152
FXUS10 KWNH 260654
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
253 AM EDT THU MAR 26 2020
VALID MAR 26/0000 UTC THRU MAR 29/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH FINAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..SURFACE LOW CROSSING THE MID ATLANTIC STATES THU NIGHT/FRI
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
..07Z UPDATE
COMPARED TO THEIR 12Z MODELS, THE 00Z UKMET/CMC SPED UP TOWARD THE
REMAINING GUIDANCE WHILE THE 00Z ECMWF ONLY MADE MINOR
ADJUSTMENTS. A GENERAL MODEL BLEND IS NOW RECOMMENDED WITH THE 00Z
NAM/GFS A LITTLE NORTH COMPARED TO THE 00Z ECMWF/UKMET/CMC.
..PREVIOUS DISCUSSION FOLLOWS
A WEAK SURFACE TO 850 MB LOW IS FORECAST TO CROSS THE MISSISSIPPI
RIVER VALLEY LATER TODAY AND NEAR THE NORTHERN MID-ATLANTIC COAST
FRIDAY MORNING. THE ENSEMBLE MEANS DO NOT SUPPORT THE SLOWER 12Z
UKMET/CMC AND LATITUDE DIFFERENCES REMAIN AMONG THE REMAINING 00Z
NAM, 00Z GFS AND 12Z ECMWF. FOR NOW, A MIDDLE GROUND BETWEEN THE
NAM/GFS/ECMWF IS PREFERRED, OR MORE SIMILAR TO THE 00Z NAM.
...MID-LEVEL TROUGH TRACKING FROM THE WEST COAST TO THE CENTRAL
PLAINS THROUGH SUN MORNING...
...SURFACE LOW MOVING FROM EASTERN CO INTO THE MID/UPPER MS
VALLEY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS, 00Z ECMWF AND 12Z UKMET BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
..07Z UPDATE
THE 00Z UKMET AND 00Z CMC SLOWED THE 500 MB TROUGH AXIS COMPARED
TO THEIR PREVIOUS 12Z MODELS, BUT NOW FALL TOWARD THE SLOWER SIDE
OF THE LATEST ENSEMBLE SPREAD. THE 00Z ECMWF ONLY MADE MINOR
ADJUSTMENTS WITH THE MID-UPPER TROUGH, SLIGHTLY FASTER THAN ITS
12Z CYCLE. CURRENTLY, THE 00Z GFS, 00Z ECMWF AND 12Z UKMET ARE
CONSIDERED BEST.
..PREVIOUS DISCUSSION FOLLOWS
TRENDS IN THE ECMWF ENSEMBLES HAVE BEEN SLOWER WITH THE MID-LEVEL
TROUGH AS IT CROSSES THE ROCKIES INTO THE GREAT PLAINS, BUT THE
GEFS HAS SPED UP SINCE PREVIOUS RUNS. THE LATEST GUIDANCE SHOWS
THE 00Z NAM WITH AN OPEN WAVE INTO THE CENTRAL U.S. WHICH IS AN
OUTLIER CONSIDERING THE REMAINING DETERMINISTIC AND ENSEMBLE
GUIDANCE. THE 12Z CMC IS REASONABLE WITH TIMING BUT WEAKER THAN
THE REMAINING AVAILABLE GUIDANCE. THE MIDDLE GROUND IS CURRENTLY
BEST SUPPORTED BY THE 00Z GFS (SLOWER THAN 18Z GEFS MEAN), AND THE
SIMILAR 12Z ECMWF/UKMET. THE 00Z GFS IS STRONGEST WITH THE LOW TO
MID-LEVEL LOW EARLY SATURDAY, BUT THE 12Z ECMWF/UKMET BECOME
STRONGEST BY SUNDAY MORNING COMPARED TO THE GFS. THE 00Z GFS IS
ALSO SLIGHTLY FASTER THAN THE AGREEABLE 12Z ECMWF/UKMET BUT THE
TRIO (GFS/ECMWF/UKMET) ARE WELL WITHIN THE MIDDLE OF THE LATEST
ENSEMBLE SPREAD.
...SHORTWAVE AND SURFACE COLD FRONT APPROACHING PACIFIC NORTHWEST
SAT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS/ECMWF/UKMET BLEND
CONFIDENCE: AVERAGE
..07Z UPDATE
AT LEAST THROUGH 12Z/29, THE 00Z GFS/ECMWF/UKMET CONTINUE TO
APPEAR BEST WITH THE TROUGH AXIS AS IT REACHES THE WEST COAST. THE
00Z CMC REMAINS FLAT LIKE ITS 12Z CYCLE. DIFFERENCES GROW BEYOND
12Z/29 WITH THE UKMET SLOWING DOWN, BUT THE 00Z GFS/ECMWF/UKMET
ARE OKAY UNTIL THAT POINT IN TIME.
..PREVIOUS DISCUSSION FOLLOWS
TIMING AND STRENGTH DIFFERENCES EXIST WITH A SHORTWAVE AND RELATED
COLD COLD FRONT NEARING THE PACIFIC NORTHWEST THIS WEEKEND. THE
00Z NAM IS FASTER THAN THE ENSEMBLE MEANS AND THE 12Z CMC IS
WEAKEST. THE 00Z GFS, 12Z ECMWF AND 12Z UKMET ARE REASONABLE IN
THE MIDDLE OF THE DIFFERENCES SEEN IN TIMING AND AMPLITUDE AND IN
DECENT AGREEMENT WITH THE ENSEMBLE MEANS.
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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