991
FXUS10 KWNH 311715
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
114 PM EDT SUN MAY 31 2020
VALID MAY 31/1200 UTC THRU JUN 04/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION INCLUDING PRELIMINARY PREFERENCES AND
CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
UPPER LEVEL TROUGH AND COLD FRONT ACROSS THE EASTERN U.S.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH 12Z TUESDAY
CONFIDENCE: AVERAGE
WHILE DIFFERENCE CONTINUE TO DEVELOP DOWNSTREAM ACROSS ATLANTIC
CANADA, MODELS REMAIN IN GOOD AGREEMENT WITH THE EVOLUTION OF THE
UPPER TROUGH AS IT CONTINUES TO SWING ACROSS THE NORTHEAST U.S.
THROUGH EARLY TUESDAY.
UPPER LEVEL LOW SLOWLY LIFTING FROM NORTHERN MEXICO INTO THE
SOUTHERN PLAINS SUNDAY-TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
OVERALL, MODELS ARE IN GENERALLY GOOD AGREEMENT - SHOWING A BROAD
UPPER LOW DRIFTING NORTH ACROSS THE SOUTHERN PLAINS THROUGH EARLY
TUESDAY BEFORE WEAKENING AS REMNANT ENERGY SPREADS EAST INTO THE
LOWER MISSISSIPPI VALLEY ON WEDNESDAY.
SHORTWAVE LIFTING ACROSS THE PACIFIC NORTHWEST INTO CENTRAL CANADA
LATE SUNDAY INTO EARLY MONDAY,
THEN DROPPING SOUTHEAST INTO THE NORTHEAST U.S. LATE TUESDAY INTO
EARLY WEDNESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND, BUT WITH LESS WEIGHT GIVEN TO THE
12Z GFS OR 00Z ECMWF LATE TUESDAY AND WEDNESDAY
CONFIDENCE: BELOW AVERAGE
MODELS ARE IN GOOD AGREEMENT THROUGH EARLY MONDAY, SHOWING THE
SHORTWAVE TROUGH CURRENTLY OVER THE PACIFIC NORTHWEST LIFTING
NORTHEAST ACROSS THE CANADIAN ROCKIES AND INTO CENTRAL CANADA BY
EARLY MONDAY. TIMING AND AMPLITUDE DIFFERENCES BEGIN TO DEVELOP
AS THE SYSTEM BEGINS TO WEAKEN AND MOVE EAST ACROSS THE TOP OF AN
UPPER RIDGE, BEFORE SPILLING SOUTHEAST ACROSS NORTHERN ONTARIO AND
WESTERN QUEBEC INTO THE NORTHEAST U.S. TUESDAY NIGHT INTO
WEDNESDAY. DIFFICULT TO COMPLETELY RULE OUT ANY SOLUTION;
HOWEVER, SUSPECT THE 00Z ECMWF IS PROBABLY TOO AMPLIFIED GIVEN THE
CONFLUENT FLOW. THIS IS FURTHER SUPPORTED BY THE LESS AMPLIFIED
00Z EC ENSEMBLE MEAN. ALSO, THE 12Z GFS LOOKS BE A LITTLE SLOW,
BOTH WITH THE WEAK WAVE DROPPING SOUTHEAST INTO NORTHEAST U.S.
WEDNESDAY MORNING AND WITH THE TRAILING FRONT EXTENDING BACK
ACROSS THE GREAT LAKES. AGAIN, THE PROGRESSIVE NATURE OF THE
FLOW, ALONG WITH THE MODEL CONSENSUS WOULD TEND TO SUPPORT
SOMETHING FASTER.
UPPER LEVEL TROUGH MOVING FROM THE PACIFIC NORTHWEST MONDAY TO THE
NORTHERN PLAINS AND UPPER MIDWEST TUESDAY-WEDNESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: LEAN TOWARD THE 00Z UKMET/ECMWF/EC ENSEMBLE MEAN
CONFIDENCE: BELOW AVERAGE
MODELS CONTINUE TO SHOW TIMING AND AMPLITUDE DIFFERENCES WITH THIS
FEATURE, ESPECIALLY AS IT MOVES EAST OF THE CASCADES MONDAY NIGHT.
BY LATE MONDAY AS THE SYSTEM MOVES ACROSS THE PACIFIC NORTHWEST,
THE NCEP GUIDANCE IS GENERALLY DEEPER THAN THE OVERNIGHT RUNS OF
THE UKMET, ECMWF AND EC ENSMEAN. THIS CONTINUES DOWNSTREAM ACROSS
THE NORTHERN ROCKIES AND THROUGH THE NORTHERN PLAINS AND UPPER
MIDWEST, WITH THE NCEP GUIDANCE BECOMING SLOWER AS WELL THAN THE
FLATTER UKMET, ECMWF AND EC ENSMEAN. GIVEN THE PROGRESSIVE NATURE
OF THE FLOW, RECOMMEND LEANING TOWARD THE FASTER/FLATTER SOLUTIONS.
CUT-OFF LOW DEVELOPING WEST OF SOUTHERN CALIFORNIA EARLY IN THE
WEEK
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: LEAN TOWARD THE 00Z ECMWF/EC ENSEMBLE MEAN
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
MODELS ARE IN GOOD AGREEMENT INDICATING A CLOSED, CUT-OFF LOW
DEVELOPING OFF OF THE SOUTHERN CALIFORNIA AND NORTHERN BAJA
CALIFORNIA COASTS LATE MONDAY INTO EARLY TUESDAY. THERE ARE STILL
SOME MODEL DIFFERENCES WITH RESPECT TO POSITION LATER IN THE
PERIOD, WITH MOST OF THE GUIDANCE INDICATING A CENTER SOUTHWEST OF
THE 12Z GFS AND 06Z GEFS MEAN. COMPARED WITH ITS 00Z RUN, THE GFS
IS SHOWING SOME SHIFT IN THAT DIRECTION AS WELL - LENDING SUPPORT
FOR A MORE SOUTHWESTERLY SOLUTION, SUCH AS THE 00Z ECMWF AND EC
ENSEMBLE MEAN.
SHORTWAVE MOVING ACROSS WESTERN CANADA AND THE NORTHWESTERN U.S.
LATE TUESDAY-EARLY WEDNESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: LEAN TOWARD THE 00Z ECMWF/EC ENSEMBLE MEAN
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE NCEP GUIDANCE, ESPECIALLY THE GFS, IS MORE AMPLIFIED THAN THE
GENERAL DETERMINISTIC AND ENSEMBLE CONSENSUS AS THE SYSTEM MOVES
EAST OF THE ROCKIES INTO THE CANADIAN PRAIRIE AND U.S. HIGH PLAINS
WEDNESDAY MORNING.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
PEREIRA
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