940
FXUS10 KWNH 281841
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
240 PM EDT THU MAY 28 2020
VALID MAY 28/1200 UTC THRU JUN 01/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION INCLUDING FINAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...AMPLIFYING NORTHERN STREAM TROUGH ACROSS THE GREAT LAKES AND
NORTHEAST THROUGH SUNDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF/UKMET/CMC BLEND THROUGH 00Z/31, THEN A
GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
A NORTHERN STREAM, MID-LEVEL SHORTWAVE TROUGH INITIALLY OVER
SOUTH-CENTRAL CANADA AND THE UPPER MISSISSIPPI VALLEY IS FORECAST
TO AMPLIFY AND TRACK EAST INTO SATURDAY. AS ENERGY IN THE BASE OF
THIS TROUGH TRANSLATES EASTWARD, SOME TIMING DIFFERENCES DEVELOP
WITH THE 12Z GFS FASTEST AND 00Z CMC SLOWEST. THE 12Z CMC SPED UP
FROM ITS 00Z RUN AND THE 12Z ECMWF NUDGED ONLY SLIGHTLY FASTER.
MEANWHILE THE 12Z UKMET REMAINS SIMILAR WITH TIMING COMPARED TO
ITS PREVIOUS 00Z CYCLE. THE 12Z ECMWF/UKMET/CMC FIT THE TIMING OF
THE ENSEMBLE MEANS BEST WHILE THE 12Z NAM IS CLOSE BUT A SLIGHT
BIT SLOWER. THIS MID-LEVEL SHORTWAVE WILL QUICKLY BRUSH NORTHERN
NEW ENGLAND SATURDAY MORNING.
ON THE HEELS OF THE ADVANCING SHORTWAVE ACROSS THE NORTHEAST,
ADDITIONAL AMPLIFICATION OF A LONGWAVE TROUGH OVER THE EASTERN
HALF OF CANADA INTO THE GREAT LAKES AND NORTHEASTERN U.S. IS
EXPECTED. FROM SATURDAY NIGHT INTO SUNDAY NIGHT, A -1 TO -1.5
STANDARDIZED 500 MB HEIGHT ANOMALY WILL SET UP OVER THE NORTHERN
MID-ATLANTIC AND NORTHEAST IN ASSOCIATION WITH THE UPPER LEVEL
TROUGH. THIS IS GOOD MODEL AGREEMENT WITH THE DEPTH AND TIMING OF
THE TROUGH FOR THE LATTER HALF OF THE WEEKEND, RESULTING IN A
GENERAL MODEL BLEND FROM LATE SATURDAY THROUGH SUNDAY.
...CLOSED LOW OVER ARKANSAS AND MISSOURI THAT BECOMES ABSORBED BY
NORTHERN STREAM FLOW...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE 12Z MODELS SHOW SIMILARLY WITH THIS SYSTEM.
...CLOSED UPPER LEVEL LOW THAT REACHES NORTHERN MEXICO ON FRIDAY
AND BECOMES SLOW MOVING THROUGH THE WEEKEND...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
A COMPACT CLOSED UPPER LEVEL LOW, QUICKLY TRACKING SOUTH INTO THE
SOUTHERN HIGH PLAINS THIS AFTERNOON, IS EXPECTED TO REACH NORTHERN
MEXICO FRIDAY MORNING AND SLOW ITS MOVEMENT BEFORE BRIEFLY
STALLING THROUGH SATURDAY MORNING. A SLOW DRIFT OF THE 500-300 MB
UPPER LOW TOWARD THE SOUTH AND WEST ACROSS NORTH-CENTRAL MEXICO IS
FORECAST ON SUNDAY. WHILE THERE ARE SOME MINOR TIMING/PLACEMENT
DIFFERENCES AMONG THE 12Z DETERMINISTIC GUIDANCE, STRONGER TRENDS
IN THE 12Z UKMET/CMC ALLOWS FOR THEIR INCLUSION INTO A GENERAL
MODEL BLEND FOR THE PREFERENCE.
..POST-TROPICAL CYCLONE BERTHA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
ALL OF THE LATEST GUIDANCE IS IN GOOD AGREEMENT WITH TAKING THE
SURFACE LOW ASSOCIATED WITH BERTHA TOWARD THE NORTH INTO
SOUTHEASTERN QUEBEC LATE THURSDAY EVENING. DISSIPATION OF THE
REMNANT LOW IS FORECAST THROUGH FRIDAY MORNING AHEAD OF AN
APPROACHING COLD FRONT.
...SUBTROPICAL CLOSED LOW REACHING CENTRAL CALIFORNIA BY
SATURDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH SATURDAY MORNING, FOLLOWED
BY A 12Z NAM, 12Z GFS AND 12Z ECMWF BLEND
CONFIDENCE: AVERAGE
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 00Z UKMET SHOWS
MORE AMPLIFICATION WITH AN UPSTREAM TROUGH AXIS OVER THE EASTERN
PACIFIC, INTERACTING MORE WITH THE CA CLOSED LOW RESULTING IN A
MERGED TROUGH AXIS JUST WEST OF CA/OR LATE SATURDAY AFTERNOON AND
WEST OF THE MODEL CONSENSUS INTO SUNDAY MORNING. MEANWHILE,
THROUGH SATURDAY NIGHT, THE 00Z CMC SHOWS SLIGHTLY MORE SEPARATION
BETWEEN THE TWO FEATURES. WHILE SOME MINOR LONGITUDE DIFFERENCES
EXIST AMONG THE 12Z NAM AND THE 12Z GFS/00Z ECMWF, A BLEND OF
THESE 3 MODELS IS RECOMMENDED GIVEN THEIR AGREEMENT WITH ONE
ANOTHER AND THE LATEST ENSEMBLE GUIDANCE.
NO SIGNIFICANT CHANGES 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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