705
FXUS10 KWNH 281832
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
231 PM EDT SAT SEP 28 2019
VALID SEP 28/1200 UTC THRU OCT 02/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..OVERALL PATTERN ACROSS THE CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND, LOWER WEIGHT ON 12Z GFS BY DAY 3
CONFIDENCE: ABOVE AVERAGE
---18Z UPDATE---
NO CHANGE TO THE PRELIMINARY PREFERENCE. THE PRIMARY DIFFERENCE
CONTINUES TO BE WITH LOWER HEIGHTS IN THE GFS AS COMPARED TO THE
OTHER GLOBAL MODELS FROM THE FOUR CORNERS INTO THE NORTHERN PLAINS
AFTER 30.18Z. THE 12Z NAM IS CLOSER TO THE OTHER GLOBAL MODELS
THAN THE GFS.
---PREVIOUS DISCUSSION---
MODELS CONTINUE TO SHOW VERY GOOD AGREEMENT ON THE SYNOPTIC
PATTERN OVER THE NEXT FEW DAYS, AS AN AMPLIFIED FLOW PATTERN
PERSISTS ACROSS THE CONUS. THESE TYPE OF PATTERNS TEND TO HAVE
BETTER PREDICTABILITY, AND MODEL SPREAD IN THIS CASE IS NOT
PARTICULARLY LARGE. THEREFORE, FORECAST CONFIDENCE IS HIGHER THAN
AVERAGE, AND A MULTI-MODEL BLEND IS THE PREFERENCE AT THIS TIME.
THE MOST NOTABLE DIFFERENCES ARE WITH THE POSITION OF THE TROUGH
AXIS IN THE WEST BY DAY 2-3 (MONDAY INTO TUESDAY). THE 12Z GFS AND
06Z GEFS ENSEMBLE MEMBERS TEND TO PUSH THE TROUGH FURTHER EAST
THAN THE CONSENSUS OF THE OTHER MODELS. THIS SEEMS TO BE PARTIALLY
DUE TO A WEAKER DEPICTION OF THE RIDGE IN THE SOUTHEAST, AND THUS
HEIGHT FALLS SPILL OUT INTO THE NORTHERN AND CENTRAL PLAINS AND
SOUTHERN ROCKIES FASTER IN THE GFS. GRADUALLY LESS WEIGHT WAS
PLACED ON THE GFS BY DAY 3, AND THE RESULTING BLEND PRODUCED
MID-UPPER LEVEL HEIGHT FIELDS VERY SIMILAR TO THE ECMWF ENSEMBLE
MEAN. THIS MAY LEAD TO SLIGHTLY SLOWER INITIATION OF CONVECTION
OVER THE PLAINS BY THE END OF THE PERIOD.
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML
LAMERS
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