390
FXUS10 KWNH 131842
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
241 PM EDT FRI MAR 13 2020
VALID MAR 13/1200 UTC THRU MAR 17/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH FINAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..CLOSED LOW DEVELOPING OVER PACIFIC NW THROUGH SATURDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH 00Z/16
12Z ECMWF/UKMET/CMC BLEND 00Z/16 - 00Z/17
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
MODEL DIFFERENCES REMAIN SMALL UNTIL SUNDAY EVENING WHEN THE 12Z
GFS ENDS UP FARTHER SOUTH WITH THE 700-500 MB LOW OFF OF THE WEST
COAST. THE 12Z GFS IS NOT AN OUTLIER WHEN CONSIDERING THE
AVAILABLE ENSEMBLE GUIDANCE BUT GIVEN GREATER SUPPORT FOR A
NON-GFS SOLUTION BY SUNDAY. THE NEW 12Z ECMWF/UKMET/CMC CAME IN
AND SPLIT THE DIFFERENCE BETWEEN THE SOUTHWARD DISPLACED 12Z GFS
AND SLOWER/NORTHERN 12Z NAM. THIS MIDDLE GROUND LOOKS PREFERABLE
AND SO THE FINAL PREFERENCE HAS BEEN ADJUSTED TO REFLECT THE
UPDATED THINKING.
...WEAKENING MID-LEVEL SHORTWAVE TRACKING THROUGH THE SOUTHWEST
TODAY, WEAKENING ACROSS THE MIDWEST LATE SATURDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-12Z NAM BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
ONLY MINOR TIMING/AMPLITUDE DIFFERENCES REMAIN WITH THE MID-LEVEL
SHORTWAVE AS IT TRACKS EAST THROUGH THE OH VALLEY. THE 12Z NAM, AS
WITH PREVIOUS CYCLES, CONTINUES TO LOOK TOO FAST, HOWEVER NOT BY A
LOT. A NON-12Z NAM BLEND OF GUIDANCE LOOKS REASONABLE WITH THIS
SYSTEM.
THERE ARE SOME LATITUDE DIFFERENCES WITH THE TRAILING FRONT ACROSS
THE SOUTHERN STATES BY SATURDAY INTO SUNDAY WITH A WEAKER SURFACE
LOW NOTED IN THE 12Z GFS TRACKING ACROSS THE MISSISSIPPI RIVER
VALLEY ALLOWING FOR A MORE SOUTHERN-PLACED WARM FRONT. THE GFS IS
NOT AN OUTLIER, BUT THERE IS LESS SUPPORT FOR IT AMONG THE
REMAINING DETERMINISTIC GUIDANCE. ENSEMBLE MEANS SUPPORT A MIDDLE
GROUND WHICH CAN BE REPRESENTED BY A GENERAL BLEND, REMOVING THE
FASTER TIMING OF THE 12Z NAM ACROSS THE EASTERN U.S.
THE 12Z ECMWF/UKMET/CMC DID NOT MAKE SIGNIFICANT DIFFERENCES FROM
THEIR PREVIOUS 00Z CYCLES, SO THE PREFERENCE REMAINS THE SAME FOR
THIS FINAL DISCUSSION.
...BASE OF LONGWAVE TROUGH OVER THE NORTH-CENTRAL U.S. BY MONDAY
EVENING...
..RELATED COLD FRONT ACROSS THE UPPER MIDWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-12Z GFS BLEND
CONFIDENCE: AVERAGE
THE 12Z GFS STANDS OUT AS THE FASTER MODEL WITH THIS SYSTEM, A NON
12Z GFS BLEND WILL BE PREFERRED GIVEN THE REMAINING DETERMINISTIC
AND ENSEMBLE GUIDANCE (INCLUDING THE 06Z GEFS) IS SLOWER THAN THE
12Z GFS. WHILE THE 12Z GEFS MATCHES THE TIMING OF THE 12Z GFS WITH
THE FRONT, NO SIGNIFICANT CHANGES NOTED WITH THE 12Z
ECMWF/UKMET/CMC TRANSLATE INTO KEEPING THE PREFERENCE THE SAME FOR
THIS FINAL DISCUSSION.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
OTTO
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page