467
FXUS10 KWNH 091950
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
250 PM EST THU JAN 09 2020
VALID JAN 09/1200 UTC THRU JAN 13/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...SHORTWAVE ENTERING OR/CA TONIGHT, AMPLIFYING ACROSS THE FOUR
CORNERS/HIGH PLAINS FRI AND THROUGH MS VALLEY INTO GREAT LAKES
LATE SAT INTO SUN...
..DEEPENING SURFACE LOW OVER THE LOWER MS VALLEY FRI/SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/ECMWF BLEND
CONFIDENCE: ABOVE AVERAGE
19Z UPDATE: NO SIGNIFICANT UPDATES NOTED WITH THE REST OF THE 12Z
GUIDANCE. THE CMC REMAINS A SLOW OUTLIER WHILE SOME COMPONENTS OF
THE UKMET APPEAR USABLE. THE GFS/ECMWF COMPROMISE APPEAR TO BE A
GOOD APPROACH WITH THE RELATIVELY GOOD AGREEMENT IN THE MASS
FIELDS THROUGH 3 DAYS.
DIGGING SHORTWAVE TROUGH OVER SOUTHERN CALIFORNIA AND THE
SOUTHWEST U.S. WILL EJECT OUT INTO THE SOUTHERN/SOUTH-CENTRAL
PLAINS BY THIS WEEKEND, TAKING ON A NEGATIVE TILT OVER THE LOWER
TO MID-MS RIVER VALLEY. ALOFT, THERE ARE STILL SOME DIFFERENCES
NOTED WHERE THE 00Z CMC IS SLOWER THAN THE REST OF THE
DETERMINISTIC GUIDANCE AND THE AVAILABLE ENSEMBLE MEANS. THE UKMET
IS IN LINE WITH THE GFS/ECMWF AS FAR AS TIMING INITIALLY BUT THEN
TRACKS FASTER AND FURTHER EAST BY DAY 3 AS THE SYSTEM LIFTS INTO
THE GREAT LAKES. OVERALL, THE GFS/ECMWF HAVE BEEN THE MOST
CONSISTENT OVER THE LAST SEVERAL MODEL CYCLES AND APPEAR TO BE
LOCKING IN ON SIMILAR SOLUTIONS. AT THE SURFACE, THERE REMAINS
SOME LATITUDINAL DIFFERENCES IN THE LOW TRACK BUT A CONSENSUS
APPROACH LEANS TOWARD A GFS/ECMWF BLEND WHILE THE UKMET/CMC OFFER
THE MOST DIFFERENT SOLUTIONS. THOUGH OVERALL THE DIFFERENCES IN
QPF APPEAR FAIRLY MINIMAL AND MORE ON THE MESOSCALE LEVEL. THE
OVERALL DIFFERENCES ARE VERY SMALL BUT WITH OVERALL GOOD AGREEMENT
AND WITHIN TIGHTENING ENSEMBLE SUITE, WILL SUPPORT A 12Z GFS, 00Z
ECMWF BLEND AT SLIGHTLY ABOVE AVERAGE CONFIDENCE, BUT STILL
INCREASING.
...NEXT UPPER TROUGH OVER THE NORTHWEST BY SAT SHEARING INTO
LONGER WAVE TROF OVER INTERMOUNTAIN WEST SUN...
...PHASING/SHARPENING THIRD SHORTWAVE ALONG BC COAST INTO PAC NW
LATE SUN...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH 11.00Z; THEN NON-NAM BLEND
CONFIDENCE: ABOVE AVERAGE
19Z UPDATE: TYPICAL BIASES REMAIN IN PLACE ACROSS THE NORTHWEST
(GFS FAST; ECMWF SLOW) THOUGH THE 12Z CMC DID TREND FASTER AND NOW
IS CLOSER TO THE ECMWF TIMING WITH THE FIRST SYSTEM FRIDAY/FRIDAY
NIGHT. THE NAM STILL APPEARS TO BE AN OUTLIER ENOUGH TO NOT
INCLUDE BEYOND 11.00Z, SO NO REAL CHANGE TO THE MODEL BLEND
PREFERENCE.
LONGWAVE TROUGHING WILL GENERALLY BE LOCKED IN PLACE ACROSS THE
WESTERN/INTERIOR WEST THROUGH THE FORECAST PERIOD AS A SERIES OF
SYSTEMS WORK THROUGH THE PACIFIC NORTHWEST. UPPER LEVEL ENERGY
BOTTLED UP ACROSS INTERIOR CANADA SLOWLY REMAINS IN PLACE THROUGH
THE PERIOD, WHILE A COUPLE STRONGER, COMPACT SHORTWAVES MOVE INTO
THE PACIFIC NORTHWEST. THE FIRST, ARRIVING LATE FRIDAY INTO
SATURDAY IS NOW WELL REPRESENTED AND AGREED UPON BY THE LATEST
MODEL GUIDANCE WHERE A GENERAL MODEL BLEND CAN BE APPLIED (THROUGH
48 HOURS 11.00Z). BEYOND THAT PERIOD, THE NAM IS TOO FAST WITH THE
NEXT SHORTWAVE AND LOW PRESSURE MOVING ONSHORE AND SHOULD BE
DISCARDED BEYOND 60 HOURS. THE GFS/ECMWF ARE IN FAIRLY GOOD
AGREEMENT THOUGH THE GFS IS A TAD FASTER THAN THE ECMWF. THE CMC
IS ON THE SLOWER SIDE OF THE MODEL SPREAD, BUT COULD PROBABLY BE
INCORPORATED AS WELL. SO OUTSIDE OF THE VERY FAST NAM FOR DAY 2/3,
THE REST OF THE AVAILABLE MODELS APPEAR USABLE IN THE FORECAST
PERIOD.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
TAYLOR
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