272
FXUS10 KWNH 011749
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
148 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: 12Z HREF, 00Z CMC/UKMET/ECMWF BLEND...<48 HOURS
00Z CMC/UKMET/ECMWF BLEND...>48 HOURS
CONFIDENCE: SLIGHTLY BELOW 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 GFS 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 STRONGER NAM AND A LIKELIHOOD
THAT THE GFS IS TOO WEAK, A CONSENSUS OF THE 12Z HREF SUITE AND
NON-NCEP GUIDANCE WILL BE PREFERRED THROUGH 48 HOURS, AND THEN A
NON-NCEP BLEND THEREAFTER.
..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 00Z 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
00Z NON-NCEP MODELS ARE IN BETWEEN THE NAM AND GFS CAMPS. THE
LATEST ENSEMBLE MEANS SUPPORT PER THE GEFS MEAN AND ECENS MEAN ARE
SUPPORTIVE OF THE NON-NCEP GUIDANCE, AND THUS A BLEND OF THE 00Z
CMC/UKMET/ECMWF SOLUTIONS WILL BE PREFERRED.
..UPPER LOW/TROUGH OFF THE PACIFIC NORTHWEST BY SUNDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM BLEND
CONFIDENCE: 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 00Z ECMWF/UKMET SOLUTIONS CLUSTERED FARTHER WEST. THE 00Z
CMC IS IN BETWEEN THE TWO CAMPS. THERE IS VERY LITTLE ENSEMBLE
SUPPORT FOR THE NAM SOLUTION, AND SO A NON-NAM BLEND WILL BE
PREFERRED.
..UPPER TROUGH OVER THE GULF COAST/SOUTHEAST
..WAVE AXIS IMPACTING FLORIDA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z 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 00Z CMC BECOMES THE STRONGEST SOLUTION, WITH THE
12Z NAM AND 00Z UKMET A TAD WEAKER. THE 12Z GFS AND 00Z 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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