349
FXUS10 KWNH 221930
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
330 PM EDT SUN SEP 22 2019
VALID SEP 22/1200 UTC THRU SEP 26/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...DEEP TROUGH CROSSING THE UPPER MS VALLEY TONIGHT, GREAT LAKES
MONDAY, NORTHEAST TUESDAY, CANADIAN MARITIMES WEDNESDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: MULTI-MODEL CONSENSUS, CLOSE TO THE 12Z NAM/GFS/ECMWF
CONFIDENCE: ABOVE AVERAGE
MODEL DIFFERENCES WITH THE TROUGH ARE RATHER SMALL THROUGH TONIGHT
AS THE ENERGY CROSSES THE UPPER MS VALLEY, THE GREAT LAKES ON
MONDAY, AND NORTHEAST ON TUESDAY.
THE PRIMARY DIFFERENCES DEVELOP AS THE MID LEVEL CIRCULATION
DEPARTS NEW ENGLAND ON WED, WITH BOTH TIMING AND TRACK DIFFERENCES
GRADUALLY GROWING. A CONSENSUS APPROACH IS SUGGESTED UNTIL BETTER
CLUSTERING DEVELOPS OVER THE CANADIAN MARITIMES ON WED. THE 12Z
ECMWF TRENDED TOWARDS THE 12Z NAM AND GFS, SO CLUSTERING HAS
IMPROVED THIS RUN.
..UPPER TROUGH DIGGING INTO THE WEST BY MONDAY
..CLOSED LOW EVOLUTION OVER THE SOUTHWEST BY TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF 00Z-12Z ECMWF/12Z GFS/00Z UKMET
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
REGARDING THE SECOND TROUGH MOVING INTO THE WEST, THE MODEL
GUIDANCE IS WELL CLUSTERED AND IN GOOD AGREEMENT WITH RESPECT TO
TIMING AND DEPTH THROUGH MOST OF MONDAY. THE MODEL MAJORITY SHOWS
A CLOSED 500 MB LOW DEVELOPING AS THE ENERGY DIGS SOUTH INTO THE
SOUTHWEST ON TUESDAY. THE LOW DRIFTS SOUTH TO SOUTHWEST NEAR THE
MEXICAN BORDER WED, POSSIBLY OVER THE
NORTHERN GULF OF CA OR JUST A TAD EAST OF HERE OVER NORTHWEST
MAINLAND MEXICO WEDNESDAY.
THE 06Z GEFS MEAN AND 12Z NAM ARE STILL FARTHER EAST WITH THE
CLOSED LOW SOLUTION, AND 12Z UKMET A TAD FURTHER WEST.
ALL OF THE MODELS DO INDICATE SOME INTERACTION WITH THE REMNANT
MOISTURE AND ENERGY ASSOCIATED WITH THE REMNANTS OF
LORENA, WHICH HAS BEEN DECLARED POST-TROPICAL, AND IS EXPECTED TO
DISSIPATE TONIGHT. GIVEN THE MUCH BETTER DETERMINISTIC CLUSTERING
WITH THE CLOSED LOW EVOLUTION AMONG THE 00-12Z ECMWF/12Z GFS/00Z
UKMET, THE PREFERENCE WILL BE TO BLEND THESE SOLUTIONS.
..UPPER TROUGH OVER THE NORTHERN PLAINS BY TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: MULTI-MODEL CONSENSUS OF 12Z ECMWF/12Z UKMET/12Z GFS
CONFIDENCE: ABOVE AVERAGE
THE MODELS HAVE GOOD AGREEMENT OVERALL WITH THE DETAILS OF A
NORTHERN STREAM TROUGH AND ASSOCIATED COLD FRONT CROSSING THE
NORTHERN HIGH PLAINS BY TUESDAY AND UPPER MIDWEST BY WEDNESDAY.
MINOR TIMING AND AMPLITUDE/PHASING DIFFERENCES EXIST TUE NIGHT AND
WED AMONG THE GLOBAL MODELS AND THEIR ENSEMBLE MEANS. THE
SOLUTIONS CLUSTER WELL SO A CONSENSUS APPROACH TO BLEND THE
ECMWF/GFS/UKMET SHOULD WORK WELL.
...UPPER TROUGH APPROACHING VANCOUVER ISLAND WED
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: MULTI-MODEL CONSENSUS OF 12Z ECMWF/12Z UKMET/06Z GFS
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE MODELS INDICATE A 700 MB-500 MB WAVE DEVELOPS WEST OF
VANCOUVER ISLAND AND MOVES EAST TOWARDS THE COAST ON WED, POSSIBLY
EXTENDING AS FAR SOUTH AS NORTHERN WA STATE. THE 12Z NAM/06Z
GFS/12Z UKMET/12Z ECMWF ALL SHOW THE WAVE, WITH TYPICAL TIMING
DIFFERENCE FROM MODEL TO MODEL AND FROM ONE RUN TO THE NEXT. THE
NAM STANDS OUT WITH LOWER 700 MB HEIGHTS THAN OTHER SOLUTIONS, SO
LESS WEIGHTING SHOULD BE GIVEN TO THE NAM, GIVEN CONFLUENT FLOW
HINDERING AMPLIFICATION. USE OF A ECMWF/UKMET/GFS CONSENSUS IS
RECOMMENDED DUE TO A SIMILAR AMPLITUDE AND TRACK OF THE 700 MB
WAVE.
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML
PETERSEN
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