389
FXUS10 KWNH 240450
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1250 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: BLEND OF THE 00Z NAM/12Z CMC AND 12Z ECMWF
CONFIDENCE: SLIGHTLY 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 00Z GFS IS A BIT OF A PROGRESSIVE
OUTLIER WITH THE SYSTEM, WHEREAS THE 12Z UKMET GRADUALLY BECOMES
THE SLOWEST SOLUTION. THE 00Z NAM, 12Z CMC AND 12Z ECMWF ALL
CLUSTER IN BETWEEN THE CAMPS, AND BETTER APPROXIMATE THE
MULTI-MODEL CONSENSUS, SO A BLEND OF THESE SOLUTIONS WILL BE
PREFERRED.
..AMPLIFYING TROUGH OVER THE SOUTHERN HIGH PLAINS
..CLOSED LOW EVOLUTION TOWARD THE LOWER MS VALLEY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z NAM/12Z CMC AND 12Z ECMWF
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 18Z GEFS MEAN. MEANWHILE, THE 12Z UKMET
GRADUALLY BECOMES A SLOWER AND MORE AMPLIFIED OUTLIER WITH THE
SYSTEM AS IT LINGERS WELL SOUTH OVER THE LOWER MS VALLEY. THE
UKMET ALSO SHOWS MUCH MORE INTERACTION WITH THE AREA OF DISTURBED
WEATHER OVER THE GULF OF MEXICO. THE 00Z NAM, 12Z CMC AND 12Z
ECMWF REFLECT BETTER MODEL CLUSTERING AND ENSEMBLE AGREEMENT, AND
THUS A BLEND OF THESE SOLUTIONS WILL BE PREFERRED ALBEIT WITH
SOMEWHAT LIMITED CONFIDENCE ON THE MASS FIELD FRONT.
..LOW PRESSURE DEVELOPMENT OVER THE GULF OF MEXICO
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z ECENS/18Z GEFS MEANS
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 12Z UKMET WHICH IS
AN OUTLIER WITH THE HEIGHT FALLS OVER THE LOWER MS VALLEY 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 LATITUDINAL SPREAD WITH WHERE THE
LOW IS CENTERED. THE 00Z GFS IS FARTHEST SOUTH BY SUNDAY, WHERE AS
THE 00Z NAM IS FARTHER NORTH. THE 12Z CMC/ECMWF SOLUTIONS ARE
ELONGATED WITH THE LOW IN BETWEEN THE NAM AND GFS CAMPS. 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. FOR NOW, WITH LOW CONFIDENCE ON THE MASS FIELD
DETAILS AT THE SURFACE, A BLEND OF THE 18Z GEFS AND 12Z ECENS
MEANS WILL BE PREFERRED.
..UPPER TROUGH DIGGING ACROSS THE INTERMOUNTAIN WEST BY SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z ECMWF/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 12Z 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 12Z UKMET APPEARS TO BE TOO
SLOW. A PREFERENCE TOWARD 12Z 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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