012
FXUS10 KWNH 091632
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1231 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 NAM/GFS EVALUATION AND REGIONAL PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..CLOSED LOW AFFECTING THE SOUTHWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z NAM AND 00Z ECMWF/CANADIAN
A CLOSED LOW OFF SOUTHERN CALIFORNIA WILL BE SLOW TO MOVE
EASTWARD, INTERACTING WEAKLY WITH THE NORTHERN STREAM, MORE ZONAL
FLOW 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 CANADIAN AND NOW
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 00Z ECMWF/CANADIAN, WITH NAM/GFS VIABLE
TO MARCH 12/00Z
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 BY THE CANADIAN RUN. 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. WILL RE-EVALUATE
AFTER SEEING ANY TRENDS IN THE OTHER GLOBAL MODELS THIS AFTERNOON.
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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