959
FXUS10 KWNH 262113
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
512 PM EDT TUE MAY 26 2020
VALID MAY 26/1200 UTC THRU MAY 30/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION INCLUDING LATEST PREFERENCES AND
CONFIDENCE...UPDATED
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
OVERALL PATTERN ACROSS THE CONTINENTAL U.S.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH 12Z THURSDAY, THEN 12Z
GFS/UKMET/ECMWF BLEND
EXCEPTION: 12Z ECENS/GFS/NAM FOR SOUTHEAST U.S.
COASTAL LOW
CONFIDENCE: MODERATE-HIGH
THE OVERALL WEATHER PATTERN ACROSS THE NATION WILL BE FEATURED
WITH A LARGE TROUGH AND UPPER LOW SITUATED ACROSS THE PLAINS, AND
UPPER LEVEL RIDGE AXES ACROSS BOTH THE WEST COAST AND EAST COAST
TO BEGIN THE FORECAST PERIOD TUESDAY AFTERNOON. THE BROAD UPPER
LOW SLOW TRACKS TOWARDS THE EAST FROM NORTHERN TEXAS TO OVER
ARKANSAS BY THURSDAY, WITH THE BLOCK PATTERN PREVENTING THINGS
FROM BECOMING MORE PROGRESSIVE. MEANWHILE, 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 THE
DISTURBANCE OFF THE FLORIDA COAST WILL ALSO LIFT TOWARDS THE
NORTH. BY THE END OF THE FORECAST PERIOD, A WELL DEVELOPED UPPER
LOW APPROACHES CENTRAL AND SOUTHERN CALIFORNIA, WHICH WILL
EVENTUALLY BRING AN END TO THE CURRENT HEAT WAVE ACROSS MUCH OF
THE DESERT SOUTHWEST AND CALIFORNIA.
MODELS OVERALL ARE IN VERY GOOD AGREEMENT THROUGH ABOUT 12Z
THURSDAY NATIONWIDE, WITH SOME MINOR DIFFERENCES EMERGING BEYOND
THAT. THE 12Z NAM TENDS TO HOLD ONTO THE CLOSED LOW OVER THE
MID-SOUTH A LITTLE LONGER THAN THE REMAINING GUIDANCE, WHICH
FAVORS A QUICKER PROGRESSION TO AN OPEN WAVE THAT MERGES WITH THE
NORTHERN STREAM TROUGH. IT ALSO BECOMES STRONGER WITH THE
SHORTWAVE CROSSING THE GREAT LAKES. THE CMC IS NOTED AS SLIGHTLY
STRONGER WITH THE UPPER RIDGE ACROSS THE DESERT SOUTHWEST, BUT
OTHERWISE IN GOOD AGREEMENT WITH THE EVOLUTION ACROSS THE
EAST-CENTRAL U.S. MODEL AGREEMENT IS ABOVE AVERAGE WITH THE UPPER
LOW APPROACHING CALIFORNIA BY THE END OF THE WEEK, AND A
MULTI-DETERMINISTIC BLEND WILL WORK QUITE WELL FOR THAT REGION.
AND FOR THE DISTURBANCE NEAR THE EAST COAST, THE ECMWF BEGINS TO
STRAY MORE TOWARDS THE NORTHWEST WITH THE LOW ON WEDNESDAY ACROSS
GEORGIA, WHEREAS THE 12Z ECENS IS CLOSER TO THE MODEL CONSENSUS IN
KEEPING THE LOW CLOSER TO THE SOUTH CAROLINA COAST, BEFORE SLOWLY
DISSIPATING.
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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