010
FXUS10 KWNH 291831
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
231 PM EDT MON JUN 29 2020
VALID JUN 29/1200 UTC THRU JUL 03/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CLOSED LOW ANCHORED OVER NEW ENGLAND
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM BLEND
CONFIDENCE: ABOVE AVERAGE
19Z UPDATE: THE 12Z CMC TRENDED TOWARD THE PREFERRED BLEND OF THE
ECMWF/GFS/UKMET THOUGH STILL HAVE SOME TIMING ISSUES, ESPECIALLY
LATE IN THE DAY 3 PERIOD. BUT IT'S MUCH IMPROVED AND PROBABLY CAN
BE INCORPORATED NOW. THIS LEAVES THE 12Z NAM AS THE MAIN OUTLIER,
WHICH WILL STILL BE KEPT OUT OF THE BLEND PREFERENCE.
---PREVIOUS DISCUSSION---
UPPER LEVEL ENERGY OVER NEW ENGLAND WILL REMAIN IN PLACE OVER THE
AREA THROUGH MID-WEEK WITH REALLY GOOD MODEL AGREEMENT SEEN FROM
THE LATEST 12Z GUIDANCE THROUGH ABOUT 60 HOURS. BEYOND THAT, AN
APPROACHING SHORTWAVE TROUGH FROM SOUTHERN QUEBEC WILL APPROACH
NEW ENGLAND AND HELP KICK OUT AND ABSORB THE WEAKENING CLOSED LOW.
THE CMC AND NAM ARE THE MOST SLUGGISH, HOLDING BACK ENERGY OVER
THE NORTHEAST AND NEW ENGLAND THE LONGEST, WHICH IS OUT OF PLACE
COMPARED TO THE ENSEMBLE MEAN. FOR NOW, WILL PREFER A BLEND THAT
EXCLUDES THE 12Z NAM AND 00Z CMC.
DEEP UPPER TROUGH/CLOSED LOW ACROSS THE INTERMOUNTAIN WEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z GFS/ECMWF/UKMET
CONFIDENCE: AVERAGE
19Z UPDATE: FAIRLY GOOD AGREEMENT STILL WITH THE 12Z GUIDANCE IN
THE LARGE SCALE SENSE, THOUGH THE 12Z CMC REMAINS AN OUTLIER AND
UNFAVORABLE AS IT IS SIGNIFICANTLY OUT OF PHASE WITH THE OTHER
DETERMINISTIC MODELS (AND ENSEMBLE MEANS). OTHERWISE, NO
SIGNIFICANT CHANGES TO THE MODEL BLEND PREFERENCE INCORPORATING
THE 12Z GFS, ECMWF, AND UKMET.
---PREVIOUS DISCUSSION---
STRONG UPPER LEVEL LOW OVER THE INTERMOUNTAIN WEST WILL LIFT
NORTHEAST OVER THE NORTHERN ROCKIES THROUGH TOMORROW BEFORE
ABSORBING WITH ANOTHER APPROACHING SHORTWAVE TROUGH FROM SOUTHWEST
CANADA, LEADING TO A LARGE CLOSED LOW OVER THE PACIFIC NORTHWEST
TO NORTHERN ROCKIES THROUGH MUCH OF THE WEEK BEFORE RETROGRADING
BACK TO THE NORTHWEST BY THURSDAY NIGHT/FRIDAY AS RIDGING BUILDS
DOWNSTREAM OVER THE CENTRAL US. INITIALLY, THE CMC DROPS OUT OF
FAVOR WITH SEVERAL TIMING ISSUES RELATED TO INDIVIDUAL VORT LOBES
ROUNDING THE LARGE SCALE LOW. FOR DAY 2/3, THE LARGE SCALE
EVOLUTION IS WELL AGREED UPON BY THE GFS/ECMWF/UKMET, EXCEPT FOR
THE END OF DAY 3 WHEN A FINAL SHORTWAVE TROUGH MOVES ONSHORE THE
PACIFIC NORTHWEST. HERE, THERE ARE SOME TIMING ISSUES WHERE THE
GFS IS A BIT FAST AND UKMET ON THE SLOWER SIDE. FOR NOW, WILL
PREFER A BLEND COMPOSING OF THE 12Z GFS, 00Z ECMWF/UKMET.
MCV/WEAK MID-LEVEL LOW OVER MN
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
MCV AND ASSOCIATED WEAK MID-LEVEL SHORTWAVE WILL CONTINUE TO LIFT
NORTHWARD OUT OF MINNESOTA THROUGH WESTERN ONTARIO OVER THE NEXT
24 HOURS. MODEL AGREEMENT IS ABOVE AVERAGE WITH VERY GOOD
CLUSTERING SEEN IN THE LATEST GUIDANCE. THE ONLY NOTABLE
DIFFERENCE IS A SLIGHT LAG IN THE 00Z CMC COMPARED TO THE REST OF
THE DETERMINISTIC GUIDANCE, BUT OVERALL THIS SHOULD NOT AFFECT
MUCH IN THE WAY OF SENSIBLE WEATHER, SO A GENERAL MODEL BLEND IS
PREFERRED.
SHORTWAVE AMPLIFYING TOWARD MID MS VALLEY BY MONDAY NIGHT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH 48 HOURS; GFS/ECMWF/UKMET
BLEND DAY 48-84 HOURS
CONFIDENCE: SLIGHTLY BELOW AVERAGE
A CONVECTIVELY ENHANCED MCV IS FORECAST TO TRACK FROM THE ARKLATEX
REGION NORTHEAST BEFORE STALLING OVER THE MID-MS RIVER VALLEY
MID-WEEK. VIRTUALLY ALL OF THE DETERMINISTIC MODELS HAVE THIS
SIGNAL WITH RELATIVELY GOOD AGREEMENT THROUGH 48 HOURS, BUT BEYOND
THAT TIME FRAME, MORE NOTABLE DIFFERENCES ARE SEEN. THE
DEVELOPMENT AND EXPANSION OF THE NORTHERN ROCKIES TROUGHING, SOME
MODELS ALLOW THE MID-MS MCV TO BE PICKED UP AND LIFTS NORTHWARD
THROUGH THE UPPER MIDWEST. CONVERSELY, THE ECMWF /CMC AND THE NAM
TO SOME DEGREE, SHOW MORE SEPARATION. AS HEIGHTS BUILD BY THE END
OF THE PERIOD, SOME MODELS ALLOW A PIECE OF THE ENERGY TO DROP
SOUTHEASTWARD IN A PSUEDO-NORTHWEST FLOW REGIME, TAKING THE ENERGY
TOWARD THE GULF COAST. ALL IN ALL, IT'S A LOW CONFIDENCE FORECAST
WITH SEVERAL COMPETING SYSTEMS. THE BEST CONSENSUS APPROACH RIGHT
NOW WOULD FAVOR A BLEND COMPOSING OF THE ECMWF/GFS/UKMET FOR NOW
BUT NOTING THE STRONG AND POTENTIALLY SIGNIFICANT SENSIBLE WEATHER
DIFFERENCES FOR DAY 2/3.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
TAYLOR
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