353
FXUS10 KWNH 280453
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1252 AM EDT THU MAY 28 2020
VALID MAY 28/0000 UTC THRU MAY 31/1200 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION INCLUDING INITIAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
AMPLIFYING NORTHERN STREAM TROUGH ACROSS THE GREAT LAKES AND
NORTHEAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF/UKMET/00Z GFS BLEND
CONFIDENCE: MODERATE-HIGH
A NORTHERN STREAM TROUGH INITIALLY OVER SOUTH-CENTRAL CANADA IS
FORECAST TO AMPLIFY OVER THE FEW COUPLE OF DAYS, AND WILL HERALD A
PATTERN CHANGE FOR MUCH OF THE CENTRAL AND EASTERN U.S. BY THE END
OF THE WEEK AS A RELATIVELY STRONG COLD FRONT TRACKS SOUTHWARD
FROM CANADA, BRINGING A HIGH QUALITY AIRMASS FOR MUCH OF THE
NORTH-CENTRAL U.S. TO CLOSE OUT THE WEEK. THIS BUILDING TROUGH
WILL BE AMPLIFIED ENOUGH TO EXERT ITS INFLUENCE ON THE SOUTHERN
U.S. CLOSED LOW, WHICH WILL THEN EVOLVE INTO A PHASED SYNOPTIC
SCALE TROUGH FROM THE DEEP SOUTH TO THE GREAT LAKES BY FRIDAY
AFTERNOON AND INTO THE WEEKEND. THE MAIN MODEL DIFFERENCE THAT
BECOMES APPARENT BY FRIDAY NIGHT IS A CONSIDERABLY STRONGER
SHORTWAVE WITH THE 12Z CMC THAT PERSISTS THROUGH EARLY SUNDAY.
THE NAM IS ALSO STRONGER, BUT NOT TO THE DEGREE OF THE CMC. THERE
IS ENOUGH AGREEMENT AMONG THE ECMWF/UKMET/GFS TO MERIT A BLEND OF
THOSE THREE MODELS.
CLOSED LOW OVER ARKANSAS THAT BECOMES ABSORBED BY NORTHERN STREAM
FLOW
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: MODERATE-HIGH
THE BROAD UPPER LOW INITIALLY OVER ARKANSAS SLOWLY LIFTS
NORTHEASTWARD TO SOUTHERN ILLINOIS BY THURSDAY EVENING, BEFORE
BECOMING ABSORBED AND MERGED WITH THE BUILDING TROUGH FROM THE
GREAT LAKES REGION. A GENERAL MODEL BLEND WORKS HERE BEFORE THE
SYSTEM MERGES.
TROPICAL DEPRESSION BERTHA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: DETERMINISTIC CONSENSUS WITH GREATER WEIGHTING TO 00Z
NAM IS CLOSE TO 3Z WPC ADVISORY
CONFIDENCE: REFER TO WPC ADVISORY
BERTHA MADE LANDFALL ALONG THE CENTRAL COAST OF SOUTH CAROLINA
WEDNESDAY AND IS CURRENTLY TRACKING INLAND ACROSS THE
APPALACHIANS. AS THE SYSTEM WEAKENS, IT IS FORECAST BY WPC TO
MOVE NORTHWARD ACROSS WEST VIRGINIA AND THEN WESTERN PENNSYLVANIA
BEFORE DISSIPATING. CURRENTLY, A NAM/GFS BLEND IS CLOSE TO THE 3Z
WPC ADVISORY FOR BERTHA BEFORE THE SYSTEM WEAKENS AND MERGES WITH
AN ADVANCING MID-LEVEL TROUGH OVER THE GREAT LAKES REGION LATE
THURSDAY.
SUBTROPICAL CLOSED LOW REACHING CENTRAL CALIFORNIA BY SATURDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH SATURDAY MORNING, THEN 12Z
ECMWF/UKMET BLEND
CONFIDENCE: MODERATE-HIGH
THE MODELS SHOW GOOD AGREEMENT ON THE TRACK OF A CLOSED LOW
APPROACHING CENTRAL/NORTHERN CALIFORNIA BY SATURDAY, BUT DIFFER
WITH TIMING BY SATURDAY MORNING AND BEYOND. THE 12Z CMC BECOMES
SLOWER WITH BRINGING THE SYSTEM INLAND AND SOUTH OF THE ENSEMBLE
MEANS. BY SATURDAY NIGHT, THE GFS BECOMES FASTER IN BRINGING THE
SHORTWAVE NORTHWARD ON THE WEST SIDE OF THE BUILDING WESTERN HIGH
PLAINS RIDGE, AND THE NAM INDICATES THE STRONGEST SOLUTION AS THE
FEATURE LIFTS NORTHWARD ACROSS THE PACIFIC NORTHWEST. A GENERAL
MODEL BLEND WORKS WELL THROUGH SATURDAY MORNING, AFTER WHICH A 12Z
ECMWF/UKMET BLEND WOULD WORK.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
HAMRICK
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