700
FXUS10 KWNH 271848
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
248 PM EDT SUN OCT 27 2019
VALID OCT 27/1200 UTC THRU OCT 31/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH FINAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...DEPARTING MID-LEVEL TROUGH CURRENTLY OVER SOUTHERN
ONTARIO/QUEBEC...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE LATEST MODEL GUIDANCE IS IN GOOD AGREEMENT WITH THE TRACK OF
THE NEGATIVELY TILTED SHORTWAVE OVER THE GREAT LAKES REGION ON 12Z
SUNDAY AND IT'S ASSOCIATED PARENT SURFACE LOW WEAKENING INTO
CANADA AS A SECONDARY LOW DEVELOPS NEAR THE COAST OF NEW ENGLAND
SUNDAY NIGHT. A GENERAL MODEL BLEND WILL BE PREFERRED. NO
SIGNIFICANT CHANGES WERE NOTED WITH THE 12Z ECMWF/UKMET/CMC
COMPARED TO THEIR PREVIOUS 00Z RUNS.
..MID-LEVEL TROUGH EJECTING INTO THE CENTRAL PLAINS ON MONDAY
..SURFACE COLD FRONT OVER THE LOWER/MID MS VALLEY BY TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
ALTHOUGH THERE REMAIN SOME MINOR TIMING DIFFERENCES WITH A
SHORTWAVE REACHING THE CENTRAL PLAINS FROM THE GREAT BASIN ON
MONDAY, THERE IS ENOUGH AGREEMENT TO SUPPORT A GENERAL MODEL
BLEND. OVERALL SPREAD IN THE DETERMINISTIC/ENSEMBLE GUIDANCE HAS
REDUCED ENOUGH TO WHERE ANY FUTURE ADJUSTMENTS SHOULD BE MINOR AND
WITHIN THE NOISE OF MODEL RUN TO RUN VARIABILITY. NO SIGNIFICANT
CHANGES WERE NOTED WITH THE 12Z ECMWF/UKMET/CMC COMPARED TO THEIR
PREVIOUS 00Z RUNS.
..SHORTWAVE/CLIPPER LOW OVER MT/ND BY MONDAY EVENING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
NO SIGNIFICANT DIFFERENCES EXIST WITH THIS SYSTEM AND RUN TO RUN
CONTINUITY HAS BEEN GOOD SO ABOVE AVERAGE CONFIDENCE EXISTS FOR A
GENERAL MODEL BLEND.
...POWERFUL CLOSED LOW IN THE INTERMOUNTAIN WEST TUESDAY INTO
WEDNESDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 12Z GFS BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
ENSEMBLE SPAGHETTI 552 DAM HEIGHTS AT 500 MB SHOW SHRINKING SPREAD
VALID WEDNESDAY OVER THEIR PAST 4 CYCLES (12Z/00Z ONLY). THE 12Z
GFS HOWEVER, JUMPED SIGNIFICANTLY EAST/FASTER WITH THIS SYSTEM AND
IS AN OUTLIER OUTSIDE OF THE LATEST ENSEMBLE ENVELOPE. NON 12Z GFS
SOLUTIONS ARE IN RELATIVELY GOOD AGREEMENT BUT THE 12Z
ECMWF/UKMET/CMC ALL NUDGED EAST TO SOME DEGREE VALID WEDNESDAY.
THIS MAKES THE 12Z NAM LIE A BIT TOWARD THE WESTERN SIDE OF THE
LATEST MODEL CLUSTERING. THE DEGREE OF SEPARATION BETWEEN THE
CLOSED LOW AND A NORTHERN STREAM PORTION NEAR HTE U.S.-CANADIAN
BORDER MAKES THE DIFFERENCE. AT THIS TIME, A 12Z ECMWF/UKMET/CMC
BLEND IN THE MIDDLE OF THE LATEST SPREAD WILL BE PREFERRED, WITH
THE 12Z NAM REMOVED.
..POTENTIAL DISTURBANCE IN THE GULF OF MEXICO EARLY NEXT WEEK
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
THERE IS CURRENTLY AN AREA OF DISTURBED WEATHER JUST EAST OF THE
YUCATAN PENINSULA WHICH SOME OF THE MODELS TRACK AROUND THE
WESTERN SIDE OF THE SUBTROPICAL ATLANTIC RIDGE AND INTO THE GULF
OF MEXICO. THE LATEST MODELS ARE IN SUFFICIENTLY GOOD ENOUGH
AGREEMENT HERE TO SUPPORT A GENERAL MODEL BLEND. NO SIGNIFICANT
CHANGES WERE NOTED WITH THE 12Z ECMWF/UKMET/CMC COMPARED TO THEIR
PREVIOUS 00Z RUNS.
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML
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