113
FXUS10 KWNH 241725
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
125 PM EDT THU OCT 24 2019
VALID OCT 24/1200 UTC THRU OCT 28/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH LATEST PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...NORTHERN STREAM SHORTWAVE TROUGH PIVOTING ACROSS THE UPPER
MIDWEST-GREAT LAKES-NORTHEAST THU NIGHT-FRI NIGHT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
ANOTHER FAST-MOVING SHORTWAVE TROUGH CLIPPING THE NORTHERN PLAINS
THIS AFTERNOON 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 SOUTHERN STREAM TROUGH OVER THE SOUTHERN PLAINS TO
LOWER-MID MISSISSIPPI VALLEY THROUGH SAT...
...INITIALLY CLOSED MID/UPPER LOW EVOLVING TO AN OPEN TROUGH
ACROSS THE OHIO VALLEY-GREAT LAKES-NORTHERN NEW ENGLAND SAT NIGHT
AND SUN...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z ECMWF/ECENS MEAN
CONFIDENCE: SLIGHTLY BELOW AVERAGE
THE MODELS CONTINUE TO SHOW VERY GOOD AGREEMENT IN TAKING AN
AMPLIFYING SHORTWAVE CURRENTLY OVER THE SOUTHERN ROCKIES FARTHER
SOUTH ACROSS THE SOUTHERN PLAINS BY FRIDAY MORNING. SIGNIFICANT
MODEL DISAGREEMENTS THOUGH TAKE SHAPE THEREAFTER AS THE SYSTEM
CLOSES OFF AND PIVOTS NORTHEAST TOWARD THE MID MS VALLEY FRI NIGHT
AND SAT, WITH THE MODEL DIFFERENCES CONTINUING SAT NIGHT AND SUN
AS THE SYSTEM ENCOUNTERS MORE CONFLUENCE AND BECOMES AN OPEN
TROUGH ACROSS THE OH VALLEY-GREAT LAKES-NORTHERN NEW ENGLAND.
ALTHOUGH THE 12Z OPERATIONAL GFS HAS TRENDED SLOWER COMPARED TO
ITS PREVIOUS FEW RUNS WITH THE MID/UPPER TROUGH PROGRESSION OVER
THE WEEKEND (TOWARD THE 00Z GEFS MEAN), BOTH THE 12Z GFS AND 00Z
GEFS MEAN REMAIN ON THE FASTER EDGES OF THE GUIDANCE SPREAD.
MEANWHILE, THE 12Z NAM HAS ALSO TRENDED SLOWER WITH THE TROUGH
(CLOSER TO THE EC/ECENS MEAN), HOWEVER LIKE THE UKMET, MAINTAIN A
BIT MORE AMPLIFICATION BY 12Z SUN AS THE TROUGH REACHES THE UPPER
GREAT LAKES REGION.
THE 00Z UKMET MEANWHILE AGAIN APPEARS TO EXHIBIT MORE MORE
INTERACTION WITH THE AREA OF DISTURBED WEATHER OVER THE GULF OF
MEXICO. THE 00Z CMC MEANWHILE REMAINS A BIT SLOWER THAN THIS
CONSENSUS, AND BASED ON THE MODEL CLUSTERING AND ENSEMBLE
AGREEMENT, A BLEND OF THE 00Z ECMWF AND ECENS MEAN WILL BE
PREFERRED, THOUGH CONFIDENCE REMAINS BELOW AVERAGE CONSIDERING THE
GUIDANCE SPREAD.
..LOW PRESSURE DEVELOPMENT OVER THE GULF OF MEXICO
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z GFS/00Z ECMWF
CONFIDENCE: SLIGHTLY 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 THURSDAY NIGHT OVER THE BAY OF CAMPECHE BEFORE
THE SYSTEM LIKELY MERGES WITH A STRONG FRONT ENTERING THE WESTERN
GULF OF MEXICO. THE QUESTION WILL BE HOW QUICKLY THIS FEATURE WILL
BECOME ABSORBED INTO THE AFOREMENTIONED TROUGH OVER THE SOUTHERN
PLAINS AND LOWER-MID MS VALLEY ON SATURDAY -- AND WHETHER OR NOT
ANOTHER SURFACE LOW WILL BE LEFT BEHIND SOUTH OF THE MAIN UPPER
HEIGHT FALLS AND ALONG THE TAIL END OF THE SURFACE FRONT/LOW-LEVEL
BAROCLINIC ZONE. BOTH THE 12Z GFS AND 00Z ECMWF HAVE A SEPARATE
WEAK SURFACE LOW (1006-1010 MB) ALONG GULF COAST NEAR MOBILE AND
THE WESTERN FL PANHANDLE BY EARLY SUNDAY, WITH THE GFS A BIT
FASTER. BOTH OF THESE MODELS HAD PREVIOUSLY INDICATED A SURFACE
REFLECTION LINGERING IN THE GULF (IN ADDITION TO A SEPARATE
SURFACE LOW FARTHER INLAND ASSOCIATED WITH THE DEEPER COLD CORE
TROUGH), AND BOTH HAVE TRENDED MORE PROGRESSIVE WITH THE LOW
TRACK, THOUGH THE GFS WAS NOTABLY FASTER COMPARED TO THE 00Z RUNS.
FOR THE TIME BEING A BLEND BETWEEN THE 12Z GFS AND 00Z ECMWF WOULD
SEEM TO BE A GOOD COMPROMISE, WHICH WOULD MAINTAIN CONTINUITY FROM
THE PREVIOUS MODEL PREFERENCE. CONFIDENCE HOWEVER REMAINS BELOW
AVERAGE HERE, CONSIDERING THE LACK OF CONSENSUS AMONG THE OTHER
GUIDANCE.
...POSITIVELY TILTED UPPER TROUGH DIGGING ACROSS THE WESTERN CONUS
SAT-SUN...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z ECMWF/00Z CANADIAN/12Z UKMET
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 12Z NAM AND
GFS, ALONG WITH THE 00Z GEFS MEAN, REMAIN A TAD TOO PROGRESSIVE
COMPARED TO THE NON-NCEP MODEL CONSENSUS BY LATE SUN (00Z MON) --
THOUGH IT SHOULD BE NOTED THAT BOTH THE 12Z NAM AND GFS HAVE
TRENDED SLOWER TOWARD THE NON-NCEP CONSENSUS. AS SUCH, A NON-NCEP
MODEL CONSENSUS IS PREFERRED WITH THIS SYSTEM, ESPECIALLY BY
SUNDAY.
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML
HURLEY
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