887
FXUS10 KWNH 280657
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
157 AM EST TUE JAN 28 2020
VALID JAN 28/0000 UTC THRU JAN 31/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH FINAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...SPLIT FLOW TROUGH CROSSING THE MOUNTAIN WEST OVERNIGHT AND
REACHING THE SOUTHEAST WEDNESDAY NIGHT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 28/00Z GFS/ECMWF/UKMET
CONFIDENCE: AVERAGE
THE LATEST NCEP RUNS REMAINS IN DECENT AGREEMENT WITH THE SYNOPTIC
PATTERN...ALTHOUGH THE 28/00Z NAM WAS A WEAK AND SLOW OUTLIER BY
THE END OF DAY 3. THE CANADIAN WAS CLUSTERED BETTER WITH THE NCEP
GUIDANCE THAN IT WAS IN PREVIOUS RUNS, BUT IT ALSO BECAME AN
OUTLIER BY 00Z THURSDAY...LEAVING THE UKMET IN DECENT AGREEMENT
WITH THE NCEP GUIDANCE EVEN IT WAS A TAD SLOW COMPARED WITH
CONSENSUS. THIS LEAVES THE PREVIOUS MODEL CHOICES PRETTY MUCH IN
TACT WITH A COMBINATION OF THE 28/00Z GFS/UKMET RESULTING IN A
GOOD STARTING POINT FOR THIS SYSTEM...WITH THE NAM AND CMC STILL
NOT PREFERRED.
...SPLIT FLOW TROUGH IN NORTHERN STREAM FROM THE UPPER MIDWEST TO
THE MID-ATLANTIC THURSDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: MODIFIED VERSION OF 28/00Z GFS/ECMWF/EC ENSEMBLE MEAN
CONFIDENCE: BELOW AVERAGE
THE 28/00Z SUITE OF GUIDANCE TENDED TO SHOW MORE SPREAD THAN IN
PREVIOUS RUNS AS SHORTWAVE ENERGY DROPPS FROM SASKATCHEWAN AND
MANITOBA INTO THE UPPER MIDWEST TUESDAY NIGHT INTO WEDNESDAY
MORNING. CONSIDERING THAT IT IS THE NORTHERN BRANCH OF SPLIT FLOW
AND DOWNSTREAM FROM AN AMPLIFYING RIDGE...IT IS A REGION WHERE
BELOW AVERAGE PREDICTABLITY IS NOT SURPRISING. BOTH THE 28/00Z
GFS AND ECMWF SHOWED A MORE AMPLIFIED WAVE THAT PROPAGATES INTO
THE OHIO VALLEY...WITH MID-LEVEL HEIGHTS SOME 60 METERS TO 80
METERS LOWER THAN OTHER GUIDANCE. THAT APPEARS TO BE A CONSEQUENCE
OF HOW MUCH CONNECTION THESE MODELS SHOW BETWEEN THIS WAVE AND THE
SOUTHERN BRANCH OF THE SPLIT STREAM MENTIONED ABOVE...WITH BOTH
OPERATIONAL ECMWF AND GFS SHOWING WHAT APPEARS TO BE AN
UNREALISTICALLY SHARP AMPLITUDE FOR A MID-LEVEL WAVE. FEEL THAT
THE 28/00Z ECMWF/GFS AND THE 27/12Z EC ENEMBLES MAY HAVE A BETTER
HANDLE ON THE TIMING OF THE WAVE AND THE IDEA THAT THE WAVE WILL
BE MORE AMPLIFIED THAN SHOWN BY OTHER MODELS...BUT FEEL THAT THE
RESULTING MASS FIELDS AND DERIVED PARAMTERS SHOULD BE TEMPERED TO
OFFSET WHAT SEEMS TO BE AN OVER AMPLIFIED SOLUTION.
...PROGRESSIVE UPPER TROUGH OVER THE PACIFIC NORTHWEST AND
AMPLIFYING INTO THE SOUTHERN PLAINS WEDNESDAY/THURSDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
YET ANOTHER IN A SERIES OF SYSTEMS MOVING IN FROM THE PACIFIC WILL
MOVE ONSHORE LATER TODAY AND THEN DIG INTO THE SOUTHWESTERN U.S.
ON DAYS 2/3. THE MODELS TENDED TO HANDLE THE RIDGE BUILDING TO
THE WEST OF THIS SYSTEM OVER THE EASTERN NORTH PACIFIC OCEAN AND
THAT RESULTS IN A FAIRLY CONSISTENT SOLUTION DOWNSTREAM AS THE
TROUGH DROPS SOUTHWEST AND AMPLIFIES NEAR THE BASE OF THE TROUGH.
THE 28/00Z RUNS OF THE GFS AND UKMET REMAIN A BIT MORE PROGRESSIVE
SIMILAR TO THE 27/12Z AND 28/00Z RUNS OF THE ECMWF. GIVEN THE
MAGNITUDE OF THE RIDGE BUILDING UPSTREAM, WOULD TEND TO STAY AWAY
FROM THE SOLUTIONS WHICH ARE FASTER TO MOVE THE SYSTEM OFF THE THE
EAST. STILL THINK THAT TRENDS SUGGEST THAT A SOLUTION SOMEWHERE
IN THE MIDDLE IS THE MOST PROBABLE OUTCOME AT THIS TIME THROUGH
12Z FRIDAY.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
BANN
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