834
FXUS10 KWNH 181713
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1209 PM EST SAT JAN 18 2020
VALID JAN 18/1200 UTC THRU JAN 22/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..UPPER TROUGH/LOW CROSSING THE GREAT LAKES/NORTHEAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
A DEEP CLOSED LOW CROSSING THE UPPER MIDWEST WILL QUICKLY EJECT
EAST ACROSS THE GREAT LAKES ALONG WITH A DEEPENING AREA OF LOW
PRESSURE GOING THROUGH THIS EVENING. THE CLOSED LOW WILL OPEN UP
INTO A BROAD TROUGH ACROSS THE NORTHEAST BEFORE EXITING THROUGH
SOUTHEAST CANADA BY SUNDAY. THE MODEL SPREAD WITH THIS SYSTEM IS
VERY MODEST NOW, SO A GENERAL MODEL BLEND WILL BE PREFERRED.
..AMPLIFYING SHORTWAVE CROSSING THE MIDWEST SUNDAY/MONDAY
..CLOSED LOW EVOLUTION OVER THE SOUTHEAST BY TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z GFS/00Z UKMET AND 00Z ECMWF
CONFIDENCE: AVERAGE
A PROGRESSIVE, BUT VIGOROUS, NORTHERN STREAM SHORTWAVE WILL DIG
SOUTHEAST FROM CANADA AND CROSS THE UPPER MIDWEST SUNDAY NIGHT
BEFORE THEN SWINGING DOWN THROUGH THE OH/TN VALLEYS ON MONDAY. BY
TUESDAY, THE SYSTEM WILL DEEPEN INTO A CLOSED LOW OVER THE
SOUTHEAST. THE 12Z NAM BECOMES A BIT OF A SLOWER AND DEEPER
OUTLIER WITH THE ENERGY AS IT ARRIVES OVER THE TN VALLEY AND
SOUTHEAST. THE 00Z CMC BECOMES A BIT WEAKER AND FASTER THAN THE
REMAINING GUIDANCE BY CONTRAST. THIS LEAVES THE 12Z GFS, 00Z UKMET
AND 00Z ECMWF SPLITTING THE DIFFERENCE, AND A BLEND OF THESE
SOLUTIONS WILL BE PREFERRED.
..SHORTWAVE/FRONT CLIPPING THE PACIFIC NORTHWEST BY MONDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE GUIDANCE SUPPORTS A PROGRESSIVE PACIFIC SHORTWAVE TROUGH
CLIPPING THE PACIFIC NORTHWEST BY EARLY MONDAY. THERE IS SOME
MODEST TIMING SPREAD SEEN WITH THE DETAILS OF A VERY WEAK SURFACE
WAVE AND ATTENDANT FRONTAL SYSTEM, BUT A GENERAL MODEL BLEND WILL
BE PREFERRED AT THIS TIME TO RESOLVE THESE MINOR DIFFERENCES.
..SOUTHERN STREAM SHORTWAVE CROSSING CALIFORNIA BY MONDAY
..ENERGY CROSSING THE SOUTHWEST ON TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-UKMET BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
SOUTHERN STREAM SHORTWAVE ENERGY WILL BE CROSSING ESPECIALLY
CENTRAL/SOUTHERN AREAS OF CALIFORNIA ON MONDAY AHEAD OF A DEEP
UPPER TROUGH/CLOSED LOW FARTHER OFFSHORE OF THE WEST COAST. THIS
ENERGY WILL THEN EJECT QUICKLY DOWN ACROSS THE SOUTHWEST ON
TUESDAY. THE 00Z UKMET ENDS UP BEING SLOWER AND DEEPER THAN THE
REMAINING SUITE BY TUESDAY. WILL PREFER A NON-UKMET BLEND WITH
THIS SYSTEM FOR NOW.
..DEEP UPPER TROUGH OFFSHORE THE WEST COAST ON MONDAY
..ENERGY ARRIVING ACROSS THE PACIFIC NORTHWEST BY TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-GFS BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE GUIDANCE DEPICTS A PROGRESSIVE AND DEEP UPPER TROUGH/CLOSED
LOW OFFSHORE THE WEST COAST BY MONDAY WHICH WILL ADVANCE INLAND BY
TUESDAY. THE TIMING DETAILS OF THE SYSTEM ARE GENERALLY WELL
AGREED UPON, ALTHOUGH TOWARD THE END OF THE PERIOD, THE 12Z GFS
BECOMES SLOWER AND DEEPER THAN THE REMAINING SOLUTIONS AS THE
ENERGY CROSSES INTO THE PACIFIC NORTHWEST. THE LATEST GEFS AND
ECENS MEANS SUGGEST THE GFS IS AN OUTLIER SOLUTION. GIVEN
REASONABLY DECENT AGREEMENT SEEN WITH THE REMAINING GUIDANCE, A
NON-GFS BLEND WILL BE PREFERRED.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
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