678
FXUS10 KWNH 070635
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
135 AM EST THU NOV 07 2019
VALID NOV 07/0000 UTC THRU NOV 10/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
..00Z MODEL EVALUATION WITH FINAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..SHORTWAVES CUTTING INTO THE PACIFIC NORTHWEST RIDGE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z NAM/00Z ECMWF BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE
..07Z UPDATE
THE MODELS CONTINUE TO MAKE RUN TO RUN CHANGES REGARDING EASTERN
PACIFIC SHORTWAVES INTO THE EXISTING RIDGE OFF OF THE NORTHWEST
COAST. THE 00Z GFS REMAINS AN OUTLIER WITH ITS COLD FRONTAL
PROGRESSION THROUGH THE GREAT PLAINS SUNDAY MORNING WITH A NON-GFS
BLEND PREFERRED.
ACROSS THE NORTHWEST, THE 00Z ECMWF BACKED OFF ON THE
INTENSITY/POSITION OF A SHORTWAVE VALID 00Z/10, WEST OF BRITISH
COLUMBIA, WHICH IMPACTS THE ORIENTATION OF LOW-MID LEVEL FLOW INTO
THE PACIFIC NORTHWEST. THE 00Z ECMWF NOW MORE CLOSELY MATCHES THE
00Z NAM WHILE THE 00Z CMC/UKMET REMAIN A BIT MORE AGGRESSIVE WITH
THE SHORTWAVE FEATURE. THE 00Z ECMWF AND 00Z NAM REPRESENT A FAIR
MIDDLE GROUND AND WILL BE PREFERRED.
..PREVIOUS DISCUSSION FOLLOWS
SIGNIFICANT DIFFERENCES SHOW UP WITH THE TIMING OF SHORTWAVES
CURRENTLY OVER THE PACIFIC OCEAN, AS THEY TRACK DOWNSTREAM INTO AN
ANOMALOUS RIDGE LOCATED JUST WEST OF THE NORTH AMERICAN COASTLINE.
THE 00Z NAM/GFS ARE SLOWER WITH ONE OF THESE SHORTWAVES REACHING
THE SOUTHERN COAST OF BRITISH COLUMBIA ON FRIDAY COMPARED TO THE
12Z ECMWF/UKMET/CMC. MEANWHILE, AMPLIFICATION OF TROUGHING WILL
OCCUR ACROSS WESTERN CANADA AS THE FEATURE DROPS SOUTH TOWARD THE
NORTHERN U.S. SATURDAY INTO SUNDAY. THE 00Z GFS IS SHARPER WITH
THIS NEXT WAVE WITH A MORE AMPLIFIED RIDGE JUST OFFSHORE OF THE
PACIFIC NORTHWEST. THE GFS SOLUTION IS A NEAR OUTLIER WHEN LOOKING
AT THE 570 DAM LINE AT 500 MB COMPARED TO ENSEMBLE SPAGHETTI
PLOTS. WHILE DIFFERENCES REMAIN WITH THE NON GFS GUIDANCE, A 00Z
NAM/12Z ECMWF BLEND IS AN ACCEPTABLE COMPROMISE AT THIS POINT.
..REMAINDER OF OVERALL PATTERN ACROSS THE CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
..07Z UPDATE
NO SIGNIFICANT CHANGES WERE NOTED IN THE 00Z ECMWF/UKMET/CMC
COMPARED TO THEIR PREVIOUS 12Z CYCLES TO WARRANT ANY CHANGES TO
THE PREFERENCE.
..PREVIOUS DISCUSSION FOLLOWS
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.
THERE IS GOOD AGREEMENT OUTSIDE OF THE PACIFIC NORTHWEST AND
CENTRAL U.S./CANADIAN BORDER THROUGH SUNDAY MORNING WITH A GENERAL
MODEL BLEND SUFFICING. A LARGE COLD FRONT WILL SWEEP THROUGH THE
EAST COAST WITH A SURFACE LOW ALONG THE FRONT DEEPENING NEAR NOVA
SCOTIA THURSDAY NIGHT INTO FRIDAY. ACROSS THE SOUTHWEST, SOME
MINOR DIFFERENCES SHOW UP WITH A CLOSED UPPER LEVEL LOW OFFSHORE
SOUTHERN CALIFORNIA/NORTHERN BAJA CALIFORNIA. THE 00Z NAM/GFS ARE
CLOSER TO THE COAST WHEREAS THE 12Z ECMWF/UKMET/CMC ARE DISPLACED
FARTHER FROM THE COAST. AT THIS POINT, THROUGH SUNDAY MORNING, A
GENERAL MODEL BLEND WILL WORK HERE AS WELL.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
OTTO
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page