859
FXUS10 KWNH 231847
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
245 PM EDT TUE JUN 23 2020
VALID JUN 23/1200 UTC THRU JUN 27/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CLOSED LOW OVER ONTARIO/QUEBEC
TROUGH CROSSING THE EASTERN U.S.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE LARGE CLOSED UPPER LOW OVER ONTARIO IS EXPECTED TO SLOWLY
ADVANCE EASTWARD THROUGH WESTERN QUEBEC OVER THE NEXT FEW DAYS AS
THE SOUTHWARD EXTENSION OF A BROADER TROUGH CROSSES THROUGH THE
EASTERN U.S. THIS WILL DRIVE A COLD FRONT TOWARD THE MID-ATLANTIC
AND NEW ENGLAND WEDNESDAY BEFORE THEN SLOWING DOWN AND ONLY VERY
SLOWLY DRIFTING OFFSHORE BY FRIDAY WHILE THE SOUTHWEST TAIL OF THE
FRONT HANGS UP OVER THE SOUTHEAST. MODEL SPREAD AT LEAST
SYNOPTICALLY IS RATHER MINIMAL, SO A GENERAL MODEL BLEND WILL BE
PREFERRED.
SHORTWAVE CROSSING THE PACIFIC NORTHWEST AND PLAINS
ENERGY DIGGING INTO THE SOUTHWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z NAM/GFS
CONFIDENCE: AVERAGE
THE LATEST GUIDANCE CONTINUES TO ADVERTISE A SHORTWAVE TROUGH
CROSSING THE PACIFIC NORTHWEST ON WEDNESDAY AND THEN AMPLIFYING
THROUGH THE CENTRAL/NORTHERN ROCKIES GOING THROUGH THURSDAY. AS
THIS IS OCCURRING, SOME OF THE ENERGY WILL BE SEPARATING OUT AND
DIGGING FARTHER SOUTH INTO THE SOUTHWEST. ON FRIDAY, THE NORTHERN
PORTION OF THE ORIGINAL TROUGH WILL EJECT OUT ACROSS THE CENTRAL
AND NORTHERN PLAINS, WITH THE GUIDANCE FAVORING A SOUTHERN STREAM
TROUGH LINGERING NEAR THE FOUR CORNERS REGION. WITH THE INITIAL
SURGE OF THE NORTHERN STREAM PORTION OF THE TROUGH, THE 12Z UKMET
IS NOW SEEN AS BEING A TAD MORE PROGRESSIVE/WEAKER WITH THE
ENERGY. WITH THE SOUTHERN STREAM ENERGY, THE 12Z ECMWF AND 12Z CMC
BOTH TEND TO HOLD ENERGY BACK FARTHER TO THE WEST OVER THE
SOUTHWEST COMPARED TO THE 12Z NAM/GFS SOLUTIONS. THE 12Z UKMET
WITH THIS ENERGY IS ACTUALLY CLOSE TO THE NAM/GFS CAMPS, BUT IS A
LITTLE WEAKER. OVERALL, THE NAM/GFS CAMP HAS BETTER ENSEMBLE
SUPPORT FOR THE TIME BEING, AND SO A BLEND OF THESE SOLUTIONS WILL
BE PREFERRED WITH BOTH ENERGY STREAMS.
MID-LEVEL TROUGHING OVER THE LOWER MS VALLEY/TEXAS
MCVS EJECTING ACROSS SOUTHEAST TEXAS AND THE GULF COAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z NAM/GFS/ECMWF
CONFIDENCE: AVERAGE
A BROAD MID TO UPPER-LEVEL TROUGH IS EXPECTED TO BECOME REMOVED
FROM THE WESTERLIES AND SLOWLY MEANDER OVER THE LOWER MS RIVER
VALLEY AND TX OVER THE NEXT COUPLE OF DAYS. IN THE MEANTIME, A
STRONG MCV OVER NORTH-CENTRAL TX THIS MORNING IS EXPECTED TO
GRADUALLY SETTLE SOUTHEASTWARD TOWARD THE SOUTHEAST TX COASTAL
PLAIN TONIGHT AND BECOME AN ACTIVE FOCUS FOR RENEWED CONVECTION
AND POTENTIALLY SOME VERY HEAVY RAINFALL GOING THROUGH EARLY
WEDNESDAY. THIS ENERGY SHOULD THEN DRIFT EAST THROUGH THURSDAY AND
GENERALLY SHEAR ACROSS THE GULF COAST STATES. HOWEVER, OUT AHEAD
OF THIS ENERGY IS AN MCV WHICH IS CURRENTLY OVER THE WESTERN GULF
OF MEXICO, AND THE MODELS AGREE IN TAKING THAT ENERGY
NORTHEASTWARD AND INLAND ACROSS SOUTHEAST LA AND SOUTHERN MS GOING
THROUGH EARLY WEDNESDAY.
THE 12Z NON-NCEP MODELS HAVE COME AROUND TO THE STRONGER NAM/GFS
REFLECTIONS OF THE ENERGY OVER THE WESTERN GULF OF MEXICO AND
ESPECIALLY THE MCV AND ATTENDANT LOW CENTER OVER NORTH-CENTRAL TX.
IN FACT, ALL OF THE MODELS SUGGEST A LOW CENTER DROPPING DOWN
ACROSS SOUTHEAST TX THROUGH EARLY WEDNESDAY WHICH THEN ADVANCES
EASTWARD THROUGH LA AND SOUTHERN MS GOING THROUGH THURSDAY.
HOWEVER, THERE IS SOME SIGNIFICANT TIMING SPREAD AS THE 12Z GFS
AND ESPECIALLY THE 12Z ECMWF ARE SLOWER TO ADVANCE IT EAST. THE
12Z NAM THOUGH IS ACTUALLY ONLY A TAD FASTER THAN THE GFS. THE 12Z
UKMET IS A STRONG AND FAST OUTLIER SOLUTION, WHILE THE THE 12Z CMC
IS THE WEAKEST SOLUTION. BY LATE WEDNESDAY AND EARLY THURSDAY, THE
GUIDANCE FAVORS SOME ADDITIONAL SHORTWAVE/MCV ENERGY DROPPING
SOUTHEAST THROUGH TX WHICH WILL HELP TO REINFORCE THE BROADER MID
TO UPPER-LEVEL TROUGH OVER THE REGION. THE GUIDANCE IS RATHER WEAK
WITH THIS ADDITIONAL ENERGY FOR TIME BEING. BASED ON THE LATEST
MODEL GUIDANCE AND CLUSTERING, A BLEND OF THE NAM/GFS AND ECMWF
WILL NOW BE PREFERRED AND ESPECIALLY WITH THE CMC/UKMET SOLUTIONS
BEING THE BIGGER MASS FIELD OUTLIERS WITH THE MCV/LOW EVOLUTION
THROUGH SOUTHEAST TX AND DOWNSTREAM OVER THE GULF COAST REGION.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
ORRISON
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page