880
FXUS10 KWNH 270430
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1229 AM EDT SUN OCT 27 2019
VALID OCT 27/0000 UTC THRU OCT 30/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..TROUGH/CLOSED LOW CURRENTLY OVER THE OH VALLEY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE LATEST MODEL GUIDANCE SHOWS THE UPPER TROUGH AND ASSOCIATED
LOW CENTER OVER THE OH VALLEY CROSSING THROUGH THE LOWER GREAT
REGION EARLY SUNDAY. THE ENERGY THOUGH WILL BE ENCOUNTERING
INCREASINGLY CONFLUENT DOWNSTREAM FLOW ALOFT AND THE SYSTEM WILL
WEAKEN SUBSTANTIALLY LATE SUNDAY AS IT REACHES THE NORTHEAST. AS
THE ATTENDANT COLD FRONT REACHES THE EAST COAST, THE ORIGINAL LOW
CENTER WILL DAMPEN OUT IN FAVOR OF A NEW AREA OF CYCLOGENESIS NEAR
SOUTHERN NEW ENGLAND. THIS LOW CENTER WILL MOVE EAST AND OFFSHORE
MONDAY AS THE REMNANT ENERGY ALOFT SHIFTS EAST TOWARD THE WESTERN
ATLANTIC AND CONTINUES TO WEAKEN. ALL OF THE MODELS ARE IN GOOD
AGREEMENT NOW WITH THE DETAILS OF THE MASS FIELD EVOLUTION, AND SO
A GENERAL MODEL BLEND WILL BE PREFERRED.
..DEEP TROUGH DIGGING ACROSS THE INTERMOUNTAIN WEST/PLAINS
..CLOSED LOW EVOLUTION OVER THE FOUR CORNERS BY WEDNESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z UKMET/CMC/ECMWF
CONFIDENCE: ABOVE AVERAGE
A STRONG DEEP LAYER RIDGE OVER THE GULF OF AK THIS WEEKEND WILL
SHIFT TOWARD NORTHWEST CANADA EARLY NEXT WEEK WHICH WILL ALLOW
SHORTWAVE ENERGY TO DIG SOUTH ACROSS SOUTHWEST CANADA AND THEN
INTO INTERMOUNTAIN WEST AND HIGH PLAINS THROUGH THE PERIOD,
LEADING TO THE DEVELOPMENT OF A DEEP LONGWAVE TROUGH OVER THE
INTERMOUNTAIN WEST AND PLAINS BY TUESDAY. AS ADDITIONAL ENERGY
DIGS INTO THE BACKSIDE OF THE TROUGH ON WEDNESDAY, THERE SHOULD BE
A CLOSED LOW EVOLUTION THAT SETTLES DOWN TOWARD THE FOUR CORNERS
REGION. GRADUALLY THE 00Z NAM BECOMES A BIT STRONGER THAN ALL OF
THE GLOBAL MODELS AS THE CLOSED LOW EVOLUTION TAKES SHAPE. AND BY
THE END OF THE PERIOD, THE 00Z GFS BECOMES THE MOST PROGRESSIVE
SOLUTION IN PIVOTING THE ENERGY FARTHER EAST ACROSS CO, WHEREAS
THE REMAINING GUIDANCE HAS THE CLOSED LOW OVER UT. THE BETTER
MODEL CLUSTERING RESIDES WITH THE 12Z NON-NCEP GUIDANCE, SO A
BLEND OF THE UKMET, CMC AND ECMWF WILL BE PREFERRED WHICH IS
STRONGLY SUPPORTED BY THE LATEST GEFS MEAN AND ECENS MEAN.
..SHORTWAVE/CLIPPER LOW OVER MT/ND BY MONDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
AS THE HIGHLY AMPLIFIED DEEP LAYER FLOW PATTERN EVOLVES ACROSS
NORTH AMERICA EARLY NEXT WEEK, THE GUIDANCE FAVORS A VIGOROUS
SHORTWAVE/JET-STREAK DIVING SOUTHEAST TOWARD THE NORTHERN HIGH
PLAINS ON MONDAY WHICH WILL DRIVE A CLIPPER LOW AND REINFORCING
COLD FRONT SOUTHEAST ACROSS MT/ND. THE MODELS ARE IN GOOD
AGREEMENT WITH THIS FEATURE, SO A GENERAL MODEL BLEND WILL BE
PREFERRED.
..SURFACE COLD FRONT OVER THE LOWER/MID MS VALLEY BY TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z GFS/12Z ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
AS THE DEEP LONGWAVE TROUGH EJECTS OUT OVER THE PLAINS SUNDAY AND
MONDAY, A COLD FRONT WILL SETTLE WELL SOUTH AND EAST, AND WILL BE
APPROACHING THE LOWER/MIDDLE MS VALLEY REGION LATE MONDAY AND
TUESDAY. SOME INCREASE IN MODEL SPREAD WITH THE TIMING OF THE
FRONT AND THE DETAILS OF A WAVE OF LOW PRESSURE RIDING NORTHEAST
UP ALONG IT IS SEEN BY EARLY TUESDAY. MOST NOTABLY, THE 12Z UKMET
BECOMES THE SLOWEST SOLUTION WITH THE BOUNDARY AS IT CROSSES THE
MS VALLEY AND APPROACHES THE OH VALLEY. WITH RESPECT TO THE
FRONTAL WAVE, THE 00Z NAM IS MOST PROGRESSIVE WITH IT. IN GENERAL,
THE 00Z GFS AND 12Z ECMWF TEND TO CLUSTER TOGETHER RATHER WELL AND
HAVE FAVORABLE SUPPORT FROM THEIR RESPECTIVE ENSEMBLE SUITES, SO A
BLEND OF THE GFS AND ECMWF WILL BE PREFERRED FOR NOW.
..POTENTIAL DISTURBANCE IN THE GULF OF MEXICO EARLY NEXT WEEK
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-UKMET BLEND
CONFIDENCE: AVERAGE
THERE IS CURRENTLY AN AREA OF DISTURBED WEATHER SOUTH OF CUBA
WHICH SOME OF THE MODELS TRACK AROUND THE WESTERN SIDE OF THE
SUBTROPICAL ATLANTIC RIDGE AND INTO THE GULF OF MEXICO. THERE ARE
VARYING SOLUTIONS SEEN IN THE LATEST DETERMINISTIC GUIDANCE
THROUGH TUESDAY MORNING WITH THE 12Z UKMET THE MOST DEVELOPED.
HOWEVER, FOR NOW, THE PREFERENCE WILL BE FOR A NON-UKMET BLEND
WHICH DOWNPLAYS ANYTHING MORE ORGANIZED IN AGREEMENT WITH THE
LATEST THINKING FROM THE NHC.
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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