402
FXUS10 KWNH 120459
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1158 PM EST WED DEC 11 2019
VALID DEC 12/0000 UTC THRU DEC 15/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...SOUTHERN STREAM/SOUTHEAST TO MID ATLANTIC AND NORTHEAST SURFACE
LOW FRI-SUN...
PREFERENCE: 00 UTC GFS AND 12 UTC ECMWF/UKMET/CANADIAN BLEND
CONFIDENCE: AVERAGE
DETAILS WITH UPPER SUPPORT/IMPULSES SEEM SMALL SCALE AND NOISY,
WITH LARGER GUIDANCE VARIANCE MORE EVIDENT WITH SURFACE BASED
SYSTEM PROGRESSIONS/QPF INTO THE WEEKEND. THE 00 UTC NAM AND TO A
LESSER EXTENT THE 12 UTC GFS ARE FASTER TO LIFT NORTHWARD THE MAIN
EAST COAST COASTAL PLAIN LOW THAN THE 12 UTC ECMWF, UKMET, AND
CANADIAN. THE LATEST 18 UTC GEFS AND 12 UTC ECMWF ENSEMBLE LOW
CLUSTERS OFFER BETTER SUPPORT FOR THE SLOWER SOLUTIONS, BUT IT
WILL BE INTERESTING IF THE 00 UTC ENSEMBLES SPEED UP GIVEN THE
FAST UPSTREAM/POS-TILT FLOW DRIVING FLOW ALOFT AND SMALL
WAVELENGTH SPACING BETWEEN IMPULSES.
...NORTHERN STREAM SHORTWAVES ACROSS THE NORTHERN PLAINS TO THE
UPPER MS VALLEY AND UPPER GREAT LAKES...
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
PREFER A GENERAL MODEL BLEND WITH REASONABLY WELL CLUSTERED MODEL
AND ENSEMBLE SOLUTIONS DESPITE FAST FLOW WITH NUMEROUS EMBEDDED
SMALLER SCALE IMPUSLES AND SOME WEEKEND STREAM INTERACTIONS. A
COMPOSITE SEEMS REASONABLE AND OFFERS DECENT CONTINUITY GIVEN
COMPLEXITY.
..WEST/ROCKIES/PLAINS
PREFERENCE: 00 UTC GFS AND 12 UTC ECMWF COMPOSITE WITH MORE
WEIGHTING ON THE GFS
CONFIDENCE: SLIGHTLY BELOW AVERAGE
A STRONG DAY 1 SURGE OF PACIFC ENERGY BREACHING THE NORTHWEST
COAST SEEMS PRETTY WELL DEFINED IN SATELLITE AND GUIDANCE, WITH
LATEST BLENDED TPW LOOPS SHOWING A LONG FETCH MOISTURE CONNECTION
INTO THE TROPICAL PACIFIC. THE INLAND PROGRESSION OF ADDIONAL
PACIFIC SYSTEM ENERGY INTO CA AND THE SOUTHWEST OVER THE WEEKEND
LEADS TO MORE PRONOUNCED SURFACE DIFFERENCES WITH THE 12 UTC
ECMWF/CANADIAN/UKMET AND ECMWF ENSEMBLES SHOWING FASTER
PROGRESSION OVER THE WEST AND QUICKER TO DEVELOP SOUTHERN HIGH
PLAINS CYCLOGENESIS AND POST-FRONTAL HIGH PRESSURE SPILLAGE THAN
THE 00 UTC GFS/NAM AND 18 UTC GEFS. AT THIS POINT, THE 00 GFTS UTC
TREND FOR MORE AMPLITUDE/LESS PROGRESSION MAY BE REASONABLE GIVEN
UPSTREAM MID-UPPER LEVEL RIDGE AMPLITUDE, BUT SUGGEST HOLDING ONTO
SOME BLEND WITH THE 12 UTC ECMWF CONSIDERING FORECAST
SPREAD/UNCERTAINTY.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
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