129
FXUS10 KWNH 011845
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
244 PM EDT THU AUG 01 2019
VALID AUG 01/1200 UTC THRU AUG 05/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION AND PREFERENCES/CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..CENTRAL U.S
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM BLEND
CONFIDENCE: AVERAGE
THE MAIN FORECAST ISSUE FOR THIS TIME PERIOD IS THE SHORTWAVE
ENERGY RIDING OVER THE TOP OF THE MID-LEVEL RIDGE THAT RETROGRADES
SLOWLY WESTWARD ACROSS THE FOUR CORNERS AREA THROUGH SATURDAY. THE
MODELS SHOW THE ENERGY DROPPING DOWN ACROSS SD/NE TONIGHT THROUGH
MIDDAY ON FRIDAY AND THEN ACROSS EASTERN KS FRIDAY NIGHT AND EARLY
SATURDAY. THE 12Z UKMET IS THE WEAKEST OF ALL OF THE GUIDANCE WITH
THE ENERGY AS IT DROPS DOWN THE EAST SIDE OF THE RIDGE AXIS, BUT
THE 12Z NAM IS BY FAR THE MOST INTENSE AND APPEARS NOTABLY TOO
STRONG IN RELATION TO NOT ONLY THE GLOBAL MODELS, BUT ALSO THE
CONSENSUS OF THE 12Z HIRES GUIDANCE, ALTHOUGH THE 12Z NAM-CONEST
DOES EDGE STRONGER THAN THE REMAINING HIRES MODELS (ARW, ARW2,
NMMB) BY EARLY SATURDAY. THE NAM-CONEST THOUGH AT LEAST IS A MORE
MODEST VERSION OF NAM ITSELF. THE NAM TRACKS ITS MID-LEVEL ENERGY
AND A SUPPORTING WAVE OF LOW PRESSURE WELL EAST OF ALL OF THE
GLOBAL MODELS GOING THROUGH SATURDAY AND INTO SUNDAY, WHICH ALSO
LEADS THE NAM TO BE MUCH WETTER FARTHER OFF TO THE EAST INVOLVING
PARTS OF THE MIDDLE AND LOWER MS VALLEYS (MO/AR/MS)VERSUS THE
GLOBAL MODELS. ACCOUNTING FOR THE NAM BEING SUCH A STRONG OUTLIER,
AND WITH THE REMAINING GUIDANCE AT LEAST CLUSTERING BETTER ON A
TRACK OF THE MID-LEVEL ENERGY AND SURFACE DETAILS, A NON-NAM BLEND
WILL BE PREFERRED.
..NORTHEAST U.S./SOUTHEAST CANADA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
ACROSS THE NORTHEAST AND QUEBEC, THERE IS GENERALLY GOOD MODEL
AGREEMENT WITH THE EVOLUTION OF THE MID-LEVEL CLOSED LOW AND
LARGER SCALE TROUGH AXIS, SO A GENERAL MODEL BLEND IS PREFERRED
HERE, AS OPERATIONAL MODELS CLUSTER WELL WITH THE ENSEMBLE MEANS.
..PACIFIC NORTHWEST/SOUTHWEST CANADA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z CMC/UKMET/ECMWF
CONFIDENCE: AVERAGE
THE GUIDANCE AGREES IN TAKING A POSITIVELY TILTED LONGWAVE TROUGH
ACROSS PORTIONS OF THE PACIFIC NORTHWEST AND BRITISH COLUMBIA OFF
TO THE EAST TOWARD CENTRAL AND SOUTHERN CANADA GOING INTO THE
WEEKEND. THE 12Z NAM BECOMES A STRONGER OUTLIER WITH SHORTWAVE
ENERGY AMPLIFYING INTO THE BASE OF THE TROUGH BY SUNDAY. THE 12Z
GFS IS WEAKER WITH THE SHORTWAVE ENERGY, BUT HAS A STRONGER CLOSED
MID-LEVEL LOW OVER CENTRAL CANADA BY THE END OF THE PERIOD. THE
12Z NON-NCEP MODELS ARE IN BETWEEN THE NAM AND GFS CAMPS. THE
LATEST ENSEMBLE MEANS PER THE GEFS MEAN AND ECENS MEAN ARE
SUPPORTIVE OF THE NON-NCEP GUIDANCE, AND THUS A BLEND OF THE 12Z
CMC/UKMET/ECMWF SOLUTIONS WILL BE PREFERRED.
..UPPER LOW/TROUGH OFF THE PACIFIC NORTHWEST BY SUNDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM BLEND
CONFIDENCE: ABOVE AVERAGE
THE MODELS TAKE A PORTION OF THE ENERGY TRAVERSING SOUTHWEST
CANADA AND PINCH OFF A NEW TROUGH/CLOSED LOW JUST OFFSHORE OF
WA/OR BY SUNDAY. THE 12Z NAM IS FARTHEST EAST WITH THIS ENERGY,
WITH THE REMAINING GLOBAL MODELS NOW WELL CLUSTERED TOGETHER A BIT
FARTHER WEST AND SUPPORTED BY THE LATEST ENSEMBLE MEANS. WILL
PREFER A NON-NAM BLEND AS A RESULT.
..UPPER TROUGH OVER THE GULF COAST/SOUTHEAST
..WAVE AXIS IMPACTING FLORIDA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z CMC/UKMET/ECMWF SOLUTIONS
CONFIDENCE: SLIGHTLY BELOW AVERAGE
A BROAD UPPER TROUGH OVER THE GULF COAST STATES AND ADJACENT AREAS
OF THE SOUTHEAST WILL BE INTERACTING WITH A SURFACE TROUGH
IMPACTING THE EAST COAST OF FLORIDA OVER THE NEXT COUPLE OF DAYS.
THE 12Z NAM AND 12Z GFS TEND TO BE A TAD STRONGER THAN THE
NON-NCEP GUIDANCE WITH THIS TROUGHING, ALTHOUGH THE NAM BECOMES
THE BIGGER OUTLIER AS A RESULT OF ITS APPARENT MISHANDLING OF THE
ENERGY DROPPING DOWN FROM THE CENTRAL PLAINS INTO THE LOWER MS
VALLEY. REGARDING THE SURFACE TROUGH IMPACTING FLORIDA, THE
GUIDANCE IS GRADUALLY SUPPORTING DEVELOPMENT OF A WEAK LOW CENTER
ALONG THIS AS IT LIFTS NORTHEAST UP OFF THE SOUTHEAST COASTLINE
THIS WEEKEND. THE 12Z UKMET BECOMES THE STRONGEST SOLUTION, WITH
THE 12Z NAM AND 12Z CMC A TAD WEAKER. THE 12Z GFS AND 12Z ECMWF
ARE THE WEAKEST SOLUTIONS, BUT STILL SUPPORT A LOW CENTER. THE GFS
IS FARTHEST WEST OF ALL THE GUIDANCE WITH THE TRACK. THE NAM AND
GFS ARE GENERALLY CONSIDERED MORE OUTLIER SOLUTIONS COMPARED TO
THE OTHER GLOBAL MODELS AND THE ENSEMBLE MEANS, SO WILL PREFER A
NON-NCEP MODEL BLEND AT THIS POINT.
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML
ORRISON
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