136
FXUS10 KWNH 180439
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1238 AM EDT MON MAY 18 2020
VALID MAY 18/0000 UTC THRU MAY 21/1200 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION INCLUDING PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
TROPICAL STORM ARTHUR
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NATIONAL HURRICANE CENTER OFFICIAL TRACK
BEST MODEL PROXY: 12Z ECMWF/00Z GFS BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
TROPICAL STORM ARTHUR, CURRENTLY WELL OFFSHORE THE SC COAST WILL
BRUSH THE OUTER BANKS EARLY MONDAY, BEFORE TURNING NORTHEAST AWAY
FROM THE EASTERN U.S. TUESDAY. DETERMINISTIC MODEL GUIDANCE HAS
CONVERGED ON A SOLUTION WITH LESS SPREAD NOTED THAN 24 HOURS AGO.
THE BEST MODEL BLEND PROXY TO THE OFFICIAL NHC TRACK IS A BLEND OF
THE 00Z GFS AND 12Z ECMWF, CLOSE TO THE MODEL CONSENSUS, WHICH
TAKES THE SYSTEM TO ABOUT CAPE HATTERAS AND THEN ON A
NORTH/NORTHEAST TURN AWAY FROM THE SHORE.
CONSOLIDATION OF MIDWEST AND GULF COAST SHORTWAVES INTO CUT-OFF
UPPER LOW
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
A PAIR OF SHORTWAVES OVER THE CENTRAL US, ONE OVER IOWA AND THE
OTHER ALONG THE CENTRAL GULF REGION, WILL CONSOLIDATE OVER THE
NEXT DAY INTO A LARGE CUT-OFF LOW THAT SETTLES OVER THE TENNESSEE
VALLEY EARLY NEXT WEEK. MODEL GUIDANCE HAS IMPROVED IN THE LAST
COUPLE OF CYCLES AND THERE HAS BEEN SOME TIGHTENING IN THE MODEL
SPREAD SUCH THAT FROM A MODEL MASS FIELD PERSPECTIVE, A GENERAL
MODEL BLEND IS SUFFICIENT.
DEEP UPPER LEVEL TROUGH BUILDING IN ACROSS THE WESTERN U.S.
FOLLOWED BY SECONDARY SHORTWAVE TROUGH APPROACHING PAC NW
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH 20.12Z, THEN ECMWF/UKMET
BLEND
CONFIDENCE: ABOVE AVERAGE
WITH THE AMPLIFYING UPPER LEVEL PATTERN ACROSS THE CONTINENTAL
U.S., AN AMPLIFIED UPPER LEVEL TROUGH IS FORECAST TO BECOME
ESTABLISHED OVER THE WEST COAST AND THEN THE INTERMOUNTAIN WEST BY
THE MIDDLE OF THE WEEK AS A BIG UPPER LOW FROM THE NORTHEAST
PACIFIC TRACKS SOUTHEASTWARD. THIS WILL ALSO BE IN RESPONSE TO A
BUILDING DOWNSTREAM RIDGE AXIS ACROSS THE PLAINS AS AN OMEGA BLOCK
PATTERN DEVELOPS. BY DAY 3, A SECONDARY SHORTWAVE TROUGH IS
FORECAST TO DROP DOWN TOWARD THE PACIFIC NORTHWEST AND HERE, THERE
ARE SOME MODEL DIFFERENCES. THE GFS IS ON THE FASTER SIDE OF THE
SPREAD. A BLEND COMPOSED OF THE ECMWF/UKMET IS PREFERRED HERE FOR
DAY 3.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
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