939
FXUS10 KWNH 301912
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
311 PM EDT THU APR 30 2020
VALID APR 30/1200 UTC THRU MAY 04/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION INCLUDING FINAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...DEEP TROUGH/CLOSED LOW IMPACTING THE EAST THROUGH FRIDAY AND
EARLY SATURDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~
PREFERENCE: 30/12Z ECMWF/EC ENSEMBLE MEAN/CMC BLEND
CONFIDENCE: AVERAGE
THE MODELS WERE IN DECENT AGREEMENT WITH THE PROGRESSION OF THE
TROUGH THROUGH ABOUT 00Z SATURDAY...AT WHICH TIME THE NCEP
GUIDANCE BECOMES FASTER THAN NON-NCEP GUIDANCE. BY THAT POINT, A
MAJORITY OF THE DIFFERENCES IN PLACEMENT AND STRENGTH ARE OUT AT
SEA...ALTHOUGH THOSE DIFFERENCES ALSO HAVE IMPACTS UPSTREAM OF NEW
ENGLAND. THE 30/12Z ECMWF AND UKMET BOTH ACCELERATED THE TROUGH
AXIS COMPARED WITH THEIR PREVIOUS RUNS BUT THEY REMAINED SLOWER
THAN THE NCEP GUIDANCE. AT THIS POINT, THE LATEST ENSEMBLES STILL
SUPPORT THE NON-NCEP OPERATIONAL SOLUTIONS...SO OUR PREFERENCE
REMAINS WITH THE ECMWF/ENSEMBLE MEAN AND CANADIAN.
...SHORTWAVE CROSSING THE NORTHWEST TODAY AND MOVING INTO WESTERN
ONTARIO SATURDAY MORNING...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 30/12Z ECMWF/UKMET/CMC BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE GFS FROM THE 30/12Z RUN STILL STANDS OUT THE GREATEST WITH A
MORE AMPLIFIED AND SLOWER 500 MB SHORTWAVE TRACK BY MID-DAY
FRIDAY...AT ODDS WITH TRENDS FROM THE 30/12Z ECMWF AND 30/00Z CMC.
THE LOWER MID-LEVEL HEIGHTS IN THE GFS ALSO MADE IT EASY FOR A
SECOND SHORTWAVE ORIGINATING IN NORTHERN SASKATCHEWAN TO DROP
SOUTHEASTWARD AND PRODUCE A DEEPENING CLOSED MID-LEVEL LOW OVER
ONTARIO AND QUEBEC BY EARLY SUNDAY. WHILE THE MID-LEVEL HEIGHT
PATTERN IN THE ECMWF AND UKMET LEAVES ROOM FOR A SPOT-LOW, NEITHER
OF THEM DEVELOPS A DEEPENING MID- AND UPPER-LEVEL LOW LIKE THE
GFS. AS A RESULT, WILL CONTINUE TO FAVOR A BLEND OF THE 30/12Z
ECMWF/UKMET/CMC.
...700-500 MB SHORTWAVE REACHING THE CENTRAL PLAINS SATURDAY
MORNING...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 30/12Z ECMWF/UKMET/CMC BLEND
CONFIDENCE: AVERAGE
THE 12Z SUITE OF NCEP AND NON-NCEP GUIDANCE ALIKE MAINTAINED
DECENT CONTINUITY WITH THEIR RESPECTIVE RUNS...MEANING THAT THE
NAM AND GFS WERE SOUTH WITH THIS FEATURE COMPARED WITH THE
NON-NCEP GUIDANCE. THE LATEST ENSEMBLE SPAGHETTI PLOTS STILL
OFFER MORE SUPPORT TO THE NON-NCEP GUIDANCE...SO NO CHANGES TO THE
MODEL PREFERENCE WAS MADE. CONVECTIVE UNCERTAINTY LOWERS
CONFIDENCE WITH THIS FEATURE.
..DEEP TROUGH OFFSHORE THE WEST COAST BY SATURDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 30/12Z UKMET BLEND
CONFIDENCE: AVERAGE
DESPITE THE DECENT AGREEMENT FROM THE 30/12Z MODELS...ENSEMBLE
SPAGHETTI PLOTS STILL SUGGEST THAT A NON-UKMET BLEND WILL WORK
BEST. ENOUGH SPREAD REMAINED TO ALLOW FOR ADJUSTMENTS IN THE
FUTURE.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
BANN
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