255
FXUS10 KWNH 241845
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
245 PM EDT SUN MAY 24 2020
VALID MAY 24/1200 UTC THRU MAY 28/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION INCLUDING FINAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SHORTWAVE TROUGH CROSSING THE GREAT LAKES THROUGH SUNDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: HIGH
A MID-LEVEL CROSSING THE NORTHERN GREAT LAKES THIS EVENING WILL BE
ADVANCING ACROSS NORTHERN NEW ENGLAND ON MONDAY ALONG THE NORTHERN
PERIPHERY OF THE BUILDING EAST COAST RIDGE. THE MODELS ARE IN
GOOD AGREEMENT WITH THIS SYSTEM, AND SO A GENERAL MODEL BLEND WILL
BE PREFERRED.
SHORTWAVE OVER THE NORTHERN PLAINS THROUGH MONDAY NIGHT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF/NAM/UKMET
CONFIDENCE: MODERATE-HIGH
A CLOSED LOW INITIALLY OVER WYOMING AND EASTERN MONTANA IS
FORECAST TO EVOLVE INTO AN OPEN WAVE AS IT REACHES THE WESTERN
DAKOTAS BY MONDAY AFTERNOON. BY TUESDAY THIS DISTURBANCE SHOULD
BECOME ABSORBED BY THE WESTERLIES ACROSS SOUTHERN CANADA. THE 12Z
GFS IS STRONGER AND A LITTLE FASTER WITH THE TROUGH AS IT CROSSES
THE DAKOTAS, AND THE CMC IS THE WEAKEST SOLUTION AND FARTHER EAST
WITH THE SURFACE LOW OVER THE UPPER MIDWEST. A BLEND OF THE 12Z
ECMWF/NAM/UKMET WORKS WELL AS A STARTING POINT IN THE FORECAST.
SYNOPTIC SCALE TROUGH OVER THE WEST EVOLVING INTO CLOSED LOW OVER
SOUTHERN PLAINS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF/GFS/GEFS MEAN/00Z EC MEAN
CONFIDENCE: MODERATE
A SYNOPTIC SCALE UPPER TROUGH INITIALLY OVER THE INTERMOUNTAIN
WEST IS FORECAST TO EMERGE OVER THE CENTRAL AND SOUTHERN PLAINS
OVER THE NEXT COUPLE OF DAYS, AND THEN EVOLVE INTO A CUT-OFF UPPER
LOW SITUATED OVER TEXAS AND OKLAHOMA BY THE MIDDLE OF THE WEEK.
THERE WILL BE A COUPLE OF SMALLER SHORTWAVES PIVOTING AROUND THE
SOUTHERN PERIPHERY OF THE TROUGH EMERGING FROM THE ROCKIES, AND
THESE WILL LIFT NORTHEASTWARD ACROSS THE SOUTHERN PLAINS AND SERVE
TO ENHANCE CONVECTION ACROSS THAT REGION. THE 12Z GFS IS MORE
AMPLIFIED WITH THESE SHORTWAVES AND IS ALSO STRONGER WITH THE
DEVELOPING CLOSED LOW OVER THE RED RIVER VALLEY. BY WEDNESDAY
MORNING, THE NAM IS FARTHER TO THE WEST WITH THE LOW COMPARED TO
THE OTHER MODELS, AND THE UKMET IS SLIGHTLY FARTHER SOUTH. BOTH
THE 12Z GFS AND ECMWF HAVE GOOD ENSEMBLE SUPPORT, AND THUS A BLEND
OF THESE MODELS ALONG WITH THEIR ENSEMBLE MEANS WILL SUFFICE.
MID-LEVEL TROUGH AND WEAK SURFACE LOW IMPACTING FLORIDA EARLY IN
THE WEEK
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z NAM/GFS/ECMWF BLEND
CONFIDENCE: MODERATE
AN UPPER LEVEL RIDGE WILL BE BUILDING ACROSS THE SOUTHEAST AND THE
EAST COAST THROUGH THE BEGINNING OF THE WEEK. SOUTH OF THE UPPER
RIDGE WILL BE A LOW-MID LEVEL TROUGH AXIS THAT WILL GRADUALLY LIFT
NORTHWARD TO THE EASTERN GULF OF MEXICO, WITH A WEAK SURFACE WAVE
OF LOW PRESSURE LIKELY DEVELOPING ALONG IT BY MONDAY. ALTHOUGH
THIS DOES NOT APPEAR PARTICULARLY IMPRESSIVE IN TERMS OF MASS
FIELDS, IT WILL BE SIGNIFICANT FOR QPF PURPOSES. THE 12Z UKMET
REMAINS A LITTLE MORE SUPPRESSED WITH THE 700 MB TROUGH ACROSS
CUBA AND THE FLORIDA STRAITS, AND THIS KEEPS THE HEAVIEST RAINFALL
FARTHER SOUTH THAN THE RELATIVELY WELL CLUSTERED NAM/GFS/ECMWF.
THE 12Z CMC, ALBEIT TO A LESSER DEGREE, ALSO APPEARS FARTHER SOUTH
WITH ITS QPF AXIS THROUGH DAY 2 ACROSS SOUTH FLORIDA. AN INITIAL
BLEND CONSISTING OF THE 12Z NAM/GFS/ECMWF SHOULD WORK WELL AND
MAINTAINS GOOD CONTINUITY WITH EARLIER PREFERENCES.
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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