381
FXUS10 KWNH 300650
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
249 AM EDT MON MAR 30 2020
VALID MAR 30/0000 UTC THRU APR 02/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH FINAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...CLOSED LOW OVER GREAT LAKES AND NEW ENGLAND WITH SURFACE
CYCLOGENESIS OFFSHORE NEW ENGLAND MONDAY EVENING...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE MODELS SHOW SIMILARLY WITH THE MID-LEVEL LOW CROSSING THE
NORTHEAST TUESDAY MORNING AND THE SUBSEQUENT SURFACE LOW FORECAST
TO TRACK NEAR 40N. NO SIGNIFICANT DIFFERENCES WERE NOTED WITH THE
00Z ECMWF/UKMET/CMC COMPARED TO THEIR PREVIOUS 12Z CYCLES.
...SOUTHWEST SHORTWAVE AND SOUTHERN TIER SURFACE LOW REACHING THE
EAST COAST BY TUESDAY EVENING...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z NAM, 00Z GFS AND 12Z ECMWF BLEND
CONFIDENCE: AVERAGE
NO SIGNIFICANT DIFFERENCES WERE NOTED WITH THE 00Z ECMWF/UKMET/CMC
COPMARED TO THEIR PREVIOUS 12Z CYCLES.
THE 12Z/00Z UKMET BECOMES FLATTEST WITH THE MID-LEVEL SHORTWAVE
TRACKING ACROSS THE SOUTHERN U.S. THROUGH TUESDAY/WEDNESDAY WHILE
THE 12Z/00Z CMC IS SLOWER AND FARTHER SOUTH WITH THE MAIN
VORTICITY MAX ASSOCIATED WITH THE SHORTWAVE TROUGH. THOUGH SOME
TIMING DIFFERENCES GROW ON WEDNESDAY AMONG THE 00Z NAM, 00Z GFS
AND 12Z/00Z ECMWF WITH THE MID-LEVEL TROUGH, AND SUBSEQUENT
SURFACE LOW TO STRENGTHEN OFFSHORE OF THE MID-ATLANTIC COAST,
THESE DIFFERENCES HAVE MORE IMPACTS INTO THE WESTERN ATLANTIC THAN
THE MAINLAND U.S. PERHAPS THE 00Z NAM (WESTERN SIDE OF ENSEMBLE
SPREAD) SHOULD BE GIVEN LESS WEIGHT ON WEDNESDAY GIVEN BETTER
ENSEMBLE AGREEMENT FOR THE 00Z GFS AND 00Z ECMWF.
...CLOSED UPPER LOW/TROUGH APPROACHING PACIFIC NORTHWEST THROUGH
MONDAY THEN REACHING WESTERN HIGH PLAINS BY MIDWEEK...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z NAM, 00Z GFS AND 12Z ECMWF BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE
A FAIR DEGREE OF SPREAD REMAINS WITH THIS SYSTEM AND CONFIDENCE IS
ONLY AVERAGE GIVEN COMPLEX INTERACTIONS WITH MULTIPLE SHORTWAVE
SPOKES AROUND THE MAIN CLOSED LOW WHICH SETS UP OVER SOUTHWESTERN
CANADA FOR TUESDAY AND WEDNESDAY. ENSEMBLE SPAGHETTI HEIGHT TRENDS
AT 500 MB HAVE BEEN CONVERGING UPON A SINGLE SOLUTION BUT
DIFFERENCES REMAIN WITH THE GEFS AND CMC MEMBERS BISECTING THE
FAVORED MIDDLE GROUND.
OVERALL DETERMINISTIC TRENDS SINCE YESTERDAY SHOW GREATER
DEFINITION WITH 2 OR 3 MAIN SHORTWAVE SPOKES TRACKING THROUGH THE
NORTHWEST. THE ENSEMBLE MEANS SHOW RELATIVELY GOOD AGREEMENT WITH
THESE FEATURES WITH THE 00Z NAM, 00Z GFS AND 12Z ECMWF CLOSEST TO
THE MEANS. THE 12Z UKMET IS LESS DEFINED WITH THESE SHORTWAVE
SPOKES WHILE THE 12Z CMC EVOLVES INTO A FAIRLY DIFFERENT PATTERN
ALOFT.
THE MAIN TREND WITH THE 00Z ECMWF/UKMET/CMC COMPARED TO THEIR
PREVIOUS 12Z CYCLES WAS TO BE WEAKER OR TUCKED CLOSE TO THE CENTER
OF THE MAIN CLOSED LOW WITH VARIOUS SHORTWAVES CIRCLING THROUGH
THE NORTHWEST. WHILE THE 00Z ECMWF MEAN MAY JUST FOLLOW THE 00Z
ECMWF TREND ONCE IT BECOMES AVAILABLE, THE PREFERENCE IS TO STAY
TOWARD THE MIDDLE GROUND, AWAY FROM THE EDGES OF THE DETERMINISTIC
GUIDANCE AND TOWARD THE LATEST AVAILABLE ENSEMBLE MEAN BLEND.
TIMING DIFFERENCES AMONG THE 12Z ECMWF, 00Z NAM AND 00Z GFS REMAIN
WITH A BLENDED APPROACH TOWARD THE MIDDLE OF THESE THREE
PREFERRED. THE 00Z GFS IS LIKELY STILL A BIT TOO FAST/EAST WITH A
SHORTWAVE TRACKING INTO SOUTHERN MANITOBA ON WEDNESDAY GIVEN
TRENDS IN THE ENSEMBLES AND THE REMAINING PLACEMENT OF THE
DETERMINISTIC GUIDANCE.
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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