415
FXUS10 KWNH 211710
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1206 PM EST TUE JAN 21 2020
VALID JAN 21/1200 UTC THRU JAN 25/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH LATEST PREFERENCES AND FORECAST
CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~
..CLOSED LOW OFF THE SOUTHEAST COAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE UPPER LOW DROPPING ACROSS THE SOUTHEAST WILL CONTINUE
EAST-SOUTHEAST AND OFFSHORE TONIGHT BEFORE CROSSING JUST NORTH OF
THE BAHAMAS ON WEDNESDAY. RELATIVELY STRONG CYCLOGENESIS WILL
OCCUR OVER THE NEXT 12 TO 24 HOURS, WITH LOW PRESSURE THEN PULLING
EAST AND WELL AWAY FROM THE U.S. BY LATER WEDNESDAY AND THURSDAY.
THE GUIDANCE COMPRISED OF THE GLOBAL MODEL SUITE AND SHORTER RANGE
HIRES MODELS SHOW RELATIVELY GOOD AGREEMENT WITH THE TIMING
EVOLUTION OF THE LOW, WITH JUST SOME MODEST SPREAD WITH THE DEPTH
OF SURFACE LOW PRESSURE. AT THIS POINT, A GENERAL MODEL BLEND WILL
BE PREFERRED SINCE NO ONE SOLUTION AT THIS POINT APPEARS TO BE AN
OUTLIER.
..CURRENT UPPER LOW/TROUGH CROSSING INTO THE PACIFIC NORTHWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE DEEP LAYER CLOSED LOW JUST OFFSHORE THE PACIFIC NORTHWEST WILL
WEAKEN INTO A PROGRESSIVE TROUGH AS IT CROSSES BRITISH COLUMBIA
THROUGH TONIGHT, BUT IS FORECAST TO THEN REORGANIZE AND DEEPEN
OVER SOUTHERN ALBERTA ON WEDNESDAY BEFORE DROPPING SOUTHEAST
ACROSS THE NORTHERN HIGH PLAINS. AT LEAST THROUGH WEDNESDAY, THE
MODELS ARE IN GOOD AGREEMENT WITH THIS SYSTEM.
..BINARY INTERACTION OF CLOSED LOWS OVER THE PLAINS ON THURSDAY
..CONSOLIDATED DEEP LAYER CLOSED LOW OVER THE OH VALLEY FRIDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~
PREFERENCE: 12Z GFS/00Z UKMET/00Z ECMWF BLEND...THURSDAY
00Z ECENS MEAN (OR GFS/UKMET/ECMWF BLEND)...FRIDAY
CONFIDENCE: BELOW AVERAGE
GUIDANCE CONTINUES TO SUGGEST BINARY INTERACTION OF CLOSED LOWS
ACROSS THE PLAINS ON THURSDAY, WITH ONE CLOSED LOW DROPPING
SOUTHEAST ACROSS THE NORTHERN PLAINS, AND ANOTHER DEVELOPING
FARTHER SOUTH OVER THE CENTRAL PLAINS/LOWER MO VALLEY BY LATE
THURSDAY. AT LEAST THROUGH THURSDAY, THE 12Z NAM APPEARS TO BE A
DEEP OUTLIER WITH THE COLLECTIVE MASS FIELD EVOLUTION, WITH THE
00Z CMC TOO SLOW. BY EARLY FRIDAY, THE TWO CLOSED LOW BEGIN TO
CONSOLIDATE AND MOVE THROUGH THE OH VALLEY. THE 12Z GFS AND 12Z
NAM ARE FARTHER NORTH WITH THE MERGED SYSTEM, WITH THE NAM NOTABLY
SLOWER/DEEPER. OF THE 00Z NON-NCEP MODELS, THE UKMET IS SIMILARLY
AS FAST AS THE GFS, BUT IS FARTHER SOUTH. THE CMC AND ECMWF ARE
ALSO BOTH FARTHER SOUTH BUT SLOWER. THE LATEST GEFS MEAN FAVORS
THE FARTHER NORTH/FASTER GFS, BUT THE LATEST CMCE/ECENS CLUSTERS
ARE A LITTLE SLOWER YET A LITTLE NORTH OF THE DETERMINISTIC
CMC/ECMWF. THE MODEL PREFERENCE THROUGH THURSDAY WILL BE FOR A
BLEND OF THE GFS/UKMET AND ECMWF, HOWEVER, BY FRIDAY PREFERENCE
WILL BE TOWARD THE 00Z ECENS MEAN WHICH BEST APPROXIMATES THE
MODEL CONSENSUS, AND ACTS A BLEND OF THE GFS/UKMET AND ECMWF
SOLUTIONS WITH THEIR LATITUDINAL AND TIMING SPREADS. CONFIDENCE IN
THE DETAILS OF THE MASS FIELD EVOLUTION REMAINS LIMITED.
..SHORTWAVE CROSSING THE PACIFIC NORTHWEST ON FRIDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE MODELS BRING A PROGRESSIVE, LOW-AMPLITUDE SHORTWAVE IN ACROSS
THE PACIFIC NORTHWEST ON FRIDAY. THE GLOBAL MODELS SHOW DECENT
AGREEMENT WITH THE 12Z NAM A TAD MORE OUT OF TOLERANCE. WILL
PREFER A NON-NAM BLEND AT THIS POINT.
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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