979
FXUS10 KWNH 151900
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
159 PM EST FRI NOV 15 2019
VALID NOV 15/1200 UTC THRU NOV 19/0000 UTC
A..SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..UPPER LOW OVER THE SOUTHEAST
..EAST COAST COASTAL LOW EVOLUTION
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z HREF (MINUS NMMB) AND 00Z CMC/ECMWF BLEND < 36 HRS
12Z ECMWF/GEFS MEAN AND 00Z ECENS MEAN BLEND >36 HRS
CONFIDENCE: AVERAGE...BECOMING BELOW AVERAGE AFTER 36 HRS
AN UPPER LOW DEEPENING OVER THE SOUTHEAST WILL MOVE EAST AND
FOSTER MULTIPLE AREAS OF CYCLOGENESIS OFF THE SOUTHEAST COASTLINE
TONIGHT THROUGH EARLY SATURDAY. ALL OF THE MODELS STRONGLY SUPPORT
LOW PRESSURE BECOMING TUCKED IN RELATIVELY CLOSE SOUTHEAST NC
THROUGH THIS PERIOD, BUT THEREAFTER, THE 12Z NAM BECOMES AN
OUTLIER IN SUPPORTING LOW PRESSURE REMAINING FOCUSED IN CLOSER TO
SOUTHEAST NC. THE GLOBAL MODELS AND THE HIRES MODEL SUITE SUGGEST
THE INITIAL LOW CENTER DAMPENING OUT AND EVEN CYCLONICALLY LOOPING
AROUND A NEW AREA OF LOW PRESSURE DEVELOPING TO THE SOUTH ALONG
THE ATTENDANT FRONT OFF THE SOUTHEAST COASTLINE. OF THE GLOBAL
MODELS, THE 12Z UKMET FOCUSES ITS LOW PRESSURE EVOLUTION A BIT
FARTHER TO THE SOUTHWEST AND AWAY FROM THE MODEL CONSENSUS WHICH
EXTENDS OUT THROUGH 36 HOURS. MEANWHILE, THE 12Z GFS COLLECTIVELY
WITH ITS LOW CENTERS ENDS UP A BIT FARTHER EAST OF THIS CONSENSUS.
THE BETTER MODEL CLUSTERING THROUGH 36 HOURS IS WITH THE 00Z
CMC/ECMWF ALONG WITH THE 12Z ARW/ARW2 AND 12Z NAM-CONEST. THE 12Z
NMMB IS A NORTHERLY OUTLIER WITHIN THE HIRES MODEL SUITE.
AFTER 36 HOURS, AS LOW PRESSURE CONSOLIDATES OFF THE SOUTHERN
MID-ATLANTIC COASTLINE, THE 12Z GFS TAKES THE LOW CENTER NORTHWARD
AND TO THE EAST OF ALL OF THE AVAILABLE DETERMINISTIC GUIDANCE.
THE 12Z NAM, 12Z CMC AND 12Z UKMET END UP MUCH FARTHER WEST WITH A
MORE SIGNIFICANT IMPACT TO THE NORTHEAST AS THE LOW CENTER GETS
PULLED IN TOWARD THE COAST OR JUST OFFSHORE OF NEW ENGLAND. THIS
CLUSTER OF SOLUTIONS THAT TRACKS FARTHER WEST IS HIGHLY TIED INTO
THERE BEING MORE INTERACTION WITH THE UPSTREAM SHORTWAVE TROUGHING
THAT AMPLIFIES INTO THE OH/TN VALLEYS AND BECOMES NEGATIVELY
TILTED ACROSS THE CENTRAL/SOUTHERN APPALACHIANS LATER SUNDAY AND
INTO MONDAY. THIS RESULTS IN A BACKING OF THE LARGE SCALE FLOW
ACROSS THE NORTHEAST WHICH FORCES THE LOW TRACK FARTHER WEST. THE
12Z ECMWF ACTUALLY TRENDED A LITTLE FARTHER EAST WITH THIS LATEST
CYCLE AND IS ONLY A LITTLE WEST OF THE GFS SOLUTION. HOWEVER, THE
12Z GEFS MEAN AND 00Z ECENS MEAN ARE VERY CLOSE TO THE
DETERMINISTIC ECMWF AT THIS POINT. HAVING SAID THAT, THE 12Z CMCE
MEAN IS STRONGLY SUPPORTIVE OF A UKMET/CMC/NAM CONSENSUS. SO,
THERE REMAINS A DIVIDED CAMP WITH RESPECT TO THE SURFACE LOW
EVOLUTION OFF THE EAST COAST. THE PREFERENCE BEYOND 36 HOURS WILL
BE TO LEAN TOWARD A BLEND OF THE 12Z ECMWF/GEFS MEAN AND 00Z ECENS
MEAN AT THIS POINT, WITH BELOW AVERAGE CONFIDENCE.
..AMPLIFYING TROUGH ACROSS THE CENTRAL/EASTERN U.S
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND < 48 HRS
12Z ECMWF/GEFS MEAN AND 00Z ECENS MEAN BLEND > 48 HRS
CONFIDENCE: AVERAGE...BECOMING BELOW AVERAGE AFTER 48 HRS
A SHORTWAVE WILL DROP SOUTHEAST DOWN ACROSS THE INTERMOUNTAIN
REGION AND BEGIN TO AMPLIFY THROUGH SATURDAY. THIS ENERGY WILL
TRAVERSE THE PLAINS/MIDWEST THROUGH EARLY SUNDAY AND THEN BECOME
NEGATIVELY TILTED BY SUNDAY NIGHT AS IT CROSSES THE OH/TN VALLEYS.
SIGNIFICANT MODEL SPREAD EXISTS BY MONDAY AS THE ENERGY CROSSES
THE CENTRAL/SOUTHERN APPALACHIANS AND MID-ATLANTIC REGION, AS THE
12Z CMC/ECMWF SOLUTIONS ARE SLOWER THAN THE 12Z NAM/GFS/UKMET
SOLUTIONS. THERE IS SOME SUPPORT FOR THE SLOWER CONSENSUS FROM THE
00Z ECENS MEAN, 12Z GEFS MEAN, AND ESPECIALLY THE LATEST 12Z CMCE
MEAN. BASED ON THE LATEST ENSEMBLE GUIDANCE, AND DETERMINISTIC
TRENDS, A BLEND OF THE 12Z ECMWF/GEFS MEAN AND 00Z ECENS MEAN WILL
BE PREFERRED AFTER 48 HOURS, WITH A GENERAL MODEL BLEND SUFFICING
PRIOR TO THIS.
..CLOSED LOW DEVELOPMENT OFFSHORE SOUTHERN CALIFORNIA ON FRI
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-CMC BLEND
CONFIDENCE: AVERAGE
THE MODELS MAINTAIN THE IDEA OF A CLOSED LOW DEVELOPING AND
EVOLVING OFFSHORE SOUTHERN CA WITH THE LOW DROPPING SOUTH TO THE
WEST OF THE BAJA PENINSULA THROUGH THE WEEKEND. THIS SYSTEM WILL
HAVE AN INTERACTION WITH T.S. RAYMOND OVER THE EASTERN TROPICAL
PACIFIC AS ITS ENERGY AND MOISTURE WILL BE PULLED NORTH TOWARD THE
BAJA PENINSULA THROUGH THE PERIOD. THE 12Z CMC GRADUALLY BECOMES A
BIT OF A WESTERLY OUTLIER WITH THE EVOLUTION OF THE SYSTEM, SO A
NON-CMC BLEND WILL BE PREFERRED AT THIS TIME.
..UPPER TROUGH ARRIVING ACROSS THE PACIFIC NORTHWEST ON MON
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z UKMET/ECMWF
CONFIDENCE: AVERAGE
THE MODELS BRING A PROGRESSIVE SHORTWAVE TROUGH AND ASSOCIATED
SURFACE LOW IN TOWARD THE PACIFIC NORTHWEST ON MONDAY.. THE 12Z
NAM AND 12Z GFS ARE ON THE FASTER SIDE OF THE GUIDANCE, WITH THE
12Z CMC/ECMWF/UKMET SOLUTIONS SLOWER. OVERALL, THE CMC IS A SLOW
OUTLIER. THE LATEST ENSEMBLE SUITES TEND TO FAVOR A SOLUTION A
LITTLE SLOWER THAN THE FASTER DETERMINISTIC CONSENSUS WHICH
SUGGESTS A SOLUTION TOWARD A BLEND OF THE UKMET AND ECMWF WOULD
SUFFICE FOR NOW.
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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