394
FXUS10 KWNH 180450
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1250 AM EDT THU JUN 18 2020
VALID JUN 18/0000 UTC THRU JUN 21/1200 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
EASTERN U.S. CLOSED LOW AND COASTAL FRONT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
CLOSED UPPER LOW CURRENTLY OVER NC/VA WILL GRADUALLY WEAKEN AND
LIFT NORTH/NORTHEAST OVER THE NEXT COUPLE OF DAYS AND SLOWLY
EVOLVE INTO AN OPEN WAVE. THERE IS EXCELLENT AGREEMENT IN THE
LATEST MODEL GUIDANCE WITH THIS EVOLUTION BOTH ALOFT AND AT THE
SURFACE, PARTICULARLY THROUGH 48 TO 60 HOURS. AFTERWARD, AS THE
OPEN WAVE BEGINS TO BECOME ABSORBED INTO THE APPROACHING TROUGHING
FROM THE GREAT LAKES, THE GFS SHOWS A FASTER PROGRESSION AS THE
WAVE KICKS NORTHEAST. IT'S NOT ENOUGH TO TOSS OUT AS AN OUTLIER
FOR NOW, BUT LESS INCLUSION OF THE 00Z GFS IS SUPPORTED FOR DAY 3
ACROSS THIS REGION.
CLOSED LOW DEVELOPING OVER NORTHERN HIGH PLAINS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z UKMET/ECMWF/ECENS BLEND
CONFIDENCE: AVERAGE
SHORTWAVE ENERGY OVER THE CENTRAL/NORTH-CENTRAL ROCKIES CURRENTLY
WILL EVOLVE INTO A LARGE CLOSED LOW OVER SOUTHERN CANADA LATER
THURSDAY INTO THURSDAY NIGHT WHICH IS THEN EXPECTED TO PERSIST
THROUGH THE REMAINDER OF THE FORECAST PERIOD. ALONG THE SOUTHERN
PERIPHERY OF THAT FLOW, A FEW IMPULSES MOVE THROUGH, ONE OF WHICH
PASSES THROUGH THE ROCKIES FRIDAY NIGHT INTO SATURDAY. HERE, THE
GFS IS NOTICEABLY DEEPER, DIGGING THE WAVE FURTHER SOUTH THAT ANY
OF THE OTHER DETERMINISTIC GUIDANCE. THE NAM WAS CONSIDERED LESS
USEFUL WITH THE CLOSED UPPER LOW, AS IT IS TOO FAST TO PROGRESS IT
TO THE NORTHEAST COMPARED TO THE REST OF THE GUIDANCE WHICH SHOWS
REASONABLE AGREEMENT THROUGH DAY 3. GIVEN SOME OF THE LIMITATIONS
OF THE GFS AND NAM, A UKMET AND ECMWF BASED BLEND IS PREFERRED.
TROUGH APPROACHING THE PACIFIC NORTHWEST BY FRIDAY NIGHT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GFS/ECMWF BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE
ANOTHER FAST MOVING SHORTWAVE TROUGH WILL APPROACH THE PACIFIC
NORTHWEST EARLY SATURDAY WHICH IS THEN EXPECTED TO REMAIN IN PLACE
THROUGH THE WEEKEND. THE 00Z GFS WAS A NOTICEABLE OUTLIER BEING
WAY TOO FAST WITH THE INITIAL SHORTWAVE ENERGY COMING ONSHORE LATE
FRIDAY NIGHT AND EARLY SATURDAY. AT THE SURFACE, LOW PRESSURE IS
FORECAST TO BRUSH AND SKIRT THE PAC NW AND HEAD TOWARD B.C. AND
HERE THE MODELS DIFFER SLIGHTLY IN STORM TRACK AND DEPTH. THE GFS
IS TO THE LEFT/WEST OF THE CONSENSUS WHILE THE ECMWF IS TO THE
RIGHT. GIVEN SOME OF THE TIMING ISSUES, A BLEND OF THE GFS/ECMWF
WOULD LIKELY YIELD A DESIRABLE RESULT AT THIS TIME.
TAYLOR
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500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
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