816
FXUS10 KWNH 240644
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
243 AM EDT THU OCT 24 2019
VALID OCT 24/0000 UTC THRU OCT 27/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH LATEST PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..INITIAL TROUGH OVER THE UPPER MIDWEST/GREAT LAKES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
AN INITIAL UPPER TROUGH OVER THE UPPER MIDWEST WILL CROSS THE
GREAT LAKES REGION ON THURSDAY AND DAMPEN OUT BY FRIDAY AS THE
ENERGY SHEARS NORTHEAST INTO SOUTHEAST CANADA. THE MODELS ARE IN
VERY GOOD AGREEMENT ON THE DETAILS OF THIS SYSTEM, AND SO A
GENERAL MODEL BLEND WILL BE PREFERRED.
..SECONDARY TROUGH OVER THE UPPER MIDWEST/GREAT LAKES ON FRI
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
A SECONDARY SHORTWAVE TROUGH CLIPPING THE NORTHERN PLAINS BY LATER
THURSDAY WILL CROSS THE THE UPPER MIDWEST THURSDAY NIGHT AND CROSS
THROUGH THE GREAT LAKES ON FRIDAY, BEFORE THEN ADVANCING EAST OVER
THE NORTHEAST BY SATURDAY. THE LATEST GUIDANCE IS COLLECTIVELY IN
SUFFICIENTLY GOOD ENOUGH AGREEMENT THAT A GENERAL MODEL BLEND CAN
BE PREFERRED.
..AMPLIFYING TROUGH OVER THE SOUTHERN HIGH PLAINS
..CLOSED LOW EVOLUTION TOWARD THE LOWER MS VALLEY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z NAM/ECMWF/GEFS MEAN
CONFIDENCE: SLIGHTLY BELOW AVERAGE
THE MODELS SHOW VERY GOOD AGREEMENT IN TAKING AN AMPLIFYING
SHORTWAVE CURRENTLY OVER CO FARTHER SOUTH DOWN ACROSS THE SOUTHERN
HIGH PLAINS THROUGH THURSDAY AND THEN GRADUALLY EAST ACROSS THE
BROADER SOUTHERN PLAINS ON FRIDAY. SIGNIFICANT MODEL DISAGREEMENTS
THOUGH TAKE SHAPE THIS WEEKEND THOUGH AS THE SYSTEM CLOSES OFF AND
ADVANCES EAST TOWARD THE LOWER MS VALLEY AND THEN NORTHEAST TOWARD
THE OH/TN VALLEY REGION. AFTER ABOUT 48 HOURS, THE 00Z GFS BECOMES
A PROGRESSIVE OUTLIER WITH THE HEIGHT FALLS AND IS NOTABLY MORE
PROGRESSIVE THAN EVEN THE 00Z GEFS MEAN. MEANWHILE, THE 00Z UKMET
GRADUALLY BECOMES A SLOWER AND MORE AMPLIFIED OUTLIER WITH THE
SYSTEM. THE UKMET ALSO SHOWS MUCH MORE INTERACTION WITH THE AREA
OF DISTURBED WEATHER OVER THE GULF OF MEXICO. THE 00Z NAM IS
RATHER CLOSE TO THE 00Z ECMWF, AND BOTH OF THESE MODELS ARE
STRONGLY SUPPORTED BY THE 00Z GEFS MEAN. THE 00Z CMC IS A BIT
SLOWER THAN THIS CONSENSUS, AND BASED ON THE MODEL CLUSTERING AND
ENSEMBLE AGREEMENT, A BLEND OF THE NAM/ECMWF AND GEFS MEAN WILL BE
PREFERRED, BUT AGAIN WITH SOMEWHAT LIMITED CONFIDENCE ON THE MASS
FIELD FRONT.
..LOW PRESSURE DEVELOPMENT OVER THE GULF OF MEXICO
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z GEFS/12Z ECENS MEAN
CONFIDENCE: BELOW AVERAGE
THE LATEST SATELLITE IMAGERY CONFIRMS AN AREA OF DISTURBED WEATHER
OVER THE BAY OF CAMPECHE WHICH THE MODELS UNANIMOUSLY DEPICT
LIFTING NORTH ACROSS THE WESTERN AND THEN NORTH-CENTRAL GULF OF
MEXICO OVER THE NEXT FEW DAYS. THERE IS SUBSTANTIAL SUPPORT AMONG
THE DETERMINISTIC GLOBAL AND HIRES MODEL SUITES FOR A LOW PRESSURE
CENTER TO DEVELOP EITHER THURSDAY NIGHT OR EARLY FRIDAY OVER THE
BAY OF CAMPECHE BEFORE THE SYSTEM LIKELY MERGES WITH A STRONG
FRONT ENTERING THE WESTERN GULF OF MEXICO. THE 00Z UKMET, WHICH IS
AN OUTLIER SOLUTION WITH THE HEIGHT FALLS OVER THE LOWER MS VALLEY
BY SATURDAY, SUGGESTS THE LOW CENTER GETS PICKED UP BY THE
AMPLIFYING TROUGH AND DEEPENS AS AN EXTRATROPICAL CYCLONE ACROSS
PORTIONS OF THE CENTRAL GULF COAST STATES THIS WEEKEND. THE
CONSENSUS OF THE REMAINING DETERMINISTIC GUIDANCE SUGGESTS A LOW
CENTER GETS LEFT ALONG THE FRONT ACROSS THE CENTRAL GULF OF MEXICO
BY SUNDAY AS THE UPPER TROUGH OVER THE LOWER MS VALLEYS LIFTS WELL
NORTHEAST ACROSS THE OH/TN VALLEYS, ALTHOUGH THERE IS SUBSTANTIAL
LATITUDINAL SPREAD WITH WHERE THE LOW IS CENTERED AMONG THE
VARIOUS MODELS. THE 00Z GFS IS FARTHEST SOUTH BY SUNDAY, WITH A
LOW NORTHWEST OF THE YUCATAN PENINSULA WHEREAS THE 00Z CMC IS MUCH
FARTHER OFF TO THE NORTHEAST AND INLAND BY SUNDAY OVER THE
SOUTHEAST. THE 00Z NAM AND ECMWF ARE BOTH SLOWER THAN THE CMC, BUT
WELL NORTH OF THE GFS. THE GEFS AND ECENS SUITES OVERALL SUPPORT
AT LEAST A WEAK LOW CENTER IN THE VICINITY OF THE CENTRAL GULF OF
MEXICO BY SUNDAY, BUT THERE ARE A NUMBER OF GEFS MEMBERS THAT
ACTUALLY SUPPORT A SEPARATE LOW CENTER DEVELOPING OVER THE
NORTHWEST GULF OF MEXICO BY LATE FRIDAY ALONG THE AFOREMENTIONED
FRONT THAT THEN IMPACTS SOUTH-CENTRAL LA BY SATURDAY. SO, IN
ESSENCE, THERE IS GEFS SUPPORT FOR THREE LOW CENTERS, WITH ONE
OVER THE BAY OF CAMPECHE, ONE OVER THE NORTHWEST GULF OF MEXICO
AND ONE FARTHER NORTH OVER THE LOWER MS VALLEY BY EARLY SATURDAY.
GIVEN THE HIGHLY UNCERTAIN EVOLUTION OF THIS LOW CENTER AND DEGREE
OF MODEL SPREAD, A BLEND OF THE 00Z GEFS AND 12Z ECENS MEANS WILL
BE PREFERRED.
..UPPER TROUGH DIGGING ACROSS THE INTERMOUNTAIN WEST BY SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z ECMWF/12Z ECENS MEAN
CONFIDENCE: AVERAGE
A STRONG DEEP LAYER RIDGE IS FORECAST TO EVOLVE OVER THE GULF OF
AK THIS WEEKEND WHICH WILL ALLOW SHORTWAVE ENERGY TO DIG SOUTH
ACROSS SOUTHWEST CANADA AND THEN INTO INTERMOUNTAIN WEST AND
NORTHERN PLAINS BY SUNDAY. THERE IS SUPPORT FOR SOME STREAM
SEPARATION OVER THE INTERMOUNTAIN WEST BY SUNDAY WHICH IS MORE
STRONGLY SUPPORTED BY THE 00Z NON-NCEP MODELS. THE 00Z NAM AND 00Z
GFS BOTH APPEAR TO BE GENERALLY A TAD TOO PROGRESSIVE. THERE IS A
BIT BETTER ENSEMBLE SUPPORT OVERALL FOR A SLIGHTLY SLOWER
EVOLUTION OF THE ENERGY, ALTHOUGH THE 00Z UKMET APPEARS TO BE TOO
SLOW. A PREFERENCE TOWARD 00Z ECMWF AND 12Z ECENS MEAN WILL BE
PREFERRED WHICH OVERALL BETTER FITS THE MODEL CONSENSUS.
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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