721
FXUS10 KWNH 290445
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1244 AM EDT MON JUN 29 2020
VALID JUN 29/0000 UTC THRU JUL 02/1200 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
AN UPPER-LEVEL LOW INITIALLY OVER SOUTHERN QUEBEC IS FORECAST TO
REACH CENTRAL NEW ENGLAND BY MONDAY AND THEN BECOME ANCHORED IN
PLACE THROUGH THE MIDDLE OF THE WEEK AS IT BECOMES CUT OFF FROM
THE MAIN NORTHERN STREAM FLOW. THE 00Z NAM TENDS TO DROP MORE
ENERGY FARTHER SOUTH COMPARED TO THE GLOBAL MODELS WHICH OVERALL
ARE FAIRLY WELL CLUSTERED THROUGH THE PERIOD. WILL PREFER A
NON-NAM BLEND AS A RESULT.
DEEP UPPER TROUGH/CLOSED LOW ACROSS THE INTERMOUNTAIN WEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z GFS/12Z UKMET/12Z ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
A STRONG MID-UPPER LEVEL LOW CURRENTLY OVER THE PACIFIC NORTHWEST
IS FORECAST TO CONTINUE AMPLIFYING ACROSS THE NORTHERN ROCKIES AND
INTERMOUNTAIN WEST THROUGH TUESDAY MORNING AS AN UPPER-LEVEL RIDGE
BUILDS ACROSS THE MIDWEST AND GREAT LAKES REGION. THEREAFTER, THE
CORE OF THE UPPER LOW SHOULD BE REFOCUS FARTHER NORTH OVER
SOUTHWEST CANADA GOING THROUGH WEDNESDAY AND THURSDAY. THIS WILL
YIELD A QUASI OMEGA-BLOCK PATTERN ACROSS THE NORTH-CENTRAL U.S.
THROUGH THE MIDDLE OF THE WEEK. THE 00Z NAM IS OVERALL A BIT
STRONGER THAN THE GLOBAL MODELS WHICH IT HAS BEEN TENDING TO
ADVERTISE OVER THE LAST COUPLE OF DAYS. THE 12Z CMC THOUGH IS
AGAIN SLOWER TO LIFT THE ENERGY NORTH OUT OF THE INTERMOUNTAIN
WEST, AND AS IT EVENTUALLY DOES SO, IT ENDS UP SHIFTING STRONGER
HEIGHT FALLS FARTHER EAST WITH GREATER IMPACTS ACROSS THE NORTHERN
HIGH PLAINS COMPARED TO THE OTHER MODELS. WILL AGAIN PREFER THE
BETTER AGREEMENT/CLUSTERING OF THE 00Z GFS, 12Z UKMET AND 12Z
ECMWF SOLUTIONS WITH THIS SYSTEM.
MCV/WEAK MID-LEVEL LOW OVER MN
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z GFS/12Z UKMET/12Z ECMWF
CONFIDENCE: AVERAGE
A STRONG MCV AND ASSOCIATED WEAK MID-LEVEL LOW CENTER CURRENTLY
OVER MN IS EXPECTED TO LIFT NORTH THROUGH WESTERN ONTARIO OVER THE
NEXT COUPLE OF DAYS. OVERALL, THE 12Z CMC APPEARS TO BE TOO SLOW
WITH THE FORWARD MOTION, AND EVEN THE 00Z NAM LAGS THE MODEL
CONSENSUS A TAD BY LATER MONDAY AND TUESDAY. A SOMEWHAT MORE
PROGRESSIVE SOLUTION IS EXPECTED BASED ON THE MODEL TRENDS OVER
THE LAST 12 TO 24 HOURS AND THE LATEST SATELLITE IMAGERY. A BLEND
OF THE 00Z GFS, 12Z UKMET AND 12Z ECMWF WILL BE PREFERRED FOR THE
TIME BEING.
SHORTWAVE AMPLIFYING TOWARD MID MS VALLEY BY MONDAY NIGHT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON_ECMWF BLEND...THROUGH 60 HOURS
NON-NAM BLEND...AFTER 60 HOURS
CONFIDENCE: SLIGHTLY BELOW AVERAGE
THE GUIDANCE SUPPORTS A CONVECTIVELY ENHANCED SHORTWAVE OR MCV
LIFTING NORTHEAST ACROSS EASTERN TX AND TOWARD THE MID MS VALLEY
BY MONDAY NIGHT. OVERALL, THE 12Z ECMWF APPEARS TO BE A BIT TOO
WEAK WITH THE EVOLUTION OF THIS SYSTEM, BUT ALL OF THE MODELS DO
SUPPORT THE ENERGY CROSSING UP THROUGH MO AND IA GOING THROUGH
TUESDAY. HOWEVER, THERE IS SIGNIFICANT MODEL SPREAD THEREAFTER AS
THE MODELS DISAGREE ON WHETHER THE ENERGY GETS PULLED NORTH
THROUGH THE UPPER MIDWEST AHEAD OF THE DEEP UPSTREAM TROUGH OVER
THE WEST, OR IF THE SYSTEM GETS LEFT BEHIND IN THE MIDDLE OF THE
MEAN LAYER RIDGE OVER THE MIDWEST. THE 00Z GFS AND 12Z UKMET
SUPPORT THE ENERGY LIFTING NORTH THROUGH THE UPPER MIDWEST, BUT
THE 00Z SUGGEST THE ENERGY GETS LEFT BEHIND OVER IA AND THEN
BEGINS TO ACTUALLY SETTLE BACK DOWN TO THE SOUTH WHILE WEAKENING.
THE 12Z CMC AND 12Z ECMWF BOTH SUGGEST THE ENERGY WILL TEND TO
SPLIT APART WITH SOME OF THE ENERGY BREAKING AWAY TO THE NORTH AND
SOME OF IT DROPPING DOWN TO THE SOUTH. A NON-ECMWF BLEND WILL BE
PREFERRED THROUGH ABOUT 60 HOURS, WITH A NON-NAM BLEND AFTER 60
HOURS. CONFIDENCE WITH THIS EVOLUTION THOUGH IS CERTAINLY A BIT
LIMITED.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
ORRISON
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