682
FXUS10 KWNH 022016
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
315 PM EST THU JAN 02 2020
VALID JAN 02/1200 UTC THRU JAN 06/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH FINAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..UPPER LOW OVER MEXICO SHEARING TO THE NORTHEAST
..FRONTAL WAVE IMPACTING THE GULF COAST/TN VALLEY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
ONLY MINOR TIMING DIFFERENCES REMAIN WITH THE SHORTWAVE SHEARING
EASTWARD AND THE RELATED WEAK SURFACE LOW TO TRACK FROM MS TOWARD
THE EAST.
...AMPLIFYING LONGWAVE TROUGH ACROSS THE CENTRAL U.S.
..SURFACE LOW FROM THE LOWER MS VALLEY TO THE NORTHEAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z GEFS/00Z ECENS MEAN
(NEAREST TO 12Z GFS/12Z ECMWF)
CONFIDENCE: BELOW AVERAGE
THE INTERACTION BETWEEN A NORTHERN STREAM AND SOUTHERN STREAM
COMPONENT EMBEDDED WITHIN A LONGWAVE TROUGH PROGRESSING EASTWARD
FROM THE CENTRAL U.S. TRANSLATES INTO A DIFFICULT FORECAST
EVOLUTION. BY 12Z/04, THE 12Z GFS BEGINS TO PUSH AHEAD OF THE
REMAINING GUIDANCE WITH THE SOUTHERN STREAM AXIS OF VORTICITY
ALONG THE NORTHERN GULF COAST, DUE TO A MORE AMPLIFIED NORTHERN
STREAM COMPONENT ACROSS THE MIDWEST. HOWEVER, 12 HOURS LATER, AT
00Z/05, THE 12Z NAM IS FASTEST WITH ITS 500 MB TROUGH AXIS OVER
THE EASTERN U.S., FOLLOWED BY THE 12Z GFS/UKMET. THE 12Z CMC WAS
SLOWEST WITH THE 12Z ECMWF IN THE MIDDLE, BUT HAVING NUDGED FASTER
COMPARED TO ITS 00Z RUN. THE 12Z UKMET ALSO TRENDED FASTER
COMPARED TO ITS 00Z RUN.
WITH A FAIR DEGREE OF CONFIDENCE, IT CAN BE SAID THAT THE 12Z NAM
AND 12Z CMC HAVE A LOW LIKELIHOOD OF VERIFYING. HOWEVER, AMONG THE
REMAINING 12Z GFS/ECMWF/UKMET, THE RESULTING SURFACE LOW SHOWS
MODERATE SPREAD. WHILE THE ENSEMBLE SCATTER LOW PLOTS ARE RATHER
BROAD IN THEIR DEPICTION VALID 12Z/05, THE 12Z GFS'S SURFACE LOW
IS ON THE NORTHERN SIDE OF THE SURFACE LOWS, WHILE THE 12Z UKMET
IS EAST/FAST. THE 12Z ECMWF IS TOWARD THE SOUTH SIDE BUT A
SIGNIFICANT NUMBER OF ENSEMBLE SURFACE LOW PLOTS ARE WEST OF THE
12Z GFS/12Z ECMWF POSITION, HENCE THE RATHER AGREEABLE 12Z GEFS
AND 00Z ECMWF MEANS ARE WEST OF THEIR DETERMINISTIC COUNTERPARTS.
THE PREFERENCE IS TO BE BETWEEN THE 12Z GFS/12Z ECMWF BUT WITH A
SLIGHTLY WESTWARD TRACK OF THEIR SURFACE LOWS GIVEN ENSEMBLE MEAN
PLACEMENT. DUE TO POOR ENSEMBLE AGREEMENT AND POOR RUN TO RUN
CONSISTENCY IN THE GUIDANCE, CONFIDENCE IS BELOW AVERAGE.
..SHORTWAVE TROUGH/LOW IMPACTING THE PACIFIC NORTHWEST
..ENERGY EJECTING OUT ACROSS THE PLAINS/MIDWEST BY SAT/SUN
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF
CONFIDENCE: AVERAGE
THE PREFERENCE IS TO GO TOWARD THE MIDDLE OF THE LATEST
ENSEMBLE/DETERMINISTIC MODEL SPREAD. THE 12Z NAM IS FASTEST
FOLLOWED BY THE 12Z GFS AS THE SHORTWAVE TROUGH TRACKS EAST INTO
THE NORTHERN PLAINS. THE RESULTING COLD FRONT SHOWS SIMILARLY, BUT
THE 12Z ECMWF APPEARS TO BE IN THE FAVORED MIDDLE GROUND POSITION
DESPITE A SLIGHTLY FASTER TREND COMPARED TO ITS 00Z CYCLE. EVEN
CONSIDERING THE FASTER 12Z NAM, MODEL SPREAD IS RELATIVELY SMALL
THROUGH SUNDAY EVENING ACROSS THE UPPER MIDWEST AND SOUTHERN
PLAINS.
...NEXT MID-LEVEL TROUGH AXIS TO REACH THE PACIFIC NORTHWEST BY
SUN...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 12Z CMC BLEND
CONFIDENCE: AVERAGE
WHILE SOME AMPLITUDE DIFFERENCES EXIST WITH AN UPPER TROUGH AXIS
NEARING THE PACIFIC NORTHWEST BY SUNDAY, TIMING DIFFERENCES ARE
GREATER. THE RELATIVELY AGREEABLE ENSEMBLE MEANS SUPPORT A FASTER
TIMING WHEN COMPARED TO THE 12Z CMC. WHILE MINOR DIFFERENCES EXIST
AMONG THE REMAINING 12Z DETERMINISTIC GUIDANCE, A NON 12Z CMC
BLEND APPEARS REASONABLE FOR THIS SYSTEM AT THIS POINT IN TIME.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
OTTO
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page