603
FXUS10 KWNH 281848
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
247 PM EDT SAT MAR 28 2020
VALID MAR 28/1200 UTC THRU APR 1/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH FINAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
19Z UPDATE: THE 12Z CMC REMAINS MORE AMPLIFIED THAN THE MODEL
CONSENSUS WITH THE TROUGH CROSSING THE SOUTHERN TIER STATES, AND
THEN BECOMES SLOWER BY THE END OF THE FORECAST PERIOD TUESDAY
EVENING. WITH THE ARRIVAL OF THE LATEST UKMET, CMC, AND ECMWF,
THE NAM IS NOW THE MOST PROGRESSIVE SOLUTION ACROSS THE DEEP SOUTH
AND THE UKMET IS NOW A PART OF THE PREFERRED MODEL BLEND HERE.
THE UKMET HAS ALSO TRENDED CLOSER TO THE CONSENSUS WITH THE FRONT
APPROACHING THE PACIFIC NORTHWEST.
UPPER MIDWEST TO EAST COAST STORM SYSTEM
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM CONSENSUS AFTER 12Z MONDAY
CONFIDENCE: HIGH
THE CLOSED LOW CURRENTLY OVER THE CENTRAL PLAINS WILL CONTINUE
TRACKING TOWARDS THE GREAT LAKES REGION BY SUNDAY AFTERNOON, AND
THEN REACH NEW ENGLAND BY MONDAY NIGHT. SECONDARY CYCLOGENESIS IS
FORECAST NEAR THE NORTHEAST COAST BY MONDAY MORNING. THE MODELS
ARE IN GOOD AGREEMENT THROUGH MONDAY MORNING, AFTER WHICH THE 12Z
NAM BECOMES SLOWER WITH THE PROGRESSION OF THE PARENT UPPER LOW
AND SURFACE LOW ACROSS SOUTHERN ONTARIO AND NEW ENGLAND, AND ALSO
SLIGHTLY WEAKER. THE UKMET IS SLIGHTLY CLOSER TO THE COAST WITH
THE EVOLUTION OF THE COASTAL LOW, BUT STILL CLOSER ENOUGH TO BE
CONSIDERED PART OF THE MODEL BLEND AT THIS TIME.
SOUTHWEST SHORTWAVE SPURRING SOUTHERN PLAINS CYCLOGENESIS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z UKMET/12Z GFS/12Z ECMWF
CONFIDENCE: MODERATE
A SHORTWAVE TROUGH CURRENTLY NEAR CALIFORNIA WILL TRACK EASTWARD
ACROSS THE DESERT SOUTHWEST AND REACH THE CENTRAL/SOUTHERN PLAINS
BY MONDAY NIGHT. THIS WILL SPUR LEE CYCLOGENESIS OVER EASTERN NEW
MEXICO/COLORADO AND EVOLVE INTO AN ORGANIZED STORM SYSTEM ACROSS
THE SOUTHERN TIER OF THE NATION. THE UKMET BECOMES SLOWER AS
EARLY AS MONDAY MORNING ACROSS THE SOUTHWEST, AND THIS TREND
CONTINUES THROUGH THE REMAINDER OF THE FORECAST PERIOD. THE CMC
BECOMES MORE AMPLIFIED BY MONDAY NIGHT ACROSS THE SOUTHERN PLAINS
AND LIES OUTSIDE MUCH OF THE ENSEMBLE SPREAD. ALTHOUGH THERE ARE
MINOR DIFFERENCES AMONG THE NAM, GFS, AND ECMWF, THERE IS ENOUGH
OVERALL AGREEMENT IN THESE SOLUTIONS TO MERIT THIS BLEND AS A
STARTING POINT IN THE FORECAST PROCESS.
CLOSED LOW AND UPPER LEVEL TROUGH APPROACHING PACIFIC NORTHWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/12Z ECMWF/12Z UKMET
CONFIDENCE: MODERATE
A BROAD UPPER LEVEL GYRE DROPPING SOUTHEASTWARD FROM THE GULF OF
ALASKA WILL BRING HEIGHT FALLS TO MUCH OF THE NORTHWESTERN U.S. BY
MONDAY MORNING. THIS WILL RESULT IN THE PASSAGE OF A COLD FRONT
ACROSS THE PACIFIC NORTHWEST ON MONDAY. THE NAM IS FASTER WITH
THE ARRIVAL OF THE HEIGHT FALLS, AND THE UKMET IS SLIGHTLY SLOWER
WITH THE ARRIVAL OF THE COLD FRONT. CONFIDENCE IN THE EVOLUTION
IS SOLID, BUT INTERNAL CHANGES AND RUN-TO-RUN VARIATIONS ARE
LIKELY TO SUGGEST CONFIDENCE OVERALL IN THE BLEND IS AVERAGE TO
SLIGHTLY BELOW AVERAGE.
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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