616
FXUS10 KWNH 271659
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1258 PM EDT WED MAY 27 2020
VALID MAY 27/1200 UTC THRU MAY 31/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z NAM/GFS EVALUATION INCLUDING PRELIMINARY PREFERENCES AND
CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...NORTHERN STREAM, UPPER LEVEL TROUGH TRACKING FROM THE NORTHERN
PLAINS TODAY TO THE GREAT LAKES ON FRIDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NEAR THE 00Z ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
MODEL DIFFERENCES WITH TIMING BEGIN TO APPEAR LATE THURSDAY INTO
FRIDAY MORNING AS THE 12Z GFS BEGINS TO TRACK THE TROUGH AXIS MORE
QUICKLY TO THE EAST, WHILE THE 12Z NAM BEGINS TO SLOW ITS TIMING
RELATIVE TO THE REMAINING MODEL GUIDANCE. THESE DIFFERENCES
CONTINUE THROUGH SATURDAY. FOR REASONS MENTIONED BELOW, THE 00Z
CMC GIVEN ITS DIFFERENCES WITH HOW A CLOSED LOW TO THE SOUTH MERGE
INTO THE TROUGH AXIS PROGRESSING THROUGH THE GREAT LAKES REGION.
THE 00Z UKMET IS ON PACE WITH THE 00Z ECMWF UNTIL FRIDAY NIGHT
WHEN IT SLOWS DOWN COMPARED TO THE 00Z ECMWF. SINCE THE ENSEMBLE
MEANS SHOW GOOD AGREEMENT AND MATCH CLOSELY TO THE 00Z ECMWF, AND
RUN TO RUN CONSISTENCY HAS BEEN FAIRLY GOOD WITH THE 00Z ECMWF AND
ITS ENSEMBLE MEAN, A PREFERENCE NEAR THE 00Z ECMWF IS RECOMMENDED
FOR THIS SYSTEM.
...DEEP CLOSED LOW OVER THE SOUTHERN PLAINS AND LOWER MS VALLEY,
WEAKENING TOWARD THE OH/TN VALLEYS BY FRIDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-00Z CMC BLEND
CONFIDENCE: ABOVE AVERAGE
12Z
ONLY THE 00Z CMC DIFFERS SIGNIFICANT WITH THIS SYSTEM AS IT IS
SLOWER TO BRING THE WEAKENING CLOSED LOW NORTHWARD TOWARD THE
CENTRAL APPALACHIANS. GOOD SUPPORT EXISTS WITH THE REMAINING
DETERMINISTIC AND ENSEMBLE GUIDANCE TO SUPPORT A NON-00Z CMC BLEND.
..TROPICAL STORM BERTHA ALONG THE SOUTHEASTERN U.S. COAST
---
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z NAM/GFS CLOSEST TO 15Z NHC ADVISORY
CONFIDENCE: REFER TO NHC PRODUCTS
COMPACT T.S. BERTHA MADE LANDFALL ALONG THE CENTRAL COAST OF SC
EARLIER THIS MORNING AND IS CURRENTLY TRACKING INLAND. AS THE
SYSTEM WEAKENS, IT IS FORECAST BY NHC TO MOVE NORTHWARD INTO THE
CENTRAL APPALACHIANS. THE 00Z UKMET/CMC STAND OUT EARLY AND ARE
ALREADY SOUTHWEST/SLOWER WITH THE CENTER OF BERTHA COMPARED TO
OBSERVATIONS, WITH THE DEVIATION CONTINUING THROUGH THURSDAY. A
BLEND OF THE 12Z NAM/GFS ARE RELATIVELY CLOSE TO OBSERVATIONS AT
15Z TODAY REGARDING POSITION AND MATCH REASONABLY WELL TO THE 15Z
NHC ADVISORY TRACK BEFORE THE SYSTEM WEAKENS/MERGES WITH AN
ADVANCING MID-LEVEL TROUGH OVER THE GREAT LAKES REGION LATE
THURSDAY.
..SUBTROPICAL CLOSED LOW REACHING CENTRAL CA BY SATURDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH 00Z/30
NEAR THE 00Z ECMWF 00Z/30 - 00Z/31
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE MODELS SHOW GOOD AGREEMENT ON THE TRACK OF A CLOSED LOW
APPROACHING CA THIS WEEKEND BUT DIFFER WITH TIMING BY SATURDAY
MORNING (12Z/30). THE 12Z NAM, 00Z UKMET AND 00Z CMC END UP SLOWER
TO BRING THE LOW INLAND ACROSS NORTHERN CA. BY SATURDAY EVENING
(00Z/31), THE 12Z GFS PULLS AHEAD OF THE REMAINING GUIDANCE.
ENSEMBLE SUPPORT AND TRENDS SUPPORT A MIDDLE GROUND BEST
REPRESENTED BY THE 00Z ECMWF ON SATURDAY. PRIOR TO SATURDAY
HOWEVER, A GENERAL MODEL BLEND CAN BE USED FOR THIS SYSTEM.
..DEEP TROUGH/CLOSED LOW OVER THE NORTHEAST PACIFIC
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE MODELS SHOW SIMILARLY WITH THIS SYSTEM.
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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