946
FXUS10 KWNH 171653
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1152 AM EST FRI JAN 17 2020
VALID JAN 17/1200 UTC THRU JAN 21/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..PROGRESSIVE CENTRAL TO EASTERN U.S. STORM SYSTEM
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z GFS AND 00Z ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
A PROGRESSIVE UPPER TROUGH CROSSING THE INTERMOUNTAIN WEST ALONG
WITH A LEAD MID-LEVEL TROUGH/CLOSED LOW FEATURE OVER THE CENTRAL
PLAINS WILL GENERALLY CONSOLIDATE LATER TODAY AND TONIGHT OVER THE
UPPER MIDWEST WITH A DEEPENING AREA OF SURFACE LOW PRESSURE. BY
SATURDAY, THE GUIDANCE AGREES IN DEPICTING A DEEP CLOSED LOW
CROSSING THE GREAT LAKES THAT THEN OPENS UP INTO A BROAD TROUGH
ACROSS THE NORTHEAST BEFORE EXITING THROUGH SOUTHEAST CANADA BY
SUNDAY. THE 12Z NAM AND 00Z UKMET ARE A TAD NORTH OF THE
MULTI-MODEL SUITE OF GUIDANCE WITH THE LOW CENTER AS IT CROSSES
THE GREAT LAKES, AND THE UKMET IS MORE DISTINCT NORTHERLY OUTLIER
RELATIVE TO THE TRACK ACROSS THE NORTHEAST. THE 12Z NAM AND 00Z
CMC BOTH GRADUALLY END UP A TAD MORE PROGRESSIVE THAN THE MODEL
CONSENSUS AS THE SYSTEM CROSSES AND EXITS THE NORTHEAST. OVERALL,
THE 12Z GFS AND 00Z ECMWF BOTH HAVE GOOD AGREEMENT WITH THEIR MASS
FIELDS AND MORE CLOSELY REPRESENT THE MODEL CONSENSUS, AND GIVEN
GOOD ENSEMBLE SUPPORT, A BLEND OF THE GFS AND ECMWF WILL BE
PREFERRED.
..AMPLIFYING SHORTWAVE CROSSING THE MIDWEST SUNDAY/MONDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM BLEND
CONFIDENCE: SLIGHTLY ABOVE 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. THE
12Z NAM ULTIMATELY ENDS UP A TAD SLOW WITH THIS SYSTEM, BUT
GENERALLY THE MODEL DIFFERENCES WITH THIS FEATURE ARE MINIMAL
OTHERWISE. A NON-NAM BLEND WILL BE PREFERRED FOR THE MASS FIELDS
OF THIS SYSTEM.
..SHORTWAVE/FRONT CLIPPING THE PACIFIC NORTHWEST BY MONDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
THE GUIDANCE SUPPORTS A PROGRESSIVE PACIFIC SHORTWAVE TROUGH
CLIPPING THE PACIFIC NORTHWEST BY EARLY MONDAY. THE 00Z CMC/UKMET
ARE A TAD DEEPER WITH THE SYSTEM COMPARED TO THE 12Z NAM/GFS AND
00Z ECMWF AND SUGGEST A SOMEWHAT BETTER DEFINED LOW CENTER LIFTING
NEAR THE NORTHERN END OF VANCOUVER ISLAND AS A TRAILING COLD FRONT
CLIPS THE COASTAL RANGES OF WESTERN WA. WILL PREFER A GENERAL
MODEL BLEND TO RESOLVE THE MODEL SPREAD AT THIS POINT, AS THERE IS
AT LEAST SOME MODEST ENSEMBLE SUPPORT FOR THE CMC/UKMET SOLUTIONS.
..SOUTHERN STREAM SHORTWAVE CROSSING CALIFORNIA BY MONDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z NAM/GFS AND 00Z ECMWF
CONFIDENCE: 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. THE
00Z UKMET APPEARS TO BE A BIT TOO SLOW WITH THIS SYSTEM, WITH THE
00Z CMC PROBABLY TOO PROGRESSIVE. THE MODEL CONSENSUS IS GENERALLY
BETTER REPRESENTED BY A BLEND OF THE 12Z NAM/GFS AND 00Z ECMWF,
AND HAS GOOD ENSEMBLE SUPPORT, SO A BLEND OF THESE SOLUTIONS WILL
BE PREFERRED.
..DEEP UPPER TROUGH OFFSHORE THE WEST COAST ON MONDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z NAM/GFS AND 00Z UKMET
CONFIDENCE: BELOW AVERAGE
THE GUIDANCE DEPICTS A PROGRESSIVE AND DEEP UPPER TROUGH/CLOSED
LOW OFFSHORE THE WEST COAST BY MONDAY. THE TIMING DETAILS OF THE
SYSTEM ARE GENERALLY WELL AGREED UPON, BUT THE 12Z NAM/GFS AND 00Z
UKMET ALL TAKE THE CLOSED LOW A TAD SOUTH OF THE 00Z CMC AND
ESPECIALLY THE 00Z ECMWF. THE ENSEMBLES MEANS ARE SPLIT AS WELL,
WITH THE GEFS MEAN SUPPORTING THE SOUTHERLY CAMP, AND THE ECENS
MEAN IN FAVOR OF THE ECMWF ALBEIT PERHAPS A TAD SLOWER. THE
FARTHER NORTH ECMWF/ECENS MEAN CONSENSUS APPEARS TO BE RELATED TO
SOMEWHAT STRONGER ENERGY THESE SOLUTIONS HAVE OVER THE GULF OF AK.
THE PREFERENCE FOR NOW WILL BE TOWARD THE MORE SOUTHERLY
CONSENSUS, BUT WITH LIMITED CONFIDENCE.
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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