792
FXUS10 KWNH 260411
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1210 AM EDT SAT OCT 26 2019
VALID OCT 26/0000 UTC THRU OCT 29/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..SHORTWAVE TROUGH CROSSING THE NORTHEAST ON SATURDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
A SHORTWAVE TROUGH CURRENTLY CLIPPING THE GREAT LAKES WILL ADVANCE
EAST ACROSS THE NORTHEAST EARLY SATURDAY MORNING AND THEN EXIT
THROUGH THE CANADIAN MARITIMES LATE IN THE DAY. ANY MODEL
DIFFERENCES WITH THIS SYSTEM ARE MINOR AND THEREFORE A GENERAL
MODEL BLEND WILL BE PREFERRED.
..AMPLIFIED TROUGH/CLOSED LOW LIFTING TOWARD THE OH VALLEY
..POST T.C. OLGA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-UKMET BLEND
CONFIDENCE: ABOVE AVERAGE
EFFECTIVE AT 03Z, T.S. OLGA HAS MERGED WITH THE STRONG COLD FRONT
ADVANCING EAST ACROSS THE LOWER MS VALLEY AND IS NOW AN
EXTRATROPICAL CYCLONE POSITIONED 170 MILES SOUTH-SOUTHEAST OF LAKE
CHARLES, LA. THE LATEST MODEL GUIDANCE SHOWS THE LOW CENTER
LIFTING NORTHEAST AND INLAND BY EARLY SATURDAY MORNING OVER
SOUTH-CENTRAL LA WITH THE SYSTEM THEN RAPIDLY LIFTING
NORTH-NORTHEAST TOWARD THE OH VALLEY LATER IN THE AFTERNOON AND
ACROSS THE LOWER GREAT LAKES REGION BY EARLY SUNDAY. THE
SUPPORTING UPPER TROUGH WILL BE ENCOUNTERING INCREASINGLY
CONFLUENT DOWNSTREAM FLOW ALOFT WITH TIME AND THE SYSTEM WILL
WEAKEN SUBSTANTIALLY LATE SUNDAY AS IT REACHES THE NORTHEAST. AS
THE ATTENDANT COLD FRONT REACHES THE EAST COAST LATE SUNDAY, 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 GENERALLY SHOW GOOD AGREEMENT AT THIS POINT WITH THE MASS
FIELD DETAILS, ALTHOUGH THE 12Z UKMET IS SEEN AS BEING STILL A TAD
TOO SLOW WITH ITS HEIGHT FALLS AND SURFACE LOW EVOLUTION, SO A
NON-UKMET BLEND WILL BE PREFERRED.
..DEEP TROUGH DIGGING ACROSS THE INTERMOUNTAIN WEST/PLAINS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 18Z GEFS/00Z ECENS MEAN
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
A STRONG DEEP LAYER RIDGE IS FORECAST TO EVOLVE OVER THE GULF OF
AK THIS WEEKEND AND 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. THE 12Z CMC AND 12Z
UKMET ARE BOTH A LITTLE SLOWER THAN THE 00Z NAM/GFS AND 12Z ECMWF
WITH THE INITIAL SURGE OF ENERGY THAT PIVOTS ACROSS THE FOUR
CORNERS REGION SUNDAY THROUGH MONDAY. THE LATEST GEFS MEAN AND
ECENS MEAN SUPPORT A SOLUTION TOWARD THE MODESTLY MORE PROGRESSIVE
CAMP. TOWARD THE END OF THE PERIOD WITH THE DETAILS OF THE
LONGWAVE TROUGH, THE NAM APPEARS TO BE PERHAPS SLIGHTLY TOO DEEP
OVER THE ROCKIES AND IMMEDIATE HIGH PLAINS WITH THE ENERGY. THE
GLOBAL MODELS DO NOT DIFFER SUBSTANTIALLY, BUT AT THIS POINT, A
SIMPLE BLEND OF THE LATEST GEFS MEAN AND ECENS MEAN WILL BE
PREFERRED.
..SHORTWAVE/CLIPPER LOW OVER MT/ND BY MONDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: 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 GUIDANCE IS IN GOOD
AGREEMENT WITH THE DETAILS OF THIS SYSTEM AND SO A GENERAL MODEL
BLEND WILL BE PREFERRED.
..SURFACE COLD FRONT OVER THE LOWER/MID MS VALLEY BY TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 18Z GEFS/00Z ECENS MEAN
CONFIDENCE: 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. SPREAD INCREASES WITH THE TIMING OF THE FRONT AS THE 00Z
GFS BECOMES MORE PROGRESSIVE THAN THE REMAINING GUIDANCE.
MEANWHILE, THE 12Z UKMET BECOMES THE SLOWEST. THERE IS ALSO SOME
SUPPORT FOR A WEAK WAVE OF LOW PRESSURE TO DEVELOP ALONG THE FRONT
AND LIFT UP ACROSS THE GREAT LAKES REGION BY THE END OF THE
PERIOD. THE 12Z ECMWF IS THE STRONGEST SOLUTION WITH THIS FEATURE
AND OVERALL IS AN OUTLIER. THE BETTER MODEL CLUSTERING WITH THE
SURFACE FRONT AND THE SURFACE WAVE IS WITH THE LATEST GEFS MEAN
AND ECENS MEAN, SO A BLEND OF THESE SOLUTIONS WILL BE PREFERRED.
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML
ORRISON
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