788
FXUS10 KWNH 251645
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1244 PM EDT MON MAY 25 2020
VALID MAY 25/1200 UTC THRU MAY 29/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z NAM/GFS EVALUATION INCLUDING LATEST PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
WEAKENING LONG WAVE TROUGH CROSSING THE NORTHERN PLAINS
SHORT WAVE ENERGY IN THE NORTHERN STREAM TRACKING ACROSS THE
NORTHERN PLAINS WED
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/00Z ECMWF BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
BOTH THE 12Z NAM/GFS ARE CLOSE TO THE CONSENSUS WITH THE INITIAL
LONG WAVE TROUGH OVER THE NORTHERN HIGH PLAINS WEAKENING ACROSS
THE NORTHERN PLAINS TUE AS IT ENCOUNTERS MID LEVEL RIDGING
BUILDING NORTHWESTWARD FROM THE NORTHERN MID ATLANTIC/SOUTHERN NEW
ENGLAND. BOTH MODELS ARE CLOSE TO THE CONSENSUS WITH SHORT WAVE
ENERGY COMING ACROSS THE BRITISH COLUMBIA COAST EARLY TUE, WHICH
THEN MOVES ALONG THE INTERNATIONAL BORDER INTO EARLY WED.
AFTER THAT TIME, THE 12Z NAM SLOWS WITH THE EVOLVING FEATURE, AS
THE 00Z UKMET/CMC REMAIN FLATTER WITH THE MID LEVEL WAVE. ALMOST
ALL MODELS HAVE SLOWED WITH THIS FEATURE IN THE LAST THREE MODEL
RUNS, THOUGH THE 12Z GFS/00Z ECMWF HAVE BEEN THE MOST CONSISTENT
WITH ITS DURING THAT TIME. THESE MODELS ALSO HAVE THE SUPPORT OF
THEIR RESPECTIVE ENSEMBLE MEAN SOLUTION.
BASED ON THIS, A 12Z GFS/00Z ECWMF BLEND IS PREFERRED. IN THE FAST
FLOW, THERE IS BOUND TO BE SOME TIMING ISSUES UNTIL WE GET CLOSER
TO THE EVENT, BUT FOR NOW FORECAST CONFIDENCE REMAINS SLIGHTLY
ABOVE AVERAGE.
FULL LATITUDE OVER THE ROCKIES EVOLVING INTO CLOSED LOW OVER
SOUTHERN PLAINS/LOWER AND MID MS VALLEY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/00Z ECMWF/00Z CMC BLEND
CONFIDENCE: AVERAGE
THE 12Z NAM/GFS ARE CLOSE TO THE MODEL CONSENSUS AS SHORT WAVE
ENERGY OVER THE SOUTHWEST DROPS INTO THE BASE OF THE DEVELOPING
FULL LATITUDE TROUGH ACROSS THE WESTERN HIGH PLAINS THROUGH
26/00Z. THE 12Z NAM BECOMES FASTER WITH THE FEATURE AS IT CROSSES
THE SOUTHERN PLAINS INTO THE LOWER MS VALLEY, AS IT IS NOT AS
SHARP WITH THE RIDGE OVER THE CENTRAL ROCKIES.
IN CONTRAST, THE 12Z GFS REMAINS CLOSE TO THE CONSENSUS WITH THE
CLOSING MID LEVEL LOW AS IT REACHES THE LOWER AND MID MS VALLEY BY
29/00Z. THE 00Z UKMET REMAINS SLOWER AND FURTHER SOUTH WITH THE
MID LEVEL SYSTEM (AND THIS TREND HAS BEEN EMERGING OVER THE PAST
THREE MODEL CYCLES), THOUGH ITS UPSTREAM DEPICTION OF THE RIDGING
IS CLOSE TO THE CONSENSUS.
WITH DIFFERENCES IN THE UPSTREAM RIDGE SEEMINGLY HOLDING SOME
INFLUENCE ON HOW THE CLOSED MID LEVEL SYSTEM EVOLVES, FORECAST
CONFIDENCE IS ONLY AVERAGE. SINCE THE 12Z GFS/00Z ECMWF HAVE BEEN
THE MOST CONSISTENT WITH THE FEATURE (AND HAVE SUPPORT OF THEIR
ENSEMBLE MEANS), THIS BLEND IS PREFERRED.
MID-LEVEL TROUGH AND WEAK SURFACE LOWS IMPACTING FLORIDA/SOUTHEAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/00Z ECMWF BLEND
CONFIDENCE: AVERAGE
THE 12Z NAM/GFS SHOW THE MID LEVEL SHORT WAVE ENERGY OVER THE
CENTRAL GULF OF MEXICO EARLY IN THE PERIOD, WHICH IS CLOSE TO THE
MODEL CONSENSUS. HOWEVER, THE MID LEVEL FEATURE BECOMES MORE
DIFFICULT TO DISCERN WITH TIME AS IT TRACKS TOWARD TUE MORNING,
WITH ANOTHER MID LEVEL SHORT WAVE CROSSING THE BAHAMAS. BOTH THE
12Z NAM/GFS ARE CLOSE TO THE CONSENSUS WITH THIS FEATURE AS WELL.
WHILE THE 12Z NAM/GFS ARE CLOSE ON THE SUBTLE WAVE FORMING ALONG
THE MIDDLE FL EAST COAST BEFORE 12Z TUE. WHILE THERE IS GOOD
ENSEMBLE AGREEMENT THAT THE WAVE TRACKS TOWARD GA/SC, THE 12Z NAM
SEEMS TOO STRONG WITH ITS SURFACE LOW AS IT CROSSES THE SC COAST
NEAR 27/12Z. THE 12Z GFS/00Z ECMWF HAVE ENSEMBLE SUPPORT BRINGING
THE WEAK SURFACE WAVE INTO GA/WESTERN SC DURING THIS TIME. SINCE
THERE IS BETTER AGREEMENT WITH THIS FEATURE AMONG THESE SOLUTIONS,
THE 12Z GFS/00Z ECMWF BLEND WAS PREFERRED, BUT GIVEN THE SPREAD IN
THE TRACK OF THE SURFACE LOW, FORECAST CONFIDENCE IS ONLY AVERAGE.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
HAYES
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