695
FXUS10 KWNH 171905
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
204 PM 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/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 12Z 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 12Z
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 12Z 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-GFS 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 GLOBAL MODELS HAVE OVERALL TRENDED SLOWER, AND TOWARD THE
ALREADY SLOWER NAM SOLUTION. THE OUTLIER SOLUTION AT THIS POINT IS
NOW THE GFS WHICH APPEARS TO BE TOO PROGRESSIVE. THUS, A NON-GFS
BLEND WILL BE PREFERRED GIVEN THE STRONG NON-NCEP MODEL TREND
TOWARD THE NAM.
..SHORTWAVE/FRONT CLIPPING THE PACIFIC NORTHWEST BY MONDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-UKMET BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE GUIDANCE SUPPORTS A PROGRESSIVE PACIFIC SHORTWAVE TROUGH
CLIPPING THE PACIFIC NORTHWEST BY EARLY MONDAY. THE 12Z UKMET IS A
TAD DEEPER WITH THE SYSTEM COMPARED TO THE REMAINING SUITE OF
GUIDANCE, AND IS ALSO A TAD SLOWER WITH ITS SURFACE REFLECTION
WHICH IS A SOMEWHAT STRONGER SURFACE LOW/WAVE ALONG AN A FRONTAL
BOUNDARY NEARING VANCOUVER ISLAND AND TRAILING NEAR THE COASTAL
RANGES OF WESTERN WA. A NON-UKMET BLEND WILL BE PREFERRED WITH
THIS SYSTEM.
..SOUTHERN STREAM SHORTWAVE CROSSING CALIFORNIA BY MONDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
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
12Z GFS/CMC SOLUTIONS EDGE TOWARD THE MORE PROGRESSIVE SIDE OF THE
GUIDANCE, WITH THE 12Z UKMET/ECMWF SLOWER. THE 12Z NAM TENDS TO
SPLIT THE DIFFERENCE. THE LATEST GEFS ENSEMBLE CLUSTER FAVORS THE
MORE PROGRESSIVE CAMP, WITH THE ECENS ENSEMBLE CLUSTER SIDING WITH
THE SLOWER CAMP. OVERALL, THE DIFFERENCES ARE RELATIVELY MODEST,
SO A GENERAL MODEL BLEND WILL BE PREFERRED TO RESOLVE THIS.
..DEEP UPPER TROUGH OFFSHORE THE WEST COAST ON MONDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z GEFS/00Z ECENS MEANS
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 LATEST NAM/GFS AND
UKMET ALL TAKE THE CLOSED LOW A TAD SOUTH OF THE CMC AND
ESPECIALLY THE 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. A CHECK OF THE
LATEST CMCE MEAN SUGGESTS THE NORTHERLY CMC/ECMWF CAMP HAVING SOME
SUPPORT. BASED ON THE LATEST SPREAD/SPLIT IN CAMPS, A BLEND OF THE
GEFS/ECENS MEANS WILL BE PREFERRED AT THIS TIME.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
ORRISON
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