739
FXUS10 KWNH 110434
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1233 AM EDT WED MAR 11 2020
VALID MAR 11/0000 UTC THRU MAR 14/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..CLOSED LOW AFFECTING THE SOUTHWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
A CLOSED LOW OFF THE CALIFORNIA COAST CURRENTLY WILL SLOWLY MOVE
EASTWARD TOWARD THE SOUTHWEST U.S., WITH SEVERAL MID-LEVEL
VORTICITY CENTERS REVOLVING AROUND THE COMMON CENTER OF THE LOW.
OVERALL, THE LATEST DETERMINISTIC AND ENSEMBLE GUIDANCE SHOWS VERY
SIMILAR LARGE SCALE MASS FIELD DEPICTIONS THROUGH THE NEXT 84
HOURS. THE MAIN DIFFERENCES ARE THE ORIENTATION AND AXIS OF
HEAVIER QPF TIED TO THE PLUME OF ATMOSPHERIC MOISTURE. THE ECMWF
QPF IS DISPLACED FURTHER TO THE WEST (SOUTHERN CA/NV), SIMILAR TO
THE CMC AND UKMET. WHILE THE GFS/NAM DEPICTS HIGHER AMOUNTS TO THE
EAST OVER AZ. SO WHILE THE MASS FIELDS ARE SIMILAR AND A GENERAL
MODEL BLEND IS PREFERRED, THERE ARE SOME IMPORTANT DIFFERENCES
NOTED IN THE QPF FIELDS, PARTICULARLY IN THE DAY 2/3 TIME FRAME.
...NORTHERN STREAM TROUGH TRACKING FROM THE NORTHERN ROCKIES,
UPPER MIDWEST TOWARD THE NORTHEAST THROUGH FRIDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GFS/ECMWF BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
A LOWER AMPLITUDE LONGWAVE TROUGH WILL TRACK THROUGH THE NORTHERN
CONUS FROM WEDNESDAY THROUGH FRIDAY. AT THE SURFACE, A COLD FRONT
WILL STEADILY TRACK TO THE EAST AND SOUTH. THE UKMET APPEARS TO BE
TOO FAST WITH THE TROUGH PROGRESSION WHILE NOW, THE 00Z NAM IS ON
THE SLOWER END OF THE MODEL SPREAD. AS THE SURFACE LOW DEEPENS
NORTH OF THE GREAT LAKES, THE NAM IS DISPLACED TO THE NORTHWEST
FURTHER THAN THE REST OF THE MODELS WHILE THE CMC'S DEPICTION OF
THE COLD FRONT IS SLOWER ACROSS GREAT LAKES / MID-ATLANTIC REGION.
FOR NOW, WILL FAVOR A GFS/ECMWF BLEND WHICH SEEMS TO BE A
CONSENSUS APPROACH COMPARED TO THE ENSEMBLES.
..CLOSED LOW DEVELOPING OVER PACIFIC NW FRIDAY/SATURDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
SHORTWAVE ENERGY ROUNDING THE BASE OF A RIDGE EXTENDING INTO THE
GULF OF ALASKA IS EXPECTED TO QUICKLY DROP SOUTH/SOUTHEAST ALONG
THE WESTERN COAST OF NORTH AMERICA, EVENTUALLY EVOLVING INTO A
LARGE CLOSED LOW OVER THE PACIFIC NORTHWEST LATE IN THE WEEK AND
THIS WEEKEND. OVERALL THE GUIDANCE IS IN REASONABLE SHAPE FOR THE
MASS FIELDS, THE EXCEPTION BEING THE 00Z NAM WHICH IS DEEPER AND
SLOWER THAN THE REST OF THE DETERMINISTIC GUIDANCE. THE 00Z GFS
TRENDED SLOWER COMPARED TO ITS EARLIER RUNS AND IS A BIT SLOWER
COMPARED TO THE 12Z NON-NCEP GUIDANCE. BASED ON THE SETUP, THIS
MAKES SENSE AND THE OTHER GUIDANCE IS LIKELY TO TREND THAT WAY.
FOR NOW, A NON-NAM BLEND IS PREFERRED FOR THIS REGION.
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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