951
FXUS10 KWNH 290653
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
252 AM EDT SUN MAR 29 2020
VALID MAR 29/0000 UTC THRU APR 01/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z NAM/GFS EVALUATION WITH PRELIMINARY PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...CLOSED LOW WEAKENING FROM THE UPPER MIDWEST TO THE NORTHEAST
THROUGH TUESDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE
ONLY MINOR TIMING/THERMAL/STRENGTH DIFFERENCES REMAIN WITH THIS
SYSTEM AS THE POWERFUL CLOSED LOW OVER THE UPPER MIDWEST ON SUNDAY
MORNING, WEAKENS TOWARD THE NORTHEAST FOR MONDAY AND TUESDAY. AS A
SECONDARY LOW DEVELOPS IN THE GUIDANCE SUNDAY NIGHT NEAR THE NEW
ENGLAND COAST, MINOR PLACEMENT DIFFERENCES DEVELOP WITH PERHAPS
THE 12Z UKMET CLOSEST TO THE COAST, BUT OVERALL DIFFERENCES IN THE
LATEST DETERMINISTIC AND ENSEMBLE GUIDANCE ARE MINOR.
...SOUTHWEST SHORTWAVE SPURRING SOUTHERN PLAINS CYCLOGENESIS EARLY
IN THE WEEK...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 75% 12Z ECMWF, 25% 00Z NAM BLEND
CONFIDENCE: AVERAGE
SOME TIMING DIFFERENCES DEVELOP EARLY WITH THE SHORTWAVE TROUGH
ACROSS THE SOUTHWEST. THE 00Z NAM ENDS UP FASTER THAN MOST OF THE
GUIDANCE THROUGH MONDAY WHILE THE 12Z UKMET/CMC END UP SLOWER.
WHILE THE SLOWER/FARTHER SOUTH TRACK OF THE 12Z UKMET/CMC'S
SHORTWAVE CONTINUES THROUGH WEDNESDAY MORNING, THE 00Z NAM TIMING
SLOWS MORE IN LINE WITH THE BEST ENSEMBLE CLUSTERING WHILE THE 00Z
GFS PULLS AHEAD. THE 12Z ECMWF IS CONSIDERED THE BEST MODEL FOR
THIS SYSTEM WITH THE 00Z NAM SECOND BEST BUT THE 00Z NAM IS A BIT
STRONGER, COLDER AND NORTH THAN THE REMAINING GUIDANCE.
CLOSED LOW AND UPPER LEVEL TROUGH APPROACHING PACIFIC NORTHWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS/12Z ECMWF/12Z UKMET BLEND
CONFIDENCE: AVERAGE
WHILE THE 00Z GFS ENDS UP SLOWER WITH THE TIMING OF THE LEAD
SHORTWAVE TROUGH MOVING ACROSS THE U.S./CANADIAN BORDER MONDAY
NIGHT INTO TUESDAY, LOCATED ON THE FRONT EDGE OF A LONGWAVE TROUGH
OVERTAKING THE NORTHWEST, WHEN THE 00Z GFS IS COMBINED WITH THE
12Z ECMWF AND 12Z UKMET, A REASONABLE BLEND IS REACHED. THE 00Z
NAM IS CONSIDERED TOO AMPLIFIED WITH HEIGHTS INTO THE
INTERMOUNTAIN WEST, WHILE THE 12Z CMC IS FLATTER/WEAKER WITH THE
OVERALL LONGWAVE TROUGH.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
OTTO
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