926
FXUS10 KWNH 271953
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
352 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 MODEL EVALUATION INCLUDING FINAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...NORTHERN STREAM, UPPER LEVEL TROUGH TRACKING FROM THE NORTHERN
PLAINS TODAY TO THE GREAT LAKES ON FRIDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF/UKMET BLEND
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
12Z/00Z CMC IS NOT PREFERRED GIVEN ITS DIFFERENCES WITH HOW A
CLOSED LOW TO THE SOUTH MERGES INTO THE TROUGH AXIS PROGRESSING
THROUGH THE GREAT LAKES REGION. THE 12Z UKMET ADJUSTED TO THE
CONSISTENT ECMWF COMPARED TO THE PREVIOUSLY SLOWER 00Z UKMET.
SINCE THE ENSEMBLE MEANS SHOW GOOD AGREEMENT AND MATCH CLOSELY TO
THE 12Z ECMWF/UKMET, AND RUN TO RUN CONSISTENCY HAS BEEN FAIRLY
GOOD WITH THE ECMWF AND ITS ENSEMBLE MEAN, A PREFERENCE NEAR THE
12Z ECMWF AND SLIGHTLY SLOWER 12Z UKMET 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-12Z CMC BLEND
CONFIDENCE: ABOVE AVERAGE
ONLY THE 00Z CMC DIFFERS SIGNIFICANT WITH THIS SYSTEM AS IT IS
SLOWER TO BRING THE WEAKENING CLOSED LOW NORTHWARD TOWARD THE
CENTRAL APPALACHIANS. THE 12Z CMC TRENDED TOWARD THE CONSENSUS BUT
ONLY A LITTLE, SO THE PREFERENCE REMAINS FOR A NON-CMC BLEND. GOOD
SUPPORT EXISTS WITH THE REMAINING DETERMINISTIC AND ENSEMBLE
GUIDANCE TO SUPPORT A NON-12Z CMC BLEND.
..TROPICAL STORM BERTHA ALONG THE SOUTHEASTERN U.S. COAST
---
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z DETERMINISTIC BLEND IS CLOSE 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. THE
PREVIOUSLY SLOWER 00Z ECMWF/UKMET/CMC TRENDED TOWARD THE 12Z
NAM/GFS WITH THEIR 12Z CYCLES. CURRENTLY, A 12Z DETERMINISTIC
BLEND IS CLOSE TO THE 15Z NHC ADVISORY FOR BERTHA 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
12Z ECMWF/UKMET BLEND 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 ENDS UP SLOWER TO BRING THE LOW
INLAND ACROSS NORTHERN CA BY SATURDAY EVENING (00Z/31) AND THE 12Z
GFS PULLS AHEAD OF THE REMAINING GUIDANCE. THE 12Z ECMWF/UKMET
TRENDED IN THE DIRECTION OF THE FASTER 12Z GFS BUT NOT QUITE TO
ITS EXTENT. THE CMC REMAINS SIMILAR TO ITS PREVIOUS 00Z CYCLE WITH
A SLOWER TRANSLATION INLAND WITH THE SHORTWAVE. ENSEMBLE SUPPORT
AND TRENDS CONTINUE TO SUPPORT A MIDDLE GROUND, BUT RECENT TRENDS
INCLUDE A NUDGE IN THE DIRECTION OF THE FASTER GUIDANCE FOR THE
FINAL PREFERENCE NEAR THE 12Z ECMWF/UKMET. 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 AND NO SIGNIFICANT
DIFFERENCES WERE NOTED WITH THE 12Z ECMWF/UKMET/CMC COMPARED TO
THEIR PREVIOUS 00Z CYCLES.
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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