655
FXUS10 KWNH 071848
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
147 PM EST THU NOV 07 2019
VALID NOV 07/1200 UTC THRU NOV 11/0000 UTC
..SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
..12Z MODEL EVALUATION WITH FINAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..SHORTWAVES CUTTING INTO THE PACIFIC NORTHWEST RIDGE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 07/00Z ECMWF ENSEMBLE MEAN AND THE 07/12Z NAM AND ECMWF
CONFIDENCE: SLIGHTLY BELOW AVERAGE
THE 12Z SUITE OF NUMERICAL GUIDANCE CONTINUES TO STRUGGLE IN HOW
THE HANDLE NUMEROUS AND HARD-TO-TIME SHORTWAVE TROUGHS RIDING
AROUND THE PERIPHERY OF AN ANOMALOUSLY STRONG MID/UPPER LEVEL
RIDGE OVER THE EASTERN NORTH PACIFIC OCEAN. THE 07/12Z GFS HAS
MORE ENERGY, AND THEREFORE A STRONGER/FASTER FRONTAL PROGRESSION
INTO THE U.S. PACIFIC NORTHWEST WHILE THE 07/12Z NAM AND ECMWF
CLUSTERED BETTER TOGETHER. EVEN THOUGH THE CMC/UKMET WERE MORE
AGGRESSIVE THAN THE ECMWF WITH THE PATTERN, THOSE MODELS REMAINDER
CLOSER TO THE NAM/ECMWF IDEA THAN THEY DID WITH THE GFS. NO CHANGE
IN THE PREFERENCE BASED ON THE 12Z NON-NCEP SUITE.
..REMAINDER OF OVERALL PATTERN ACROSS THE CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH DAY 2, THEN LESS WEIGHT TO
GFS ON SUNDAY
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE START OF THE SHORT RANGE PERIOD SHOWS BROAD TROUGHING ALONG
THE EASTERN 2/3 OF THE NORTHERN U.S., PRECEDED UPSTREAM BY
ANOMALOUS RIDGING OVER THE EASTERN PACIFIC INTO THE PACIFIC
NORTHWEST. BY SATURDAY/SUNDAY, THE FLOW IS EXPECTED TO FLATTEN A
BIT ALTHOUGH ANOTHER SHORTWAVE SHOULD SEND ANOTHER ARCTIC FRONT
INTO THE NORTHERN U.S..
EXCEPT FOR THE GFS BEING MARGINALLY STRONGER WITH THE DEPARTING
TROUGH OVER THE EASTERN U.S. ON SATURDAY, THE MODEL AGREEMENT WAS
GENERALLY GOOD IN TERMS OF BOTH POSITION AND INTENSITY. HOWEVER,
SHORTWAVE ENERGY DROPPING OUT OF CANADA LATE SATURDAY OR EARLY
SUNDAY WAS STRONGER IN THE GFS THAN OTHER GLOBAL MODELS WHICH
RESULTED IN IT HAVING MASS FIELDS THAT WERE DEEPER/STRONGER FROM
THE UPPER MIDWEST TO NORTHERN ROCKIES WITH CORRESPONDINGLY COLDER
THERMAL FIELDS. FOR THAT REASON, THINK A GENERAL MODEL BLEND
WORKS EARLY ON DAY 3...ALTHOUGH INCREASINGLY LESS WEIGHT OF THE
GFS SHOULD PROBABLY BE USED AS DURING DAY 3. ONE CAVEAT IS THAT
COLD AIR SURGING FROM CANADA OFTEN TIMES PROGRESSES SOUTHWARD
FASTER THAN INDICATED BY THE MODELS...WHICH MEANS THE GFS IDEA
CAN'T BE RULED OUT ENTIRELY.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
BANN
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