589
FXUS10 KWNH 070458
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1258 AM EDT THU MAY 07 2020
VALID MAY 07/0000 UTC THRU MAY 10/1200 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z NAM/GFS EVALUATION INCLUDING LATEST PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...SHORT WAVE TRACKING FROM THE NORTHERN ROCKIES ACROSS THE OH
VALLEY TO THE MID ATLANTIC...
...STRONG VORTEX MOVING FROM ONTARIO INTO LABRADOR
..DEEPENING SURFACE LOW FROM THE OH VALLEY TO THE NORTHEAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS/12Z ECMWF/12Z ECENS MEAN BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE 00Z NAM/GFS ARE CLOSE TO THE CONSENSUS TAKING THE STRONG SHORT
WAVE FROM WESTERN MT INTO MO THROUGH 08/12Z. AFTER THAT TIME, THE
00Z NAM SHEARS OUT THE SHORT WAVE ENERGY IN THE FAST FLOW OVER THE
MID ATLANTIC STATES. THE 00Z NAM THEN TAKES THE SURFACE LOW FROM
THE OH VALLEY TO THE NORTHERN MID ATLANTIC COAST MORE QUICKLY,
MOVING IT ACROSS SOUTHWEST NOVA SCOTIA (MUCH LIKE THE 12Z UKMET)
AFTER 09/12Z.
BY CONTRAST, THE 00Z GFS PHASES THE SHORT WAVE ENERGY THE VORTEX
DROPPING SOUTHEAST FROM ONTARIO, AND RESULTING IN A MORE
SOUTHWESTERLY MID LEVEL FLOW AHEAD OF THE VORTEX. THE MORE
SOUTHWESTERLY FLOW ALLOWS THE SURFACE LOW TO TRACK FURTHER WEST
ACROSS DOWNEAST ME (MUCH LIKE THE MUCH MORE CONSISTENT 12Z ECMWF,
BUT JUST A BIT SLOWER AND A TOUCH DEEPER). THE 12Z CMC FOLLOWS A
SIMILAR PATH, THOUGH IT IS QUICKER WITH THE PHASING, ALLOWING ITS
SURFACE LOW TO RACE AHEAD OF 00Z GFS/12Z ECMWF CONSENSUS WITH THE
TRACK OF LOW.
OBVIOUSLY, THE KEY TO THE FORECAST IS GOING TO BE JUST HOW THE
SHORT WAVE OVER THE NORTHERN ROCKIES THIS MORNING PHASES WITH THE
VORTEX DROPPING OUT OF ONTARIO. THE BETTER AGREEMENT BETWEEN THE
00Z GFS/12Z ECMWF INCREASES CONFIDENCE FOR A SOLUTION FURTHER WEST
(BOLSTERED BY THE SUPPORT OF THE 12Z ECMWF ENSEMBLE MEAN).
FORECAST CONFIDENCE HAS INCREASED A BIT BECAUSE OF THE AGREEMENT,
BUT IT IS CLEAR THAT THE PHASING SCENARIO IS NOT QUITE LOCKED IN
YET.
...SHORTWAVE/SURFACE LOW IMPACTING THE NORTHERN ROCKIES AND
NORTHERN PLAINS FRI/SAT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS/12Z ECMWF BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE
THE 00Z NAM/GFS ARE CLOSE TO THE CONSENSUS TAKING SHORT WAVE
ENERGY OUT OF ALBERTA/MANITOBA BEFORE 09/00Z AND TRACKING IT
ACROSS THE NORTHERN PLAINS SAT. THE 00Z NAM BECOMES FASTER THAN
THE CONSENSUS (AS DOES THE 12Z UKMET/CMC) AFTER THAT TIME, AS IT
APPEARS TO FEEL THE EDGE OF THE VORTEX MOVING INTO LABRADOR. THE
12Z GFS IS CLOSER TO THE 12Z ECMWF/12Z ECMWF ENSEMBLE MEAN WITH
THE MOVEMENT OF THE SHORT WAVE. THIS BLEND APPEARS TO BE THE BEST
CONSENSUS OF MID LEVEL SOLUTIONS.
HOWEVER, THERE IS MORE SPREAD CONCERNING THE TRACK OF THE SURFACE
LOW THAT DEVELOPING AHEAD OF THE MID LEVEL SYSTEM, ESPECIALLY
TOWARD 10/00Z. BASED ON THE INCREASING SPREAD OF THE SURFACE LOW,
FORECAST CONFIDENCE IS SLIGHTLY BELOW AVERAGE.
..SHORT WAVE ENERGY CROSSING SOUTHERN CA BY THE SUN MORNING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE 00Z NAM/GFS ARE CLOSE TO THE CONSENSUS TAKING SHORT WAVE
ENERGY FROM 30N 126W AND TRACKING IT TOWARD THE SOUTHERN CA COAST
BY THE END OF THE PERIOD. GIVEN THE RELATIVELY TIGHT CLUSTERING
WITH RESPECT TO THE MID LEVEL FEATURE, A GENERAL MODEL BLEND IS
PREFERRED, WITH SLIGHTLY ABOVE AVERAGE FORECAST CONFIDENCE.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
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