074
FXUS10 KWNH 270509
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
108 AM EDT WED MAY 27 2020
VALID MAY 27/0000 UTC THRU MAY 30/1200 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION INCLUDING LATEST PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
RELOADING NORTHERN STREAM TROUGH OVER NORTHERN PLAINS BY WEDNESDAY
CROSSING THE UPPER MIDWEST AND GREAT LAKES THURSDAY/FRIDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z GFS AND 12Z ECMWF
CONFIDENCE: ABOVE AVERAGE
THE MODELS SHOW A NEW NORTHERN STREAM TROUGH AMPLIFYING OVER
SOUTHERN CANADA AND THE NORTHERN PLAINS GOING THROUGH WEDNESDAY.
THIS ENERGY SHOULD THEN MOVE ACROSS THE UPPER MIDWEST BY THURSDAY
AND THE GREAT LAKES BY FRIDAY. THIS WILL DRIVE SURFACE LOW
PRESSURE ACROSS SOUTHERN CANADA WITH A TRAILING COLD FRONT THAT
WILL BE CROSSING THE NORTHERN PLAINS AND MIDWEST, AND REACHING THE
EAST COAST BY THE END OF THE PERIOD. THE MODEL SPREAD WITH THE
GLOBAL MODELS IS RELATIVELY MODEST, BUT THE BIGGER CONCERN IS WITH
THE 00Z NAM WHICH IS A BIT SLOWER WITH THE OVERALL TROUGH
PROGRESSION, AND ALSO AN OUTLIER WITH ITS STRONG SHORTWAVE DIGGING
ACROSS THE OH VALLEY FRIDAY NIGHT AND EARLY SATURDAY. THE BETTER
GLOBAL MODEL CLUSTERING AND ENSEMBLE SUPPORT WOULD FAVOR A BLEND
OF THE 00Z GFS AND 12Z ECMWF, AND SO A BLEND OF THESE SOLUTIONS
WILL BE PREFERRED.
DEEP CLOSED LOW OVER THE SOUTHERN PLAINS AND LOWER MS VALLEY
WEAKENING TOWARD THE OH/TN VALLEYS BY FRIDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE MODELS ALL AGREE IN TAKING THE CUT-OFF UPPER LOW CENTERED OVER
THE RED RIVER OF THE SOUTH GRADUALLY OFF TO THE EAST THROUGH THE
ARKLATEX EARLY WEDNESDAY AND ADJACENT AREAS OF THE LOWER MS VALLEY
GOING THROUGH EARLY THURSDAY. HOWEVER, BY LATE THURSDAY THE SYSTEM
SHOULD WEAKEN INTO AN OPEN WAVE AND LIFT EAST-NORTHEAST TOWARD THE
LOWER OH/TN VALLEYS AND THEN BECOME ABSORBED EARLY FRIDAY BY THE
STRONGER NORTHERN STREAM TROUGHING ARRIVING ACROSS THE GREAT
LAKES. MODEL SPREAD IS MINIMAL WITH THIS, SO A GENERAL MODEL BLEND
WILL BE PREFERRED.
MID-LEVEL TROUGH AND SURFACE LOW IMPACTING THE SOUTHEAST
ENERGY REACHING THE SOUTHERN/CENTRAL APPALACHIANS AND MID-ATLANTIC
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-ECMWF BLEND
CONFIDENCE: AVERAGE
A MID-LEVEL TROUGH WILL BE LIFTING NORTH ACROSS THE INTERIOR OF
THE SOUTHEAST AND THROUGH THE SOUTHERN APPALACHIANS ON WEDNESDAY,
WITH WEAKENING REMNANTS OF THIS THEN REACHING THE CENTRAL
APPALACHIANS AND MID-ATLANTIC BY EARLY THURSDAY. THE 00Z NAM AND
00Z GFS ARE AGAIN A TAD MORE PROGRESSIVE IN BRINGING THIS ENERGY
NORTHWARD, WITH THE NON-NCEP MODELS ALL A LITTLE SLOWER.
MEANWHILE, AT THE SURFACE, A LOW PRESSURE CENTER OFF THE EAST
COAST OF FL IS EXPECTED TO LIFT NORTH AND MOVE INLAND ACROSS THE
CAROLINAS BY LATE WEDNESDAY. THE 00Z NAM AND 00Z GFS ARE ALSO
FASTER THAN THE NON-NCEP MODELS WITH THIS, HOWEVER THE 12Z ECMWF
IS A LEFT-MOVING OUTLIER WITH ITS LOW TRACK ACROSS CENTRAL AND
NORTHERN GA. THE 12Z CMC/UKMET MODELS AT LEAST FOLLOW THE 00Z
NAM/GFS CAMP, BUT ARE A BIT SLOWER. BASED ON WHERE THE CURRENT LOW
CENTER, A COMPROMISE BETWEEN SLOWER FASTER CAMPS IS SUGGESTED,
WHICH WILL ALLOW FOR THE LOW TO CROSS CENTRAL TO NORTHEAST COASTAL
AREAS OF SC AND THEN LIFT NORTH THROUGH CENTRAL NC GOING THROUGH
WEDNESDAY NIGHT. SO, FROM A MASS FIELD PERSPECTIVE CONSIDERING THE
MID-LEVEL TROUGH AND THE SURFACE LOW SITUATION, A NON-ECMWF BLEND
WILL BE PREFERRED.
SUBTROPICAL CLOSED LOW REACHING CENTRAL CA BY SATURDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE MODELS TAKE A LARGE UPPER LOW OVER THE SUBTROPICAL PACIFIC
CENTERED NEAR 25.5N AND 131.5W OFF TO THE NORTHEAST OVER THE NEXT
FEW DAYS, AND BRING IT TOWARD CENTRAL CA BY SATURDAY IN RESPONSE
TO STRONGER NORTHERN STREAM TROUGHING IMPINGING ON IT FROM
UPSTREAM OVER THE EASTERN PACIFIC. THE MODELS ARE IN GOOD
AGREEMENT WITH THE DEPTH AND TIMING OF THIS SYSTEM, SO A GENERAL
MODEL BLEND WILL BE PREFERRED.
DEEP TROUGH/CLOSED LOW OVER THE NORTHEAST PACIFIC
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-UKMET BLEND
CONFIDENCE: ABOVE AVERAGE
THE MODELS GRADUALLY DRIVE A DEEP UPPER TROUGH AND ASSOCIATED
CLOSED LOW IN ACROSS THE NORTHEAST PACIFIC WITH AN EMPHASIS ON THE
GULF OF AK BY SATURDAY. THE SOUTHERN EXTENSION OF THE TROUGH WILL
BE INFLUENCING THE AFOREMENTIONED UPPER LOW LIFTING NORTHEAST OUT
OF THE SUBTROPICS, BUT WILL ALSO BE ENCROACHING ON THE PACIFIC
NORTHWEST BY SATURDAY. THE 12Z UKMET IS MOST OUT OF PHASE WITH THE
HEIGHT FALL EVOLUTION AND SUGGESTS A FASTER ARRIVAL OF SHORTWAVE
ENERGY OVER THE PACIFIC NORTHWEST WHICH THE REMAINING MODELS ARE
WELL CLUSTERED IN KEEPING OFFSHORE AT LEAST FOR THIS PERIOD. SO, A
NON-UKMET BLEND WILL BE PREFERRED WITH THE ENERGY OVER THE
NORTHEAST PACIFIC BASIN FOR THE TIME BEING FOR THIS PERIOD.
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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