456
FXUS10 KWNH 310658
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
258 AM EDT TUE MAR 31 2020
VALID MAR 31/0000 UTC THRU APR 03/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH FINAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..CENTRAL PLAINS SHORTWAVE AND SOUTHERN U.S. SURFACE LOW
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE
..07Z UPDATE
THERE WAS SOME CONVERGENCE TOWARD A COMMON GROUND FROM THE
DIFFERENCES DISCUSSED BELOW. A GENERAL MODEL COMPROMISE CONTINUES
TO BE PREFERRED.
..PREVIOUS DISCUSSION FOLLOWS
DIFFERENCES ARE RELATIVELY MINOR WITH THIS SYSTEM RESULTING IN A
GENERAL MODEL BLEND FOR THE PREFERENCE. HOWEVER, THE 00Z GFS
APPEARED A BIT TOO FAST WITH THE MID-LEVEL SHORTWAVE AS IT REACHES
THE SOUTHEAST, AND THE 00Z NAM WAS THE FARTHEST NORTH AND/OR WEST
WITH THE RESULTANT SURFACE LOW WHICH TRACKS INTO THE WESTERN
ATLANTIC. THE PREFERENCES IS TOWARD THE LATEST ENSEMBLE MEANS
GIVEN GOOD CLUSTERING FROM ENSEMBLE SCATTER LOW PLOTS AND
SPAGHETTI HEIGHTS.
..BROAD UPPER LEVEL GYRE OVER NORTHWEST
...SHORTWAVE "SPOKE #1" TRACKING FROM THE NORTHERN HIGH PLAINS
INTO SASKATCHEWAN/MANITOBA WEDNESDAY INTO THURSDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z NAM/ECMWF/UKMET BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE
..07Z UPDATE
THE 00Z UKMET SPED UP TOWARD THE REMAINING MODEL CONSENSUS AND THE
00Z ECMWF EDGED CLOSER TO THE NAM/UKMET FAVORED MIDDLE GROUND.
HOWEVER, THE 00Z CMC REMAINS A BIT WEAKER THAN THE CONSENSUS
DESPITE A STRONGER TREND COMPARED TO ITS 12Z CYCLE.
..PREVIOUS DISCUSSION FOLLOWS
THE 00Z GFS IS AN EASTERN OUTLIER WITH THIS FEATURE, HAVING
TRENDED EVEN FARTHER AWAY FROM THE EDGE OF THE ENSEMBLE SPAGHETTI
HEIGHT PLOTS EARLY THURSDAY. THE 12Z CMC IS ILL DEFINED WITH THIS
SHORTWAVE AND IS A WEAKER OUTLIER WITH RESPECT TO ENSEMBLE
SPAGHETTI HEIGHTS. THE 12Z UKMET IS A BIT SLOWER THAN THE
CONSENSUS.
THE BEST COMPROMISE AT THIS TIME IS OF THE STRONGER 00Z NAM AND
WEAKER 12Z ECMWF GIVEN THEY ARE IN SIMILAR LOCATIONS AND IN DECENT
AGREEMENT FROM THE ENSEMBLE MEANS.
..BROAD UPPER LEVEL GYRE OVER NORTHWEST
...SHORTWAVE "SPOKE #2" TRACKING FROM WA/OR WEDNESDAY MORNING TO
THE NORTHERN PLAINS BY FRIDAY MORNING...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z NAM, 00Z/12Z UKMET BLEND
CONFIDENCE: BELOW AVERAGE
..07Z UPDATE
THE 00Z ECMWF/CMC BACKED OFF FROM THEIR 12Z CYCLES WHICH WERE
FASTER AND STRONGER WITH THE SHORTWAVE AS IT NEARS THE NORTHERN
PLAINS. HOWEVER, THE PLACEMENT OF THEIR VORTICITY MAXIMA IS A
LITTLE WEST OR NORTH OF THE ENSEMBLE MEANS. WHILE THE 00Z UKMET
NUDGED IN THE DIRECTION OF THE 00Z ECMWF/CMC, BLENDING WITH THE
00Z NAM AND PREVIOUS 12Z/30 CYCLE IS CONSIDERED BEST AT THIS TIME.
THERE REMAINS POOR RUN TO RUN CONTINUITY WITH THIS SYSTEM WHICH
KEEPS CONFIDENCE LOW.
..PREVIOUS DISCUSSION FOLLOWS
THE MODELS HAVE BROAD AGREEMENT ON A POSITIVELY TILTED SHORTWAVE
TROUGH OVER THE GREAT BASIN FOR THURSDAY, EJECTING OUT INTO THE
NORTHERN PLAINS BY FRIDAY MORNING, PERHAPS AS A NEGATIVELY TILTED
TROUGH. THE 12Z ECMWF/CMC ARE FASTER THAN THE REMAINING GUIDANCE
WITH THIS FEATURE WITH THE 12Z CMC RATHER STRONG AS WELL. THE 00Z
GFS IS SLOWER THAN THE REMAINING CONSENSUS WHILE THE 00Z NAM AND
12Z UKMET FORM A RELATIVELY GOOD COMPROMISE IN THE MIDDLE OF THE
AVAILABLE MODELS.
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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