322
FXUS10 KWNH 270644
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
244 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 00Z 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 00Z 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-UKMET, 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 00Z ECMWF
IS STILL SOMEWHAT OF A LEFT-MOVER WITH ITS LOW TRACK RELATIVE TO
THE MODEL CONSENSUS. HOWEVER, THE 00Z UKMET TRENDED SLIGHTLY LEFT
OF ITS PREVIOUS TRACK AND IS ACTUALLY NOW VERY CLOSE TO THE ECMWF.
SO, AT LEAST THE ECMWF TRENDED NOTABLY TO THE RIGHT OF ITS 12Z
CYCLE OUTLIER SOLUTION AND APPEARS A BIT MORE REASONABLE ALTHOUGH
IT IS LIKELY STILL A BIT TOO FAR TO THE LEFT. BASED ON WHERE THE
CURRENT LOW CENTER IS, A COMPROMISE BETWEEN SLOWER AND FASTER
CAMPS IS SUGGESTED, WHICH WILL ALLOW FOR THE LOW TO CROSS CENTRAL
COASTAL AREAS OF SC (LIKELY NEAR CHARLESTON) AND THEN LIFT NORTH
THROUGH SOUTH-CENTRAL NC (LIKELY EAST OF CHARLOTTE) GOING THROUGH
WEDNESDAY NIGHT. SO, FROM A MASS FIELD PERSPECTIVE CONSIDERING THE
MID-LEVEL TROUGH AND THE SURFACE LOW SITUATION, THE ECMWF AND
UKMET ARE BOTH AT LEAST MODEST OUTLIERS STILL WHEN COMPARED TO THE
NAM, GFS, CMC AND THE LATEST ENSEMBLE MEANS. SO, A NON-UKMET/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, ALTHOUGH THERE
IS A LITTLE BIT OF LATITUDINAL SPREAD WITH THE UPPER LOW PLACEMENT
AT THE END OF THE PERIOD AS THE 00Z CMC/UKMET SOLUTIONS ARE A
LITTLE SOUTH OF THE 00Z NAM/GFS/ECMWF MODELS. A GENERAL MODEL
BLEND WILL BE PREFERRED AT THIS TIME.
DEEP TROUGH/CLOSED LOW OVER THE NORTHEAST PACIFIC
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL 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 LATEST GUIDANCE IS NOW WELL CLUSTERED
WITH THE EVOLUTION OF THIS, SO A GENERAL MODEL BLEND WILL BE
PREFERRED WITH THIS.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
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