190
FXUS10 KWNH 281855
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
155 PM EST THU NOV 28 2019
VALID NOV 28/1200 UTC THRU DEC 02/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH FINAL PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..DEEP CLOSED LOW CROSSING THE INTERMOUNTAIN WEST/PLAINS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z NAM AND 12Z ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
..19Z UPDATE
ONLY MINOR CHANGES WERE NOTED WITH THE LATEST 12Z ECMWF/UKMET/CMC
COMPARED TO THEIR PREVIOUS 00Z CYCLES. THE 12Z ECMWF ADJUSTED
SLIGHTLY SOUTH WITH THE MID AND LOW-LEVEL LOW TRACKING ACROSS THE
MIDDLE OF THE NATION WHICH LOOKS OKAY GIVEN SOME OF THE MODEL
SPREAD NOTED BELOW. THE 12Z CMC IS REASONABLY CLOSE TO THE
PREFERRED NAM/ECMWF BLEND, BUT THE CMC ENDS UP A BIT FASTER THAN
THE DETERMINISTIC MODELS AS THE SYSTEM APPROACHES THE EAST COAST.
THE 12Z UKMET REMAINED WEAKER THAN IDEAL AND IS STILL NOT
PREFERRED.
..PREVIOUS DISCUSSION FOLLOWS
THE 12Z GFS HAS BEEN TRENDED TOWARD THE PREFERRED MODEL CONSENSUS,
BUT IT REMAINS STRONGER AND INITIALLY A BIT FARTHER WEST WITH ITS
LOW LEVEL LOW THAT FORMS IN THE CENTRAL HIGH PLAINS FRIDAY NIGHT.
THE RESULT IS FOR SIGNIFICANTLY WARMER AIR FROM THE GFS IN THE LOW
LEVELS TO BE DRAWN NORTHWARD INTO THE NORTH-CENTRAL U.S. FRIDAY
NIGHT THROUGH SATURDAY. THE ECMWF MEAN AS WELL AS THE ECMWF HAVE
BEEN FAIRLY CONSISTENT WITH SURFACE AND 850 MB LOW POSITIONS OVER
THEIR PAST 4 12/00Z CYCLES. THE STRENGTH OF THE 12Z NAM COULD BE A
BIT WEAK BUT WHEN BLENDED WITH THE STRONGER 00Z ECMWF, A FAVORABLE
BLEND IS REACHED. THIS BLEND APPLIES TO POSITION AS WELL WITH THE
00Z ECMWF'S SURFACE LOW A BIT TOWARD THE NORTH SIDE OF THE LATEST
MODEL SPREAD. THE 00Z UKMET APPEARS TOO WEAK WHILE THE 00Z CMC
POSITION IS OFF FROM THE PREFERRED CONSENSUS. THIS BLEND APPLIES
THROUGH SUNDAY EVENING AS THE STORM SYSTEM NEARS THE EAST COAST
WITH SECONDARY LOW DEVELOPMENT ALONG THE NORTHERN MID-ATLANTIC
COAST.
..UPPER LOW APPROACHING THE WEST COAST BY SUNDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z GFS AND 00/12Z ECMWF
CONFIDENCE: AVERAGE
..19Z UPDATE
DIFFERENCES REMAIN WITH THE INTERACTION OF A SMALLER REMNANT
CLOSED LOW OVER THE PACIFIC NORTHWEST ON SATURDAY AND AN
APPROACHING CLOSED LOW FROM THE EASTERN PACIFIC. THE ECMWF/UKMET
CAMP SHOWS TWO MAIN CIRCULATIONS BUT WITH A DOMINANT ONE TO THE
NORTH, WHILE THE 12Z NAM/GFS SHOW ONE CIRCULATION WITH THE LOBE OF
VORTICITY TO THE SOUTH MOVING MORE QUICKLY TOWARD THE COAST. A 12Z
GFS AND 00Z/12Z ECMWF BLEND REMAINS THE PREFERENCE GIVEN THE
BLENDS REPRESENTATION BETWEEN THE TWO CAMPS. ENSEMBLE SPREAD
REMAINS FAIRLY LARGE AT THIS POINT THROUGH SUNDAY.
..PREVIOUS DISCUSSION FOLLOWS
BY SUNDAY, A NEW CLOSED LOW WILL BE EVOLVING OFFSHORE OF THE WEST
COAST ALONG WITH LOW PRESSURE AT THE SURFACE. THE 00Z CMC AND 00Z
UKMET BOTH APPEAR TO BE A TAD TOO WEAK WITH THIS SYSTEM AS WELL AS
DISPLACED FROM THE FAVORABLE ENSEMBLE MEAN POSITIONS. THE 12Z NAM
APPEARS TO BE DISPLACED TOO FAR WEST ON SUNDAY WITH THE 00Z ECMWF
CLOSER TO THE COAST. THE 12Z GFS SPLITS THE DIFFERENCE BUT LIES
CLOSER TO THE NAM POSITION. THE GEFS AND ECMWF MEANS SUPPORT A
MIDDLE GROUND, BETWEEN THE 12Z GFS AND 00Z ECMWF CONCERNING THE
500 MB LOW. REGARDING COLD FRONTAL TIMING, THE 12Z NAM IS SLOWEST
WITH THE 00Z ECMWF TOWARD THE FASTER SIDE. A BLEND OF THE 00Z
ECMWF WITH THE SLIGHTLY SLOWER 12Z GFS IS PREFERRED OVER THE
SLOWER 12Z NAM GIVEN DIFFERENCES IN POSITION IN THE 700-500 MB
LOW.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
OTTO
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