600
FXUS10 KWNH 160450
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1245 AM EDT THU APR 16 2020
VALID APR 16/0000 UTC THRU APR 19/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z NAM/GFS MODEL EVALUATION WITH PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...NORTHERN STREAM SHORT WAVE CROSSING THE ROCKIES AND THE OHIO
VALLEY THU/FRI MOVING INTO SOUTHERN NEW ENGLAND SAT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF/UKMET BLEND
CONFIDENCE: AVERAGE
WHILE THE 00Z NAM/GFS ARE CLOSE TO THE CONSENSUS AS THE SHORT WAVE
IN THE ROCKIES CROSSING THE CENTRAL PLAINS, BOTH BECOME FASTER
THAN THE CONSENSUS AHEAD OF SHORT WAVE ENERGY DROPPING INTO THE
FLOW FROM THE PACIFIC NORTHWEST. THE DIFFERENCES BECOME MORE
AMPLIFIED WITH TIME ACROSS THE OHIO VALLEY AND SOUTHERN NEW
ENGLAND. THE FASTER TIMING OF THE SHORT WAVE RESULTS IN THE
SURFACE WAVE MOVING FASTER ALONG A FRONTAL BOUNDARY STRETCHING
ACROSS OHIO VALLEY INTO FRI. THE 12Z ECMWF/UKMET HAVE CONSISTENTLY
BEEN SLOWER WITH THE MID LEVEL FEATURE AND THE SURFACE WAVE, SO
THIS PAIR COMPRISE THE PREFERRED BLEND HERE.
IT SHOULD BE NOTED THAT AS THE SURFACE LOW DEEPENS OFF THE NEW
ENGLAND COAST SAT, THE 12Z UKMET BECOMES FASTER THEN THE 12Z
ECMWF/ECMWF ENSEMBLE MEAN. BY THAT TIME, MOST OF THE SENSIBLE
WEATHER IS EXPECTED TO BE OFF THE COAST. GIVEN THE SPREAD IN THE
NCEP VS NON-NCEP GUIDANCE, FORECAST CONFIDENCE IS JUST AVERAGE.
..SHORT WAVE ENERGY CROSSING WEST COAST FRI AND SOUTHWEST SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF/UKMET BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE
AS THE CLOSED MID LEVEL LOW OFF THE NORTHERN CA COAST EARLY DROPS
INTO SOUTHERN CA, IT OPENS UP INTO A LONG WAVE TROUGH. THE 00Z
NAM/GFS ARE CLOSE TO THE CONSENSUS THROUGH THIS POINT. HOWEVER, AS
THE LONG WAVE TROUGH STARTS TO WEAKEN, THE 00Z GFS BECOMES FASTER
THAN THE CONSENSUS AS IT REACTS TO ADDITIONAL UPSTREAM SHORT WAVE
ENERGY AFTER 18/12Z. THE 00Z NAM BECOMES FLATTER, SEEMINGLY
LOSING THE ENERGY IN THE MID LEVELS TOO QUICKLY. WITH THIS WAVE,
THE 12Z ECMWF/UKMET HAVE THE MOST CONSISTENCY, THOUGH THERE ARE
TIMING ISSUES HERE AS WELL.
TRAILING SHORT WAVE ENERGY FROM NORTHERN CA FOLLOWS A PATH SIMILAR
TO THE FIRST MID LEVEL WAVE LATE IN THE PERIOD. THE INTERACTION
BETWEEN THE TWO SHORT WAVES IS CAUSING SOME ISSUES FOR THE
GUIDANCE, AS THE 00Z GFS IS SLOWER THAN THE CONSENSUS, WHILE THE
00Z NAM IS A BIT FASTER. THE TIMING ISSUES SUGGEST THAT MODELS ARE
NOT HANDLING THE INTERACTION WELL. BASED ON THIS, FORECAST
CONFIDENCE IS SLIGHTLY BELOW AVERAGE.
..SHORT WAVE CROSSING ALBERTA/MANITOBA SAT
..SURFACE COLD FRONT ACROSS THE NORTHERN PLAINS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-00Z NAM BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE 00Z NAM/GFS ARE CLOSE TO THE CONSENSUS DROPPING SHORT WAVE
ENERGY INTO THE DEVELOPING BROAD LONG WAVE TROUGH OVER THE
NORTHERN PLAINS BY THE END OF THE PERIOD. HOWEVER, THE 00Z NAM
BECOMES SLOWER THAN THE CONSENSUS WITH THE ATTENDING COLD FRONT
ACROSS THE NORTHERN PLAINS AND UPPER MS VALLEY, ESPECIALLY AFTER
18/00Z.
SINCE THERE IS GENERALLY GOOD CLUSTERING WITH THE SURFACE AND MID
LEVEL FEATURES, ONLY THE 00Z NAM IS NOT INCLUDED IN THE
PREFERENCE, WITH SLIGHTLY ABOVE AVERAGE CONFIDENCE.
...SHORTWAVE AMPLIFYING FROM BC COAST INTO THE PACIFIC NORTHWEST
SAT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS/12Z ECWMF BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE
SHORT WAVE ENERGY DROPPING ACROSS WESTERN CANADA AFTER 17/12Z
STARTS ERODING THE MID LEVEL RIDGING ACROSS THE PACIFIC NORTHWEST,
EVENTUALLY FORMING A CLOSED MID LEVEL OVER
WA/OR BY 19/12Z. THE 00Z NAM/GFS ARE CLOSE TO THE CONSENSUS
THROUGH THIS PROCESS, WITH THE 00Z GFS CLOSE TO THE 12Z ECMWF/12Z
ECMWF MEAN WITH THE PLACEMENT OF THE CLOSED LOW. THE 00Z NAM
BECOMES FASTER WITH THE MID LEVEL SYSTEM. NEVER FULLY CLOSING OFF.
THIS COULD BE DUE TO HOW IT HANDLES THE RIDGING THAT POKES UP
ALONG THE BC COAST.
THERE IS STILL A FAIR AMOUNT OF SPREAD WITH THE EVOLUTION OF THE
MID LEVEL SYSTEM, SO FORECAST CONFIDENCE IS SLIGHTLY BELOW 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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page