABLE TO MARCH 12/00Z
CONFIDENCE: AVERAGE
WITHIN GENERALLY PROGRESSIVE AND BROAD SCALE FLOW, SOME
AMPLIFICATION IS EXPECTED ACROSS THE NORTH-CENTRAL U.S. BY
MIDWEEK. ENSEMBLE SPAGHETTI PLOTS DATING BACK SEVERAL CYCLES HAVE
SHOWN THE FAST GFS TO BE EITHER AN OUTLIER OR AT LEAST SETTING THE
VERY EDGE OF THE SOLUTION ENVELOPE. SOME DETAILS OVER THE NORTH
PACIFIC ALSO LOOK A LITTLE SPURIOUS IN THE GFS, WHERE AS
TELECONNECTIONS / ADVECTION ARGUMENTS WOULD ARGUE FOR A CLOSED LOW
FORMING MORE AT THE LATITUDE REFLECTED IN THE ECMWF, OF 38 NORTH,
BY MARCH 13/00Z. FOR THESE REASONS WE FAVOR THE ECMWF...WHICH WAS
JOINED AT 00Z AND 12Z CANADIAN RUNS AS WELL AS THE 12Z UKMET. IN
THE 12Z CYCLE THE NCEP MODELS ARE GETTING CLOSER, AND MAYBE THEY
WILL PROVE TO BE CORRECT IN DEPICTING A STRONGER SURFACE LOW OVER
THE CANADIAN PRAIRIE PROVINCES. BEYOND DAY 2, HOWEVER, THE NAM AND
GFS STILL STAND OUT AS BEING A LITTLE FAST OVER THE UPPER MIDWEST.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
BURKE
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